ORCID Profile
0000-0003-3803-8429
Current Organisations
University of Adelaide
,
South Australian Health and Medical Research Institute
,
Royal Adelaide Hospital
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Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2016
DOI: 10.1161/CIRCEP.116.004050
Abstract: In ventricular scar, impulse spread is slow because it traverses split and zigzag channels of surviving muscle. We aimed to evaluate scar electrograms to determine their local delay (activation time) and inequality in voltage splitting (entropy), and their relationship to channels. We reasoned that unlike innocuous channels, which are often short with multiple side branches, ventricular tachycardia (VT) supporting channels have very slow impulse spread and possess low entropy because of their longer protected length and relative lack of side-branching. Patients with ischemic cardiomyopathy and multiple VT were studied. In initial mapping stage (16 patients and 58 VTs), left ventricular endocardial mapping was performed in sinus rhythm. Detailed pace mapping was used to identify VT channels and confirmed, when feasible, by entrainment. Scar electrograms were analyzed in time and voltage domains to determine mean activation time, dispersion in activation time, and entropy. Predictive performances of these properties to detect VT channels were tested. In the application stage (7 patients and 20 VTs), these properties were prospectively tested to guide catheter ablation. A mean number of 763±203 s ling points were taken. From 1770 pace maps, 47 channels corresponded to VTs. A combination of scar electrograms with the latest mean activation time and minimum entropy, in a high activation dispersion region, accurately recognized regions containing VT channels (κ=0.89, sensitivity=86%, specificity=100%, positive predictive value=93%, and negative predictive value=100%). Finally, focused ablation within 5-mm rim of the prospective channel regions eliminated 18 of 20 inducible VTs. Activation time and entropy mapping in the scar accurately identify VT channels during sinus rhythm. The method integrates principles of reentry formation to recognize VT channels without pace mapping or mapping during VT.
Publisher: Wiley
Date: 24-11-2008
DOI: 10.1111/J.1540-8167.2008.01253.X
Abstract: Sites of complex fractionated atrial electrograms (CFAE) and dominant frequency (DF) have been implicated in maintaining atrial fibrillation (AF) however, their relationship is poorly understood. Twenty patients underwent biatrial high-density contact mapping (507 +/- 150 points atient) during AF. CFAE were characterized using software to quantify electrogram complexity (CFE-mean). Spectral analysis determined the frequency with greatest power and sites of high DF with a frequency gradient. CFE-mean was higher (less fractionated) for right compared with left atria (P < 0.001) and in paroxysmal compared with persistent AF (P < 0.001). DF was lower for right compared with left atria (P = 0.02) and in paroxysmal compared with persistent AF (P < 0.001). There was significant regional variation in DF in paroxysmal (P < 0.001) but not persistent AF. Highest DF points clustered together with 5.2 +/- 1.7 clusters atient. Correlation between CFE-mean and DF was poor on a point-by-point basis (r =-0.17, P < 0.001), but moderate on an in idual basis (r =-0.50, P = 0.03). Exploration of their spatial relationship demonstrated CFAE areas in close proximity (median 5 mm, IQR 2-10) to high DF sites within 10 mm in 80% and 10-20 mm in 10%. Simultaneous activation mapping at these sites further supports this observation. Greater fractionation and higher DF are seen in persistent AF and left atria during AF. Preferential areas of high DF are observed in paroxysmal but not persistent AF. CFAE and DF correlate within an in idual but not point-by-point. Exploration of their spatial relationship demonstrates CFAE in areas adjacent to high DF, and this is supported by activation mapping at these sites.
Publisher: IOP Publishing
Date: 12-03-2010
DOI: 10.1088/0967-3334/31/4/007
Abstract: The left atrium is a complex chamber, which plays an integral role in the maintenance of physiologic hemodynamic and electrical stability of the heart and is involved in many disease states, most commonly atrial fibrillation. Preserving regions of the left atrium that contribute the greatest to atrial mechanical function during curative strategies for atrial fibrillation are important. We present here a new application of the CARTO electroanatomical mapping system in the assessment of the left atria mechanical function. Electroanatomical data were collected in course of the electrophysiological procedure in 11 control patients and 12 patients with paroxysmal atrial fibrillation. The three-dimensional geometry of the left atria was reconstructed in 10 ms intervals and segmented into distinct regions. For each segment, a regional ejection fraction was calculated. We found that anterior, septal and lateral segments have significantly greater regional ejection fraction than atria roof, inferior and posterior segments. Therefore, we hypothesize that in order to minimize the impact on atrial mechanical function, an important determinant of thromboembolic risk, damage should be minimized to these atrial regions.
Publisher: Wiley
Date: 06-2020
DOI: 10.1111/IMJ.14855
Publisher: Elsevier BV
Date: 10-2012
Publisher: Springer Science and Business Media LLC
Date: 30-05-2019
Publisher: Springer Science and Business Media LLC
Date: 07-10-2013
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.JACEP.2019.08.016
Abstract: The goal of this study was to describe functional endocardial-epicardial dissociation (FEED), signal complexities, and three-dimensional activation dynamics of the human atrium with structural heart disease (SHD). SHD commonly predisposes to arrhythmias. Although progressive remodeling is implicated, direct demonstration of FEED in the human atrium has not been reported previously. Simultaneous intraoperative mapping of the endocardial and epicardial lateral right atrial wall was performed by using 2 high-density grid catheters during sinus rhythm, pacing drive (600 ms and 400 ms cycle length), and premature extrastimulation (PES). Unipolar electrograms (EGMs) were exported into custom-made software for activation and phase mapping. Difference of ≥20 ms between paired endocardial and epicardial electrodes defined dissociation. EGMs with ≥3 deflections were classified as fractionated. Sixteen patients (mean age 60.5 ± 4.1 years 18.7% with a history of atrial fibrillation) with SHD (43% ischemia, 57% valvular disease) were included. A total of 9,218 EGMs were analyzed. Compared with sinus rhythm, phase and activation analyses showed significant FEED during pacing at 600 ms and 400 ms (phase mapping 22.4% vs. 10% [p < 0.0001] and 25.8% vs. 10% [p < 0.0001], respectively activation mapping 25.4% vs. 7.8% [p < 0.0001] and 27.7% vs. 7.8% [p < 0.0001]) and PES (phase mapping 34% vs. 10% [p < 0.0001] activation mapping 29.5% vs. 7.8% [p < 0.0001]). Fractionated EGMs occurred significantly more during PES compared with sinus rhythm (50.2% vs. 39.5% p < 0.0001). Activation patterns differed significantly during pacing drive and PES, with preferential epicardial exit during the latter (15.9% vs. 13.8% p = 0.046). Simultaneous endocardial-epicardial mapping revealed significant FEED with signal fractionation and preferential epicardial breakthroughs with PES. Such complex three-dimensional interaction in electrical activation provides mechanistic insights into atrial arrhythmogenesis with SHD.
Publisher: Elsevier BV
Date: 11-2018
DOI: 10.1016/J.IJCARD.2018.04.076
Abstract: Sleep disordered breathing (SDB) is highly prevalent in patients with atrial fibrillation, heart failure and hypertension and is associated with increased risk of mortality, cardiovascular (CV) events and arrhythmias. Current assessment of the severity of SDB is mainly based on the apnea-hypopnea index (AHI) representing the number of hypopneas and apneas per hour of sleep. However, this event-based parameter alone may not sufficiently reflect the complex pathophysiological mechanisms underlying SDB potentially contributing to CV outcome risk. In this review article, we highlight important limitations and pitfalls of current assessment, quantification and interpretation of SDB-severity in patients with CV disease and will discuss pathophysiological considerations from preclinical and clinical mechanistic studies and possible clinical implications.
Publisher: Oxford University Press (OUP)
Date: 20-07-2017
Publisher: American Medical Association (AMA)
Date: 10-12-2012
Publisher: Massachusetts Medical Society
Date: 02-12-2004
DOI: 10.1056/NEJMOA041018
Publisher: Oxford University Press (OUP)
Date: 18-03-2019
Publisher: Elsevier BV
Date: 11-2018
Publisher: Elsevier BV
Date: 1997
DOI: 10.1016/S0167-8140(96)01858-0
Abstract: Between 1979 and 1989, 48 cases of extradural spinal cord and cauda equina compression in patients with lymphoma (24) and myeloma (24) received local radiation therapy for control of cord compression. Twenty five (52%) of the cases were treated by surgical decompression prior to irradiation. Thirty five (73%) of the cases received chemotherapy following the diagnosis of spinal cord compression. Post-treatment outcome was assessed at a minimum follow-up of 24 months to determine the significant clinical and treatment factors following irradiation. Seventeen (71%) of the lymphoma and 15 (63%) of the myeloma patients achieved local control, here defined as improvement to, or maintenance of ambulation with minimal or no assistance for 3 months from the start of radiotherapy. At a median follow-up of 30 (2-98) for the lymphoma and 10 (1-87) months for the myeloma patients, the results showed that survival following local radiation therapy for cord compression was independently influenced by the underlying disease type in favour of lymphoma compared to myeloma (P < 0.01). The median duration of local control and survival figures were 23 and 48 months for the lymphomas compared to 4.5 and 10 months for the myeloma cases. Survival was also independently influenced by preservation of sphincter function at initial presentation (P < 0.02) and the achievement of local control following treatment (P < 0.01). We conclude that while disease type independently impacts on outcome following treatment of spinal cord compression in lymphoma and myeloma, within both of these disease types the achievement of local control of spinal cord compression is an important management priority, for without local control survival may be adversely affected.
Publisher: BMJ
Date: 20-06-2018
Publisher: Elsevier BV
Date: 05-2004
Publisher: Springer Science and Business Media LLC
Date: 19-01-2019
DOI: 10.1007/S10840-019-00508-Z
Abstract: The role of the autonomic nervous system in the genesis of atrial fibrillation (AF) has been well studied however, the converse remains poorly understood. Pulmonary veins (PV) contain receptors important in cardiac reflexes. Here, we evaluated reflex responses in patients with paroxysmal AF (PAF) to lower body negative pressure (LBNP). Thirty-four PAF patients (including 14 PAF patients post successful PV Isolation PVI) were compared to 14 age and sex-matched controls. Mean arterial pressure (MAP), heart rate (HR), systemic vascular resistance index (SVRI), cardiac index (CI), and stroke volume index (SVI) were measured continuously during - 0, - 20, and - 40 mmHg LBNP. LBNP reduces venous return, deactivating atrial receptors, thereby eliciting a reflex increase in SVRI to maintain MAP. AF patients have higher BMI than the controls (p = 0.02). In control subjects, LBNP did not alter MAP as SVRI increased. In PAF patients, LBNP resulted in a reduction in MAP (- 4.8%) with attenuated SVRI response (+ 4.2%) compared to controls (p < 0.05). However, in the post-PVI group, SVRI increase was similar to controls (p = 0.12) although that was insufficient to maintain MAP. In all patients, both reduction in SVI and CI and increase in HR were similar in response to LBNP. This study provides novel clinical evidence of autonomic dysfunction in PAF patients. Successful PVI results in partial recovery of the cardiac reflex. Therefore, not only does autonomic disturbance predispose to AF but it is also a consequence of AF potentially contributing to disease progression. This could help explain the dictum "AF begets AF."
Publisher: Elsevier BV
Date: 03-2019
Publisher: Wiley
Date: 15-04-2010
DOI: 10.1111/J.1540-8167.2009.01644.X
Abstract: The area of the functional sinus node complex exceeds that of the anatomical sinus node however, reasons for this discrepancy are unknown. We aimed to characterize the functional sinus node complex in health and disease with high-density simultaneous mapping. Sinus node activity was characterized in 15 reference patients after ablation for supraventricular tachycardia. A further 16 patients were studied following ablation of chronic atrial flutter to determine effects of atrial remodeling. High-density simultaneous mapping of the sinus node complex was performed using a multi-electrode array. In reference patients, distance from superior vena cava-right atrial (SVC-RA) junction to earliest activation (EA) was 4 +/- 4 mm and sinus break-out (SBO) 9 +/- 6 mm. Preferential pathways of conduction were observed between EA and SBO. For patients with flutter, these distances were greater (EA: 15 +/- 12 mm, P = 0.003 SBO: 23 +/- 11 mm, P < 0.001). Conduction time along preferential pathways was 15 +/- 5 ms for reference patients and 23 +/- 8 ms for patients with flutter (P = 0.005). Following pacing, distance from SVC-RA junction to EA and SBO lengthened to 13 +/- 8 mm (P = 0.006) and 16 +/- 10 mm (P = 0.02), respectively, in reference patients, and 19 +/- 12 mm (P = 0.045), 28 +/- 9 mm (P = 0.02) in patients with flutter. This resulted in caudal shifts in EA and SBO of 10 +/- 9 mm and 7 +/- 8 mm in reference patients but diminished shifts in patients with flutter 4 +/- 7 mm and 4 +/- 6 mm. The functional sinus node complex demonstrates dynamic changes in activation. There are preferential pathways of conduction from sinus node to atrial myocardium. The remodeled atria demonstrate longer conduction times along preferential pathways and a restricted functional sinus node complex.
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.IJCARD.2018.10.101
Abstract: The key drivers of symptom severity and health-related quality of life (hr-QOL) in patients with atrial fibrillation (AF) remain unclear. We aimed to determine the relative contribution to symptom severity and hr-QOL of clinical factors including left ventricular (LV) diastolic function and ventricular rate control during AF and of psychological functioning. Seventy-eight consecutive patients with symptomatic AF and preserved LV systolic function underwent detailed evaluation of i) AF symptom severity and hr-QOL ii) clinical factors including left ventricular (LV) diastolic function, AF burden, and ventricular rate during AF and iii) state and trait aspects of psychological functioning. Moderate-to-severe AF-related symptoms were reported by 64% of the study population whilst 36% reported no more than mild symptoms. Worse symptom severity was associated with a higher score on the Perceived Stress Scale (16.7 ± 4.4 vs. 5.4 ± 4.4, p < 0.0001) and higher prevalence of the Type D Personality (20/50 vs. 4/28, p = 0.012). In multivariable models, only a predisposition to subjectively appraise life situations as stressful (higher PSS score) and a personality with a higher degree of negative affectivity and social inhibition (higher TDPS score) were independent predictors of higher AF symptom severity and poorer hr-QOL. No clinical factors including AF burden, ventricular rates during AF or LV diastolic function were significant predictors of AF-specific symptoms or hr-QOL. In a tertiary AF population with preserved LV systolic function, only psychological functioning consistently predicts both AF-related symptoms and hr-QOL. LV diastolic function, AF burden, and ventricular rate during AF are not independent predictors.
Publisher: Elsevier BV
Date: 09-2018
DOI: 10.1016/J.HLC.2018.04.296
Abstract: Regular exercise contributes to improved cardiovascular health and reduced cardiovascular mortality. Previous studies have shown that regular physical activity and high cardiorespiratory fitness both contribute to a reduction in incident atrial fibrillation (AF). However, the risk of AF appears to be paradoxically increased by participation in endurance exercise. Although the mechanisms are not well understood, exercise-induced changes in autonomic tone alongside the development of an arrhythmogenic atrial substrate, appear to contribute to an excess of AF amongst athletes, despite an overall reduction in cardiovascular disease incidence. This review will (i) summarise the evidence showing that regular physical activity and exercise reduces AF incidence, (ii) review the evidence that supports an increase in AF risk by regular endurance exercise, and (iii) discuss the mechanisms and risk factors that may contribute to AF susceptibility amongst otherwise healthy athletes.
Publisher: Elsevier BV
Date: 09-2014
DOI: 10.1016/J.CLINTHERA.2014.08.002
Abstract: Recent studies have highlighted significant variations in the management of recent-onset sustained atrial fibrillation (AF). We aim to provide a succinct and clear management algorithm for physicians treating patients with recent-onset sustained AF. We performed a comprehensive search of the literature on the management of recent-onset sustained AF with focus on studies reporting cardioversion of AF, antiarrhythmic agents, and anticoagulation. We also reviewed recent practice guidelines on AF management. This review provides a guide on a tailored management approach of patients with recent-onset sustained AF. After initial detailed clinical assessment, optimal rate and rhythm control options can be provided, depending on hemodynamic stability, duration of AF episode, and AF stroke risk. Issues surrounding electrical and pharmacologic cardioversion are discussed in detail. We emphasize the importance of thromboembolic risk assessment and appropriate anticoagulation surrounding the point of cardioversion. Last, we highlighted the need for appropriate specialized follow-up care after acute AF management. Despite the highly heterogeneous clinical presentations, management of recent-onset sustained AF must include stroke risk assessment, appropriate anticoagulation, and follow-up care in all patients beyond optimum rate and rhythm control strategies.
Publisher: Springer Science and Business Media LLC
Date: 22-07-2010
Publisher: Elsevier BV
Date: 11-2009
DOI: 10.1016/J.AMJCARD.2009.06.055
Abstract: Atrial fibrillation (AF) has been established as an independent predictor of long-term mortality after acute myocardial infarction. However, this is less well defined across the whole spectrum of acute coronary syndromes (ACSs). The Acute Coronary Syndrome Prospective Audit is a prospective multicenter registry with 12-month outcome data for 3,393 patients (755 with ST-segment elevation myocardial infarction, 1942 with high-risk non-ST-segment elevation ACS [NSTE-ACS], and 696 with intermediate-risk NSTE-ACS). A total of 149 patients (4.4%) had new-onset AF and 387 (11.4%) had previous AF. New-onset AF was more, and previous AF was less frequent in those with ST-segment elevation myocardial infarction than in those with high-risk NSTE-ACS or intermediate-risk NSTE-ACS (p <0.001). Compared to patients without arrhythmia, patients with new-onset AF and previous AF were significantly older and had more high-risk features at presentation (p <0.004). Patients with new-onset AF more often had left main coronary artery disease, resulting in a greater rate of surgical revascularization (p <0.001). Only new-onset AF resulted in adverse in-hospital outcomes (p <0.001). Only patients with previous AF had greater long-term mortality (hazard ratio 1.42, p <0.05). New-onset AF was only associated with a worse long-term composite outcome (hazard ratio 1.66, p = 0.004). However, the odds ratio for the composite outcome was greatest for patients with new-onset AF with intermediate-risk NSTE-ACS (odds ratio 3.9, p = 0.02) than for those with high-risk NSTE-ACS (odds ratio 2.0, p = 0.01) or ST-segment elevation myocardial infarction (odds ratio 1.4, p = 0.4). In conclusion, new-onset AF was associated with worse short-term outcomes and previous AF was associated with greater mortality even at long-term follow-up. The prognostic burden of new-onset AF differed with the type of ACS presentation.
Publisher: BMJ
Date: 2005
Publisher: Oxford University Press (OUP)
Date: 21-12-2022
Abstract: This study aimed to investigate the impact of sex on the clinical profile, utilization of rhythm control therapies, cost of hospitalization, length of stay, and in-hospital mortality in patients admitted for atrial fibrillation (AF) in the United States. We used data from the Nationwide Inpatient S le for the year 2018. Regression analysis was performed to investigate differences between men and women. A P-value ≤ 0.05 was considered significant. We included 82592 patients with a primary diagnosis of of AF 50.8% women. Women were significantly older (mean age 74 vs. 67 years, P < 0.001) and had a higher CHA2DS2-VASc score (median 4 vs. 2, P < 0.001) than men. Women had relatively higher in-hospital mortality (0.9% vs. 0.8%, P = 0.070) however, after adjustment for known risk factors female sex was no longer a predictor of mortality (P = 0.199). In sex-specific regression analyses, increased age, chronic obstructive pulmonary disease, previous stroke, heart failure, and chronic kidney disease were risk factors for in-hospital mortality in both sexes, vascular disease only in women, and race and alcohol abuse only in men. After adjusting for potential confounders, female sex was associated with lower likelihood of receiving catheter ablation [adjusted odds ratio (aOR) 0.69, 95% confidence interval (CI) 0.64-0.74] and electrical cardioversion (aOR 0.69, 95% CI 0.67-0.72), and with longer hospitalization (aOR 1.33, 95% CI 1.28-1.37), whereas sex had no influence on hospitalization costs (P = 0.339). There were differences in the risk profile, management, and outcomes between men and women hospitalized for AF. Further studies are needed to explore why women are treated differently regarding rhythm control procedures.
Publisher: Elsevier BV
Date: 03-2020
Publisher: IOP Publishing
Date: 26-03-2014
DOI: 10.1088/0967-3334/35/5/763
Abstract: The left atrium (LA) plays an important role in the maintenance of hemodynamic and electrical stability of the heart. One of the conditions altering the atrial mechanical function is atrial fibrillation (AF), leading to an increased thromboembolic risk due to impaired mechanical function. Preserving the regions of the LA that contribute the greatest to atrial mechanical function during curative strategies for AF is important. The purpose of this study is to introduce a novel method of regional assessment of mechanical function of the LA. We used cardiac MRI to reconstruct the 3D geometry of the LA in nine control and nine patients with paroxysmal atrial fibrillation (PAF). Regional mechanical function of the LA in pre-defined segments of the atrium was calculated using regional ejection fraction and wall velocity. We found significantly greater mechanical function in anterior, septal and lateral segments as opposed to roof and posterior segments, as well as a significant decrease of mechanical function in the PAF group. We suggest that in order to minimize the impact of the AF treatment on global atrial mechanical function, damage related to therapeutic intervention, such as catheter ablation, in those areas should be minimized.
Publisher: Wiley
Date: 05-2006
DOI: 10.1111/J.1540-8159.2006.00392.X
Abstract: Sinus node disease is characterized by the presence of significant sinus bradycardia or prolonged sinus pauses, and is attributed to either primary failure of sinus node automaticity or sino-atrial conduction disturbance. We present two patients with symptomatic bradycardia due to idiopathic global atrial inexcitability.
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.JACC.2015.03.002
Abstract: Obesity and atrial fibrillation (AF) frequently coexist. Weight loss reduces the burden of AF, but whether this is sustained, has a dose effect, or is influenced by weight fluctuation is unknown. This study sought to evaluate the long-term impact of weight loss and weight fluctuation on rhythm control in obese in iduals with AF. Of 1,415 consecutive patients with AF, 825 had a body mass index ≥ 27 kg/m(2) and were offered weight management. After screening for exclusion criteria, 355 were included in this analysis. Weight loss was categorized as group 1 (≥ 10%), group 2 (3% to 9%), and group 3 (<3%). Weight trend and/or fluctuation was determined by yearly follow-up. We determined the impact on the AF severity scale and 7-day ambulatory monitoring. There were no differences in baseline characteristics or follow-up among the groups. AF burden and symptom severity decreased more in group 1 compared with groups 2 and 3 (p < 0.001 for all). Arrhythmia-free survival with and without rhythm control strategies was greatest in group 1 compared with groups 2 and 3 (p < 0.001 for both). In multivariate analyses, weight loss and weight fluctuation were independent predictors of outcomes (p < 0.001 for both). Weight loss ≥ 10% resulted in a 6-fold (95% confidence interval: 3.4 to 10.3 p 5% partially offset this benefit, with a 2-fold (95% confidence interval: 1.0 to 4.3 p = 0.02) increased risk of arrhythmia recurrence. Long-term sustained weight loss is associated with significant reduction of AF burden and maintenance of sinus rhythm. (Long-Term Effect of Goal directed weight management on Atrial Fibrillation Cohort: A 5 Year follow-up study [LEGACY Study] ACTRN12614001123639).
Publisher: Elsevier BV
Date: 12-2019
Publisher: Wiley
Date: 10-01-2007
Publisher: Elsevier BV
Date: 08-2004
Publisher: Research Square Platform LLC
Date: 12-11-2020
DOI: 10.21203/RS.3.RS-28096/V3
Abstract: Background: Clinical trials and laboratory studies from around the world have shown that GC Tooth Mousse Plus® (TMP) is effective in protecting teeth from tooth decay and erosion, buffering dental plaque pH, remineralising white spot lesions and reducing dentine hypersensitivity. However, no other study has assessed the experiences of oral health, before, during and after in iduals becoming regular users of TMP. Aim: To identify how participants’ oral health status changed after introducing TMP into their oral hygiene routine.Methods: A qualitative study using Charmaz’s grounded theory methodology was conducted. Fifteen purposively s led regular users of TMP were interviewed. Transcripts were analysed after each interview. Data analysis consisted of transcript coding, detailed memo writing, and data interpretation.Results: Participants described their experiences of oral health and disease, before, during and after introducing TMP into their daily oral hygiene routine, together with the historical, biological, financial, psychosocial, and habitual dimensions of their experiences. Before becoming a regular user of TMP, participants described themselves as having a damaged mouth with vulnerable teeth, dry mouth, and sensitivity. Various aspects of participants’ histories were relevant, such as, family history and history of oral disease. Having a damaged mouth with vulnerable teeth, dry mouth and sensitivity was explained by those elements. Despite some initial barriers, once being prescribed TMP by a dental professional, a three-fold process of change was initiated: starting a new oral hygiene routine, persevering daily, and experiencing reinforcing outcomes. This process led to a fundamental lifestyle change. Participants transitioned from having a damaged mouth with vulnerable teeth to having a comfortable mouth with strong teeth at the same time participants felt empowered by this newly found status of being able to keep their teeth for life. Barriers and facilitators for incorporating TMP on daily oral hygiene routine were also identified.Conclusions: Participants valued having a comfortable mouth with strong teeth, which did not require repeated restorations. Seeing concrete results in their mouths and experiencing a more comfortable mouth boosted adherence to daily applications of TMP, which was maintained over time.
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.JACEP.2019.08.007
Abstract: Education has long been recognized as an important component of chronic condition management. Whereas education has been evaluated in atrial fibrillation (AF) populations as part of multifaceted interventions, it has never been tested as a single entity. The aim of this review is to describe the rationale for and role of education as part of comprehensive AF management. The development and use of educational material as part of the intervention of a randomized controlled trial, the HELP-AF (Home-Based Education and Learning Program in AF) study, will be described. This study was designed to determine the impact of a home-based structured educational program on outcomes in in iduals with AF. An educational resource was developed to facilitate delivery of 4 key messages targeted at empowering in iduals to self-manage their condition. The key messages focused on strategies for managing future AF episodes, the role of pharmacotherapy in the treatment of AF, the appropriate use of medicines to manage stroke risk and the role of cardiovascular risk factor management in AF. To support structured educational visiting, an educational booklet titled Living Well With Atrial Fibrillation (AF) was developed by a multidisciplinary team and was further refined following input from expert clinicians and patient interviews. Using a structured educational visiting approach, education was delivered by trained clinicians within the patient's home.
Publisher: Elsevier BV
Date: 12-2016
Publisher: Oxford University Press (OUP)
Date: 17-07-2018
Publisher: JMIR Publications Inc.
Date: 19-05-2021
DOI: 10.2196/24470
Abstract: Atrial fibrillation (AF) screening using mobile single-lead electrocardiogram (ECG) devices has demonstrated variable sensitivity and specificity. However, limited data exists on the use of such devices in low-resource countries. The goal of the research was to evaluate the utility of the KardiaMobile device’s (AliveCor Inc) automated algorithm for AF screening in a semirural Ethiopian population. Analysis was performed on 30-second single-lead ECG tracings obtained using the KardiaMobile device from 1500 TEFF-AF (The Heart of Ethiopia: Focus on Atrial Fibrillation) study participants. We evaluated the performance of the KardiaMobile automated algorithm against cardiologists’ interpretations of 30-second single-lead ECG for AF screening. A total of 1709 single-lead ECG tracings (including repeat tracing on 209 occasions) were analyzed from 1500 Ethiopians (63.53% [953/1500] male, mean age 35 [SD 13] years) who presented for AF screening. Initial successful rhythm decision (normal or possible AF) with one single-lead ECG tracing was lower with the KardiaMobile automated algorithm versus manual verification by cardiologists (1176/1500, 78.40%, vs 1455/1500, 97.00% P .001). Repeat single-lead ECG tracings in 209 in iduals improved overall rhythm decision, but the KardiaMobile automated algorithm remained inferior (1301/1500, 86.73%, vs 1479/1500, 98.60% P .001). The key reasons underlying unsuccessful KardiaMobile automated rhythm determination include poor quality/noisy tracings (214/408, 52.45%), frequent ectopy (22/408, 5.39%), and tachycardia ( bpm 167/408, 40.93%). The sensitivity and specificity of rhythm decision using KardiaMobile automated algorithm were 80.27% (1168/1455) and 82.22% (37/45), respectively. The performance of the KardiaMobile automated algorithm was suboptimal when used for AF screening. However, the KardiaMobile single-lead ECG device remains an excellent AF screening tool with appropriate clinician input and repeat tracing. Australian New Zealand Clinical Trials Registry ACTRN12619001107112 www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=378057& isReview=true
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.JACC.2014.09.028
Abstract: The long-term outcome of atrial fibrillation (AF) ablation demonstrates attrition. This outcome may be due to failure to attenuate the progressive substrate promoted by cardiovascular risk factors. The goal of this study was to evaluate the impact of risk factor and weight management on AF ablation outcomes. Of 281 consecutive patients undergoing AF ablation, 149 with a body mass index ≥27 kg/m(2) and ≥1 cardiac risk factor were offered risk factor management (RFM) according to American Heart Association/American College of Cardiology guidelines. After AF ablation, all 61 patients who opted for RFM and 88 control subjects were assessed every 3 to 6 months by clinic review and 7-day Holter monitoring. Changes in the Atrial Fibrillation Severity Scale scores were determined. There were no differences in baseline characteristics, number of procedures, or follow-up duration between the groups (p = NS). RFM resulted in greater reductions in weight (p = 0.002) and blood pressure (p = 0.006), and better glycemic control (p = 0.001) and lipid profiles (p = 0.01). At follow-up, AF frequency, duration, symptoms, and symptom severity decreased more in the RFM group compared with the control group (all p < 0.001). Single-procedure drug-unassisted arrhythmia-free survival was greater in RFM patients compared with control subjects (p < 0.001). Multiple-procedure arrhythmia-free survival was markedly better in RFM patients compared with control subjects (p < 0.001), with 16% and 42.4%, respectively, using antiarrhythmic drugs (p = 0.004). On multivariate analysis, type of AF (p < 0.001) and RFM (hazard ratio 4.8 [95% confidence interval: 2.04 to 11.4] p < 0.001) were independent predictors of arrhythmia-free survival. Aggressive RFM improved the long-term success of AF ablation. This study underscores the importance of therapy directed at the primary promoters of the AF substrate to facilitate rhythm control strategies.
Publisher: Elsevier BV
Date: 07-2023
Publisher: Elsevier BV
Date: 04-2017
DOI: 10.1016/J.HRTHM.2016.12.033
Abstract: Controversy exists about the impact of acute atrial fibrillation (AF) termination and prolongation of atrial fibrillation cycle length (AFCL) during ablation on long-term procedural outcome. The purpose of this study was to analyze the influence of AF termination and AFCL prolongation on freedom from AF in patients from the STAR AF II (Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial-Part II) trial. Acute changes in AFCL and AF termination were collected during the index procedure of the STAR AF II trial and compared to recurrence of AF at 18 months. Recurrence was assessed by ECG, Holter (3, 6, 9, 12, 18 months), and weekly transtelephonic ECG monitoring for 18 months. AF terminated in 8% of the pulmonary vein isolation (PVI) arm, 45% in the PVI+complex electrogram arm, and 22% of the PVI+linear ablation arm (P <.001), but freedom from AF did not differ among the 3 groups (P = .15). Freedom from AF was significantly higher in patients who presented to the laboratory in sinus rhythm (SR) compared to those without AF termination (63% vs 44%, P = .007). Patients with AF termination had an intermediate outcome (53%) that was not significantly different from those in SR (P = .84) or those who did not terminate (P = .08). AF termination was a univariable predictor of success (P = .007), but by multivariable analysis, presence of early SR was the strongest predictor of success (hazard ratio 0.67, P = .004). Prolongation of AFCL was not predictive of 18-month freedom from AF. Acute AF termination and prolongation in AFCL did not consistently predict 18-month freedom from AF. Presence of SR before or early during the ablation was the strongest predictor of better outcome.
Publisher: Wiley
Date: 07-06-2005
DOI: 10.1111/J.1540-8167.2005.50124.X
Abstract: Occlusion of LCX During RF Catheter Ablation. We report a case of acute occlusion of the left circumflex coronary artery during catheter ablation in the coronary sinus to complete the linear lesion between the postero-lateral mitral annulus and the left inferior pulmonary vein for the treatment of atrial fibrillation.
Publisher: Springer Science and Business Media LLC
Date: 08-2018
DOI: 10.1007/S10840-018-0429-9
Abstract: Atrial fibrillation (AF) and diseases of the cardiac conduction system frequently co-exist, and interactions between these rhythm disturbances can adversely impact patient outcomes. Concurrent AF and sinus node disease often manifests as the tachy-brady syndrome wherein the underlying sinus node dysfunction can pose a challenge to AF management. Similarly, the combination of AF and left bundle branch block increases mortality in in iduals with co-existent heart failure and h ers effective delivery of cardiac resynchronization therapy. A thorough understanding of the therapeutic interventions available for these conditions, including the role of catheter ablation and permanent pacemaker programming, is crucial for optimal management in affected patients.
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.HRTHM.2011.09.010
Abstract: The pulmonary veins (PVs) and the PV-LA (left atrium) junction are established sources of triggers initiating atrial fibrillation. In addition, they have been implicated in the maintenance of arrhythmia. To undertake high-density electrophysiological characterization of the right superior PV-LA junction in humans. Mapping was performed in 18 patients without a history of atrial fibrillation undergoing cardiac surgery. A high-density epicardial plaque was positioned at the anterior right superior pulmonary vein covering 3 regions: LA, PV-LA junction, and the PV. Isochronal maps were created during (1) sinus rhythm (SR) (2) LA pacing (LA-Pace) (3) PV pacing (PV-Pace) (4) LA programmed electrical stimulation (LA-PES) and (5) PV programmed electrical stimulation (PV-PES). Regional differences in conduction slowing/conduction block (CS/CB) and the prevalence of fractionated signals (FS) and double potentials (DPs) were assessed. A region of isochronal crowding representing CS/CB developed at the PV-LA junction in 84% of the maps. Three distinct activation patterns were seen. Pattern 1: Uniform SR activation without CS/CB. LA-Pace and PES caused 1 to 2 lines of isochronal crowding (CS/CB) at the PV-LA junction. Pattern 2: CS/CB occurred at the PV-LA junction in SR. LA/PV-Pace and LA/PV-PES caused an increase in CS/CB at the PV-LA junction with widely split DPs and FS. Pattern 3: A single incomplete line of CS at the PV-LA junction in SR. With LA/PV pacing and LA/PV-PES, multiple lines (≥3) of CS/CB developed at the PV-LA junction with evidence of circuitous activation and a marked increase in DPs and FS. High-density epicardial mapping of the right superior pulmonary vein demonstrates marked functional conduction delay and circuitous activation patterns at the PV-LA junction, creating the substrate for reentry.
Publisher: Oxford University Press (OUP)
Date: 22-10-2019
Publisher: Elsevier BV
Date: 02-2018
Publisher: Elsevier BV
Date: 10-2021
Publisher: Elsevier BV
Date: 06-2003
DOI: 10.1016/S0735-1097(03)00484-4
Abstract: The study was done to characterize the electrocardiographic and electrophysiologic features of focal atrial tachycardia originating at the mitral annulus (MA). Though the majority of left atrial tachycardias originate around the ostia of the pulmonary veins, only isolated reports have described focal tachycardia originating from the MA. Seven patients of a consecutive series of 172 patients undergoing radiofrequency ablation for focal atrial tachycardia are reported. Electrophysiologic study involved catheters positioned along the coronary sinus (CS), crista terminalis (CT), His bundle, and a mapping/ablation catheter. All seven patients had tachycardia foci originating from the superior region of the MA in close proximity to the left fibrous trigone and mitral-aortic continuity. These foci demonstrated a characteristic P-wave morphology and endocardial activation pattern. The P-wave morphology in the precordial leads typically showed a biphasic pattern, with an inverted component followed by an upright component. The P-wave was consistently of low litude in the limb leads. Earliest endocardial activity occurred at the His bundle region in all seven patients. In general, CS activation was proximal to distal, and mid-CT activation was earlier than high or low CT. Ablation was successful at the superior aspect of the MA in all patients. The MA is an unusual but important site of origin for focal atrial tachycardia, with a propensity to be localized to the superior aspect. It can be suspected as a potential anatomic site of tachycardia origin from analysis of P-wave morphology and the atrial endocardial activation sequence map. Using mapping targeted to anatomic structures achieved a high success rate for ablation.
Publisher: Oxford University Press (OUP)
Date: 31-10-2022
Abstract: In atrial fibrillation (AF) patients, untreated sleep-disordered breathing (SDB) is associated with lower success rates of rhythm control strategies and as such structured SDB testing is recommended. Herein, we describe the implementation of a virtual SDB management pathway in an AF outpatient clinic and examine the utility and feasibility of this new approach. Prospectively, consecutive AF patients accepted for AF catheter ablation procedures without previous diagnosis of SDB were digitally referred to a virtual SDB management pathway and instructed to use WatchPAT-ONE (ITAMAR) for one night. Results were automatically transferred to a virtual sleep laboratory, upon which a teleconsultation with a sleep physician was planned. Patient experience was measured using surveys. SDB testing was performed in 119 consecutive patients scheduled for AF catheter ablation procedures. The median time from digital referral to finalization of the sleep study report was 18 [11-24] days. In total, 65 patients (55%) were diagnosed with moderate-to-severe SDB. Patients with SDB were prescribed more cardiovascular drugs and had higher body mass indices (BMI, 29 ± 3.3 vs. 27 ± 4.4kg/m2, P < 0.01). Patients agreed that WatchPAT-ONE was easy to use (91%) and recommended future use of this virtual pathway in AF outpatient clinics (86%). Based on this remote SDB testing, SDB treatment was recommended in the majority of patients. This novel virtual AF management pathway allowed remote SDB testing in AF outpatient clinics with a short time to diagnosis and high patient satisfaction. Structured SDB testing results in a high detection of previously unknown SDB in AF patients scheduled for AF ablation.
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.HRTHM.2016.11.001
Abstract: Recent miniaturization of an insertable cardiac monitor (ICM) may make it possible to move device insertion from a hospital to office setting. However, the safety of this strategy is unknown. The primary objective was to compare the safety of inserting the Reveal LINQ ICM in an office vs a hospital environment. Ancillary objectives included summarizing device- and procedure-related adverse events and responses to a physician questionnaire. Five hundred twenty-one patients indicated for an ICM were randomized (1:1 ratio) to undergo ICM insertion in a hospital or office environment at 26 centers in the United States in the Reveal LINQ In-Office 2 study (ClinicalTrials.gov identifier NCT02395536). Patients were followed for 90 days. ICM insertion was successful in all 482 attempted patients (office: 251 hospital: 231). The untoward event rate (composite of unsuccessful insertion and ICM- or insertion-related complications) was 0.8% (2 of 244) in the office and 0.9% (2 of 227) in the hospital (95% confidence interval, -3.0% to 2.9% 5% noninferiority: P < .001). In addition, adverse events occurred during 2.5% (6 of 244) of office and 4.4% (10 of 227) of hospital insertions (95% confidence interval [office minus inhospital rates], -5.8% to 1.9% 5% noninferiority: P 15 minutes (16% vs 35% P < .001) and patient response was more often "very positive." Physicians considered the office location "very convenient" more frequently than the hospital location (85% vs 27% P < .001). The safety profile for the insertion of the Reveal LINQ ICM is excellent irrespective of insertion environment. These results may expand site of service options for LINQ insertion.
Publisher: Elsevier BV
Date: 12-2017
Publisher: Wiley
Date: 03-10-2023
DOI: 10.1111/JCE.16090
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.SLEEP.2010.07.018
Abstract: Upper airway obstruction (UAO) during childhood is associated with cardiovascular morbidity. The aim of this study was to investigate the cardio-respiratory response to cortical arousal during sleep in children with UAO. Standard paediatric overnight polysomnography (PSG) was conducted in 40 children with UAO (25M, 7.5±2.7yrs) prior to and 6 months following adenotonsillectomy. For comparison a control group of 40 normal, sex and age matched children (21M, 7.5±2.6yrs) underwent two PSGs without intervention at the same time points. Heart rate and respiratory rate were measured during spontaneous and respiratory arousals in stage 2 and REM sleep 15s prior to and 15s immediately following cortical arousal onset. Cortical arousal was associated with a significant increase in heart and respiratory rate in both groups of children. UAO children, however, showed a significantly higher heart rate response in stage 2 sleep (-17.5±6.0 vs. -14.4±4.8% p<0.05), a lower pre-arousal baseline respiratory rate (stage 2: 17.1±1.4 vs. 18.2±1.7 BPM p<0.01) and a prolonged increase in respiratory rate compared to control children. Cardiac and respiratory arousal responses were not significantly different from controls following adenotonsillectomy in the UAO children. UAO in children is associated with an altered cardiorespiratory response to spontaneous arousal from sleep, which may indicate early signs of autonomic dysfunction. Surgical treatment of UAO appears to reverse these outcomes.
Publisher: BMJ
Date: 16-10-2020
DOI: 10.1136/HEARTJNL-2020-317418
Abstract: To characterise the rate, causes and predictors of cessation of non-vitamin K antagonist oral anticoagulants (NOACs) in patients with atrial fibrillation (AF). Consecutive patients with AF with a long-term anticoagulation indication treated with NOACs (dabigatran, apixaban and rivaroxaban) in our centre from September 2010 through December 2016 were included. Prospectively collected data with baseline characteristics, causes of cessation, mean duration-to-cessation and predictors of cessation were analysed. The study comprised 1415 consecutive patients with AF, of whom 439 had a CHA 2 DS 2 -VASc≥1 and were on a NOAC. Mean age was 71.9±8.7 years and 37% were females. Over a median follow-up of 3.6 years (IQR=2.7–5.3), 147 (33.5%) patients ceased their index-NOAC (113 switched to a different form of OAC), at a rate of 8.8 per 100 patient-years. Serious adverse events warranting NOAC cessation occurred in 28 patients (6.4%) at a rate of 1.6 events per 100 patient-years. The mean duration-to-cessation was 4.9 years (95% CI 4.6 to 5.1) and apixaban had the longest duration-to-cessation with (5.1, 95% CI 4.8 to 5.4) years, compared with dabigatran (4.6, 95% CI 4.2 to 4.9) and rivaroxaban (4.5, 95% CI 3.9 to 5.1), pairwise log-rank p=0.002 and 0.025, respectively. In multivariable analyses, age was an independent predictor of index-NOAC cessation (HR 1.03, 95% CI 1.01 to 1.05 p=0.006). Female gender (HR 2.2, 95% CI 1.04 to 4.64 p=0.04) independently predicted serious adverse events. In this ‘real world’ cohort, NOAC use is safe and well-tolerated when prescribed in an integrated care clinic. Whether apixaban is better tolerated compared with other NOACs warrants further study.
Publisher: Elsevier BV
Date: 03-2002
DOI: 10.1016/S0735-1097(02)01691-1
Abstract: This study was designed to determine the sensitivity and specificity of concealed entrainment (CE) for the identification of a critical isthmus in the atrium. Isthmus identification during entrainment mapping of macro-reentrant atrial tachycardia (MRAT) relies on the demonstration of CE. Using the model of typical atrial flutter, entrainment was performed in 10 patients at four rates (flutter cycle length [FCL] minus 10/20/30/40 ms) from seven sites: isthmus entrance/exit, low lateral/high lateral/high septal right atrium and proximal/distal coronary sinus. Surface 12-lead electrocardiogram fusion was evaluated by three observers blind to patient status. The extent of antidromic penetration (AP) was measured off the pacing catheter positioned around the tricuspid annulus. The sensitivity for CE identifying any isthmus site was greatest at FCL-10 (100%), but the specificity was poor (54%). Conversely, specificity was greatest at FCL-40 (98%), but the sensitivity was poor (65%), with manifest entrainment (ME) observed from the isthmus entrance in 70% of episodes. At FCL-30, sensitivity (85%) and specificity (90%) were "balanced," but CE still resulted during entrainment from a non-isthmus site in five of 10 patients. Antidromic penetration increased with pacing CL shortening (p < 0.001) and correlated with the development of ME (p < 0.001). Antidromic penetration was significantly blunted from the isthmus exit compared to all other sites (p = 0.003). The sensitivity and specificity of CE for identifying an isthmus in the atrium are critically dependent on the pacing rate and the precise anatomic pacing site within the isthmus. These findings may have implications for the use of entrainment in the mapping of unknown MRAT circuits.
Publisher: Springer Science and Business Media LLC
Date: 15-05-2018
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.AHJ.2012.04.002
Abstract: The optimal ablation approach for patients with persistent atrial fibrillation (AF) remains unknown. In particular, it is unclear if pulmonary vein (PV) antral isolation (PVI) is sufficient as a lone strategy for persistent AF. Furthermore, if additional substrate ablation is to be added, the ideal approach to substrate ablation is yet to be determined. The aim of this study is to determine the optimal strategy of catheter ablation of persistent AF by comparing the efficacy of 3 strategies: PVI vs PVI plus complex fractionated electrogram (CFE) ablation (PVI + CFE) vs PVI plus linear ablation (PVI + Lines). The STAR AF II study (ClinicalTrials.gov NCT01203748) is a prospective, multicenter, randomized trial with a blinded assessment of outcomes. A total of 549 patients will be randomized in a 1:4:4 fashion to one of the investigation arms: PVI, PVI + CFE, and PVI + Lines, respectively. Patients undergoing a first-time ablation procedure for symptomatic, persistent AF that is refractory to at least 1 antiarrhythmic medication will be included. Persistent AF will be defined as a sustained episode lasting >7 days and 30 seconds at 18 months after 1 or 2 ablation procedures with or without antiarrhythmic medications. The STAR AF II study is a randomized trial designed to evaluate the optimal approach for catheter ablation of persistent AF.
Publisher: Springer Science and Business Media LLC
Date: 11-2017
Publisher: BMJ
Date: 04-2020
DOI: 10.1136/OPENHRT-2020-001257
Abstract: To undertake a systematic review and meta-analysis examining the impact of polypharmacy on health outcomes in atrial fibrillation (AF). PubMed and Embase databases were searched from inception until 31 July 2019. Studies including post hoc analyses of prospective randomised controlled trials or observational design that examined the impact of polypharmacy on clinically significant outcomes in AF including mortality, hospitalisations, stroke, bleeding, falls and quality of life were eligible for inclusion. A total of six studies were identified from the systematic review, with three studies reporting on common outcomes and used for a meta-analysis. The total study population from the three studies was 33 602 and 37.2% were female. Moderate and severe polypharmacy, defined as 5–9 medicines and medicines, was observed in 42.7% and 20.7% of patients respectively, and was associated with a significant increase in all-cause mortality (Hazard ratio [HR] 1.36, 95% CI 1.20 to 1.54, p .001 HR 1.84, 95% CI 1.40 to 2.41, p .001, respectively), major bleeding (HR 1.32, 95% CI 1.14 to 1.52, p .001 HR 1.68, 95% CI 1.35 to 2.09, p .001, respectively) and clinically relevant non-major bleeding (HR 1.12, 95% CI 1.03 to 1.22, p .01 HR 1.48, 95% CI 1.33 to 1.64, p .01, respectively). There was no statistically significant association between polypharmacy and stroke or systemic embolism or intracranial bleeding. Among other examined outcomes, polypharmacy was associated with cardiovascular death, hospitalisation, reduced quality of life and poorer physical function. Polypharmacy is highly prevalent in the AF population and is associated with numerous adverse outcomes. CRD42018105298.
Publisher: Oxford University Press (OUP)
Date: 15-07-2019
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.JACC.2007.11.037
Abstract: This study sought to characterize the conduction properties of the posterior left atrium (PLA) in patients with different forms of structural heart disease undergoing cardiac surgery. The PLA plays an important role in the initiation and maintenance of atrial fibrillation. This study included 34 patients having elective cardiac surgery. There were 4 groups of patients: normal left ventricular (LV) function (coronary artery bypass grafting [CABG]) severe LV dysfunction (LVF/CABG) severe mitral regurgitation (MR) severe aortic stenosis (AS). Epicardial mapping of the PLA was performed in sinus rhythm and during differential pacing. Activation patterns, regional conduction velocity (CV), conduction heterogeneity, anisotropy, and total plaque activation time (TAT) were assessed. Left atrial size in patients with LVF/CABG (47 +/- 7 mm) and MR (54 +/- 6 mm) was larger than patients with CABG (39 +/- 7 mm) and AS (42 +/- 6 mm p < 0.05). During pacing, all patients developed a vertical line of conduction delay running between the pulmonary veins. The extent of this conduction delay was greater in patients with LVF/CABG and MR than patients with AS and CABG (p < 0.05). Conduction heterogeneity, anisotropy, and TAT were greater in patients with LVF/CABG and MR than patients with CABG (p < 0.05). These changes resulted in circuitous wave front propagation. There is a line of functional conduction delay in a consistent anatomical location in the PLA in patients with structural heart disease. This is most marked in conditions associated with significant chronic atrial enlargement and leads to circuitous wave front propagation, suggesting a potential role in arrhythmogenesis.
Publisher: BMJ
Date: 29-09-2022
Publisher: Elsevier BV
Date: 08-2009
DOI: 10.1016/J.HRTHM.2009.04.008
Abstract: The posterior left atrium (LA) is involved in the initiation and maintenance of atrial fibrillation (AF). The purpose of this study was to compare conduction patterns on the posterior LA in patients with mitral regurgitation (MR), with and without AF. Epicardial mapping of the posterior LA was performed in 23 patients undergoing cardiac surgery. Patients were included in one of three groups: Group A-patients in sinus rhythm with normal left ventricular function undergoing coronary artery bypass grafting, Group B-patients in sinus rhythm with MR undergoing mitral valve surgery, or Group C-patients in persistent AF with MR undergoing mitral valve surgery. Conduction patterns, regional conduction velocity, conduction heterogeneity, conduction anisotropy, and complex fractionated atrial electrograms (CFAEs) were assessed. LA diameter was greater in patients in Groups C (57 +/- 4mm) and B (54 +/- 6mm) than in Group A (39 +/- 7 mm, P <0.01). Patients in Group C had a greater number of lines of conduction delay than Groups A and B (2.0 +/- 0.8 vs 1 +/- 0 and 1 +/- 0, P <0.05). The extent of conduction delay and conduction heterogeneity was greater in Group C than in Group B, which was greater than in Group A (P <0.05). The percentage of CFAEs that remained stable during AF was 61% +/- 17%. There was a significant correlation between CFAEs during AF and regions of slow conduction during pacing (R = 0.36, P <0.001). Patients with MR, LA enlargement, and AF have more extensive regions of conduction slowing in the posterior LA. Anatomically constant lines of conduction delay in this region lead to circuitous wavefront propagation. During persistent AF, fractionated electrograms in the posterior LA are distributed to regions demonstrating slow conduction, and the majority remain stable over time.
Publisher: Wiley
Date: 08-2013
DOI: 10.1111/IMJ.12201
Abstract: Implantable cardioverter defibrillators (ICD) have been demonstrated to reduce mortality in survivors of life-threatening arrhythmias (secondary prevention) and in patients at increased risk of sudden cardiac death (primary prevention). Other nations have reported significant increases in ICD use in recent years. To investigate Australian nationwide trends of ICD procedures over a 10-year period (2000-2009). A retrospective analysis of the Australian Institute of Health and Welfare's National Hospital Morbidity Database was performed to determine the annual number of ICD implantation and replacement procedures between 2000 and 2009. Rates were calculated using Australian Bureau of Statistics data on the annual estimated population. Time trends in the yearly procedure number and rate were analysed using negative binomial regression models with comparisons made by age and sex. The number of new ICD implantations increased from 708 to 3198 procedures between 2000 and 2009. Replacement procedures increased from 290 to 1378. The implantation rate (per million) increased from 37.0 to 145.6 and the replacement rate from 15.1 to 62.7. When rates were adjusted for age and sex, the implantation rate increased annually by 15.8% and the replacement rate by 16.6% (P < 0.0001). Procedures occurred most commonly in men (implantations: 80.1% replacements: 78.0%) between ages 70-79. ICD procedures increased significantly in Australia between 2000-2009. Despite these increases, other studies have suggested ICD devices are currently under-utilised. During the study period, males accounted for the majority of ICD procedures. While there are numerous reasons for this, it is not known if device under-use is more common in females.
Publisher: Elsevier BV
Date: 02-2020
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.JACC.2011.10.891
Abstract: The aim of this study was to systematically review the medical literature to evaluate the impact of AV nodal ablation in patients with heart failure and coexistent atrial fibrillation (AF) receiving cardiac resynchronization therapy (CRT). CRT has a substantial evidence base in patients in sinus rhythm with significant systolic dysfunction, symptomatic heart failure, and prolonged QRS duration. The role of CRT is less well established in AF patients with coexistent heart failure. AV nodal ablation has recently been suggested to improve outcomes in this group. Electronic databases and reference lists through September 15, 2010, were searched. Two reviewers independently evaluated citation titles, abstracts, and articles. Studies reporting the outcomes after AV nodal ablation in patients with AF undergoing CRT for symptomatic heart failure and left ventricular dyssynchrony were selected. Data were extracted from 6 studies, including 768 CRT-AF patients, composed of 339 patients who underwent AV nodal ablation and 429 treated with medical therapy aimed at rate control alone. AV nodal ablation in CRT-AF patients was associated with significant reductions in all-cause mortality (risk ratio: 0.42 [95% confidence interval: 0.26 to 0.68]), cardiovascular mortality (risk ratio: 0.44 [95% confidence interval: 0.24 to 0.81]), and improvement in mean New York Heart Association functional class (risk ratio: -0.52 [95% confidence interval: -0.87 to -0.17]). AV nodal ablation was associated with a substantial reduction in all-cause mortality and cardiovascular mortality and with improvements in New York Heart Association functional class compared with medical therapy in CRT-AF patients. Randomized controlled trials are warranted to confirm the efficacy and safety of AV nodal ablation in this patient population.
Publisher: Elsevier BV
Date: 11-2017
DOI: 10.1016/J.JACEP.2017.05.013
Abstract: This study sought to evaluate the spatial relationships of focal electrical sources (FSs) to complex fractionated atrial electrograms (CFAE) and continuous electrical activity (CEA). Fractionated atrial electrograms have been associated with atrial fibrillation (AF) drivers in computational studies and represent ablation targets in the management of persistent AF. We included a subset of 66 patients (age: 63 [56, 67] years, 69% persistent AF) with electroanatomic data from the SELECT AF (Selective complex fractionated atrial electrograms targeting for atrial fibrillation) randomized control trial that compared the efficacy of CFAE with CEA ablation in AF patients undergoing pulmonary vein antral ablation. Focal sources were identified based on bipolar electrogram periodicity and QS unipolar electrogram morphology. A total of 77 FSs (median: 1 [1st quartile, 3rd quartile: 1, 2] per patient) were identified most commonly in the pulmonary vein antrum and left atrial appendage. The proportions of FSs inside CFAE and CEA regions were similar (13% vs. 1.3%, respectively p = 0.13). Focal sources were more likely to be on the border zone of CFAEs than in CEAs (49% vs. 7.8%, respectively p = 0.012). Following ablation, 53% of patients had ≥1 unablated extrapulmonary vein FS. The median number of unablated FS was higher in patients with AF recurrence post ablation than in patients without (median: 1 [0, 1] vs. 0 [0, 1], respectively p = 0.026). One-half of the FSs detected during AF localized to the border of CFAE areas, whereas most of the FSs were found outside CEA areas. CFAE or CEA ablation leaves a number of FS unablated, which is associated with AF recurrence. These findings suggest that many CFAEs may arise from passive wave propagation, remote from FS, which may limit their therapeutic efficacy in AF substrate modification.
Publisher: SPIE
Date: 26-12-2008
DOI: 10.1117/12.810703
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 21-10-2003
DOI: 10.1161/01.CIR.0000095269.36984.75
Abstract: Background— The objective of this study was to describe the electrophysiological characteristics, anatomic distribution, and long-term outcome after focal ablation (RFA) of pulmonary vein (PV) atrial tachycardia (AT). Both atrial fibrillation (AF) and AT may be due to a rapidly firing focus in the PVs. Whether these represent two aspects of the same process is unknown. Methods and Results— Twenty-seven patients with 28 PV(16%) ATs of a consecutive series of 172 undergoing RFA for focal AT are reported. The mean age was 39±16 years, with symptoms for 9±14 years resistant to 1.7±0.8 medications. AT occurred spontaneously or with isoproterenol in all patients and was not inducible with PES in any. The distribution of PV ATs was right superior PV, 11 left superior PV, 11 left inferior PV, 5 and right inferior PV, 1 26of 28 foci (93%) were ostial. RFA was successful in 28 of 28 PV ATs acutely. RFA was focal in 25 of 28, with PV isolation of a single target vein in 3. There were 4 recurrences at a mean of 3.3 months. Repeat RFA was performed in all 4 and successful in 3 of 4. All but one recurrence occurred from the same site. Long-term success was achieved in 26 of 27 (96%) patients at mean follow-up of 25±22 months. No patients have had subsequent development of AF or AT from a different site. Conclusions— PV AT has a distribution similar to PV AF, with a propensity to upper veins. However, the majority of foci are ostial, and only a small percentage occur from deep in the PV. Focal RFA is associated with high long-term success, with freedom from both AT from other sites and from AF. PV AT is a localized process and therefore may be different from PV AF.
Publisher: BMJ
Date: 10-05-2017
DOI: 10.1136/HEARTJNL-2016-310952
Abstract: Atrial fibrillation (AF) is an emerging global epidemic associated with significant morbidity and mortality. Whilst other chronic cardiovascular conditions have demonstrated enhanced patient outcomes from coordinated systems of care, the use of this approach in AF is a comparatively new concept. Recent evidence has suggested that the integrated care approach may be of benefit in the AF population, yet has not been widely implemented in routine clinical practice. We sought to undertake a systematic review and meta-analysis to evaluate the impact of integrated care approaches to care delivery in the AF population on outcomes including mortality, hospitalisations, emergency department visits, cerebrovascular events and patient-reported outcomes. PubMed, Embase and CINAHL databases were searched until February 2016 to identify papers addressing the impact of integrated care in the AF population. Three studies, with a total study population of 1383, were identified that compared integrated care approaches with usual care in AF populations. Use of this approach was associated with a reduction in all-cause mortality (OR 0.51, 95% CI 0.32 to 0.80, p=0.003) and cardiovascular hospitalisations (OR 0.58, 95% CI 0.44 to 0.77, p=0.0002) but did not significantly impact on AF-related hospitalisations (OR 0.82, 95% CI 0.56 to 1.19, p=0.29) or cerebrovascular events (OR 1.00, 95% CI 0.48 to 2.09, p=1.00). The use of the integrated care approach in AF is associated with reduced cardiovascular hospitalisations and all-cause mortality. Further research is needed to identify optimal settings, methods and components of delivering integrated care to the burgeoning AF population.
Publisher: Elsevier BV
Date: 04-2007
DOI: 10.1016/J.IJCARD.2006.11.199
Abstract: Atrial fibrillation (AF) is the most common sustained arrhythmia to occur in humans. Several predisposing substrates such as increasing age, heart failure, hypertension and valvular heart disease have been identified. The use of illicit drugs as the substrate for AF is not frequently recognized.
Publisher: Wiley
Date: 19-07-2011
DOI: 10.1111/J.1540-8167.2010.01851.X
Abstract: All preclinical studies of atrial remodeling in heart failure (HF) have been confined to a single model of rapid ventricular pacing. To evaluate whether the atrial changes were specific to the model or represented an end result of HF, this study aimed to characterize atrial remodeling in an ovine model of doxorubicin-induced cardiomyopathy. Fourteen sheep, 7 with cardiomyopathy induced by repeated intracoronary doxorubicin infusions and 7 controls, were studied. The development of HF was monitored by cardiac imaging and hemodynamic parameters. Open chest electrophysiological study was performed using custom-made 128-electrode epicardial plaque assessing effective refractory period (ERP) and conduction velocity. Atrial tissues were harvested for structural analysis. The HF group had demonstrable moderate global HF (left ventricular ejection fraction [LVEF]: 37.1 vs 46.4% P = 0.003) and showed the following compared to controls: left atrial dilatation (P = 0.02) and dysfunction (P = 0.005) longer P-wave duration (P < 0.05) higher ERP at all cycle lengths (P ≤ 0.002) and locations (P < 0.001) slower conduction velocity (P < 0.001) increased conduction heterogeneity index (P < 0.001) increased atrial fibrosis (right atrial [RA]: 5.9 ± 2.6 vs 2.8 ± 0.9% P < 0.0001, left atrial [LA]: 3.7 ± 2.2 vs 2.4 ± 1.1% P = 0.002), and longer induced atrial fibrillation (AF) episodes (16 ± 22 vs 2 ± 3 seconds P = 0.04). In this model of HF, there was significant atrial remodeling characterized by atrial enlargement/dysfunction, increased fibrosis, slowed/heterogeneous conduction, and increased refractoriness associated with more sustained AF. These findings appear the "same sort" to previous models of HF implicating a final common substrate leading to the development of AF in HF.
Publisher: Elsevier BV
Date: 02-2015
DOI: 10.1016/J.TCM.2014.09.005
Abstract: Obesity is a global pandemic with a huge burden on the healthcare system. Obesity is not only linked to the development of risk factors for atherosclerotic vascular disease but also has a strong association with ventricular hypertrophy, heart failure, atrial fibrillation, and stroke. Recent experimental and clinical studies have demonstrated that obesity is associated with cardiac dysfunction, adipokine dysregulation, and activation of the pro-fibrotic signaling pathways leading to cardiac fibrosis, which is a key structural change responsible for atrial fibrillation. Importantly, these also have been shown to be reversible with weight reduction strategies. This review discusses the alterations in cardiac metabolism and function due to obesity. In addition, it addresses the complex and not yet fully understood mechanisms underlying cardiac fibrosis, with a focus on atrial substrate predisposing to atrial fibrillation in obesity.
Publisher: Oxford University Press (OUP)
Date: 18-03-2014
DOI: 10.1093/CVR/CVU045
Abstract: Atrial fibrillation (AF) is the most frequent cardiac arrhythmia in clinical practice. AF is often associated with profound functional and structural alterations of the atrial myocardium that compose its substrate. Recently, a relationship between the thickness of epicardial adipose tissue (EAT) and the incidence and severity of AF has been reported. Adipose tissue is a biologically active organ regulating the metabolism of neighbouring organs. It is also a major source of cytokines. In the heart, EAT is contiguous with the myocardium without fascia boundaries resulting in paracrine effects through the release of adipokines. Indeed, Activin A, which is produced in abundance by EAT during heart failure or diabetes, shows a marked fibrotic effect on the atrial myocardium. The infiltration of adipocytes into the atrial myocardium could also disorganize the depolarization wave front favouring micro re-entry circuits and local conduction block. Finally, EAT contains progenitor cells in abundance and therefore could be a source of myofibroblasts producing extracellular matrix. The study on the role played by adipose tissue in the pathogenesis of AF is just starting and is highly likely to uncover new biomarkers and therapeutic targets for AF.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2002
DOI: 10.1161/01.CIR.0000032262.31520.E5
Abstract: Background— Atrial mechanical stunning develops on termination of chronic atrial arrhythmias and is implicated in the genesis of thromboembolic complications after cardioversion. The mechanisms responsible for atrial mechanical stunning are unknown. The effects of atrial rate, isoproterenol, and calcium on atrial mechanical function in patients with atrial stunning have not been evaluated, and it is not known if atrial stunning can be reversed. Methods and Results— Thirty-five patients with chronic atrial flutter (AFL) undergoing radiofrequency ablation were studied. Fifteen patients in sinus rhythm undergoing ablation for paroxysmal AFL were studied as control for effects of the procedure. Left atrial appendage emptying velocities (LAAEVs) and spontaneous echocardiographic contrast (LASEC) were assessed by transesophageal echocardiography during AFL, after reversion to sinus rhythm, during atrial pacing at cycle lengths of 750 to 250 ms, after a postpacing pause, and with isoproterenol or calcium. With termination of AFL, LAAEV decreased from 59.0±3.7 cm/s to 18.8±1.4 cm/s ( P .0001) and LASEC grade increased from 0.9±0.1 to 2.2±0.2 ( P .0001). Pacing increased LAAEV to a maximum of 38.4±3.2 cm/s ( P .0001) and reduced LASEC grade to 1.9±0.2 ( P =0.005). Isoproterenol and calcium reversed atrial mechanical stunning with LAAEV increasing to 89.3±12.6 cm/s ( P =0.0007) and 50.2±10.5 cm/s ( P =0.005), respectively, and LASEC grade decreasing to 0.2±0.1 ( P =0.001) and 1.4±0.2 ( P =0.01), respectively. The postpacing pause increased LAAEV to 69.3±3.7 cm/s ( P .0001). No change in LAAEV was observed in the paroxysmal AFL group. Conclusion— Atrial mechanical stunning can be reversed by pacing at increased rates and through the administration of isoproterenol or calcium. These findings suggest a functional contractile apparatus in the mechanically remodeled atrium as a result of chronic atrial flutter.
Publisher: AMPCo
Date: 02-08-2018
DOI: 10.5694/MJA18.00646
Abstract: Atrial fibrillation (AF) is increasing in prevalence and is associated with significant morbidity and mortality. The optimal diagnostic and treatment strategies for AF are continually evolving and care for patients requires confidence in integrating these new developments into practice. These clinical practice guidelines will assist Australian practitioners in the diagnosis and management of adult patients with AF. Main recommendations: These guidelines provide advice on the standardised assessment and management of patients with atrial fibrillation regarding: screening, prevention and diagnostic work-up acute and chronic arrhythmia management with antiarrhythmic therapy and percutaneous and surgical ablative therapies stroke prevention and optimal use of anticoagulants and integrated multidisciplinary care. Changes in management as a result of the guideline: Opportunistic screening in the clinic or community is recommended for patients over 65 years of age. The importance of deciding between a rate and rhythm control strategy at the time of diagnosis and periodically thereafter is highlighted. β-Blockers or non-dihydropyridine calcium channel antagonists remain the first line choice for acute and chronic rate control. Cardioversion remains first line choice for acute rhythm control when clinically indicated. Flecainide is preferable to amiodarone for acute and chronic rhythm control. Failure of rate or rhythm control should prompt consideration of percutaneous or surgical ablation. The sexless CHA2DS2-VA score is recommended to assess stroke risk, which standardises thresholds across men and women anticoagulation is not recommended for a score of 0, and is recommended for a score of ≥ 2. If anticoagulation is indicated, non-vitamin K oral anticoagulants are recommended in preference to warfarin. An integrated care approach should be adopted, delivered by multidisciplinary teams, including patient education and the use of eHealth tools and resources where available. Regular monitoring and feedback of risk factor control, treatment adherence and persistence should occur.
Publisher: Elsevier BV
Date: 04-2020
Publisher: Elsevier BV
Date: 02-2006
DOI: 10.1016/J.HRTHM.2005.11.012
Abstract: Pulmonary vein (PV) isolation and linear lesions are effective in eliminating paroxysmal atrial fibrillation (AF), but linear lesions probably are not required in all patients. Noninducibility of AF has been shown to be associated with freedom from arrhythmia in 87% of patients. The purpose of this study was to prospectively evaluate the role of noninducibility in guiding a stepwise approach tailored to the patient. In 74 patients (age 53 +/- 8 years) with paroxysmal AF, PV isolation was performed during induced or spontaneous AF. If AF was inducible after PV isolation, one to two additional linear lesions were placed at the mitral isthmus and/or left atrial roof, with the endpoint of noninducibility of AF or atrial flutter. Inducibility (AF/atrial flutter, lasting > or = 10 minutes) was assessed using burst pacing at an output of 20 mA down to refractoriness from the coronary sinus and both atrial appendages. In 42 patients (57%), PV isolation restored sinus rhythm and rendered AF noninducible. In the 32 patients with persistent or inducible AF after PV isolation, a single linear lesion achieved noninducibility in 20, whereas two linear lesions were required in 12 and resulted in conversion to sinus rhythm and noninducibility in 10. Using this stepwise approach, a total of 69 patients (93%) were rendered noninducible. During follow-up of 18 +/- 4 months, 67 patients (91%) were free from arrhythmia without antiarrhythmic drugs. Repeat procedures were performed in 23 patients: repeat ablation was required to consolidate prior targets in 15 patients (20%), and "new" linear lesions, which were not predicted by inducibility during the index procedure, were required in 8 (11%). Noninducibility can be used as an endpoint for determining the subset of patients with paroxysmal AF who require additional linear lesions after PV isolation. This tailored approach is effective in 91% of patients while preventing delivery of unnecessary linear lesions.
Publisher: Elsevier BV
Date: 03-2019
Publisher: AMPCo
Date: 2013
DOI: 10.5694/MJA12.10929
Abstract: Atrial fibrillation (AF) is estimated to affect 1%-2% of the population. It is increasing in prevalence and is associated with excess mortality, considerable morbidity and hospitalisations. AF is responsible for a significant and growing societal financial burden. Catheter ablation is an increasingly used therapeutic strategy for the management of AF however, some confusion exists among those caring for patients with this condition about the role and optimal use of ablative treatments for AF. Our aim in this consensus statement is to provide recommendations on the use of primary catheter ablation for AF in Australia, on the basis of current evidence. Our consensus is that the primary indication for catheter ablation of AF is the presence of symptomatic AF that is refractory or intolerant to at least one Class 1 or Class 3 antiarrhythmic medication. In selecting patients for catheter ablation of AF, consideration should be given to the patient's age, duration of AF, left atrial size and the presence of significant structural heart disease. Best results are obtained in younger patients with paroxysmal AF, no structural heart disease and smaller atria. Ablation techniques for patients with persistent AF are still undergoing evaluation. Discontinuation of warfarin or equivalent therapies is not considered a sole indication for this procedure. After AF ablation, anticoagulation therapy is generally recommended for all patients for at least 1-3 months. Discontinuation of warfarin or equivalent therapies after ablation is generally not recommended in patients who have a CHADS 2 score (congestive heart failure, hypertension, age ≥ 75 years, diabetes, 1 point each prior stroke or transient ischaemic attack, 2 points) of ≥ 2.
Publisher: Springer Science and Business Media LLC
Date: 12-2003
DOI: 10.1007/S00059-003-2491-Y
Abstract: Catheter ablation for ventricular fibrillation in structurally normal hearts is in its infancy. Recently, catheter ablation of idiopathic ventricular fibrillation as well as ventricular fibrillation associated with the long QT and Brugada syndromes has been described. This review article is a summary of our current understanding of the technique and results of catheter ablation of ventricular fibrillation in structurally normal hearts.
Publisher: Oxford University Press (OUP)
Date: 08-03-2022
Publisher: Elsevier BV
Date: 04-2008
DOI: 10.1016/J.HRTHM.2008.01.008
Abstract: Three-dimensional virtual anatomic navigation is increasingly used during mapping and ablation of complex arrhythmias. NavX Fusion software aims to mold the virtual anatomy to the patient's computed tomography (CT) image however, the accuracy and clinical usefulness of this system have not been reported. The purpose of this study was to assess the accuracy and describe the initial experience of CT image integration using NavX Fusion for atrial fibrillation ablation. This study consisted of 55 consecutive patients undergoing atrial fibrillation ablation using NavX Fusion navigation. Left atrial NavX geometries were compared to a corresponding CT for geometric match. Geometric match, expressed as the difference in millimeters between CT and NavX geometry, was calculated for the original geometry (GEO-1), field scaled and primary fused geometry (GEO-2), and final secondary fused geometry (GEO-3). Navigational accuracy was assessed by moving the catheter to 10 discrete anatomic sites and determining the distance between the catheter tip and the closest GEO-2, GEO-3, and CT surface. Fusion integration time and procedural and fluoroscopic durations were recorded to assess clinical usefulness. GEO-1, GEO-2 and GEO-3 were associated with CT-GEO errors of 6.6+/-2.8 mm, 4.1+/-0.7 mm, 1.9+/-0.4 mm, respectively. Navigational accuracy was not significantly different for GEO-2, GEO-3, and CT at 3.4+/-1.6 mm to any surface. A significant (P < or =.001) inverse curvilinear relationship was present between case number and the time required for image integration (r(2) = 0.35) and the fluoroscopic time normalized for procedural duration (r(2) = 0.18). Image integration using the NavX Fusion software is highly accurate and is associated with a progressive reduction in fluoroscopic time relative to procedural duration.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2016
DOI: 10.1161/CIRCEP.116.004378
Abstract: Although adiposity is increasingly recognized as a risk factor for atrial fibrillation (AF), the importance of epicardial fat compared with other adipose tissue depots remains uncertain. We sought to characterize and compare the associations of AF with epicardial fat and measures of abdominal and overall adiposity. We conducted a meta-analysis of 63 observational studies including 352 275 in iduals, comparing AF risk for 1-SD increases in epicardial fat, waist circumference, waist/hip ratio, and body mass index. A 1-SD higher epicardial fat volume was associated with a 2.6-fold higher odds of AF (odds ratio, 2.61 95% confidence interval [CI], 1.89–3.60), 2.1-fold higher odds of paroxysmal AF (odds ratio, 2.14 95% CI, 1.45–3.16) and, 5.4-fold higher odds of persistent AF (odds ratio, 5.43 95% CI, 3.24–9.12) compared with sinus rhythm. Likewise, a 1-SD higher epicardial fat volume was associated with 2.2-fold higher odds of persistent compared with paroxysmal AF (odds ratio, 2.19 95% CI, 1.66–2.88). Similar associations existed for postablation, postoperative, and postcardioversion AF. In contrast, associations of abdominal and overall adiposity with AF were less extreme, with relative risks per 1-SD higher values of 1.32 (95% CI, 1.25–1.41) for waist circumference, 1.11 (95% CI, 1.08–1.14) for waist/hip ratio, and 1.22 (95% CI, 1.17–1.27) for body mass index. Strong and graded associations were observed between increasing epicardial fat and AF. Moreover, the strength of associations of AF with epicardial fat is greater than for measures of abdominal or overall adiposity. Further studies are needed to assess the mechanisms and clinical relevance of epicardial fat.
Publisher: Wiley
Date: 25-09-2009
DOI: 10.1111/J.1540-8159.2009.02484.X
Abstract: Cycle length alternation in atrioventricular reentrant tachycardia due to alternating conduction time over the dual atrioventricular (AV) nodal pathways has been well described. Atriofascicular pathways with decremental conduction characteristics (Mahaim fibers) are known to contain accessory AV nodal tissue. We describe a case of cycle-length alternans in antidromic tachycardia through an atriofascicular pathway because of alternation in conduction time in the antegrade limb. The possible mechanisms of this phenomenon, rarely described in atriofascicular pathways, are discussed.
Publisher: Elsevier BV
Date: 11-2016
DOI: 10.1016/J.CCL.2016.06.006
Abstract: Exercise training has considerable health benefits. However, recent research has demonstrated a greater risk of atrial arrhythmias in endurance athletes. The mechanisms promoting atrial fibrillation in athletes are unclear but there seems to be a central role for atrial remodeling, accompanied by autonomic alterations and inflammation. Animal studies have provided unique insights, yet prospective human data are lacking. Treatment options seem to yield similar efficacy to that seen in a nonathletic population and may be justified as an early rhythm control strategy. Further studies are required to enhance understanding of the cardiac adaptations to intensive exercise training.
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.JACC.2007.10.056
Abstract: This study sought to determine the characteristics of atrial electrograms predictive of slowing or termination of atrial fibrillation (AF) during ablation of chronic AF. There is growing recognition of a role for electrogram-based ablation. Forty consecutive patients (34 male, 59 +/- 10 years) undergoing ablation for chronic AF persisting for a median of 12 months (range 1 to 84 months) were included. After pulmonary vein isolation and roof line ablation, electrogram-based ablation was performed in the left atrium and coronary sinus. Targeted electrograms were acquired in a 4-s window and characterized by: 1) percentage of continuous electrical activity 2) bipolar voltage 3) dominant frequency 4) fractionation index 5) mean absolute value of derivatives of electrograms 6) local cycle length and 7) presence of a temporal gradient of activation. Electrogram characteristics at favorable ablation regions, defined as those associated with slowing (a >or=6-ms increase in AF cycle length) or termination of AF were compared with those at unfavorable regions. The AF was terminated by electrogram-based ablation in 29 patients (73%) after targeting a total of 171 regions. Ablation at 37 (22%) of these regions was followed by AF slowing, and at 29 (17%) by AF termination. The percentage of continuous electrical activity and the presence of a temporal gradient of activation were independent predictors of favorable ablation regions (p = 0.016 and p = 0.038, respectively). Other electrogram characteristics at favorable ablation regions were not significantly different from those at unfavorable ablation regions. Catheter ablation at sites displaying a greater percentage of continuous activity or a temporal activation gradient is associated with slowing or termination of chronic AF.
Publisher: Elsevier BV
Date: 06-2006
DOI: 10.1016/J.JACC.2006.02.050
Abstract: The purpose of this study was to characterize the occurrence of phrenic nerve injury (PNI) and its outcome after radiofrequency (RF) ablation of atrial fibrillation (AF). It is recognized that extra-myocardial damage may develop owing to penetration of ablative energy. Between 1997 and 2004, 3,755 consecutive patients underwent AF ablation at five centers. Among them, 18 patients (0.48% 9 male, 54 +/- 10 years) had PNI (16 right, 2 left). The procedure consisted of pulmonary vein (PV) isolation in 15 patients and anatomic circumferential ablation in 3 patients, with additional left atrial lesions (n = 11) and/or superior vena cava (SVC) disconnection (n = 4). Right PNI occurred during ablation of right superior PV (n = 12) or SVC disconnection (n = 3). Left PNI occurred during ablation at the left atrial appendage. Immediate features were dyspnea, cough, hiccup, and/or sudden diaphragmatic elevation in 9, and in the remaining the diagnosis was made after ablation owing to dyspnea (n = 7) or on routine radiographic evaluation (n = 2). Four patients (22%) were asymptomatic. Complete recovery occurred in 12 patients (66%). Recovery occurred within 24 h in the two patients with left PNI and in one patient with right PNI occurring with SVC disconnection. In the other nine patients, right PNI recovery occurred after 4 +/- 5 months (1 to 12 months) with respiratory rehabilitation. After a mean follow-up of 36 +/- 33 months, six patients have persistent PNI (three with partial and three with no recovery). In this multicenter experience, PNI was a rare complication (0.48%) of AF ablation. Ablation of the right superior PV, SVC, and left atrial appendage were associated with PNI. Complete (66%) or partial (17%) recovery was observed in the majority.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2021
Publisher: Wiley
Date: 2005
DOI: 10.1111/J.1540-8159.2005.00036.X
Abstract: Linear left atrial ablation is performed in combination with pulmonary vein (PV) isolation to improve the clinical results of atrial fibrillation (AF) ablation. These procedures require long procedures and fluoroscopic exposure. The aim of the present study was to evaluate the performance of a new, nonfluoroscopic, real-time, three-dimensional navigation system for linear ablation at the left atrial roof and mitral isthmus. The study included 44 patients (54 +/- 10 years of age, 5 women) with drug-refractory AF, who underwent roof line or mitral isthmus linear ablation after 4-PV isolation. In 22 patients, ablation was performed with the navigation system (test group), and in the remainders linear ablation was performed with fluoroscopic guidance alone (control group). Conduction block was achieved in 20 patients (91%) in test group, and 21 patients (95%) in the control group (ns). Use of the navigation system was associated with a shorter fluoroscopic exposure for roof line (5.6 +/- 3.0 minutes vs 8.7 +/- 5.0 minutes, P < 0.05), and a trend for mitral isthmus ablation (7.8 +/- 7.8 minutes vs 12.1 +/- 5.9 minutes). It was also associated with a trend toward shorter procedure times for roof line (15.3 +/- 8.6 minutes vs 22.9 +/- 16.8 minutes) and mitral isthmus line (20.2 +/- 15.8 minutes vs 32.0 +/- 7.6 minutes) but no difference in duration of radiofrequency delivery. There was no procedural complication. The use of this new nonfluoroscopic imaging system was associated with a shorter fluoroscopic exposure as well as a trend toward shorter duration of linear ablation procedures for AF.
Publisher: Elsevier BV
Date: 06-2020
Publisher: Oxford University Press (OUP)
Date: 13-03-2008
Abstract: To characterize the atrial remodelling in mitral stenosis (MS). Twenty-four patients with severe MS undergoing commissurotomy and 24 controls were studied. Electrophysiological evaluation was performed in 12 patients in each group by positioning multi-electrode catheters in both atria to determine the following: effective refractory period (ERP) at 10 sites at 600 and 450 ms conduction time conduction delay at the crista terminalis (CT) and vulnerability for atrial fibrillation (AF). P-wave duration (PWD) was determined on the surface ECG. In the remaining 12 patients in each group, electroanatomic maps of both atria were created to determine conduction velocity and identify regions of low voltage and electrical silence. Patients with MS had larger left atria (LA) (P < 0.0001) prolonged PWD (P = 0.0007) prolonged ERP in both LA (P < 0.0001) and right atria (RA) (P < 0.0001) reduced conduction velocity in the LA (P = 0.009) and RA (P < 0.0001) greater number (P < 0.0001) and duration (P< 0.0001) of bipoles along the CT with delayed conduction lower atrial voltage in the LA (P < 0.0001) and RA (P < 0.0001) and more frequent electrical scar (P = 0.001) compared with controls. Five of twelve with MS and none of the controls developed AF with extra-stimulus (P = 0.02). Atrial remodelling in MS is characterized by LA enlargement, loss of myocardium, and scarring associated with widespread and site-specific conduction abnormalities and no change or an increase in ERP. These abnormalities were associated with a heightened inducibility of AF.
Publisher: Elsevier BV
Date: 10-2005
Publisher: Public Library of Science (PLoS)
Date: 25-05-2009
Publisher: American Medical Association (AMA)
Date: 20-11-2013
Abstract: Obesity is a risk factor for atrial fibrillation. Whether weight reduction and cardiometabolic risk factor management can reduce the burden of atrial fibrillation is not known. To determine the effect of weight reduction and management of cardiometabolic risk factors on atrial fibrillation burden and cardiac structure. Single-center, partially blinded, randomized controlled study conducted between June 2010 and December 2011 in Adelaide, Australia, among overweight and obese ambulatory patients (N = 150) with symptomatic atrial fibrillation. Patients underwent a median of 15 months of follow-up. Patients were randomized to weight management (intervention) or general lifestyle advice (control). Both groups underwent intensive management of cardiometabolic risk factors. The primary outcomes were Atrial Fibrillation Severity Scale scores: symptom burden and symptom severity. Scores were measured every 3 months from baseline to 15 months. Secondary outcomes performed at baseline and 12 months were total atrial fibrillation episodes and cumulative duration measured by 7-day Holter, echocardiographic left atrial area, and interventricular septal thickness. Of 248 patients screened, 150 were randomized (75 per group) and underwent follow-up. The intervention group showed a significantly greater reduction, compared with the control group, in weight (14.3 and 3.6 kg, respectively P < .001) and in atrial fibrillation symptom burden scores (11.8 and 2.6 points, P < .001), symptom severity scores (8.4 and 1.7 points, P < .001), number of episodes (2.5 and no change, P = .01), and cumulative duration (692-minute decline and 419-minute increase, P = .002). Additionally, there was a reduction in interventricular septal thickness in the intervention and control groups (1.1 and 0.6 mm, P = .02) and left atrial area (3.5 and 1.9 cm2, P = .02). In this study, weight reduction with intensive risk factor management resulted in a reduction in atrial fibrillation symptom burden and severity and in beneficial cardiac remodeling. These findings support therapy directed at weight and risk factors in the management of atrial fibrillation. anzctr.org.au Identifier: ACTRN12610000497000.
Publisher: Wiley
Date: 15-09-2017
Publisher: Oxford University Press (OUP)
Date: 26-10-2022
Publisher: Wiley
Date: 2002
DOI: 10.1046/J.1540-8167.2002.00074.X
Abstract: The term "Mahaim fiber" usually is applied to an atriofascicular fiber that inserts distally into the right bundle branch and forms the anterograde limb of a reciprocating tachycardia. One of the features that has been used to describe the physiology of Mahaim fibers is the presence of anterograde preexcitation. We describe two patients who had a clinical tachycardia consistent with a "Mahaim tachycardia" in whom there was no evidence or minimal evidence of anterograde preexcitation during sinus rhythm or atrial pacing. In both patients, the tachycardia was rendered noninducible by radiofrequency ablation at the site of Mahaim potentials at the tricuspid annulus, and a long-term cure was achieved. This is the first description of a "latent Mahaim fiber" that does not cause preexcitation but which can support antidromic reciprocating tachycardia.
Publisher: Oxford University Press (OUP)
Date: 17-02-2022
Abstract: There is a paucity of epidemiological evidence on alcohol and the risk of bradyarrhythmias. We thus characterized associations of total and beverage-specific alcohol consumption with incident bradyarrhythmias using data from the UK Biobank. Alcohol consumption reported at baseline was calculated as UK standard drinks (8 g alcohol)/week. Bradyarrhythmia events were defined as sinus node dysfunction (SND), high-level atrioventricular block (AVB), and permanent pacemaker implantations. Outcomes were assessed through hospitalization and death records, and dose–response associations were characterized using Cox regression models with correction for regression dilution bias. We studied 407 948 middle-aged in iduals (52.4% female). Over a median follow-up time of 11.5 years, a total of 8 344 incident bradyarrhythmia events occurred. Increasing total alcohol consumption was not associated with an increased risk of bradyarrhythmias. Beer and cider intake were associated with increased bradyarrhythmia risk up to 12 drinks/week however, no significant associations were observed with red wine, white wine, or spirit intake. When bradyarrhythmia outcomes were analysed separately, a negative curvilinear was observed for total alcohol consumption and risk of SND, but no clear association with AVB was observed. In this predominantly White British cohort, increasing total alcohol consumption was not associated with an increased risk of bradyarrhythmias. Associations appeared to vary according to the type of alcoholic beverage and between different types of bradyarrhythmias. Further epidemiological and experimental studies are required to clarify these findings.
Publisher: Springer Science and Business Media LLC
Date: 03-02-2023
DOI: 10.1007/S10840-023-01481-4
Abstract: Remote monitoring (RM) can facilitate early detection of subclinical and symptomatic atrial fibrillation (AF), providing an opportunity to evaluate the need for stroke prevention therapies. We aimed to characterize the burden of RM AF alerts and its impact on anticoagulation of patients with device-detected AF. Consecutive patients with a cardiac implantable electronic device, at least one AF episode, undergoing RM were included and assigned an estimated minimum CHA 2 DS 2 -VASc score based on age and device type. RM was provided via automated software system, providing rapid alert processing by device specialists and systematic, recurrent prompts for anticoagulation. From 7651 in idual, 389,188 AF episodes were identified, 3120 (40.8%) permanent pacemakers, 2260 (29.5%) implantable loop recorders (ILRs), 987 (12.9%) implantable cardioverter defibrillators, 968 (12.7%) cardiac resynchronization therapy (CRT) defibrillators, and 316 (4.1%) CRT pacemakers. ILRs transmitted 48.8% of all AF episodes. At twelve-months, 3404 (44.5%) AF 6 min, 1367 (17.9%) 6 min–6 h, 1206 (15.8%) 6–24 h, and 1674 (21.9%) ≥ 24 h. A minimum CHA 2 DS 2 -VASc score of 2 was assigned to 1704 (63.1%) of the patients with an AF episode of ≥ 6 h, 531 (31.2%) who were not anticoagulated at 12-months, and 1031 (61.6%) patients with an AF episode duration of ≥ 24 h, 290 (28.1%) were not anticoagulated. Despite being intensively managed via RM software system incorporating cues for anticoagulation, a substantial proportion of patients with increased stroke risk remained unanticoagulated after a device-detected AF episode of significant duration. These data highlight the need for improved clinical response pathways and an integrated care approach to RM. Australian New Zealand Clinical Trial Registry: ACTRN12620001232921.
Publisher: Wiley
Date: 31-08-2005
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.JACC.2010.11.045
Abstract: The aim of this study was to characterize the relationship between pericardial fat and atrial fibrillation (AF). Obesity is an important risk factor for AF. Pericardial fat has been hypothesized to exert local pathogenic effects on nearby cardiac structures above and beyond that of systemic adiposity. One hundred ten patients undergoing first-time AF ablation and 20 reference patients without AF underwent cardiac magnetic resonance imaging for the quantification of periatrial, periventricular, and total pericardial fat volumes using a previously validated technique. Together with body mass index and body surface area, these were examined in relation to the presence of AF, the severity of AF, left atrial volume, and long-term AF recurrence after ablation. Pericardial fat volumes were significantly associated with the presence of AF, AF chronicity, and AF symptom burden (all p values <0.05). Pericardial fat depots were also predictive of long-term AF recurrence after ablation (p = 0.035). Finally, pericardial fat depots were also associated with left atrial volume (total pericardial fat: r = 0.46, p < 0.001). Importantly, these associations persisted after multivariate adjustment and additional adjustment for body weight. In contrast, however, systemic measures of adiposity, such as body mass index and body surface area, were not associated with these outcomes in multivariate-adjusted models. Pericardial fat is associated with the presence of AF, the severity of AF, left atrial volumes, and poorer outcomes after AF ablation. These associations are both independent of and stronger than more systemic measures of adiposity. These findings are consistent with the hypothesis of a local pathogenic effect of pericardial fat on the arrhythmogenic substrate supporting AF.
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.HLC.2014.12.007
Abstract: Congestive Heart Failure (CHF) is an ambulatory care sensitive condition, associated with significant morbidity and mortality, rarely with cure. Outpatient based pharmacological management represents the main and most important aspect of care, and is usually lifelong. This narrative styled opinion review looks at the pharmacological agents recommended in the guidelines in context of the Northern Territory (NT) of Australia. We explore the concept of validity, a term used to describe the basis of standardising a particular trial or study and the population to which it is applicable. We aim to highlight the problems of the current guidelines based approach. We also present alternatives that could utilise the core principles from major trials, while incorporating regional considerations, which could benefit clients living in the NT and remote Australia.
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.AMJCARD.2017.07.015
Abstract: Although higher detection rates and delayed detection improve survival in implantable cardioverter defibrillator clinical trials, their effectiveness in clinical practice has limited validation. To evaluate the effectiveness of programming strategies for reducing shocks and mortality, we conducted a nationwide assessment of patients with implantable cardioverter defibrillators or cardiac resynchronization therapy defibrillators with linked remote monitoring data. We categorized patients based on the presence or absence of high rate detection and delayed detection: higher rate delayed detection (HRDD), higher rate early detection (HRED), lower rate delayed detection (LRDD), and lower rate early detection (LRED). Cox regression was used to compare mortality and shock-free survival. There were 64,769 patients (age 68 ± 12 years 27% female 46% cardiac resynchronization therapy defibrillator follow-up 1.7 ± 1.1 years). In the first year, 13% of HRDD, 14% of HRED, 18% of LRDD, and 20% in the LRED group experienced a shock. After adjustment, HRDD was associated with lower risk of shock than HRED (hazard ratio [HR] 0.93, 95% confidence interval [CI] 0.89 to 0.98, p = 0.002), LRDD (HR 0.63, 95% CI 0.60 to 0.66, p <0.001), and LRED (HR 0.58, 95% CI 0.55 to 0.61, p <0.001). HRDD was also associated with lower risk of mortality than HRED (adjusted HR 0.80, 95% CI 0.75 to 0.86, p <0.001), LRDD (HR 0.76, 95% CI 0.70 to 0.83, p <0.001), and LRED (HR 0.68, 95% CI 0.62 to 0.73, p <0.001). Similar results were observed in patients with or without a shock in the first 6 months after implant. In conclusion, high rate programming is associated with lower risk of shocks or death compared with delayed detection. Optimal outcomes are observed in patients programmed with both high rate and delayed detection.
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.HLC.2018.03.024
Abstract: Recent registry data suggests oral anticoagulation (OAC) usage remains suboptimal in atrial fibrillation (AF) patients. The aim of our study was to determine if rates of appropriate use of OAC in in iduals with AF differs between the emergency department (ED) and cardiac outpatient clinic (CO). This was a retrospective study of consecutive AF patients over a 12-month period. Data from clinical records, discharge summaries and outpatient letters were independently reviewed by two investigators. Appropriateness of OAC was assessed according to the CHA Of 455 unique ED presentations with AF as a primary diagnosis, 115 patients who were treated and discharged from the ED were included. These were compared to 259 consecutively managed AF patients from the CO. Inappropriate OAC was significantly higher in the ED compared to the CO group (65 vs. 18%, p<0.001). Treatment in the ED was a significant multivariate predictor of inappropriate OAC (odds ratio 8.2 [4.8-17.7], p<0.001). This patient level data highlights that significant opportunity exists to improve disparities in the use of guideline adherent therapy in the ED compared to CO. There is an urgent need for protocol-driven treatment in the ED or streamlined early follow-up in a specialised AF clinic to address this treatment gap.
Publisher: JMIR Publications Inc.
Date: 21-09-2020
Abstract: trial fibrillation (AF) screening using mobile single-lead electrocardiogram (ECG) devices has demonstrated variable sensitivity and specificity. However, limited data exists on the use of such devices in low-resource countries. he goal of the research was to evaluate the utility of the KardiaMobile device’s (AliveCor Inc) automated algorithm for AF screening in a semirural Ethiopian population. nalysis was performed on 30-second single-lead ECG tracings obtained using the KardiaMobile device from 1500 TEFF-AF (The Heart of Ethiopia: Focus on Atrial Fibrillation) study participants. We evaluated the performance of the KardiaMobile automated algorithm against cardiologists’ interpretations of 30-second single-lead ECG for AF screening. total of 1709 single-lead ECG tracings (including repeat tracing on 209 occasions) were analyzed from 1500 Ethiopians (63.53% [953/1500] male, mean age 35 [SD 13] years) who presented for AF screening. Initial successful rhythm decision (normal or possible AF) with one single-lead ECG tracing was lower with the KardiaMobile automated algorithm versus manual verification by cardiologists (1176/1500, 78.40%, vs 1455/1500, 97.00% i P /i & .001). Repeat single-lead ECG tracings in 209 in iduals improved overall rhythm decision, but the KardiaMobile automated algorithm remained inferior (1301/1500, 86.73%, vs 1479/1500, 98.60% i P /i & .001). The key reasons underlying unsuccessful KardiaMobile automated rhythm determination include poor quality/noisy tracings (214/408, 52.45%), frequent ectopy (22/408, 5.39%), and tachycardia (& bpm 167/408, 40.93%). The sensitivity and specificity of rhythm decision using KardiaMobile automated algorithm were 80.27% (1168/1455) and 82.22% (37/45), respectively. he performance of the KardiaMobile automated algorithm was suboptimal when used for AF screening. However, the KardiaMobile single-lead ECG device remains an excellent AF screening tool with appropriate clinician input and repeat tracing. ustralian New Zealand Clinical Trials Registry ACTRN12619001107112 www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=378057& isReview=true
Publisher: Informa UK Limited
Date: 07-2010
DOI: 10.1586/ERC.10.61
Abstract: Despite advances in the diagnosis and management of acute coronary syndrome (ACS), atrial fibrillation (AF) remains a commonly encountered complication leading to adverse short- and long-term outcomes across the whole spectrum of ACS. At present, the underlying mechanisms of AF in myocardial ischemia remain incompletely understood. This article evaluates the incidence and trends of new-onset AF in ACS, its impact on ACS management and the associated prognostic significance in patients with acute ischemic heart disease. The safety and use of oral anticoagulation treatment in ACS patients on multiple antiplatelet agents are also explored. Further experimental and clinical studies are needed to improve current understanding and management of new-onset AF in ACS patients.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2011
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.HLC.2018.10.012
Abstract: Ventricular arrhythmias (VA) are observed in the setting of structural heart disease. However, in a proportion of patients presenting with VT, the routine diagnostic modalities fail to demonstrate overt myocardial abnormality. These arrhythmias have been called idiopathic VAs. They consist of various subtypes that have been defined by their anatomic location of origin within the heart and/or their underlying mechanism. While the majority of patients are asymptomatic, some experience debilitating symptoms and may develop reversible ventricular dysfunction. Catheter ablation has been traditionally reserved for patients with incapacitating symptoms or progressive ventricular dysfunction. However, as many patients are young, and catheter ablation can be curative in >90% of cases with a low risk (<1%) of serious complications, it is increasingly being offered as a first-line treatment in symptomatic patients. The approach to arrhythmia mapping is guided by the 12-lead electrocardiograph (ECG) morphology of the ventricular tachycardia (VT). Use of three dimensional (3D) electroanatomic mapping systems and intra-cardiac echocardiography are helpful in localising sites for successful ablation.
Publisher: Wiley
Date: 30-01-2012
DOI: 10.1111/J.1440-1681.2011.05647.X
Abstract: Endothelial function is an independent predictor of adverse cardiovascular outcomes. The evaluation of endothelial function via changes in vessel diameter or blood flow may be inaccurate during atrial fibrillation (AF) because of non-uniform stroke volumes. Using peripheral arterial tonometry, 50 patients with AF (25 in AF, 25 in sinus rhythm) had digital pulse litudes assessed at baseline and during reactive hyperaemia. Hyperaemic responses were compared over varying measurement durations (5, 10 and 15beats 30s and 1-10min) to determine optimal measurement duration. Endothelial responses were significantly decreased (indicating endothelial dysfunction) in patients in AF compared with patients in sinus rhythm (1.48±0.60 vs 2.05±1.13, respectively P=0.03). Beat-to-beat pulse litude was highly variable during AF although coefficients of variation (CV) for short measurement durations were large, these decreased with longer measurement durations. Bland-Altman plots revealed that limits of agreement for short measurement durations were poor. Limits of agreement became consistently narrower when measurement durations of at least 1min were used. In contrast, limits of agreement and CV for short measurement durations during sinus rhythm were significantly narrower and smaller, respectively, than during AF over similar measurement durations. Pulse litudes are highly variable owing to the non-uniform stroke volumes in AF. Our results suggest that methods of determining endothelial function via vessel diameters or blood flow during reactive hyperaemia should use measurement durations of at least 1min to ensure accurate and reproducible results.
Publisher: Elsevier BV
Date: 06-2012
Publisher: Elsevier BV
Date: 11-2014
DOI: 10.1016/J.HRTHM.2014.07.030
Abstract: Nonvalvular atrial fibrillation (AF) confers a five-fold increased risk of stroke. Whether catheter ablation (CA) subsequently decreases prothrombotic risk is unknown. The purpose of this study was to assess the long-term effects of CA for AF on prothrombotic risk. Fifty-seven patients undergoing CA for AF were prospectively studied. Platelet activation (CD62P [platelet P-selectin] and PAC-1 [glycoprotein IIb/IIIa] expression) and endothelial function (asymmetric dimethylarginine [ADMA] levels) were measured at baseline and 6-months postablation. Thirty-seven (65%) patients remained in sinus rhythm (SR group) and 20 (35%) sustained AF recurrence (AF recurrence group) at 6-months. Patients with AF-recurrence were older, had a higher proportion of hypertension and long-standing persistent AF. There were no significant differences in CD62P (P = .3), PAC-1 (P = .1) and ADMA (P = .7) levels at baseline between the two groups. In the SR group, markers of platelet activation decreased significantly at 6-month follow-up compared to baseline log CD62P % 0.79 ± 0.28 vs 1.03 ± 0.27 (P <.05) and log PAC-1 % 0.22 ± 0.58 vs 0.89 ± 0.31 (P <.01). This was not significant in the AF-recurrence group (P = .8, log CD62P P = .1, log PAC-1). For endothelial function, ADMA levels decreased significantly at 6-months compared to baseline in the SR group (log ADMA μM/L 0.15 ± 0.02 vs 0.17 ± 0.04 P <.05), but did not alter significantly in the AF-recurrence group (P = .4, log ADMA). Catheter ablation and successful maintenance of SR leads to a decrease in platelet activation and improvement in endothelial function in patients with AF. These findings suggest that AF is an important determinant of the prothrombotic state and that this may be reduced by successful catheter ablation.
Publisher: American Medical Association (AMA)
Date: 06-2018
DOI: 10.1001/JAMACARDIO.2018.0095
Abstract: Obstructive sleep apnea (OSA) is the most common clinically significant breathing abnormality during sleep. It is highly prevalent among patients with atrial fibrillation (AF), and it promotes arrhythmogenesis and impairs treatment efficacy. The prevalence of OSA ranges from 3% to 49% in population-based studies and from 21% to 74% in patients with AF. Diagnosis and treatment of OSA in patients with AF requires a close interdisciplinary collaboration between electrophysiologists, cardiologists, and sleep specialists. Because the prevalence of OSA is high in patients with AF and most do not report daytime sleepiness, sleep-study evaluation may be reasonable for patients being considered for rhythm control strategy. Acute, transient apnea-associated atrial electrophysiological changes and increased occurrence of AF triggers associated with short episodes of intermittent deoxygenation and reoxygenation, intrathoracic pressure changes during obstructed breathing efforts, and sympathovagal activation combine to create a stimulus for AF triggers and a complex and dynamic substrate for AF during sleep. Repeated episodes of long-term OSA are eventually associated with structural remodeling and changes in electrical conduction in the atrium. Observational data suggest OSA reduces the efficacy of catheter-based and pharmacological antiarrhythmic therapy. Nonrandomized studies have shown that treatment of OSA by continuous positive airway pressure can help to maintain a sinus rhythm after electrical cardioversion and catheter ablation in patients with AF. However, it remains unclear which sleep apnea metric should be used to determine severity and guide such treatment in patients with AF. Data from nonrandomized studies of patients with AF suggest that treatment of OSA by continuous positive airway pressure may help to maintain sinus rhythm after electrical cardioversion and improve catheter ablation success rates. Randomized clinical trials are needed to confirm the association between OSA and AF the benefits of treatment of OSA and the need for and cost-effectiveness of routine OSA screening and treatment.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.HRTHM.2010.01.042
Abstract: Atrial fibrillation (AF) is associated with an increased risk of thrombus formation in the left but not the right atrium. The mechanisms underlying this differential effect on the atria are unknown. The purpose of this study was to examine whether atrial-specific differences in platelet activation are present in patients with AF. Nineteen patients (13 men and 6 women age 60 +/- 2 years) with AF undergoing ablation in sinus rhythm were studied. Blood s les from the left atrium, right atrium, and femoral vein were obtained at the start of the procedure and analyzed by whole-blood flow cytometry for expression of platelet P-selectin (CD62P), vitronectin receptor (CD51/61), and active glycoprotein IIb/IIIa receptor (PAC-1). Platelet aggregation was evaluated using adenosine diphosphate (ADP)-induced whole-blood impedance aggregometry. Seven patients with left-sided accessory pathway also were studies as a reference group for the effect of transseptal puncture on platelet reactivity. Platelet P-selectin levels were significantly elevated in the left atrium compared to the right atrium (10.2% +/- 2.5% vs 8.6% +/- 2.3%, P <.05). CD51/61 and PAC-1 levels did not differ between s ling sites. ADP-induced platelet aggregation was significantly higher in the left atrium compared to the right atrium and femoral vein (P <.05 for both). Platelet P-selectin levels and ADP-induced platelet aggregation did not differ between s ling site in the reference group. In patients with AF, left atrial platelet reactivity is increased compared to the right atria and peripheral circulation. The study data suggest that the presence of chamber-specific platelet activation may explain, in part, the propensity for left atrial thrombus formation in patients with AF.
Publisher: Elsevier BV
Date: 11-2018
Publisher: Elsevier BV
Date: 10-2012
Publisher: Wiley
Date: 21-02-2007
DOI: 10.1111/J.1540-8167.2007.00764.X
Abstract: This study evaluated the impact of catheter ablation of the coronary sinus (CS) region during paroxysmal and persistent atrial fibrillation (AF). The CS musculature and connections have been implicated in the genesis of atrial arrhythmias. Forty-five patients undergoing catheter ablation of AF were studied. The CS was targeted if AF persisted after ablation of pulmonary veins and selected left atrial tissue. CS ablation was commenced endocardially by dragging along the inferior paramitral left atrium. Ablation was continued from within the vessel (epicardial) if CS electrograms had cycle lengths shorter than that of the left atrial appendage. RF energy was limited to 35 W endocardially and 25 W epicardially. The impact of ablation was evaluated on CS electrogram cycle length (CSCL) and activation sequence, atrial fibrillatory cycle length measured in the left atrial appendage (AFCL) and on perpetuation of AF. Endocardial ablation significantly prolonged CSCL by 17 +/- 5 msec and organized the CS activation sequence (from 13% of patients before to 51% after ablation) subsequent epicardial ablation further increased local CSCL by 32 +/- 27 msec (P or =5 msec and/or AF termination was associated with more rapid activity in the CS region originally: P < or = 0.04. Catheter ablation targeting both the endocardial and epicardial aspects of the CS region significantly prolongs fibrillatory cycle length and terminates AF persisting after PV isolation in 35% of patients.
Publisher: Elsevier BV
Date: 06-2004
Publisher: Elsevier BV
Date: 07-2011
DOI: 10.1016/J.HRTHM.2011.02.016
Abstract: During acute myocardial infarction (MI), the incidence of atrial fibrillation (AF) is 6% to 22%, and its occurrence in this setting is associated with increased short- and long-term morbidity and mortality. The purpose of this case control study was evaluate the characteristics associated with the development of new-onset AF. Of 2,460 consecutive patients with acute MI, 149 (6%) were identified as having AF within 7 days of MI. After excluding patients with prior AF, previously documented heart failure, reduced left ventricular (LV) ejection fraction, valvular heart disease, LV hypertrophy, AF after coronary artery bypass grafting, or pericarditis we identified 42 AF patients in whom coronary anatomy was assessed by invasive angiography and cardiac structure and function was evaluated using transthoracic echocardiography. Another 42 patients from the same cohort with MI but no AF matched for age, gender, and LV ejection fraction were studied as controls. AF patients were more likely to present with an inferior MI (P = .002) but less likely to present with ST-segment elevation MI (P = .02). Univariate associations with AF included indexed left atrial volume (P <.001), LV filling pressure (E/e' P = .001), right atrial branch disease (P <.001), left atrial branch disease (P = .009), sinoatrial branch disease (P <.001), left main stem disease (P = .02), and time from onset of symptoms to coronary intervention (P = .002). In multivariable analysis, right and left coronary artery atrial branch disease (P = .02) were predictors of AF post-MI. Coronary artery disease affecting the atrial branches is an independent predictor for the development of AF after MI.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Wiley
Date: 02-03-2021
DOI: 10.1111/JCE.14957
Abstract: Success rates of catheter ablation in persistent atrial fibrillation (AF) remain suboptimal. A better and more targeted ablation strategy is urgently needed to optimize outcomes of AF treatment. We sought to assess the safety and efficacy of targeting atrial fibrosis during ablation of persistent AF patients in improving procedural outcomes. The DECAAF II trial (ClinicalTrials. gov identifier number NCT02529319) is a prospective, randomized, multicenter trial of patients with persistent AF. Patients with persistent AF undergoing a first‐time ablation procedure were randomized in a 1:1 fashion to receive conventional pulmonary vein isolation (PVI) ablation (Group 1) or PVI + fibrosis‐guided ablation (Group 2). Left atrial fibrosis and ablation induced scarring were defined by late gadolinium enhancement magnetic resonance imaging at baseline and at 3–12 months postablation, respectively. The primary endpoint is the recurrence of atrial arrhythmia postablation, including atrial fibrillation, atrial flutter, or atrial tachycardia after the 90‐day postablation blanking period. Patients were followed for a period of 12–18 months with a smartphone ECG Device (ECG Check Device, Cardiac Designs Inc.). With an anticipated enrollment of 900 patients, this study has an 80% power to detect a 26% reduction in the hazard ratio of the primary endpoint. The DECAAF II trial is the first prospective, randomized, multicenter trial of patients with persistent AF using imaging defined atrial fibrosis as a treatment target. The trial will help define an optimal approach to catheter ablation of persistent AF, further our understanding of influencers of ablation lesion formation, and refine selection criteria for ablation based on atrial myopathy burden.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2022
DOI: 10.1161/CIRCEP.121.010168
Abstract: Pulsed field ablation (PFA) is a novel form of ablation using electrical fields to ablate cardiac tissue. There are only limited data assessing the feasibility and safety of this type of ablation in humans. PULSED AF (Pulsed Field Ablation to Irreversibly Electroporate Tissue and Treat AF www.clinicaltrials.gov unique identifier: NCT04198701) is a nonrandomized, prospective, multicenter, global, premarket clinical study. The first-in-human pilot phase evaluated the feasibility and efficacy of pulmonary vein isolation using a novel PFA system delivering bipolar, biphasic electrical fields through a circular multielectrode array catheter (PulseSelect Medtronic, Inc). Thirty-eight patients with paroxysmal or persistent atrial fibrillation were treated in 6 centers in Australia, Canada, the United States, and the Netherlands. The primary outcomes were ability to achieve acute pulmonary vein isolation intraprocedurally and safety at 30 days. Acute electrical isolation was achieved in 100% of pulmonary veins (n=152) in the 38 patients. Skin-to-skin procedure time was 160±91 minutes, left atrial dwell time was 82±35 minutes, and fluoroscopy time was 28±9 minutes. No serious adverse events related to the PFA system occurred in the 30-day follow-up including phrenic nerve injury, esophageal injury, stroke, or death. In this first-in-human clinical study, 100% pulmonary vein isolation was achieved using only PFA with no PFA system–related serious adverse events. A graphic abstract is available for this article.
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.ORCP.2019.12.001
Abstract: Obesity is prevalent in Indigenous populations who exhibit significant differences in body fat composition. While excess regional adiposity can be partially inferred from clinical measurements, noninvasive imaging allows for direct quantification of specific fat depots. Epicardial fat is a visceral adipose tissue that has been strongly associated with cardiometabolic disease in other populations. However, this ectopic fat depot has yet to be characterized in Indigenous populations. We studied 100 in iduals matched for ethnicity (Indigenous Australian and Caucasian descent), age, gender, and body mass index. Epicardial and subcutaneous adipose tissue volumes was quantified with computed tomography. Associations of ethnicity and adiposity measures were assessed using linear regression. Indigenous in iduals had significantly greater epicardial fat volumes compared to non-Indigenous in iduals (95.8±37.5 vs 54.1±27.6cm Indigenous in iduals have significantly greater epicardial fat, but similar subcutaneous fat volumes, compared to non-Indigenous in iduals. This finding extends previous observations on body fat composition differences in these in iduals, and supports the possibility that epicardial fat and other visceral adipose depots may be contributing to the greater burden of cardiovascular disease in Indigenous populations.
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.HLC.2018.10.022
Abstract: Catheter ablation (CA) is highly efficacious for symptomatic atrial fibrillation (AF) but data predominantly comes from patients with preserved ventricular function. We performed an updated systematic review and meta-analysis of randomised controlled trials (RCT) comparing CA versus medical therapy for AF associated with heart failure (HF). Medline, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for RCTs reporting clinical outcomes of CA versus medical therapy for AF in HF patients with ≥6 months' follow-up (atrioventricular-node ablation/device therapy studies excluded). Primary endpoint was change in left ventricular ejection fraction (LVEF). Secondary endpoints were 6-minute walk test (6MWT) distance, quality of life (QoL measured by the Minnesota Living with Heart Failure Questionnaire [MLHFQ]), peri-procedural mortality, major peri-procedural complications and mid-term (≥1-year) survival. Six RCTs (n=772 patients mean age 62±11years, LVEF 30±9%) were included. Catheter ablation, compared to medical therapy was associated with: greater improvement in LVEF (mean difference [MD] 5.67% 95% Confidence Interval [CI], 3-8 I Catheter ablation is superior to medical therapy for AF in patients with heart failure resulting in greater improvement in LVEF, quality of life and functional status, with a survival benefit.
Publisher: American Physiological Society
Date: 04-2011
DOI: 10.1152/AJPHEART.01184.2010
Abstract: Elevated QT interval variability is a predictor of malignant ventricular arrhythmia, but the underlying mechanisms are incompletely understood. A recent study in dogs with pacing-induced heart failure suggests that QT variability is linked to cardiac sympathetic nerve activity. The aim of this study was to determine whether increased cardiac sympathetic activity is associated with increased beat-to-beat QT interval variability in patients with essential hypertension. We recorded resting norepinephrine (NE) spillover into the coronary sinus and single-lead, short-term, high-resolution, body-surface ECG in 23 patients with essential hypertension and 9 normotensive control subjects. To assess beat-to-beat QT interval variability, we calculated the overall QT variability (QTVN) as well as the QT variability index (QTVi). Cardiac NE spillover (12.2 ± 6.5 vs. 20.7 ± 14.7, P = 0.03) and QTVi (−1.75 ± 0.36 vs. −1.42 ± 0.50, P = 0.05) were significantly increased in hypertensive patients compared with normotensive subjects. QTVN was significantly correlated with cardiac NE spillover ( r 2 = 0.31, P = 0.001), with RR variability ( r 2 = 0.20, P = 0.008), and with systolic blood pressure ( r 2 = 0.16, P = 0.02). Linear regression analysis identified the former two as independent predictors of QTVN. In conclusion, elevated repolarization lability is directly associated with sympathetic cardiac activation in patients with essential hypertension.
Publisher: Elsevier BV
Date: 06-2017
DOI: 10.1016/J.JCMG.2017.04.001
Abstract: Type 2 diabetes mellitus (T2DM) and obesity are important contributors to nonischemic heart failure (HF) and atrial fibrillation. There is a 2- to 5-fold increase in HF associated with T2DM, and there is a 5% in HF risk in men and 7% increment in women for every unit increment in body mass index, after adjustment for traditional cardiovascular risk factors. Likewise, the risk of atrial fibrillation increases by about 6% per unit increase in body mass index. Metabolic cardiomyopathy leads to a number of changes in cardiac structure and function that can be recognized by imaging in the asymptomatic phase, and these parameters can be used for monitoring the progression of disease or the response to therapy. The purpose of this review is to familiarize clinicians with the potential benefits of early detection of preclinical myocardial abnormalities, as well as the mechanisms that might inform interventions to prevent disease progression in patients with T2DM and obesity.
Publisher: Wiley
Date: 21-04-2006
Publisher: American Medical Association (AMA)
Date: 14-05-2012
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-05-2017
Publisher: Oxford University Press (OUP)
Date: 17-01-2020
Abstract: Physical activity reduces cardiovascular disease burden and mortality, although its relationship with cardiac arrhythmias is less certain. The aim of this study was to assess the association between self-reported physical activity and atrial fibrillation (AF), ventricular arrhythmias and bradyarrhythmias, across the UK Biobank cohort. We included 402 406 in iduals (52.5% female), aged 40–69 years, with over 2.8 million person-years of follow-up who underwent self-reported physical activity assessment computed in metabolic equivalent-minutes per week (MET-min/wk) at baseline, detailed physical assessment and medical history evaluation. Arrhythmia episodes were diagnosed through hospital admissions and death reports. Incident AF risk was lower amongst physically active participants, with a more pronounced reduction amongst female participants [hazard ratio (HR) for 1500 vs. 0 MET-min/wk: 0.85, 95% confidence interval (CI) 0.74–0.98] than males (HR for 1500 vs. 0 MET-min/wk: 0.90, 95% CI 0.82–1.0). Similarly, we observed a significantly lower risk of ventricular arrhythmias amongst physically active participants (HR for 1500 MET-min/wk 0.78, 95% CI 0.64–0.96) that remained relatively stable over a broad range of physical activity levels between 0 and 2500 MET-min/wk. A lower AF risk amongst female participants who engaged in moderate levels of vigorous physical activity was observed (up to 2500 MET-min/wk). Vigorous physical activity was also associated with reduced ventricular arrhythmia risk. Total or vigorous physical activity was not associated with bradyarrhythmias. The risk of AF and ventricular arrhythmias is lower amongst physically active in iduals. These findings provide observational support that physical activity is associated with reduced risk of atrial and ventricular arrhythmias.
Publisher: Elsevier BV
Date: 09-2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 21-04-2020
DOI: 10.1161/CIR.0000000000000748
Abstract: Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, is associated with substantial morbidity, mortality, and healthcare use. Great strides have been made in stroke prevention and rhythm control strategies, yet reducing the incidence of AF has been slowed by the increasing incidence and prevalence of AF risk factors, including obesity, physical inactivity, sleep apnea, diabetes mellitus, hypertension, and other modifiable lifestyle-related factors. Fortunately, many of these AF drivers are potentially reversible, and emerging evidence supports that addressing these modifiable risks may be effective for primary and secondary AF prevention. A structured, protocol-driven multidisciplinary approach to integrate lifestyle and risk factor management as an integral part of AF management may help in the prevention and treatment of AF. However, this aspect of AF management is currently underrecognized, underused, and understudied. The purpose of this American Heart Association scientific statement is to review the association of modifiable risk factors with AF and the effects of risk factor intervention. Implementation strategies, care pathways, and educational links for achieving impactful weight reduction, increased physical activity, and risk factor modification are included. Implications for clinical practice, gaps in knowledge, and future directions for the research community are highlighted.
Publisher: IEEE
Date: 12-2012
Publisher: Elsevier BV
Date: 10-2002
DOI: 10.1016/S0002-9149(02)02601-2
Abstract: We compared transesophageal and phased-array intracardiac echocardiography (TEE/ICE) for the 2-dimensional and spectral Doppler assessment of left atrial (LA) mechanical function. TEE is commonly used to assess LA body and LA appendage mechanical function in patients who are undergoing radiofrequency ablation of typical atrial flutter. Fifteen patients underwent TEE and ICE imaging before and after ablation of typical atrial flutter. The following parameters were measured: (1) LA appendage emptying velocity and fractional area change, (2) severity of LA spontaneous echo contrast (graded 0 to 4), (3) maximal inflow velocity of the left and right upper pulmonary veins, and (5) maximal mitral valve E- and A-wave inflow velocities in sinus rhythm. Diagnostic quality imaging was achieved in all patients with TEE and ICE. Comparing TEE and ICE, the following absolute values and linear correlation coefficient (R) were obtained: preablation LA appendage emptying velocity: 0.45 +/- 0.21 versus 0.44 +/- 0.21 m/s (r = 0.95, p = <0.001) postablation LA appendage velocity: 0.33 +/- 0.24 versus 0.34 +/- 0.24 m/s (r = 0.97, p <0.001) LA appendage fractional area change: 35.3 +/- 13.7 versus 35.9 +/- 17.1% (r = 0.81, p <0.001) left upper/right upper pulmonary vein inflow velocity: 0.50 +/- 0.17/0.49 +/- 0.18 versus 0.51 +/- 0.17/0.47 +/- 0.20 m/s (r = 0.93/0.90, p <0.001) mitral valve E/A wave: 0.66 +/- 0.14/0.31 +/- 0.14 versus 0.69 +/- 0.17/0.35 +/- 0.23 (r = 0.84/0.97, p <0.002) LA spontaneous echo contrast (pre- and postablation): 1.1 +/- 1.2/1.3 +/- 1.2 versus 1.2 +/- 1.3/1.4 +/- 1.3 (r = 0.92/0.90, p <0.001). No patients were identified with LA appendage thrombus. Thus, TEE and phased-array ICE provided equivalent imaging data with high statistical correlation. ICE may be an imaging alternative to TEE in the evaluation of a "stunned" left atrium.
Publisher: BMJ
Date: 02-11-2010
Publisher: Wiley
Date: 08-2014
Abstract: Patients with atrial fibrillation (AF) are at an increased risk of thromboembolism and stroke primarily from the development of thrombi within the left atrium. Pathological changes in blood constituents and atrial endothelial damage promote left atrial thrombus formation. It is not known whether factors predisposing to left atrial thrombus formation in AF are disease specific or also evident within the normal heart. The present study examined whether there are differences in platelet reactivity, endothelial function and inflammation in blood s les obtained from intracardiac and peripheral sites in subjects within structurally normal hearts. Sixteen patients with diagnosed left-sided supraventricular tachycardia (SVT) undergoing a routine elective electrophysiological study and ablation were investigated. Blood s les were taken simultaneously from the femoral vein, right atrium and left atrium, immediately following trans-septal puncture and prior to heparin bolus administration. Between peripheral and atrial s le sites, patients with SVT showed no change in platelet reactivity or aggregation (P-selectin (CD62P) P = 0.91 platelet-derived soluble CD40 ligand P = 0.9), thrombus formation (thrombin-antithrombin complex P = 0.55), endothelial function (von Willebrand factor P = 0.75 asymmetric dimethylarginine (ADMA) P = 0.97 nitric oxide P = 0.61), or inflammation (vascular cell adhesion molecule-1 P = 0.59 intercellular adhesion molecule-1 (ICAM-1) P = 0.69). However, SVT patients had lower ADMA and ICAM-1 levels than AF patients. The present study demonstrates, for the first time, that SVT subjects with structurally normal hearts have consistent haemostatic function between atrial and peripheral sites. These results suggest that the atria of SVT patients do not contain predisposing thrombogenic, endothelial or inflammatory factors that promote and/or initiate thrombus formation.
Publisher: IEEE
Date: 05-2007
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.HRTHM.2019.02.020
Abstract: Atrial fibrillation (AF) is common after pacemaker implantation. However, the impact of pacemaker algorithms in AF prevention is not well understood. The purpose of this study was to evaluate the role of pacing algorithms in preventing AF progression. A systematic search of articles using the PubMed and Embase databases resulted in a total of 754 references. After exclusions, 21 randomized controlled trials (8336 patients) were analyzed, comprising studies reporting ventricular pacing percentage (VP%) (AAI vs DDD, n = 1 reducing ventricular pacing [RedVP] algorithms, n = 2) and atrial pacing therapies (atrial preference pacing [APP], n = 14 atrial antitachycardia pacing [aATP]+APP, n = 3 RedVP+APP+aATP, n = 1). Low VP% (<10%) lead to a nonsignificant reduction in the progression of AF (hazard ratio [HR] 0.80 95% confidence interval [CI] 0.57-1.13 P = .21 I This meta-analysis of randomized controlled trials demonstrated that algorithms to reduce VP% can be considered safe. Low burden VP% did not significantly suppress AF progression. The atrial pacing therapy algorithms could suppress PAC burden but did not prevent AF progression.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 17-08-2021
Abstract: There has been sustained focus on the secondary prevention of coronary heart disease and heart failure yet, apart from stroke prevention, the evidence base for the secondary prevention of atrial fibrillation (AF) recurrence, AF progression, and AF‐related complications is modest. Although there are multiple observational studies, there are few large, robust, randomized trials providing definitive effective approaches for the secondary prevention of AF. Given the increasing incidence and prevalence of AF nationally and internationally, the AF field needs transformative research and a commitment to evidenced‐based secondary prevention strategies. We report on a National Heart, Lung, and Blood Institute virtual workshop directed at identifying knowledge gaps and research opportunities in the secondary prevention of AF. Once AF has been detected, lifestyle changes and novel models of care delivery may contribute to the prevention of AF recurrence, AF progression, and AF‐related complications. Although benefits seen in small subgroups, cohort studies, and selected randomized trials are impressive, the widespread effectiveness of AF secondary prevention strategies remains unknown, calling for development of scalable interventions suitable for erse populations and for identification of subpopulations who may particularly benefit from intensive management. We identified critical research questions for 6 topics relevant to the secondary prevention of AF: (1) weight loss (2) alcohol intake, smoking cessation, and diet (3) cardiac rehabilitation (4) approaches to sleep disorders (5) integrated, team‐based care and (6) nonanticoagulant pharmacotherapy. Our goal is to stimulate innovative research that will accelerate the generation of the evidence to effectively pursue the secondary prevention of AF.
Publisher: Oxford University Press (OUP)
Date: 19-07-2021
Abstract: The aim of this study is to summarize data from prospective cohort studies on clinical predictors of stroke and systemic embolism in anticoagulant-naïve atrial fibrillation (AF) patients. EMBASE, MEDLINE, Global Index Medicus, and Web of Science were searched to identify all studies published by 28 November 2019. Forty-seven studies reporting data from 1 756 984 participants in 15 countries were included. The pooled incidence of stroke in anticoagulant-naïve AF patients was 23.8 per 1000 person-years (95% CI 19.7–28.2). Older age was associated with incident stroke or systemic embolism, with a pooled hazard ratio (HR) of 2.14 (95% CI 1.85–2.47), 2.83 (95% CI 2.27–3.51), and 6.87 (95% CI 6.33–7.44) for age 65–75, ≥75, and ≥85 years, respectively. Other predictors of stroke or systemic embolism included history of stroke or TIA (HR 2.84, 95% CI 2.19–3.67), hypertension (HR 1.60, 95% CI 1.37–1.86), diabetes (HR 1.28, 95% CI 1.20–1.37), heart failure (HR 1.25, 95% CI 1.11–1.40), peripheral artery disease (pooled HR 1.35, 95% CI 1.04–1.75), vascular disease (pooled HR 1.21, 95% CI 1.06–1.39), and prior myocardial infarction (pooled HR 1.08, 95% CI 1.03–1.14). Female sex was a predictor of thromboembolism in studies outside Asia (HR 1.35, 95% CI 1.15–1.59), but not in those done in Asia (HR 0.95, 95% CI 0.81–1.10). This study confirms age and prior stroke as the strongest predictors of stroke or systemic embolism in anticoagulant-naive AF patients. Other predictors include hypertension, diabetes, heart failure, and vascular disease. Female sex seems not to be universally associated with stroke or systemic embolism.
Publisher: BMJ
Date: 04-2019
DOI: 10.1136/HEARTJNL-2018-314471
Abstract: The aim of this study is to characterise hospitalisations due to atrial fibrillation (AF) compared with two other common cardiovascular conditions, myocardial infarction (MI) and heart failure (HF), in addition to the associated economic burden of these hospitalisations and contribution of AF-related procedures. The primary outcome measure was the rate of increase of AF, MI and HF hospitalisations from 1993 to 2013. The rate of increase of AF-related procedures including cardioversion and ablation were also collected, in addition to direct costs associated with hospitalisations for each of these three conditions. AF hospitalisations increased 295% over the 21-year period to a total of 61 424 in 2013. In comparison, MI and HF hospitalisations increased by only 73% and 39%, respectively, over the same period. Considering population changes, there was an annual increase in AF hospitalisations of 5.2% (incidence rate ratio [IRR] 1.052 95% CI 1.046 to 1.059 p .001). In contrast, there was a 2.2% increase per annum for MI (IRR 1.022 95% CI 1.017 to 1.027 p .001) and negligible annual change for HF hospitalisations (IRR 1.000 95% CI 0.997 to 1.002 p=0.78). Cardioversion and AF ablation increased by 10% and 26% annually, respectively. AF hospitalisation costs rose by 479% over the 21-year period, an increase that was more than double that of MI and HF. The burden of AF hospitalisations continues to rise unabated. AF has now surpassed both MI and HF hospitalisations and represents a growing cost burden. New models of healthcare delivery are required to stem this growing healthcare burden.
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.CLINPH.2010.06.017
Abstract: The aim of this study was to assess cardiac ventricular repolarization in patients with postural tachycardia syndrome (POTS) and further the possible link between ventricular repolarization and sympathetic nervous system activity. We recorded body surface ECGs together with plasma noradrenaline (NE) spillover, and muscle sympathetic nerve activity (MSNA) in twelve healthy control subjects (CON 5 males age: 23±2 yrs) and 13 subjects with postural tachycardia syndrome (POTS 4 males 32±13 yrs) during graded head-up tilt (0°-20°-30°-40°). Ventricular repolarization was assessed by computing various measures of beat-to-beat QT interval variability and T wave litude. In patients with POTS, baseline heart rates were higher and MSNA increases during tilt were more pronounced than in CON. None of the QT variability measures was significantly affected by tilt or different between CON and POTS when corrected for heart rate. Contrary, the T wave litude flattened due to tilt (p<0.001) and this effect was significantly more pronounced in POTS (32% at 40°) than in CON (21% at 40° p=0.03). Beat-to-beat variability of the QT interval is normal in patients with POTS. However, significantly more attenuated T waves during head-up tilt together with elevated MSNA levels suggest increased sympathetic outflow to the ventricular myocardium in patients with POTS. Monitoring of the T wave during tilt test may provide a non-invasive tool for assessing excessive sympathetic outflow to the ventricular myocardium.
Publisher: Oxford University Press (OUP)
Date: 15-09-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 22-06-2004
DOI: 10.1161/01.CIR.0000130645.95357.97
Abstract: Background— The modification of atrial fibrillation cycle length (AFCL) during catheter ablation in humans has not been evaluated. Methods and Results— Seventy patients undergoing ablation of prolonged episodes of AF were randomized to pulmonary vein (PV) isolation or additional ablation of the mitral isthmus. Mean AFCL was determined at a distance from the ablated area (coronary sinus) at the following intervals: before ablation, after 2- and 4-PV isolations, and after linear ablation. Inducibility of sustained AF (≥10 minutes) was determined before and after ablation. Spontaneous sustained AF (715±845 minutes) was present in 30 patients and induced in 26 (AFCL, 186±19 ms). PV isolation terminated AF in 75%, with the number of PVs requiring isolation before termination increasing with AF duration ( P =0.018). PV isolation resulted in progressive or abrupt AFCL prolongation to various extents, depending on the PV: to 214±24 ms ( P .0001) when AF terminated and to 194±19 ms ( P =0.002) when AF persisted. The increase in AFCL (30±17 versus 14±11 ms P =0.005) and the decrease in fragmentation (30.0±26.8% to 10.3±14.5% P .0001) were significantly greater in patients with AF termination. Linear ablation prolonged AFCL, with a greater prolongation in patients with AF termination (44±13 versus 22±23 ms P =0.08). Sustained AF was noninducible in 57% after PV isolation and in 77% after linear ablation. At 7±3 months, 74% with PV isolation and 83% with linear ablation were arrhythmia free without antiarrhythmics, which was significantly associated with noninducibility ( P =0.03) with a recurrence rate of 38% and 13% in patients with and without inducibility, respectively. Conclusions— AF ablation results in a decline in AF frequency, with a magnitude correlating with termination of AF and prevention of inducibility that is predictive of subsequent clinical outcome.
Publisher: Elsevier BV
Date: 09-2019
Publisher: Wiley
Date: 25-09-2019
DOI: 10.1111/JCE.14179
Publisher: Wiley
Date: 02-02-2022
DOI: 10.1111/JCE.15387
Abstract: Although single ring isolation is an accepted strategy for undertaking pulmonary vein (PV) and posterior wall isolation (PWI) during atrial fibrillation (AF) ablation, the learning curve associated with this technique as well as procedural and clinical success rates have not been widely reported. Prospectively collected data from 250 consecutive patients undergoing de novo AF ablation using single ring isolation. PWI was achieved in 212 patients (84.8%) and PV isolation without PWI was achieved in 37 patients (14.4%). Thirty-one cases (12.4%) demonstrated inferior line sparing where PWI was achieved without a continuous posterior wall inferior line. A learning curve was observed, with higher rates of PWI (98% last 50 vs. 82% first 50 cases, p = .016), higher rates of inferior line sparing (20% last 50 vs. 8% first 50 cases, p = .071) and lower ablation times (43.8 min (interquartile range [IQR]: 34.6-57.0 min) last 50 versus. 96.5 min (IQR: 80.8-115.8 min) first 50 cases p < .001). Three (1.3%) major procedure-related complications were observed. Twelve-month, single-procedure freedom from atrial arrhythmia without drugs was 70.5% (95% confidence interval [CI]: 61.5%-77.7%) and 60.0% (95% CI: 50.2%-68.4%) for paroxysmal and persistent/longstanding persistent AF. Twelve-month multi-procedure freedom from atrial arrhythmia was 92.2% (95%CI: 85.6%-95.9%) and 85.6% (95%CI: 77.2%-91.0%) for paroxysmal and persistent/longstanding persistent AF. Employing a single ring isolation approach, PWI can be achieved in most cases. There is a substantial learning curve with higher rates of PWI, reduced ablation times, and higher rates of inferior line sparing as procedural experience grows. Long-term freedom from arrhythmia is comparable to other AF ablation techniques.
Publisher: Elsevier BV
Date: 07-2009
DOI: 10.1016/J.HRTHM.2009.03.050
Abstract: Information regarding left atrial (LA) substrate in conditions predisposing to atrial fibrillation (AF) is limited. This study sought to characterize the left atrial remodeling that results from chronic atrial stretch caused by atrial septal defect (ASD). Eleven patients with hemodynamically significant ASDs and 12 control subjects were studied. The following were evaluated using multipolar catheters: effective refractory period (ERP) at 7 sites, P-wave duration (PWD), conduction time, and inducibility of AF. LA electroanatomic maps were created to determine atrial activation, and regional conduction and voltage abnormalities. Patients with ASDs showed significant LA enlargement (P <0.001), unchanged or prolonged atrial ERPs, increase in LA conduction times (P = 0.03), prolonged PWD (P <0.001), regional conduction slowing (P <0.001), greater number of double potentials or fractionated electrograms (P <0.0001), reduced atrial voltage (P <0.001), and more frequent electrical scar (P = 0.005) compared with control subjects. In addition, patients with ASDs showed a greater propensity for sustained AF with single extrastimuli (4 of 11 vs. 0 of 12, P = 0.04). ASDs are associated with chronic left atrial stretch, which results in remodeling characterized by LA enlargement, loss of myocardium, and electrical scar that results in widespread conduction abnormalities but with no change or an increase in ERP. These abnormalities were associated with a greater propensity for sustained AF.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Wiley
Date: 12-01-2005
Publisher: Oxford University Press (OUP)
Date: 14-06-2018
Abstract: Atrio-oesophageal fistula (AOF) is a potentially lethal complication of atrial fibrillation (AF) ablation. Many studies have evaluated the presence and prevention of endoscopically-detected oesophageal lesions (EDOL) as a proxy measure for risk of AOF. This systematic review and meta-analysis sought to determine the prevalence of EDOL and effectiveness of general preventive measures during AF ablation. We searched electronic databases for studies reporting prevalence or prevention of EDOL post-AF ablation. Pooled prevalence were reported with 95% confidence intervals (CI) while studies evaluating preventive measures including oesophageal temperature monitoring (OTM), esophageal manipulation and type of anaesthesia were analyzed descriptively or by random-effects modeling. Twenty-five studies were included in the analysis. Any and ulcerated EDOL pooled prevalence was 11% (95%CI, 6-15%) and 5% (95%CI, 3-7%), respectively. In six studies, there was no difference in EDOL with or without OTM (pooled OR 1.65, 95%CI, 0.22-12.55). There was no difference using a multi-sensor versus single-sensor OTM (one study) nor when using a deflectable probe (two studies). Oesophageal displacement was associated with significant instrumentation injury in one study. Two studies evaluating Oesophageal cooling showed conflicting results. General anaesthesia was associated with more EDOL than conscious sedation in two studies. The pooled prevalence of any and ulcerated EDOL post-ablation was 11% and 5%, but varied between studies. Techniques such as OTM and oesophageal displacement or cooling have not conclusively demonstrated a reduction in EDEL, while general anaesthesia may be associated with higher EDOL risk. Further randomized data are critically needed to validate and develop measures to prevent EDOL and AOF.
Publisher: Elsevier BV
Date: 05-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 24-08-2004
DOI: 10.1161/01.CIR.0000139336.69955.AB
Abstract: Background— Experimental and clinical studies have demonstrated diffuse atrial remodeling in congestive heart failure (CHF). We hypothesized that patients with CHF would demonstrate derangement of sinus node function. Methods and Results— Eighteen patients with symptomatic CHF (left ventricular ejection fraction, 26±5%) and 18 age-matched control subjects were studied. Under autonomic blockade, the following were evaluated: intrinsic sinus cycle length, corrected sinus node recovery time (CSNRT), sinoatrial conduction time, number and duration of fractionated electograms or double potentials along the crista terminalis, and location of the earliest sinus activity. Electroanatomic mapping was performed to evaluate the location and nature of the sinus node complex, to characterize sinoatrial propagation, and to evaluate conduction abnormalities and voltage litude along the crista terminalis. Patients with CHF demonstrated the following findings compared with age-matched control subjects: prolongation of the intrinsic sinus cycle length ( P =0.005), prolongation of CSNRT ( P .0001), caudal localization of sinus activity both during sinus rhythm ( P =0.03) and after pacing ( P =0.002), prolongation of sinoatrial conduction time ( P =0.02), greater number ( P .0001) and duration ( P .0001) of fractionated electrograms or double potentials along the crista terminalis, loss of voltage litude along the crista terminalis ( P =0.02), and abnormal and circuitous propagation of the sinus impulse. Conclusions— This study demonstrates that patients with CHF have significant sinus node remodeling characterized by anatomic and structural changes along the crista terminalis with a reduction in functional sinus node reserve. This finding may have implications for the development of clinical bradycardia in CHF and for the use of negatively chronotropic agents and pacing in this condition.
Publisher: Elsevier
Date: 2017
Publisher: Oxford University Press (OUP)
Date: 15-01-0003
Publisher: Oxford University Press (OUP)
Date: 03-10-2017
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.HRTHM.2017.04.043
Abstract: Evidence for epicardial-endocardial breakthrough (EEB) is derived from mapping inferences in patients with atrial fibrillation who may also have focal activations. The purpose of this study was to investigate whether EEB could be discerned during stable right atrial (RA) macroreentry using high-density high-spatial resolution 3-dimensional mapping. Macroreentry was diagnosed using 3-dimensional mapping and entrainment. Bipolar maps were reviewed for EEB defined as (1) presence of focal endocardial activation with radial spread unaccounted for by an endocardial wavefront and (2) present with the same timing on every tachycardia cycle. The EEB site was always in proximity to a line of endocardial conduction slowing or block. Distance and conduction velocity from the line of block to the EEB site was calculated. Electrograms at EEB sites were in idually analyzed for morphology and to confirm direction of activation. Entrainment was performed at EEB sites. Twenty-six patients were studied. Fourteen ex les of EEB were seen: 11 at the posterior RA (4 at the superior portion of the posterior wall and 7 at the inferior section) and 1 each at the cavotricuspid isthmus postablation, RA septum, and inferolateral RA. The mean area of the EEB site was 0.6 ± 0.2 cm EEB sites were demonstrated in stable atrial macroreentry supported by systematic entrainment confirmation and demonstration of the same phenomenon during pacing.
Publisher: BMJ
Date: 10-10-2005
Publisher: AIP Publishing
Date: 03-2007
DOI: 10.1063/1.2405128
Abstract: A dedicated nonlinear oscillator model able to reproduce the pulse shape, refractory time, and phase sensitivity of the action potential of a natural pacemaker of the heart is developed. The phase space of the oscillator contains a stable node, a hyperbolic saddle, and an unstable focus. The model reproduces several phenomena well known in cardiology, such as certain properties of the sinus rhythm and heart block. In particular, the model reproduces the decrease of heart rate variability with an increase in sympathetic activity. A sinus pause occurs in the model due to a single, well-timed, external pulse just as it occurs in the heart, for ex le due to a single supraventricular ectopy. Several ways by which the oscillations cease in the system are obtained (models of the asystole). The model simulates properly the way vagal activity modulates the heart rate and reproduces the vagal paradox. Two such oscillators, coupled unidirectionally and asymmetrically, allow us to reproduce the properties of heart rate variability obtained from patients with different kinds of heart block including sino-atrial blocks of different degree and a complete AV block (third degree). Finally, we demonstrate the possibility of introducing into the model a spatial dimension that creates exciting possibilities of simulating in the future the SA the AV nodes and the atrium including their true anatomical structure.
Publisher: Wiley
Date: 07-03-2006
Publisher: Elsevier BV
Date: 05-2009
DOI: 10.1016/J.HRTHM.2009.02.023
Abstract: Fractionated atrial electrograms (CFAEs) have been implicated in the mechanism of atrial fibrillation (AF). The prevalence and distribution of CFAEs in normal populations have not been clearly defined. This study sought to determine the influence of age on CFAEs and investigate the relationship between CFAEs and the underlying atrial substrate. Twenty-one patients without structural heart disease underwent electroanatomic mapping of their right atrium (RA). Patients were categorized into 3 groups according to age: group A, patients 60 years (66.9 +/- 7.7 years, n = 8). The proportion of points with CFAEs was analyzed for the high and low septal RA, high and low lateral RA, and high and low posterior RA. The mean atrial voltage and conduction velocity were assessed in each of these regions. The percentage of CFAEs was greater in group C (14.6% +/- 7.7%) than in group A (2.7% +/- 2.1% P = 0.001). The percentage of CFAEs in group B (8.5% +/- 3.5%) was not significantly different from that in group A (P = 0.21) and group C (P = 0.14). The CFAEs were predominantly located in the posterior RA and high septal RA. There were significant correlations between the proportion of CFAEs and age (R = 0.72 P < 0.01), atrial voltage (R = -0.57 P < 0.01), and conduction velocity (R = -0.73 P < 0.001). CFAEs increase with age and occur in regions of low atrial voltage and slowed conduction. The distribution of CFAE is predominantly along the posterior and high septal RA, regions where there are marked changes in myocardial fiber orientation. This suggests that the underlying myocardial architecture is the main influence on electrogram morphology.
Publisher: Oxford University Press (OUP)
Date: 07-08-2019
Abstract: An integrated chronic care programme in terms of a specialized outpatient clinic for patients with atrial fibrillation (AF), has demonstrated improved clinical outcomes. The aim of this study is to assess all-cause mortality in patients in whom AF management was delivered through a specialized outpatient clinic offering an integrated chronic care programme. Post hoc analysis of a Prospective Randomized Open Blinded Endpoint Clinical trial to assess all-cause mortality in AF patients. The study included 712 patients with newly diagnosed AF, who were referred for AF management to the outpatient service of a University hospital. In the specialized outpatient clinic (AF-Clinic), comprehensive, multidisciplinary, and patient-centred AF care was provided, i.e. nurse-driven, physician supervised AF treatment guided by software based on the latest guidelines. The control group received usual care by a cardiologist in the regular outpatient setting. After a mean follow-up of 22 months, all-cause mortality amounted 3.7% (13 patients) in the AF-Clinic arm and 8.1% (29 patients) in usual care [hazard ratio (HR) 0.44, 95% confidence interval (CI) 0.23–0.85 P = 0.014]. This included cardiovascular mortality in 4 AF-Clinic patients (1.1%) and 14 patients (3.9%) in usual care (HR 0.28 95% CI 0.09–0.85 P = 0.025). Further, 9 patients (2.5%) died in the AF-Clinic arm due to a non-cardiovascular reason and 15 patients (4.2%) in the usual care arm (HR 0.59 95% CI 0.26–1.34 P = 0.206). An integrated specialized AF-Clinic reduces all-cause mortality compared with usual care. These findings provide compelling evidence that an integrated approach should be widely implemented in AF management.
Publisher: Oxford University Press (OUP)
Date: 14-06-2018
Abstract: Atrial fibrillation (AF) is a progressive disease. Obesity is associated with progression of AF. This study evaluates the impact of weight and risk factor management (RFM) on progression of the AF. As described in the Long-Term Effect of Goal-Directed Weight Management in an Atrial Fibrillation Cohort: A Long-Term Follow-Up (LEGACY) Study, of 1415 consecutive AF patients, 825 had body mass index ≥ 27 kg/m2 and were offered weight and RFM. After exclusion, 355 were included for analysis. Weight loss was categorized as: Group 1 (<3%), Group 2 (3-9%), and Group 3 (≥10%). Change in AF type was determined by clinical review and 7-day Holter yearly. Atrial fibrillation type was categorized as per the Heart Rhythm Society consensus. There were no differences in baseline characteristic or follow-up duration between groups (P = NS). In Group 1, 41% progressed from paroxysmal to persistent and 26% from persistent to paroxysmal or no AF. In Group 2, 32% progressed from paroxysmal to persistent and 49% reversed from persistent to paroxysmal or no AF. In Group 3, 3% progressed to persistent and 88% reversed from persistent to paroxysmal or no AF (P < 0.001). Increased weight loss was significantly associated with greater AF freedom: 45 (39%) in Group 1, 69 (67%) in Group 2, and 116 (86%) in Group 3 (P ≤ 0.001). Obesity is associated with progression of the AF disease. This study demonstrates the dynamic relationship between weight/risk factors and AF. Weight-loss management and RFM reverses the type and natural progression of AF.
Publisher: Elsevier BV
Date: 11-2018
Publisher: Wiley
Date: 25-07-2006
DOI: 10.1111/J.1540-8167.2006.00546.X
Abstract: The pulmonary veins (PVs) are a dominant source of triggers initiating atrial fibrillation (AF). While recent evidence implicates these structures in the maintenance of paroxysmal AF, their role in permanent AF is not known. The current study aims to compare the contribution of PV activity to the maintenance of paroxysmal and permanent AF. Thirty-four patients with paroxysmal AF (n = 20) or permanent AF (n = 14) undergoing ablation were studied. Prior to ablation, 32 seconds of electrograms were acquired from each PV and the coronary sinus (CS). The frequency of activity of each PV and CS was defined as the highest litude frequency on spectral analysis. The effects of ablation on the AF cycle length (AFCL) and frequency and on AF termination were determined. Significant differences were observed between paroxysmal and permanent AF. Paroxysmal AF demonstrates higher frequency PV activity (11.0 +/- 3.1 vs 8.8 +/- 3.0 Hz P = 0.0003) but lower CS frequency (5.8 +/- 1.2 vs 6.9 +/- 1.4 Hz P = 0.01) and longer AFCL (182 +/- 17 vs 158 +/- 21 msec P = 0.002), resulting in greater PV to atrial frequency gradient (7.2 +/- 2.2 vs 4.2 +/- 2.9 Hz P = 0.006). PV isolation in paroxysmal AF resulted in a greater decrease in atrial frequency (1.0 +/- 0.7 vs -0.05 +/- 0.4 Hz P < 0.0001), greater prolongation of the AFCL (49 +/- 35 vs 5 +/- 6 msec P < 0.0001), and more frequent AF termination (11/20 vs 0/14 P = 0.0007) compared to permanent AF. Paroxysmal AF is associated with higher frequency PV activity and lesser CS frequency compared to permanent AF. Isolation of the PVs had a greater impact on the fibrillatory process in paroxysmal AF compared to permanent AF, suggesting that while the PVs have a role in maintaining paroxysmal AF, these structures independently contribute less to the maintenance of permanent AF.
Publisher: Elsevier BV
Date: 07-2004
Publisher: IEEE
Date: 07-2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-03-2019
Abstract: See Article by Lee et al
Publisher: Oxford University Press (OUP)
Date: 06-2023
Abstract: Implantable cardioverter defibrillators (ICDs) prevent sudden cardiac death. Anxiety, depression, and post-traumatic stress disorder (PTSD) are underappreciated symptoms. We aimed to systematically synthesize prevalence estimates of mood disorders and symptom severities, pre- and post-ICD insertions. Comparisons were made with control groups, as well as within ICD patients by indication (primary vs. secondary), sex, shock status, and over time. Databases (Medline, PsycINFO, PubMed, and Embase) were searched without limits from inception to 31 August 2022 4661 articles were identified, 109 (39 954 patients) of which met criteria. Random-effects meta-analyses revealed clinically relevant anxiety in 22.58% (95%CI 18.26–26.91%) of ICD patients across all timepoints following insertion and depression in 15.42% (95%CI 11.90–18.94%). Post-traumatic stress disorder was seen in 12.43% (95%CI 6.90–17.96%). Rates did not vary relative to indication group. Clinically relevant anxiety and depression were more likely in ICD patients who experienced shocks [anxiety odds ratio (OR) = 3.92 (95%CI 1.67–9.19) depression OR = 1.87 (95%CI 1.34–2.59)]. Higher symptoms of anxiety were seen in females than males post-insertion [Hedges’ g = 0.39 (95%CI 0.15–0.62)]. Depression symptoms decreased in the first 5 months post-insertion [Hedges’ g = 0.13 (95%CI 0.03–0.23)] and anxiety symptoms after 6 months [Hedges’ g = 0.07 (95%CI 0–0.14)]. Depression and anxiety are highly prevalent in ICD patients, especially in those who experience shocks. Of particular concern is the prevalence of PTSD following ICD implantation. Psychological assessment, monitoring, and therapy should be offered to ICD patients and their partners as part of routine care.
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.AMJCARD.2007.11.007
Abstract: Increased consumption of fish and/or fish oil was associated with decreased risk of sudden cardiac death (SCD). The study aim was to evaluate the antiarrhythmic effect of dietary fish oil on the inducibility of ventricular tachycardia (VT) at high risk of SCD. Patients with coronary artery disease undergoing defibrillator implantation were recruited if sustained monomorphic VT could be induced by programmed extra stimuli at 2 cycle lengths. After the initial study, 12 patients consumed 3 g/d of encapsulated fish oil for approximately 6 weeks before a repeated electrophysiologic study. To control for fluctuations in the inducibility of VT, an additional 14 patients with no dietary manipulation were also studied. Aggressiveness of stimulation required to induce VT was ranked from least aggressive to most aggressive based on cycle length and number of extra stimuli, with noninducibility ranked highest. At the repeated electrophysiologic study, in the fish-oil group, 42% had no inducible VT, 42% required more aggressive stimulation to induce VT, 8% required identical stimulation, and 8% required less stimulation compared with 7%, 36%, 36%, and 21% in the control group, respectively. Overall, there was a change to noninducible or less inducible VT in the fish-oil group, but no change in the control group (p = 0.003 and p = 0.65, respectively Wilcoxon's sign-rank test). In conclusion, dietary n-3 fatty acid supplementation decreased the inducibility of VT in patients at risk of SCD. These findings suggest that dietary fish oil can have an antiarrhythmic effect.
Publisher: Wiley
Date: 03-2001
DOI: 10.1046/J.1540-8167.2001.00343.X
Abstract: We sought to evaluate the utility of a phased-array intracardiac echocardiography (ICE) device to identify left atrial (LA) and pulmonary vein (PV) anatomy accurately guide radiofrequency ablation (RFA) to the right or left PV ostium and LA appendage (LAA) and evaluate PV blood flow before and after RFA using Doppler parameters. Twelve adult sheep were anesthetized and an Acuson 10-French, 7-MHz ICE transducer introduced via the internal jugular vein into the right atrium. The LA was imaged and PV anatomy and blood flow documented using two-dimensional and pulsed-wave Doppler. Mean LA dimensions were 4.6 +/- 0.4 x 3.5 +/- 0.5 cm mean single right and left main PV ostium diameters were 1.5 +/- 0.2 and 1.3 +/- 0.3 cm and mean right and left PV first-order branch diameters were 0.8 +/-0.2 and 0.6 +/- 0.1 cm. Mean PV maximum inflow velocity for the right PV were 0.30 +/- 0.05 m/sec and for the left PV were 0.35 +/- 0.04 m/sec. The PV ostia and LAA could be targeted accurately for RFA using ICE guidance. At pathologic evaluation, the mean distance of the lesion center to the right or left PV-LA junction was 3.0 +/- 2.0 mm. The mean distance of the lesion center to the posterior margin of the LAA was <4 mm in all cases. There was no significant increase in PV maximum inflow velocity or decrease in PV diameter following RFA at the PV ostium. Absence of PV obstruction was confirmed at pathology. Phased-array ICE allows detailed assessment of LA and PV anatomy when imaged from the right atrium accurate guidance of RFA to the PV ostium and LAA and immediate evaluation of PV patency after RFA.
Publisher: Elsevier BV
Date: 06-2014
Publisher: Wiley
Date: 27-07-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 25-02-2020
Publisher: BMJ
Date: 07-08-2020
Publisher: Wiley
Date: 05-04-2012
DOI: 10.1111/J.1540-8159.2012.03386.X
Abstract: Coronary sinus (CS) has muscular connections with atria and is often targeted to complete left atrial ablation for curing atrial fibrillation however, complete CS isolation is difficult to achieve with hard end points. We present a distinctive case of complete isolation of CS that had an unusual muscular connection.
Publisher: Informa UK Limited
Date: 12-2017
DOI: 10.2147/VHRM.S127393
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-09-2003
DOI: 10.1161/01.CIR.0000090685.13169.07
Abstract: Background— Symptomatic prolonged sinus pauses on termination of atrial fibrillation (AF) are an indication for pacemaker implantation. We evaluated sinus node function and clinical outcome in patients with prolonged sinus pauses on termination of arrhythmia who underwent ablation of paroxysmal AF. Methods and Results— Twenty patients with paroxysmal AF and prolonged sinus pauses (≥3 seconds) on termination of AF underwent ablation between May 1995 and November 2002. Patients with sinus pauses independent of episodes of AF were excluded from the analysis. The procedure included pulmonary vein and linear atrial ablation. After ablation, sinus node function was assessed during the first week and at 1, 3, and 6 months, by 24-hour ambulatory monitoring to determine the mean heart rate and heart rate range, and by exercise testing to determine the maximal heart rate. Corrected sinus node recovery time was determined at the completion of ablation and at 24.0±11.3 months at 600 and 400 ms. After AF ablation, there was a significant improvement of sinus node function, with an increase in the mean heart rate ( P =0.001), maximal heart rate ( P .0001), and heart rate range ( P .0001). The corrected sinus node recovery time decreased in all patients evaluated at 600 ms ( P =0.016) and 400 ms ( P =0.019). At 26.0±17.6 months, 18 patients (85%) had no recurrence of AF (in the absence of medication), with no symptoms attributable to bradycardia or sinus pauses on ambulatory monitoring. Two patients had infrequent episodes of AF, 1 requiring pacemaker implantation. Conclusion— Prolonged sinus pauses after paroxysms of AF may result from depression of sinus node function that can be eliminated by curative ablation of AF. This is accompanied by improvement in parameters of sinus node function, suggesting reverse remodeling of the sinus node.
Publisher: Wiley
Date: 10-1999
Publisher: Wiley
Date: 02-2002
DOI: 10.1046/J.1460-9592.2002.00201.X
Abstract: On occasion, patients with a tricuspid annuloplasty ring may require permanent cardiac pacing. Although it is technically possible to pass a ventricular transvenous lead through a tricuspid valve with an annuloplasty ring, the procedure is complicated by considerable chamber enlargement and mechanical distortion of the tricuspid valve often with severe residual tricuspid regurgitation. Over a 25-month period, transvenous ventricular lead placement following insertion of a tricuspid annuloplasty ring was successfully performed in five patients (three women). The patient mean age was 66 years (range 55-77 years). Four cases had slow atrial fibrillation and another paroxysmal atrial fibrillation requiring His-bundle ablation. Two patients had mitral valve replacement and two aortic and mitral valve replacements. All patients had residual severe to torrential tricuspid regurgitation. Seven ventricular steroid-eluting screw-in leads were used. Single leads were used in three cases, whereas in two others, two ventricular leads were attached to a dual chamber pulse generator. Although technically difficult, ventricular lead placement was successful using standard guidewires with broad curvatures. Satisfactory acute and follow-up stimulation thresholds and sensing were obtained with the only complication being an intraoperative lead dislodgement, prompting a second ventricular lead. Successful transvenous lead placement across a tricuspid annuloplasty ring is possible.
Publisher: American Physiological Society
Date: 08-2009
DOI: 10.1152/AJPHEART.00236.2009
Abstract: Changes in measures of heart rate variability (HRV) have been associated with an increased risk for sudden cardiac death. The mechanisms underlying this association are not known. The objective of this study was to assess the relationship between the amount of norepinephrine (NE) released from the cardiac sympathetic terminals and short-term HRV. The study comprised 8 healthy subjects, 12 patients with major depression, and 7 patients with panic disorder. Cardiac NE spillover was determined using direct coronary sinus blood s ling coupled with an NE isotope dilution methodology. Short-term HRV was quantified using detrended fluctuation analysis, symbolic dynamics, s le entropy, and standard time and frequency domain measures. Neither HRV nor cardiac NE spillover was significantly different between the analyzed groups. None of the standard HRV metrics was significantly correlated with cardiac NE spillover, but there was a moderate correlation between two complexity measures of HRV (symbolic dynamics) and cardiac NE spillover (patterns with 2 like variations, r = −0.37 and P = 0.05 and patterns with no variations: r = 0.34 and P = 0.06). In conclusion, there is no correlation between standard HRV measures and cardiac NE spillover in humans. Short-term complexity of heart rate is only moderately affected by sympathetic neural outflow. Therefore, the predictive value of most HRV measures for sudden cardiac death may predominantly result from their capacity to capture vagally mediated heart rate modulations.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-03-2013
Abstract: In the past decade, catheter ablation has become an established therapy for symptomatic atrial fibrillation ( AF ). Until very recently, few data have been available to guide the clinical community on the outcomes of AF ablation at ≥3 years of follow‐up. We aimed to systematically review the medical literature to evaluate the long‐term outcomes of AF ablation. A structured electronic database search (PubMed, Embase, Web of Science, Cochrane) of the scientific literature was performed for studies describing outcomes at ≥3 years after AF ablation, with a mean follow‐up of ≥24 months after the index procedure. The following data were extracted: (1) single‐procedure success, (2) multiple‐procedure success, and (3) requirement for repeat procedures. Data were extracted from 19 studies, including 6167 patients undergoing AF ablation. Single‐procedure freedom from atrial arrhythmia at long‐term follow‐up was 53.1% (95% CI 46.2% to 60.0%) overall, 54.1% (95% CI 44.4% to 63.4%) in paroxysmal AF , and 41.8% (95% CI 25.2% to 60.5%) in nonparoxysmal AF . Substantial heterogeneity (I 2 %) was noted for single‐procedure outcomes. With multiple procedures, the long‐term success rate was 79.8% (95% CI 75.0% to 83.8%) overall, with significant heterogeneity (I 2 %).The average number of procedures per patient was 1.51 (95% CI 1.36 to 1.67). Catheter ablation is an effective and durable long‐term therapeutic strategy for some AF patients. Although significant heterogeneity is seen with single procedures, long‐term freedom from atrial arrhythmia can be achieved in some patients, but multiple procedures may be required.
Publisher: Elsevier BV
Date: 2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-05-2023
DOI: 10.1161/CIRCULATIONAHA.123.063988
Abstract: Pulsed field ablation uses electrical pulses to cause nonthermal irreversible electroporation and induce cardiac cell death. Pulsed field ablation may have effectiveness comparable to traditional catheter ablation while preventing thermally mediated complications. The PULSED AF pivotal study (Pulsed Field Ablation to Irreversibly Electroporate Tissue and Treat AF) was a prospective, global, multicenter, nonrandomized, paired single-arm study in which patients with paroxysmal (n=150) or persistent (n=150) symptomatic atrial fibrillation (AF) refractory to class I or III antiarrhythmic drugs were treated with pulsed field ablation. All patients were monitored for 1 year using weekly and symptomatic transtelephonic monitoring 3-, 6-, and 12-month ECGs and 6- and 12-month 24-hour Holter monitoring. The primary effectiveness end point was freedom from a composite of acute procedural failure, arrhythmia recurrence, or antiarrhythmic escalation through 12 months, excluding a 3-month blanking period to allow recovery from the procedure. The primary safety end point was freedom from a composite of serious procedure- and device-related adverse events. Kaplan-Meier methods were used to evaluate the primary end points. Pulsed field ablation was shown to be effective at 1 year in 66.2% (95% CI, 57.9 to 73.2) of patients with paroxysmal AF and 55.1% (95% CI, 46.7 to 62.7) of patients with persistent AF. The primary safety end point occurred in 1 patient (0.7% 95% CI, 0.1 to 4.6) in both the paroxysmal and persistent AF cohorts. PULSED AF demonstrated a low rate of primary safety adverse events (0.7%) and provided effectiveness consistent with established ablation technologies using a novel irreversible electroporation energy to treat patients with AF. URL: www.clinicaltrials.gov Unique identifier: NCT04198701.
Publisher: Elsevier BV
Date: 07-2015
DOI: 10.1016/J.HRTHM.2015.03.017
Abstract: The pathophysiological relevance of complex fractionated atrial electrograms (CFAE) in atrial fibrillation (AF) remains poorly understood. The aim of this study was to comprehensively investigate how bipolar CFAE correlates with unipolar electrogram fractionation and the underlying electrophysiological substrate of AF. Ten-second unipolar AF electrograms were recorded using a high-density electrode from the left atrium of 20 patients with AF (10 with persistent AF and 10 with paroxysmal AF) undergoing cardiac surgery. Semiautomated bipolar CFAE algorithms: complex fractionated electrogram-mean, interval confidence interval, continuous electrical activity, average complex interval, and shortest complex interval were evaluated against AF substrate complexity measures following fibrillation wave reconstruction derived from local unipolar activation time. The effect of interelectrode spacing and electrode orientation on bipolar CFAE was also examined. All 5 semiautomated bipolar CFAE algorithms showed poor correlation with each other and AF substrate complexity measures (conduction velocity, number of waves or breakthroughs per AF cycle, and electrical dissociation). Bipolar CFAE also correlated poorly with fractionation index derived from unipolar electrograms. Increased interelectrode spacing resulted in an increase in bipolar CFAE detected except for the interval confidence interval algorithm. CFAE appears unaffected by bipolar electrode orientation (vertical vs horizontal). By contrast, unipolar fractionation index correlated well with AF substrate complexity measures and can be regarded as a marker for conduction block. The lack of pathophysiological relevance of bipolar CFAE analysis may in part contribute to the ergent and limited success rates of catheter ablation strategies targeting CFAE.
Publisher: Wiley
Date: 12-2005
DOI: 10.1111/J.1540-8167.2005.00225.X
Abstract: Noninducibility of sustained atrial fibrillation (AF) after pulmonary vein isolation (PVI) has been shown to be associated with a better clinical outcome. We evaluated the role of clinical variables that could predict noninducibility of sustained AF after PVI. Data were collected prospectively from 181 patients (153 male age 54 +/- 9 years) referred for ablation of drug-refractory symptomatic paroxysmal AF (duration < or =7 days). Clinical variables were evaluated with regard to their ability of predicting noninducibility of sustained AF (< or =10 minutes) after PVI. Univariate analysis was performed on all collected variables followed by multivariate analysis for variables showing a P value <0.1. After PVI, sustained AF was noninducible in 97 (54%) patients. The following clinical variables showed a significant difference between the groups: body weight, longest AF episode, duration of AF history, presence or absence of structural heart disease, left ventricular (LV) hypertrophy, prior cardioversion, left atrial (LA) parasternal, and longitudinal diameters and LV diameters. On multivariate analysis, three independent predictors of noninducibility were identified: a shorter duration of AF episodes (AF <12 hours: RR 0.01 (0.002-0.06), P < 0.001 AF 12-48 hours: RR 0.07 (0.01-0.37), P = 0.001) LA longitudinal diameter <57 mm (RR 0.33 (0.13-0.82), P = 0.016) and absence of LV hypertrophy (RR 0.15 (0.04-0.63), P = 0.01). Shorter AF episodes, smaller LA longitudinal diameter, and absence of LV hypertrophy are independent predictors of noninducibility of sustained AF after PVI.
Publisher: Oxford University Press (OUP)
Date: 03-2018
Abstract: Several techniques have been utilized for the ablation of persistent (P) and long-standing persistent (LsP) atrial fibrillation (AF) however, the best approach of substrate ablation remains poorly defined. This study aims to examine the impact of ablation approach on outcomes associated with P or LsP AF ablation by conducting a meta-analysis and regression on contemporary literature. A systematic literature review was conducted up to 29 July 2015 for scientific literature reporting on outcomes associated with P or LsP AF ablation. One hundred and thirteen studies reported outcomes in a total of 18 657 patients undergoing various ablation approaches for the treatment of P-LsP AF between 2001 and 2015. The point efficacy estimate of a single-AF ablation procedure without the use of anti-arrhythmic drugs was 43% (95% CI 39-47%). Multiple procedures and/or the use of anti-arrhythmic drugs increase success to 69% (95% CI 66-71%). Meta-regression revealed that ablation technique (P < 0.001) and left atrial size (P = 0.02) were predictive of single procedure, drug-free success. The addition of extra-pulmonary substrate approaches was associated with declining efficacy when compared to a pulmonary vein ablation alone. The efficacy of a single-AF ablation procedure for P or LsP AF is 43% however, can be increased to 69% with the use of multiple procedures and/or anti-arrhythmic drugs. Current literature supports the finding that pulmonary vein antrum ablation/isolation is at least equivalently efficacious to other contemporary P-LsP ablation strategies.
Publisher: Oxford University Press (OUP)
Date: 03-10-2007
Abstract: We present a 51-year-old morbidly obese man who underwent insertion of a single-chamber implantable cardioverter defibrillator for monomorphic ventricular tachycardia occurring after myocardial infarction. After a period of satisfactory device function, a sudden change in R-wave with atrial over-sensing heralded inappropriate defibrillation and induction of ventricular fibrillation, with subsequent death of the patient.
Publisher: Oxford University Press (OUP)
Date: 06-2004
Publisher: World Scientific Pub Co Pte Lt
Date: 03-2009
DOI: 10.1142/S0219519409002894
Abstract: Intra-cardiac blood flow imaging and visualization is challenging due to the processes involved in generating velocity fields of flow within specific chambers of interest. Visual analysis of cardiac flow or wall deformation is crucial for an accurate examination of the heart. Cardiac chamber boundary encapsulation is one of the key implementations for region definition. To provide intelligible results describing flow within the human heart, cardiac chamber segmentation is a pre-requisite so that fluid motion information can be presented within a region of interest defined by the chamber boundary. A technique that is used to establish contouring along the cardiac wall is described mathematically. This article also sets the practical foundation for flow vector synthesis and visualization in the cardiac discipline. We have outlined conceptual development and the construction of flow field based on a three-dimensional Cartesian grid that can give a greater insight into the blood dynamics within the heart. We developed a framework that is able to present both anatomical as well as flow information by overlaying velocity fields over medical images and displaying them in cine-mode. By addressing most of the methods involved from the programming perspective, procedural execution and memory efficiency have been considered. Our implemented system can be used to examine abnormal blood motion behaviour or discover flow phenomena in normal or defective hearts.
Publisher: Elsevier BV
Date: 08-2023
Publisher: Elsevier BV
Date: 03-2018
DOI: 10.1016/J.AHJ.2017.12.007
Abstract: The optimal long-term antithrombotic regimen for patients after successful catheter-based atrial fibrillation (AF) ablation is not well defined. Presently, practice variation exists, and the benefits of oral anticoagulation over antiplatelet therapy across the entire spectrum of stroke risk profile remain undefined in the postablation population. To date, there are no randomized trials to inform clinicians on this therapeutic question. The objective was to assess whether rivaroxaban is superior to acetylsalicylic acid (ASA) in reducing the risk of clinically overt stroke, systemic embolism, or covert stroke among patients without apparent recurrent atrial arrhythmias for at least 1 year after their most recent AF ablation procedure. A prospective, multicenter, open-label, randomized trial with blinded assessment of outcomes is under way (NCT02168829). Atrial fibrillation patients with at least 1 stroke risk factor (as defined by the CHA The OCEAN trial is a multicenter randomized controlled trial evaluating 2 antithrombotic treatment strategies for patients with risk factors for stroke after apparently successful AF ablation. We hypothesize that rivaroxaban will reduce the occurrence of clinically overt stroke, systemic embolism, and covert stroke when compared with ASA alone.
Publisher: Elsevier BV
Date: 06-2018
Publisher: Elsevier BV
Date: 11-2021
DOI: 10.1016/J.CJCA.2021.09.026
Abstract: In this study, we sought to estimate the prevalence of concomitant sleep-disordered breathing (SDB) in patients with atrial fibrillation (AF) and to systematically evaluate how SDB is assessed in this population. We searched Medline, Embase and Cinahl databases through August 2020 for studies reporting on SDB in a minimum 100 patients with AF. For quantitative analysis, studies were required to have systematically assessed for SDB in consecutive AF patients. Pooled prevalence estimates were calculated with the use of the random effects model. Weighted mean differences and odds ratios were calculated when possible to assess the strength of association between baseline characteristics and SDB. The search yielded 2758 records, of which 33 studies (n = 23,894 patients) met the inclusion criteria for qualitative synthesis and 13 studies (n = 2660 patients) met the meta-analysis criteria. The pooled SDB prevalence based on an SDB diagnosis cutoff of apnea-hypopnea index (AHI) ≥ 5/h was 78% (95% confidence interval [CI] 70%-86% P < 0.001). For moderate-to-severe SDB (AHI ≥ 15/h), the pooled SDB prevalence was 40% (95% CI 32%-48% P < 0.001). High degrees of heterogeneity were observed (I SDB is highly prevalent in patients with AF. Wide variation exists in the diagnostic tools and thresholds used to detect concomitant SDB in AF. Prospective systematic testing for SDB in unselected cohorts of AF patients may be required to define the true prevalence of SDB in this population.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-12-2018
DOI: 10.1161/CIRCULATIONAHA.105.546648
Abstract: Background— Endocardial mapping of localized sources driving atrial fibrillation (AF) in humans has not been reported. Methods and Results— Fifty patients with AF organized by prior pulmonary vein and linear ablation were studied. AF was considered organized if mapping during AF showed irregular but discrete atrial complexes exhibiting consistent activation sequences for % of the time using a 20-pole catheter with 5 radiating spines covering 3.5-cm diameter or sequential conventional mapping. A site or region centrifugally activating the remaining atrial tissue defined a source. During AF with a cycle length of 211±32 ms, activation mapping identified 1 to 3 sources at the origin of atrial wavefronts in 38 patients (76%) predominantly in the left atrium, including the coronary sinus region. Electrograms at the earliest area varied from discrete centrifugal activation to an activity spanning 75% to 100% of the cycle length in 42% of cases, the latter indicating complex local conduction or a reentrant circuit. A gradient of cycle length ( ms) to the surrounding atrium was observed in 28%. Local radiofrequency ablation prolonged AF cycle length by 28±22 ms and either terminated AF or changed activation sequence to another organized rhythm. In 4 patients, the driving source was isolated, surrounded by the atrium in sinus rhythm, and still firing at high frequency (228±31 ms) either permanently or in bursts. Conclusions— AF associated with consistent atrial activation sequences after prior ablation emanates mostly from localized sources that can be mapped and ablated. Some sources harbor electrograms suggesting the presence of localized reentry.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-06-2014
Publisher: Elsevier BV
Date: 04-2012
DOI: 10.1016/J.HRTHM.2011.11.013
Abstract: Whether curative ablation can prevent progression of the atrial electroanatomic remodeling associated with atrial fibrillation (AF) is not known. The purpose of this study was to determine whether successful radiofrequency ablation (RFA) of AF can prevent progression of the atrial substrate associated with AF. Detailed right atrial electroanatomic maps from 11 patients without apparent structural heart disease undergoing RFA of AF at baseline and ≥6 months following successful RFA were compared to 11 control patients undergoing electrophysiologic evaluation of supraventricular tachycardia. Bipolar voltage, conduction, effective refractory periods (ERPs), and signal complexity were assessed. At baseline compared with the control group, the AF group demonstrated (1) lower voltage (P <.001) (2) slowed conduction (P = .005) (3) more prevalent complex signals (P <.001) (4) prolonged regional refractoriness (P <.05), and (5) left atrial dilation (P = .01). At 10 ± 13 month follow-up, the AF group demonstrated the following compared to baseline: (1) lower voltage (P <.05) (2) either no improvement or further slowing of conduction (3) further prolongation of regional refractoriness (P <.05) and (4) reversal of left atrial dilation (P <.05). Patients with lone AF demonstrate evidence of an abnormal atrial substrate at baseline compared to control patients without AF. This substrate does not appear to reverse even after successful catheter ablation. These findings may have implications for long-term outcomes of ablation and for timing of ablative intervention.
Publisher: Wiley
Date: 03-2004
Publisher: Oxford University Press (OUP)
Date: 04-01-2018
Abstract: Real-time contact force (CF)-sensing radiofrequency ablation catheter for treatment of paroxysmal atrial fibrillation (PAF) allows optimization of electrode-tissue contact, which correlates with long-term success. This prospective, multicentre observational registry assessed the real-world clinical effectiveness of a CF-sensing catheter for ablation of drug-refractory PAF. Patients were followed-up at 3, 6, and 12 months after ablation. Outcome measures included isolation of targeted pulmonary veins (PVs) confirmed by entrance block (acute success), patient-reported freedom from symptomatic atrial fibrillation (AF) at 12 months (long-term effectiveness), Atrial Fibrillation Effect on Quality-of-life scores at 6 and 12 months, and incidence of predefined procedural complications. The registry enrolled 261 PAF patients (mean age 58.8 ± 11.3 years 70.7% men 91.7% Caucasian). Acute PV isolation was reported in 98.8% of patients [95% confidence interval (CI): 96.4-99.7%], and 12-month success for freedom from symptomatic AF was 75.7% (95% CI: 69.7-80.7%). Average CF for the evaluable cohort was 16.4 ± 3.9 g. There was a significant correlation between long-term effectiveness and stability of CF use [percentage of time CF was within investigator-selected working range odds ratio (95% Wald CI), 1.0 (1.00-1.1) P = 0.030]. Average CF did not correlate with 12-month success. Clinically meaningful quality of life (QoL) improvements were observed at 6 and 12 months. Primary adverse events occurred in 2.7% patients. This observational registry showed that PAF ablation with a CF-sensing catheter had high acute success rates, favourable 12-month outcomes, and a good safety profile. Patients' QoL improved significantly. Long-term effectiveness significantly correlated with stable CF with adequate catheter-tissue contact (NCT01677052).
Publisher: Oxford University Press (OUP)
Date: 29-06-2019
DOI: 10.1093/ICVTS/IVY191
Abstract: Atrial fibrillation is treated surgically by creating conduction block lesions. Radiofrequency (RF) lesions have reduced efficacy compared to 'cut-and-sew'. Catheter ablation studies demonstrate a relationship between lesion depth and contact force. We hypothesized that contact force and lesion depth are dependent on design of the bipolar surgical RF cl s. Hinged and parallel jaw style RF cl s were studied. Muscle s les were cl ed with pressure-sensitive film at increasing tissue thicknesses. Films were analysed determining cl pressure profiles. A sheep model was utilized for ablation testing using each cl style until the device indicated transmurality. Separate muscle areas had 1, 2 or 3 burns applied. The muscle was excised, sectioned every 1 cm and stained for lesion depth and fat thickness analysis. Pressure profiling comparing the proximal and distal segments of each cl style demonstrated only one statistically significant difference in the parallel cl the hinged cl had statistically significant differences (P ≤ 0.03) for all tissue thicknesses. There was no evidence for differences in the proximal lesion depth of both cl s (P = 0.13) but deeper distally in the parallel cl (10.17 mm vs 8.02 mm, P = 0.003). The logistic regression analysis demonstrated increased odds of transmurality with parallel cl s at 1, 2 or 3 burns (P = 0.03, P = 0.003 and P = 0.002). Every 1 mm increase in overlying fat decreased likelihood of transmurality by 11% (P < 0.05). The parallel and hinged cl s have different pressure profiles with higher likelihood of transmurality using the parallel cl . Fat reduces the ability of RF to deliver a transmural lesion. These findings have implications for optimal surgical RF ablation technique.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Elsevier BV
Date: 06-2010
DOI: 10.1016/J.HRTHM.2010.01.017
Abstract: Ablation of long-standing persistent atrial fibrillation (AF) is highly variable, with differing techniques and outcomes. The purpose of this study was to undertake a systematic review of the literature with regard to the impact of ablation technique on the outcomes of long-standing persistent AF ablation. A systematic search of the contemporary English scientific literature (from January 1, 1990 to June 1, 2009) in the PubMed database identified 32 studies on persistent/long-standing persistent or long-standing persistent AF ablation (including four randomized controlled trials). Data on single-procedure, drug-free success, multiple procedure success, and pharmaceutically assisted success at longest follow-up were collated. Four studies performed pulmonary vein isolation alone (21%-22% success). Four studies performed pulmonary vein antrum ablation with isolation (PVAI n = 2 38%-40% success) or without confirmed isolation (PVA n = 2 37%-56% success). Ten studies performed linear ablation in addition to PVA (n = 5 11%-74% success) or PVAI (n = 5 38%-57% success). Three studies performed posterior wall box isolation (n = 3 44%-50% success). Five studies performed complex fractionated atrial electrogram ablation (n = 5 24%-63% success). Six studies performed complex fractionated atrial electrogram ablation as an adjunct to PVA (n = 2 50%-51% success), PVAI (n = 3 36%-61% success), or PVAI and linear (n = 1 68% success) ablation. Five studies performed the stepwise ablation approach (38%-62% success). The variation in success within and between techniques suggests that the optimal ablation technique for long-standing persistent AF is unclear. Nevertheless, long-standing persistent AF can be effectively treated with a composite of extensive index catheter ablation, repeat procedures, and/or pharmaceuticals.
Publisher: Public Library of Science (PLoS)
Date: 17-11-2014
Publisher: Frontiers Media SA
Date: 12-05-0009
Publisher: Oxford University Press (OUP)
Date: 30-01-2020
Abstract: There is growing evidence that magnetic resonance imaging (MRI) scanning in patients with non-conditional cardiac implantable electronic devices (CIEDs) can be performed safely. Here, we aim to assess the safety of MRI in patients with non-conditional CIEDs. English scientific literature was searched using PubMed/Embase/CINAHL with keywords of ‘magnetic resonance imaging’, ‘pacemaker’, ‘implantable defibrillator’, and ‘cardiac resynchronization therapy’. Studies assessing outcomes of adverse events or significant changes in CIED parameters after MRI scanning in patients with non-conditional CIEDs were included. References were excluded if the MRI conditionality of the CIEDs was undisclosed number of patients enrolled was & or studies were case reports/series. 35 cohort studies with a total of 5625 patients and 7196 MRI scans (0.5–3 T) in non-conditional CIEDs were included. The overall incidence of lead failure, electrical reset, arrhythmia, inappropriate pacing and symptoms related to pocket heating, or torque ranged between 0% and 1.43%. Increase in pacing lead threshold & .5 V and impedance & Ω was seen in 1.1% [95% confidence interval (CI) 0.7–1.8%] and 4.8% (95% CI 3.3–6.4%) respectively. The incidence of reduction in P- and R-wave sensing by & % was 1.5% (95% CI 0.6–2.9%) and 0.4% (95% CI 0.06–1.1%), respectively. Battery voltage reduction of & .04 V was reported in 2.2% (95% CI 0.2–6.1%). This meta-analysis affirms the safety of MR imaging in non-conditional CIEDs with no death or implantable cardioverter-defibrillator shocks and extremely low incidence of lead or device-related complications.
Publisher: American Medical Association (AMA)
Date: 08-2017
Publisher: Elsevier BV
Date: 03-2012
DOI: 10.1016/J.JACC.2011.11.039
Abstract: The aim of this study was to evaluate the role of cardiac K(+) channel gene variants in families with atrial fibrillation (AF). The K(+) channels play a major role in atrial repolarization but single mutations in cardiac K(+) channel genes are infrequently present in AF families. The collective effect of background K(+) channel variants of varying prevalence and effect size on the atrial substrate for AF is largely unexplored. Genes encoding the major cardiac K(+) channels were resequenced in 80 AF probands. Nonsynonymous coding sequence variants identified in AF probands were evaluated in 240 control subjects. Novel variants were characterized using patch-cl techniques and in silico modeling was performed using the Courtemanche atrial cell model. Nineteen nonsynonymous variants in 9 genes were found, including 11 rare variants. Rare variants were more frequent in AF probands (18.8% vs. 4.2%, p < 0.001), and the mean number of variants was greater (0.21 vs. 0.04, p 30 ms) shortening or lengthening of action potential duration as well as increased dispersion of repolarization. Families with AF show an excess of rare functional K(+) channel gene variants of varying phenotypic effect size that may contribute to an atrial arrhythmogenic substrate. Atrial cell modeling is a useful tool to assess epistatic interactions between multiple variants.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.HLC.2014.09.012
Abstract: Catheter ablation of atrial fibrillation (AF) is an established rhythm control strategy however, the impact of co-existing LV systolic dysfunction (LVSD) on ablation success is less well understood. This systematic review compiles the outcomes of catheter ablation of atrial fibrillation in patients with LVSD. An electronic database (Pubmed, Scopus, Embase) search using the keywords 'atrial fibrillation AND ablation AND (ventricular dysfunction OR heart failure OR cardiomyopathy)' was performed for English scientific literature up to 01/01/2014. 2484 references were retrieved and evaluated for relevance by three reviewers. Reviews and reference lists of retrieved articles were also examined to ensure all relevant studies were included. Data was extracted from 19 studies, including a total of 914 patients. Single-procedure success in LVSD patients for AF ablation was 56.5% (95% CI: 48%-64%). Overall multiple-procedure (including the use of anti-arrhythmic drugs) in LVSD patients for AF ablation was 81.8% (95% CI: 75%-87%). The mean increase in LVEF following AF ablation was 13.3% (95% CI: 10.8%-15.9%). Seven studies reported improvements in exercise capacity and quality of life information using standardised criteria. The pooled rate of serious adverse events was 5.5% (95% CI: 3.7%-8.1%). Catheter ablation may be an effective therapy in AF patients with left ventricular systolic impairment, and can be associated with improvements in left ventricular function, quality of life, exercise capacity, and modest rates of serious adverse events.
Publisher: Wiley
Date: 12-2004
Publisher: Wiley
Date: 18-01-2021
DOI: 10.1111/PACE.14161
Abstract: To characterize contemporary pacemaker procedure trends. Nationwide analysis of pacemaker procedures and costs between 2008 and 2017 in Australia. The main outcome measures were total, age- and gender-specific implant, replacement, and complication rates, and costs. Pacemaker implants increased from 12,153 to 17,862. Implantation rates rose from 55.3 to 72.6 per 100,000, a 2.8% annual increase (incidence rate ratio [IRR] 1.028 95% CI, 1.02-1.04 p < .001). Pacemaker implants in the 80+ age group were 17.37-times higher than the < 50 group (95% CI 16.24-18.59 p < .001), and in males were 1.48-times higher than in females (95% CI 1.42-1.55 p < .001). However, there were similar increases according to age (p = .10) and gender (p = .68) over the study period. Left ventricular lead rates were stable (IRR 0.995 95% CI 0.98-1.01 p = .53). Generator replacements decreased from 20.5 to 18.3 per 100,000 (IRR 0.975 95% CI 0.97-0.98 p < .001). Although procedures for generator-related complications were stable (IRR 0.995 95% CI 0.98-1.01 p = .54), those for lead-related complications decreased (IRR 0.985 95% CI 0.98-0.99 p < .001). Rates for all pacemaker procedures were consistently greater in males (p < .001). Although annual costs of all pacemaker procedures increased from $178 million to $329 million, inflation-adjusted costs were more stable, rising from $294 million to $329 million. Increasing demand for pacemaker implants is driven by the ageing population and rising rates across all ages, while replacement and complication procedure rates appeared more stable. Males have consistently greater pacemaker procedure rates than females. Our findings have significant clinical and public health implications for healthcare resource planning.
Publisher: Elsevier BV
Date: 12-2017
Publisher: Wiley
Date: 08-05-2017
DOI: 10.1111/PACE.13073
Abstract: Medical technology has made significant advances over the last few decades with smaller and more dynamic pacemakers. However, technical failures leading to premature replacement is a cause of concern. We present a series of Medtronic EnRhythm devices that reached premature elective replacement indicator (ERI). The database of Centre of Heart Rhythm Disorders was searched for EnRhythm device implantation from 2006 to 2011. Battery depletion <8.5 years was considered premature considering the projected average longevity to be 8.5-10.5 years. An unexpected premature ERI was defined when it was reached within 3 months of last normal check. Device follow-up was conducted every 3 months after advisory. A total of 88 EnRhythm pacemakers were implanted. Over a median follow-up of 6.2 years (range: 0.3-9.2), 39 (44.3%) EnRhythm devices reached premature ERI. In 11 (28%), ERI was not recognized and patients were being investigated for other causes of unsteadiness or dyspnea prior to device check. Notably, three (7%) patients had premature ERI < 3.5 years. Ten (25.6%) had sudden and unexpected premature ERI. While asynchronous pacing was observed, there were no cases of absence of pacing. The rate of premature ERI for EnRhythm devices was 44.3%, significantly higher than reported by the manufacturer. Of concern, a sizeable proportion occurred unexpectedly, warranting more frequent reviews and empirical replacement in some patients. With the experience of the EnRhythm, appropriate monitoring strategies are recommended for future advisories.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 30-03-2004
DOI: 10.1161/01.CIR.0000121734.47409.AA
Abstract: Background— The normal sinus pacemaker complex is an extensive structure within the right atrium. We hypothesized that patients with sinus node disease (SND) would have evidence of diffuse atrial abnormalities. Methods and Results— Sixteen patients with symptomatic SND and 16 age-matched controls were studied. The following were evaluated: effective refractory periods (ERPs) from the high and low lateral right atrium (RA), high septal RA, and distal coronary sinus (CS) conduction time along the CS and lateral RA P-wave duration and conduction at the crista terminalis. Electroanatomic mapping was performed to define the sinus node complex and determine regional conduction velocity, double potentials, fractionated electrograms, regional voltage, and areas of electrical silence. Patients with SND demonstrated significant increase in atrial ERP at all right atrial sites, increased atrial conduction time along the lateral RA and CS, prolongation of the P-wave duration, and greater number and duration of double potentials along the crista terminalis. Electroanatomic mapping demonstrated the sinus node complex in SND to be more often unicentric, localized to the low crista terminalis at the site of the largest residual voltage litude. There was significant regional conduction slowing with double potentials and fractionation associated with areas of low voltage and electrical silence (or scar). Conclusions— SND is associated with diffuse atrial remodeling characterized by structural change, conduction abnormalities, and increased right atrial refractoriness. There was a change in the nature of sinus pacemaker activity with loss of the normal multicentric pattern of activation, caudal shift of the pacemaker complex, and abnormal and circuitous conduction around lines of conduction block.
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.IJCARD.2018.07.124
Abstract: Sleep-disordered breathing (SDB) is highly prevalent in patients with atrial fibrillation (AF) and its treatment can improve rhythm control. Polysomnography (PSG) is the gold standard for the diagnosis of SDB but its high cost and limited availability constrain its role as a standard SDB screening tool. We sought to assess the diagnostic utility of overnight oximetry in predicting SDB in AF patients. We analyzed prospectively collected data on 439 patients with documented AF (62% paroxysmal AF) who underwent PSG. Overnight oximetry was used to determine the oxygen desaturation index (ODI, number of desaturation/h) by a novel automated computer algorithm. ODI was validated against PSG derived apnea-hypopnea index (AHI). The s le consisted of 69% men with a mean age of 59.9 ± 11.3 years and body mass index of 30 ± 5 kg/m ODI derived from a simple and low-cost overnight oximetry can be used as an accessible and reliable screening tool, particularly to rule out SDB.
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.JACEP.2016.12.015
Abstract: Atrial fibrillation (AF) imposes a substantial cost burden on the healthcare system. Weight and risk factor management (RFM) reduces AF burden and improves the outcomes of AF ablation. This study sought to evaluate the cost and clinical effectiveness of integrating RFM into the overall management of AF. Of 1,415 consecutive patients with symptomatic AF, 825 patients had body mass index ≥27 kg/m There were no differences in baseline characteristics or follow-up duration (p = NS). Arrhythmia-free survival was better in the RFM compared with control subjects (Kaplan-Meier: 79% vs. 44% p < 0.001). At follow-up, RFM group had less unplanned specialist visits (0.19 ± 0.40 vs. 1.94 ± 2.00 p < 0.001), hospitalizations (0.74 ± 1.3 vs. 1.05 ± 1.60 p = 0.03), cardioversions (0.89 ± 1.50 vs. 1.51 ± 2.30 p = 0.002), emergency presentations (0.18 ± 0.50 vs. 0.76 ± 1.20 p < 0.001), and ablation procedures (0.60 ± 0.69 vs. 0.72 ± 0.86 p = 0.03). Antihypertensive (0.53 ± 0.70 vs. 0.78 ± 0.60 p = 0.04) and antiarrhythmic (0.26 ± 0.50 vs. 0.91 ± 0.60 p = 0.003) use declined in RFM. The RFM group had an increase of 0.1930 quality-adjusted life years and a cost saving of $12,094 (incremental cost-effectiveness ratios of $62,653 saved per quality-adjusted life years gained). A structured physician-directed RFM program is clinically effective and cost saving.
Publisher: Oxford University Press (OUP)
Date: 06-07-2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 13-12-2005
DOI: 10.1161/CIRCULATIONAHA.105.541052
Abstract: Background— There are no reports describing the technique, electrophysiological evaluation, and clinical consequences of complete linear block at roofline joining the superior pulmonary veins (PVs) in patients with paroxysmal atrial fibrillation (AF). Methods and Results— Ninety patients with drug-refractory paroxysmal AF undergoing radiofrequency ablation were prospectively randomized into 2 ablation strategies: (1) PV isolation (n=45) or (2) PV isolation in combination with linear ablation joining the 2 superior PVs (roofline n=45). In both groups, the cavotricuspid isthmus, fragmented peri-PV-ostial electrograms, and spontaneous non-PV foci were ablated. Roofline ablation was performed at the most cranial part of the left atrium (LA) with complete conduction block demonstrated during LA appendage pacing by the online mapping of continuous double potential and an activation detour propagating around the PVs to activate caudocranially the posterior wall of the LA. The effect of ablation at the LA roof was evaluated by the change in fibrillatory cycle length, termination and noninducibility of AF, and clinical outcome. PV isolation was achieved in all patients with no significant differences in the radiofrequency duration, fluoroscopy, or procedural time between the groups. Roofline ablation required 12±6 (median 11, range 3 to 25) minutes of radiofrequency energy delivery with a fluoroscopic duration of 7±2 minutes and was performed in 19±7 minutes. Complete block was confirmed in 43 patients (96%) and resulted in an activation delay that was shorter circumventing the left than the right PVs during LA appendage pacing (138±15 versus 146±25 ms, respectively P =0.01). Roofline ablation resulted in a significant increase in the fibrillatory cycle length (198±38 to 217±44 ms P =0.0005), termination of arrhythmia in 47% (8/17), and subsequent noninducibility of AF in 59% (10/17) of the patients inducible after PV isolation. However, LA flutter, predominantly perimitral, could be induced in 10 patients (22%) after roofline ablation. At 15±4 months, 87% of the roofline group and 69% with PV isolation alone are arrhythmia free without antiarrhythmics ( P =0.04). Conclusions— This prospective randomized study demonstrates the feasibility of achieving complete linear block at the LA roof. Such ablation resulted in the prolongation of the fibrillatory cycle, termination of AF, and subsequent noninducibility and is associated with an improved clinical outcome compared with PV isolation alone.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 02-2006
DOI: 10.1016/J.JACC.2005.10.043
Abstract: The goal of the present prospective study is to evaluate the impact of vagal excitation on ongoing atrial fibrillation (AF) during pulmonary vein (PV) isolation. The role of vagal tone in maintenance of AF is controversial in humans. Twenty-five patients (18 with paroxysmal AF, 7 with chronic AF) were selected by occurrence of vagal excitation during AF (atrioventricular [AV] block: R-R interval >3 s) produced by PV isolation. Fibrillatory cycle length (CL) in the targeted PV and coronary sinus (CS) were determined before, during, and after vagal excitation. The CL was available at PV ostium during vagal excitation in 11 patients. Forty-eight episodes of vagal excitation were observed. During vagal excitation, CL abruptly decreased both in CS and PV (CS, 164 +/- 20 ms to 155 +/- 23 ms, p < 0.0001 PV, 160 +/- 22 ms to 143 +/- 28 ms, p < 0.0001), and both returned to the baseline value with resumption of AV conduction. The decrease in PVCL occurred earlier (2.5 +/- 1.5 s vs. 4.0 +/- 2.6 s, p < 0.01) and was of greater magnitude than that in CSCL (16 +/- 16 ms vs. 8 +/- 9 ms, p < 0.01). A sequential gradient of CL was observed from PV to PV ostium and CS during vagal excitation (138 +/- 29 ms, 149 +/- 24 ms, and 159 +/- 26 ms, respectively). The decrease in CL was significantly greater in paroxysmal than in chronic AF (CS, 11 +/- 9 ms vs. 5 +/- 7 ms, p < 0.05 PV, 23 +/- 25 ms vs. 8 +/- 14 ms, p < 0.05). Vagal excitation is associated with shortening of fibrillatory CL. This occurs earlier in PV with a sequential gradient to PV ostium and CS, suggesting that vagal excitation enhances a driving role of PV.
Publisher: Springer Science and Business Media LLC
Date: 09-01-2017
Publisher: Public Library of Science (PLoS)
Date: 09-03-2009
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2013
DOI: 10.1161/CIRCEP.113.000163
Abstract: Myocardial infarction (MI) is associated with the development of atrial fibrillation (AF). We aimed to characterize the atrial abnormalities because of MI and determine the role of ischemia to the AF substrate. Forty-four sheep were studied. MI was induced by occlusion of the left circumflex artery (LCX) or left anterior descending artery (LAD). Excluding 11 with fatal arrhythmias, equal groups of animals (LCX LAD and sham-operated) underwent sequential electrophysiology study for 45 minutes to determine atrial effective refractory periods, conduction velocity, conduction heterogeneity index, and AF inducibility. Postmortem evaluation was performed with 2,3,5 triphenyl tetrazolium chloride staining. MI resulted in greater left ventricular dysfunction ( P .05), LA pressure ( P .0003), and reduction in atrial effective refractory periods ( P .0001) compared with control. 2,3,5 triphenyl tetrazolium chloride staining demonstrated that the left circumflex artery, and not the LAD, group had atrial infarction. The left circumflex artery group demonstrated the following compared with the LAD or control groups: greater slowing in atrial conduction velocity ( P .0001 and P .001) increased absolute range of conduction phase delay ( P .001 and P .001) increased conduction heterogeneity index ( P .0001 and P .001) greater AF vulnerability ( P .05 for both) and longer AF duration ( P .05 for both). LAD group had modest but significant slowing in conduction velocity ( P .01) but no change in conduction heterogeneity index or AF duration compared with control. Left ventricular infarction, which is known to result in atrial stretch, hemodynamic change, and neurohumoral activation, contributes partially to the atrial abnormalities in MI. Atrial ischemia/infarction results in greater atrial electrophysiological changes and propensity for AF forming the dominant substrate for AF in MI.
Publisher: Elsevier BV
Date: 07-2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2014
DOI: 10.1161/CIRCEP.114.001894
Abstract: The pulmonary vein–left atrial (PV–LA) junction is key in pathogenesis of AF, and acute stretch is an important stimulus to AF. We aimed to characterize the response of the junction to acute stretch, hypothesizing that stretch would result in electrophysiological changes predisposing to re-entry. Fifteen participants undergoing cardiac surgery underwent evaluation of the right superior PV–LA junction using an epicardial mapping plaque. In 10, this was performed before and after atrial stretch imposed by rapid volume expansion, and in 5, it was performed with an intervening observation period. Activation was characterized by conduction slowing and electrogram fractionation transversely across the PV–LA junction, with lines of block also demonstrated perpendicular to the junction. Conduction was decremental (plaque activation time 135.8±46.8 ms with programmed extra stimuli at 10 ms above effective refractory period versus 66.1±22.9 ms with pacing at 400 ms P .001) and percentage fractionation was greater with programmed extra stimuli at 10 ms above (33.5%±15.3% versus 20.7%±14.0%, P =0.001). Right atrial pressure increased by 2.5±1.8 mm Hg ( P =0.002) with volume expansion. Stretch resulted in conduction slowing across the PV–LA junction (increase in activation time 10.9±14.6 ms in acute stretch group versus −0.1±4.5 ms in control group P =0.002). Conduction slowing was more marked with programmed extra stimuli at 10 ms above effective refractory period than with stable pacing (13.4±16.5 ms versus 1.7±5.4 ms P =0.003). Stretch resulted in a significant increase in fractionated electrograms (7.9%±7.0% versus −0.4±3.3 P =0.004). Acute stretch results in conduction slowing across the PV–LA junction, with a greater degree of signal complexity. This substrate may be important in AF initiation and maintenance by promoting re-entry.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2017
DOI: 10.1161/CIRCEP.117.005579
Abstract: Percutaneous or surgical ablation are increasingly used worldwide in the management of atrial fibrillation. The development of atrioesophageal fistula (AEF) is among the most serious and lethal complications of atrial fibrillation ablation. We sought to characterize the clinical presentation, procedural characteristics, diagnostic investigations, and treatment outcomes of all reported cases of AEF. Electronic searches were conducted in PubMed and Embase for English scientific literature articles. Out of 628 references, 120 cases of AEF were identified using various ablation modalities. Clinical presentation occurred between 0 and 60 days postablation (median 21 days). Fever (73%), neurological (72%), gastrointestinal (41%), and cardiac (40%) symptoms were the commonest presentations. Computed tomography of the chest was the commonest mode of diagnosis (68%), although 7 cases required repeat testing. Overall mortality was 55%, with significantly reduced mortality in patients undergoing surgical repair (33%) compared with endoscopic treatment (65%) and conservative management (97%) (adjusted odds ratio, 24.9 P .01, compared with surgery). Multivariable predictors of mortality include presentation with neurological symptoms (adjusted odds ratio, 16.0 P .001) and gastrointestinal bleed (adjusted odds ratio, 4.2 P =0.047). AEF complicating atrial fibrillation ablation is associated with a high mortality. Clinicians should have a high suspicion for the development of AEF in patients presenting with infective, neurological, gastrointestinal, or cardiac symptoms within 2 months of an atrial fibrillation ablation. Investigation by contrast computed tomography of the chest with consideration of repeat testing can lead to prompt diagnosis. Surgical intervention is associated with improved survival rates.
Publisher: Elsevier BV
Date: 08-2023
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.JACEP.2019.03.005
Abstract: This study sought to determine night-to-night variability in the severity of sleep-disordered breathing (SDB) and the dynamic intrain idual relationship to daily risk of incident atrial fibrillation (AF) by using simultaneous long-term day-by-day SDB and AF monitoring. Night-to-night variability in SDB severity may result in a dynamic exposure to SDB related conditions impacting the timing and extent of cardiovascular responses. This study was an observational cohort study. Daily data for AF burden and average respiratory disturbance index (RDI) were extracted from pacemakers capable of monitoring nightly SDB and daily AF burden in 72 patients. Nightly RDI values were grouped into quartiles of severity within each patient. AF burdens of >5 min, >1 h, and >12 h were the outcome variables. A total of 32% of patients had a mean RDI of ≥20/h, indicative of overall severe SDB. There was significant night-to-night variation in RDI reflected by an absolute SD of ±6.3 events/h (range 2 to 14 events/h) within any given patient. Within each patient, the nights with the highest RDI (in their highest quartile) conferred a 1.7-fold (1.2 to 2.2 p < 0.001), 2.3-fold (1.6 to 3.5 p < 0.001), and 10.2-fold (3.5 to 29.9 p < 0.001) increase risk of having at least 5 min, 1 h, and 12 h, respectively, of AF during the same day compared with the best sleep nights (in their lowest quartiles). There is considerable night-to-night variability in SDB severity which cannot be detected by 1 single overnight sleep study. SDB burden may be a better metric with which to assess the extent of dynamic SDB related cardiovascular responses such as daily AF risk than the categorical diagnosis of SDB. (Night-to-Night Variability in Severity of Sleep Apnea and Daily Dynamic Atrial Fibrillation Risk [VARIOSA-AF] ACTRN 12618000757213).
Publisher: Elsevier BV
Date: 08-2010
DOI: 10.1016/J.AMJCARD.2010.03.069
Abstract: Atrial electrical remodeling has been shown after termination of atrial flutter (AFL) however, whether abnormalities persist beyond an arrhythmic episode is not known. We aimed to characterize the atrial substrate, remote from arrhythmia, in patients with typical AFL. We compared 20 patients, studied remote from episodes of typical AFL and without a history of atrial fibrillation, to 20 reference patients. Multipolar catheters placed at the lateral right atrium (RA), coronary sinus, crista terminalis, and septal RA measured the effective refractory period at 5 sites conduction characteristics at the crista terminalis and the conduction time along the lateral RA and coronary sinus. Electroanatomic right atrial maps were created to determine regional differences in voltage and conduction. Patients with AFL demonstrated the following compared to the reference patients: a larger right atrial volume (121 +/- 30 vs 83 +/- 24 ml, p = 0.005) a prolonged P-wave duration (122 +/- 18 vs 102 +/- 11 ms, p = 0.007) a longer right atrial activation time (107 +/- 23 vs 85 +/- 14 ms, p = 0.02) a prolonged conduction time along the lateral RA (67 +/- 4 vs 47 +/- 3 ms, p <0.001) a slower mean conduction velocity (1.2 +/- 0.2 vs 2.1 +/- 0.6 mm/ms, p <0.001) a greater proportion of fractionated electrographic findings (16 +/- 4% vs 10 +/- 6%, p = 0.006) more frequent abnormal electrographic findings at the crista terminalis (4.1 +/- 2.6 vs 1.0 +/- 1.1, p = 0.001) a prolonged corrected sinus node recovery time (318 +/- 71 vs 203 +/- 94 ms, p = 0.02) a trend toward greater effective refractory period (232 +/- 29 vs 213 +/- 12 ms, p = 0.06) and a lower voltage (2.1 +/- 0.5 vs 3.0 +/- 0.5 mV, p <0.001). In conclusion, studied remote from arrhythmia, patients with AFL demonstrated significant and diffuse atrial abnormalities characterized by structural changes, conduction abnormalities, and sinus node dysfunction. These persisting abnormalities characterize the substrate underlying typical AFL and may account for the subsequent development of atrial fibrillation.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.HRTHM.2010.03.020
Abstract: Chronic pulmonary disease and sleep apnea have been associated with the development of atrial fibrillation (AF). The purpose of this study was to characterize the atrial electrical changes that occur with hypercapnia and hypoxemia and to determine their role in AF development. Seventeen sheep (6 control, 5 hypercapnia, 6 hypoxemia) underwent open chest electrophysiologic evaluation under autonomic blockade. A 64-electrode endocardial basket catheter was positioned in the right atrium, and 2 x 128 electrode epicardial plaques were sutured to the right atrial and left atrial appendages to determine atrial refractoriness (effective refractory period [ERP]) at 9 sites and 5 cycle lengths, conduction time to fixed points on each plaque, and AF vulnerability. Hypercapnia was associated with a 152% lengthening of ERP from baseline and increased conduction time. ERPs rapidly returned to baseline, but recovery of conduction was delayed at least 117 +/- 24 minutes following resolution of hypercapnia. AF vulnerability was reduced during hypercapnia (with increased ERP) but increased significantly with subsequent return to eucapnia (when ERP normalized but conduction time remained prolonged). No significant changes in ERP, atrial conduction time, or AF vulnerability occurred in hypoxemic or control groups. Differential recovery of ERP and conduction that occurs following hypercapnia might account for the increased vulnerability to AF observed in the phase after return to eucapnia. This may explain in part the increased prevalence of AF in pulmonary disease and sleep apnea.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Oxford University Press (OUP)
Date: 19-07-2022
Publisher: Springer Science and Business Media LLC
Date: 29-08-2013
Abstract: Recently pericardial adipose tissue (PAT) has been shown to be an independent predictor of atrial fibrillation (AF). Atrial PAT may influence underlying atrial musculature creating a substrate for AF. This study sought to validate the assessment of total and atrial PAT by standard cardiovascular magnetic resonance (CMR) measures and describe and validate a three dimensional atrial PAT model. 10 merino cross sheep underwent CMR using a 1.5 Tesla system (Siemens, Sonata, Erlangen, Germany). Atrial and ventricular short axis (SA) images were acquired, using ECG -gated steady state free precession sequences. In order to quantify total volume of adipose tissue, a three dimensional model was constructed from consecutive end-diastolic images using semi-automated software. Regions of adipose tissue were marked in each slice followed by linear interpolation of pixel intensities in spaces between consecutive image slices. Total volume of adipose tissue was calculated as a total volume of the three dimensional model and the mass estimated from volume measurements. The sheep were euthanized and pericardial adipose tissue was removed and weighed for comparison to the corresponding CMR measurements. All CMR adipose tissue estimates significantly correlated with autopsy measurements (ICC 0.80 p 0.03). Intra- observer reliability in CMR measures was high, with 95% levels of agreement within 5.5% (ICC = 0.995) for total fat mass and its in idual atrial (95% CI ± 8.3%, ICC = 0.993) and ventricular components (95% CI ± 6.6%, ICC = 0.989). Inter- observer 95% limits of agreement were within ± 10.7% (ICC = 0.979), 7.4% (ICC = 0.991) and 7.2% (ICC = 0.991) for atrial, ventricular and total pericardial adipose tissue, respectively. This study validates the use of a semi-automated three dimensional atrial PAT model utilizing standard (clinical) CMR sequences for accurate and reproducible assessment of atrial PAT. The measurement of local cardiac fat stores via this methodology could provide a sensitive tool to examine the regional effect of fat deposition on atrial substrate which potentially may influence AF ablation strategies in obese patients.
Publisher: Wiley
Date: 07-2004
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2013
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.IJCARD.2016.12.029
Abstract: Despite advances in therapeutic interventions AF remains a progressive and symptomatic disease. Therefore, novel therapeutic interventions targeting the underlying arrhythmogenic substrate for AF is needed. Atrial fibrosis is an important component of the arrhythmogenic substrate of AF and may be initiated by aldosterone binding to the mineralocorticoid receptor. We hypothesized that aldosterone pathway blockade with mineralocorticoid receptor antagonists (MRA) reduces atrial fibrosis, and thus AF. We searched OVID MEDLINE, OVID EMBASE and the Cochrane Central Register of Controlled Trials from inception to June 10th, 2016 for randomized controlled trials (RCT) and observational studies addressing MRA and providing information on AF occurrence. Two independent reviewers selected and appraised the data. We performed random-effects meta-analyses. Summary odds ratios (OR) with 95% confidence intervals (CI) were calculated. We included 14 studies, 5 RCT and 9 observational cohorts, with a cumulative number of 5332 patients (male: 74.9%, age: 65.3years) 2397 (45.0%) received an MRA (spironolactone or eplerenone). During follow-up, 204 (8.5%) patients treated with MRAs, developed AF, compared to 547 (18.6%) patients, without MRA treatment. Meta-analyses showed a significant overall reduction of AF risk in MRA treated patients (OR: 0.48 CI: 0.38-0.60 p<0.001), including a reduction of new-onset AF (OR: 0.52 CI: 0.37-0.74 p<0.001) and recurrent AF (OR: 0.37 CI: 0.24-0.57 p<0.001), but not post-operative AF (POAF) (OR: 0.60 CI: 0.33-1.09 p=0.09). MRAs significantly reduce new-onset AF and recurrent AF, but not POAF. MRA treatment can be considered an additive therapeutic strategy in AF.
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.AMJCARD.2011.04.036
Abstract: An open-label study reported that ingestion of a fish oil concentrate decreased the incidence of atrial fibrillation (AF) after coronary artery bypass grafting (CABG) surgery. However, a general cardiac surgery population involves valve and CABG surgeries. We undertook a double-blinded randomized controlled trial to examine the effectiveness of fish oil supplementation on the incidence of postsurgical AF after CABG and valve procedures. The primary end point was incidence of AF in the first 6 days after surgery. Two hundred patients were randomized to receive fish oil (providing 4.6 g/day of long-chain ω-3 fatty acids) or a control oil starting 3 weeks before surgery 194 subjects completed the study, with 47 of 97 subjects in the control group and 36 of 97 subjects in the fish oil group developing AF (odds ratio 0.63, 95% confidence interval [CI] 0.35 to 1.11). There was a nonstatistically significant delay in time to onset of AF in the fish oil group (hazard ratio 0.66, 95% CI 0.43 to 1.01). There was a significant decrease in mean length of stay in the intensive care unit in the fish oil group (ratio of means 0.71, 95% CI 0.56 to 0.90). In conclusion, in a mixed cardiac surgery population, supplementation with dietary fish oil did not result in a significant decrease in the incidence of postsurgical AF. However, there was a significant decrease in time spent in the intensive care unit.
Publisher: Wiley
Date: 28-10-2005
Publisher: Oxford University Press (OUP)
Date: 08-2023
Abstract: Over the past 25 years there has been a substantial development in the field of digital electrophysiology (EP) and in parallel a substantial increase in publications on digital cardiology. In this celebratory paper, we provide an overview of the digital field by highlighting publications from the field focusing on the EP Europace journal. In this journey across the past quarter of a century we follow the development of digital tools commonly used in the clinic spanning from the initiation of digital clinics through the early days of telemonitoring, to wearables, mobile applications, and the use of fully virtual clinics. We then provide a chronicle of the field of artificial intelligence, a regulatory perspective, and at the end of our journey provide a future outlook for digital EP. Over the past 25 years Europace has published a substantial number of papers on digital EP, with a marked expansion in digital publications in recent years.
Publisher: Oxford University Press (OUP)
Date: 12-11-2016
Abstract: Background Despite atrial fibrillation representing an established risk factor for stroke, the association between atrial fibrillation and both progression of coronary atherosclerosis and major adverse cardiovascular events is not well characterized. We assessed the serial measures of coronary atheroma burden and cardiovascular outcomes in patients with and without atrial fibrillation. Methods Data were analyzed from nine clinical trials involving 4966 patients with coronary artery disease undergoing serial intravascular ultrasonography at 18-24 month intervals to assess changes in percent atheroma volume (PAV). Using a propensity weighted analysis, and following adjustment for baseline variables, patients with ( n = 190) or without ( n = 4776) atrial fibrillation were compared with regard to coronary plaque volume and major adverse cardiovascular events (death, myocardial infarction, and stroke). Results Atrial fibrillation patients demonstrated lower baseline PAV (36.0 ± 8.9 vs. 38.1 ± 8.9%, p = 0.002) and less PAV progression (-0.07 ± 0.34 vs. + 0.23 ± 0.34%, p = 0.001) compared with the non-atrial fibrillation group. Multivariable analysis revealed atrial fibrillation to independently predict both myocardial infarction [HR, 2.41 (1.74,3.35), p<0.001] 2.41 (1.74, 3.35), p < 0.00) and major adverse cardiovascular events [HR, 2.2, (1.66, 2.92), p<0.001] 2.20 (1.66, 2.92), p < 0.001]. Kaplan-Meier analysis showed that atrial fibrillation compared with non-atrial fibrillation patients had a significantly higher two-year cumulative incidence of overall major adverse cardiovascular events (4.4 vs. 2.0%, log-rank p = 0.02) and myocardial infarction (3.3 vs. 1.5%, log-rank p = 0.05). Conclusions The presence of atrial fibrillation independently associates with a heightened risk of myocardial infarction despite a lower baseline burden and progression rate of coronary atheroma. Further studies are necessary to define the pathogenesis of myocardial infarction in the setting of atrial fibrillation.
Publisher: Springer Science and Business Media LLC
Date: 31-05-2019
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.JACC.2012.11.046
Abstract: We sought to assess the effect of atrial fibrillation (AF) on atrial thrombogenesis in humans by determining the impact of rate and rhythm. Although AF is known to increase the risk of thromboembolic stroke from the left atrium (LA), the exact mechanisms remain poorly understood. We studied 55 patients with AF who underwent catheter ablation while in sinus rhythm 20 patients were induced into AF, 20 patients were atrial paced at 150 beats/min, and 15 were control patients. Blood s les were taken from the LA, right atrium, and femoral vein at baseline and at 15 min in all 3 groups. Platelet activation (P-selectin) was measured by flow cytometry. Thrombin generation (thrombin-antithrombin [TAT] complex), endothelial dysfunction (asymmetric dimethylarginine [ADMA]), and platelet-derived inflammation (soluble CD40 ligand [sCD40L]) were measured using enzyme-linked immunosorbent assay. Platelet activation increased significantly in both the AF (p < 0.001) and pacing (p < 0.05) groups, but decreased in control patients (p < 0.001). Thrombin generation increased specifically in the LA compared with the periphery in both the AF (p < 0.01) and pacing (p < 0.01) groups, but decreased in control patients (p < 0.001). With AF, ADMA (p < 0.01) and sCD40L (p < 0.001) levels increased significantly at all sites, but were unchanged with pacing (ADMA, p = 0.5 sCD40L, p = 0.8) or in control patients (ADMA, p = 0.6 sCD40L, p = 0.9). Rapid atrial rates and AF in humans both result in increased platelet activation and thrombin generation. Prothrombotic activation occurs to a greater extent in the human LA compared with systemic circulation. AF additionally induces endothelial dysfunction and inflammation. These findings suggest that although rapid atrial rates increase the thrombogenic risk, AF may further potentiate this risk.
Publisher: Elsevier BV
Date: 08-2007
DOI: 10.1016/J.TCM.2007.06.002
Abstract: Sinus node disease was previously thought to be a disease limited to the sinus node and its atrial connections. However, recent reports have demonstrated sinus node disease as a disease of the entire right atrial myocardium. These patients have widespread electrophysiological abnormalities of their atria, including prolonged refractory periods and slowed conduction. In addition to these electrical changes, there are significant structural changes, such as fibrosis and fatty infiltration, which can be detected endocardially as regions of fractionated signals, low-voltage electrograms, and electrically silent areas. In most cases, the etiology of these changes is unknown. These changes may contribute to the high prevalence of atrial fibrillation seen in patients with sinus node disease.
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.JACEP.2017.09.004
Abstract: The purpose of this study was to evaluate the effect of these therapies on healthcare utilization in a large patient cohort. Antitachycardia pacing (ATP) terminates ventricular tachycardia and avoids delivery of high-voltage shocks. Few data exist on the impact of shocks on healthcare resource utilization compared with ATP. PROVIDE (Programming Implantable Cardioverter Defibrillators in Patients With Primary Prevention Indication) was a prospective study of patients who received an implantable cardioverter-defibrillator (ICD) for primary prevention at 97 U.S. centers (2008 to 2010). We categorized the PROVIDE patients by the type of therapy delivered: no therapy, ATP only, or at least 1 shock. All ICD therapies, hospitalizations, and deaths were adjudicated. Cumulative cardiac hospitalizations, risk of all-cause death or cardiac hospitalization, and annual costs were compared between groups. Of the 1,670 patients in PROVIDE, followed up for 18.1 ± 7.6 months, 1,316 received no therapy, 152 had ATP only, and 202 received at least 1 shock. Patients receiving no therapy and those receiving only ATP had a lower cumulative hospitalization rate and were at lower risk for death or hospitalization (hazard ratio: 0.33 [p < 0.001] and 0.33 [p < 0.002], respectively). The cost of hospitalization was $2,874 per patient-year (95% confidence interval: $877 to $5,140 p = 0.002) higher for those receiving at least 1 shock than for those who received ATP only. There was no difference in outcomes or cost between patients receiving only ATP and those without therapy. Among patients implanted with an ICD for primary prevention, those who received only ATP therapy had reduced hospitalizations, mortality, and cost compared with those who received at least 1 high-voltage shock and had equivalent outcomes to patients who did not require any therapy. (Programming Implantable Cardioverter Defibrillators in Patients With Primary Prevention Indication [PROVIDE] NCT00743522).
Publisher: Public Library of Science (PLoS)
Date: 27-08-2013
Publisher: Massachusetts Medical Society
Date: 07-05-2015
Publisher: Wiley
Date: 10-2009
DOI: 10.1111/J.1445-5994.2008.01876.X
Abstract: Heart failure is a growing health issue and is associated with significant mortality risk. Device therapy is efficacious in preventing sudden death in patients with heart failure however, this evidence comes from rigorous clinical trials. It is unclear how device therapy is utilized in 'real-world' practice. The primary objective was to characterize patterns of device use in patients with heart failure at risk of sudden death and to identify barriers to guideline-driven prescription of implantable cardioverter-defibrillators. We report a cross-sectional study of patients attending general cardiology clinic over a 3-month period. Of 1003 consecutive patients attending the cardiology clinic, 176 had heart failure. Of these, 66 were potentially eligible for device therapy, but only 16 of these had actually undergone device implantation. Potentially eligible non-recipients were older (P 120 ms (P= 0.005). There was a high prevalence of underuse of evidence-based pharmacotherapies among patients with heart failure. There is substantial underuse of device therapy in patients with heart failure. Strikingly, whereas patients with symptoms of heart failure were more likely to receive a device, those being managed for ischaemic heart disease were not. There is also a high prevalence of failure to prescribe evidence-based pharmacotherapy in a tertiary hospital general cardiology clinic. This may be explained in part by the lack of a patient database to record treatment contraindications and to alert clinicians to possible gaps in patient therapy.
Publisher: Elsevier BV
Date: 02-2010
DOI: 10.1016/J.AMJMED.2009.09.013
Abstract: Energy drink consumption has been anecdotally linked with sudden cardiac death and, more recently, myocardial infarction. As myocardial infarction is strongly associated with both platelet and endothelial dysfunction, we tested the hypothesis that energy drink consumption alters platelet and endothelial function. Fifty healthy volunteers (34 male, aged 22+/-2 years) participated in the study. Platelet aggregation and endothelial function were tested before, and 1 hour after, the consumption of 250 mL (1 can) of a sugar-free energy drink. Platelet function was assessed by adenosine diphosphate-induced (1 micromol/L) optical aggregometry in platelet-rich plasma. Endothelial function was assessed via changes in peripheral arterial tonometry and expressed as the reactive hyperemia index (RHI). Compared with baseline values, there was a significant increase in platelet aggregation following energy drink consumption, while no change was observed with control (13.7+/-3.7% vs 0.3+/-0.8% aggregation, respectively, P <.01). Similarly, RHI decreased following energy drink consumption (-0.33+/-0.13 vs 0.07+/-0.12 RHI [control], P <.05). Mean arterial pressure significantly increased following energy drink consumption, compared with control (P <.05). Heart rate was unaffected by energy drink consumption. Energy drink consumption acutely increases platelet aggregation and decreases endothelial function in healthy young adults.
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.HRTHM.2017.06.021
Abstract: With the recent advent of high-density (HD) 3-dimensional (3D) mapping, the utility of entrainment is uncertain. However, the limitations of visual representation and interpretation of these high-resolution 3D maps are unclear. The purpose of this study was to determine the strengths and limitations of both HD 3D mapping and entrainment mapping during mapping of right atrial macroreentry. Fifteen patients were studied. The number and type of circuits accounting for ≥90% of the tachycardia cycle length using HD 3D mapping were verified using systematic entrainment mapping. Entrainment sites with an unexpectedly long postpacing interval despite proximity to the active circuit were evaluated. Based on HD 3D mapping, 27 circuits were observed: 12 peritricuspid, 2 upper loop reentry, 10 lower loop reentry, and 3 lateral wall circuits. With entrainment, 17 of the 27 circuits were active: all 12 peritricuspid and 2 upper loop reentry. However, lower loop reentry was confirmed in only 3 of 10, and none of the 3 lateral wall circuits were present. Mean percentage of tachycardia cycle length covered by active circuits was 98% ± 1% vs 97% ± 2% for passive circuits (P = .09). None of the 345 entrainment runs terminated tachycardia or changed tachycardia mechanism. In 8 of 15 patients, 13 ex les of unexpectedly long postpacing interval were observed at entrainment sites located distal to localized zones of slow conduction seen on HD 3D mapping. Using HD 3D mapping, "visual reentry" may be due to passive circuitous propagation rather than a critical reentrant circuit. HD 3D mapping provides new insights into regional conduction and helps explain unusual entrainment phenomena.
Publisher: Wiley
Date: 30-08-2001
Publisher: Wiley
Date: 28-10-2004
DOI: 10.1046/J.1540-8167.2004.04077.X
Abstract: We report a case of left atrial dominant rhythm demonstrated by electroanatomic mapping. The rhythm occurred after radiofrequency catheter ablation in a patient with persistent atrial fibrillation and structural heart disease.
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.AMJCARD.2013.06.011
Abstract: Implantable cardioverter-defibrillator therapy in the form of high-energy shock (HES) is associated with adverse effects. This study evaluated an alternative therapy to HES, including antitachycardia pacing (ATP) for very fast ventricular tachycardia (VFVT) and low-energy shock (LES) ≤5 J for ventricular tachycardia (VT) of any cycle length (CL). This multicenter study recruited 602 patients with standard indications for an implantable cardioverter-defibrillator. Programming was standardized into 3 zones: (1) ventricular fibrillation (VF) CL of 320 ms) treated with 3 ATP bursts, LES, and HES. The primary end point was ATP and LES efficacy and safety. After a mean follow-up of 19 ± 8 months, 2,815 device activations were recorded in 152 patients. Of 67 VFVT episodes, 34 reverted with combined ATP and LES (success rate 50.7%) with first and second ATPs successful in 36% and 13.8%, respectively. LES was used in 39 fast ventricular tachycardia and 60 slow VT episodes with success rates of 53.8% and 73.3%, respectively. Syncope occurred in 19.4%, 16.2%, and 1% of episodes because of VFVT, VF, and VT CL >250 ms, respectively. In conclusion, tiered ATP and LES therapy terminates >50% of VFVT episodes (CL, 200 to 250 ms), which otherwise would fall within the VF zone and be treated exclusively with HES. LES is efficacious and safe in patients with VT CL >250 ms with extremely low syncope rates. Limitation of ATP to a single burst in VFVT is recommended to minimize syncope.
Publisher: Wiley
Date: 11-2004
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 08-2020
Publisher: Elsevier BV
Date: 05-2018
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.CCL.2019.01.008
Abstract: Atrial fibrillation (AF) and heart failure (HF) pose international health care challenges that contribute significantly to hospitalizations, morbidity, mortality, and significant health care costs. Both AF and HF contribute to the development of each other and both are associated with a worsened prognosis when they occur together. Assessment of systolic function via transthoracic echocardiography is essential in the investigation of the AF patient. Clinical and echocardiographic assessment may classify AF patients with HF into HF with reduced ejection fraction (HF-rEF) and HF with preserved ejection fraction (HF-pEF). Such classification can assist in numerous important management decisions in AF.
Publisher: Oxford University Press (OUP)
Date: 02-02-2012
Abstract: There is increasing evidence of the role direction-dependent conduction plays in the arrhythmogenic interaction between ectopic triggers and abnormal atrial substrates. We thus sought to characterize direction-dependent conduction in chronically stretched atria. Twenty-four patients with chronic atrial stretch due to mitral stenosis and 24 reference patients with left-sided accessory pathways were studied. Multipolar catheters placed at the lateral right atrium, crista terminalis, and coronary sinus (CS) characterized direction-dependent conduction along linear catheters and across the crista terminalis. Bi-atrial electroanatomic maps were created in both sinus rhythm and an alternative wavefront direction by pacing from the distal CS. This allowed an assessment of conduction velocities, electrogram, and voltage characteristics during wavefronts propagating in different directions. While differing wavefront directions caused changes in both chronic atrial stretch and reference patients (P< 0.001 for all), these direction-dependent changes were greater in chronic atrial stretch compared with reference patients, who exhibited greater slowing in conduction velocities (P= 0.09), prolongation of bi-atrial activation time (P= 0.04), increase in number (P< 0.001) and length (P< 0.001) of lines of conduction block, increase in fractionated electrograms (P< 0.001), and decrease in voltage (P= 0.08) during left-to-right compared with right-to-left atrial activation. These direction-dependent changes were associated with a greater propensity for chronically stretched atria to develop atrial fibrillation (P= 0.02). Atrial remodelling in chronic atrial stretch exacerbates physiological direction-dependent conduction characteristics. Our data suggest that the greater direction-dependent conduction seen in patients with chronic atrial stretch may promote arrhythmogenesis due to ectopic triggers from the left atrium.
Publisher: Wiley
Date: 02-06-2011
DOI: 10.1111/J.1540-8167.2011.02089.X
Abstract: Rapid PV activity is critical in initiating and maintaining AF. The underlying substrate responsible for this remains uncertain. We sought to identify if patients with paroxysmal (PAF) and persistent atrial fibrillation (PeAF) have an abnormal substrate within the pulmonary veins (PVs). Thirty-nine patients with AF (21 PAF, 18 PeAF) were compared with 15 age-matched controls with left-sided accessory pathways (AVRT). High-density 3D electroanatomic maps of the PVs were created. PV voltage, conduction, PV muscle sleeve length, effective refractory periods (ERPs) of the PVs, posterior left atrium (PLA), left atrial appendage (LAA) and distal coronary sinus (CSd), and signal complexity were assessed. Compared with controls, the PVs of AF patients had (1) lower mean-voltage and a higher % low-voltage (2) shorter PV muscle sleeves (3) slower conduction (4) shorter ERP and (5) more prevalent complex signals. Compared with the PAF group, the PeAF group had (1) higher % low voltage (2) slower conduction and (3) more complex signals. In PAF patients, the PLA and LAA ERPs were longer than controls and the PV ERP was shorter than controls in PeAF patients PLA and LAA ERPs were reduced, but to a lesser extent than in the PVs. AF induction occurred during PV ERP testing in both AF groups, but not controls. PAF and PeAF patients demonstrate electrical and electroanatomic remodeling of the PVs compared to control patients without prior AF. Some of these changes were more marked in PeAF.
Publisher: Elsevier BV
Date: 03-2012
DOI: 10.1016/J.HRTHM.2011.10.017
Abstract: There is a known association between obstructive sleep apnea (OSA) and atrial fibrillation (AF) however, how OSA affects the atrial myocardium is not well described. To determine whether patients with OSA have an abnormal atrial substrate. Forty patients undergoing ablation of paroxysmal AF and in sinus rhythm (20 with OSA [apnea-hypopnea index ≥ 15] and 20 reference patients with no OSA [apnea-hypopnea index < 15] by polysomnography) were studied. Multipolar catheters were positioned at the lateral right atrium (RA), coronary sinus, crista terminalis, and RA septum to determine the effective refractory period at 5 sites, conduction time along linear catheters at the RA and the coronary sinus, conduction at the crista terminalis, and sinus node function (corrected sinus node recovery time). Biatrial electroanatomic maps were created to determine the voltage, conduction, and distribution of complex electrograms (duration ≥ 50 ms). The groups had no differences in the prevalence of established risk factors for AF. Patients with OSA had the following compared with those without OSA: no difference in effective refractory period (P = .9), prolonged conduction times along the coronary sinus and RA (P = .02), greater number (P = .003) and duration (P = .03) of complex electrograms along the crista terminalis, longer P-wave duration (P = .01), longer corrected sinus node recovery time (P = .02), lower atrial voltage (RA, P <.001 left atrium, P <.001), slower atrial conduction velocity (RA, P = .001 left atrium, P = .02), and more widespread complex electrograms in both atria (RA, P = .02 left atrium, P = .01). OSA is associated with significant atrial remodeling characterized by atrial enlargement, reduction in voltage, site-specific and widespread conduction abnormalities, and longer sinus node recovery. These features may in part explain the association between OSA and AF.
Publisher: Springer Science and Business Media LLC
Date: 10-02-2018
DOI: 10.1007/S10286-018-0508-0
Abstract: Renal afferent and efferent sympathetic nerves are involved in the regulation of blood pressure and have a pathophysiological role in hypertension. Additionally, several conditions that frequently coexist with hypertension, such as heart failure, obstructive sleep apnea, atrial fibrillation, renal dysfunction, and metabolic syndrome, demonstrate enhanced sympathetic activity. Renal denervation (RDN) is an approach to reduce renal and whole body sympathetic activation. Experimental models indicate that RDN has the potential to lower blood pressure and prevent cardio-renal remodeling in chronic diseases associated with enhanced sympathetic activation. Studies have shown that RDN can reduce blood pressure in drug-naïve hypertensive patients and in hypertensive patients under drug treatment. Beyond its effects on blood pressure, sympathetic modulation by RDN has been shown to have profound effects on cardiac electrophysiology and cardiac arrhythmogenesis. RDN can display anti-arrhythmic effects in a variety of animal models for atrial fibrillation and ventricular arrhythmias. The first non-randomized studies demonstrate that RDN may promote the maintenance of sinus rhythm following catheter ablation in patients with atrial fibrillation. Registry data point towards a beneficial effect of RDN to prevent ventricular arrhythmias in patients with heart failure and electrical storm. Further large randomized placebo-controlled trials are needed to confirm the antihypertensive and anti-arrhythmic effects of RDN. Here, we will review the current literature on anti-arrhythmic effects of RDN with the focus on atrial fibrillation and ventricular arrhythmias. We will discuss new insights from preclinical and clinical mechanistic studies and possible clinical implications of RDN.
Publisher: Elsevier BV
Date: 03-2007
DOI: 10.1016/J.JACC.2006.11.033
Abstract: This study sought to evaluate the effects of stepwise catheter ablation of chronic atrial fibrillation (AF) on atrial electrical and mechanical properties. Although stepwise catheter ablation of chronic AF is associated with acute arrhythmia termination and a favorable clinical outcome, atrial tissue damage following the procedure has not been evaluated. Forty patients who had previously undergone catheter ablation of chronic AF were studied. In the index procedure, termination of AF was achieved by catheter ablation alone in 36 of 40 patients (90%). Electroanatomical mapping was performed in sinus rhythm > or =1 month after the index procedure, during which the surface area of scar (bipolar voltage of <0.05 mV), low-voltage tissue (<0.5 mV), and atrial propagation were evaluated. Left atrial (LA) mechanical function was assessed by transthoracic echocardiography. Electroanatomical mapping showed areas of scar and low-voltage accounting for 31% +/- 12% and 32% +/- 17% of the total LA surface area respectively, with the ablated pulmonary vein region accounting for 20% +/- 4% of the LA surface area. The area of scar outside the pulmonary vein region represented 14% +/- 12% of the LA surface area using the initial randomized ablation strategy, and 6% +/- 8% (p = 0.02) using a specific ablation strategy. Atrial conduction was ersely affected by ablation with a wide range of LA conduction times observed (range 100 to 360 ms). The LA contraction was shown in all patients by the presence of late diastolic mitral flow (37 +/- 15 cm/s) and a mean LA active emptying fraction of 18 +/- 11%. At 9 +/- 5 months of follow-up, 39 patients (98%) were in sinus rhythm. Stepwise ablation achieving sinus rhythm in patients with chronic AF has a significant impact on LA electrical activity but is associated with recovery of LA function.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 22-09-2017
Abstract: Besides hypertension, obesity and the metabolic syndrome have recently emerged as risk factors for atrial fibrillation. This study sought to delineate the development of an arrhythmogenic substrate for atrial fibrillation in hypertension with and without concomitant obesity and metabolic syndrome. We compared obese spontaneously hypertensive rats ( SHR ‐obese, n=7–10) with lean hypertensive controls ( SHR ‐lean, n=7–10) and normotensive rats (n=7–10). Left atrial emptying function (MRI) and electrophysiological parameters were characterized before the hearts were harvested for histological and biochemical analyses. At the age of 38 weeks, SHR ‐obese, but not SHR ‐lean, showed increased body weight and impaired glucose tolerance together with dyslipidemia compared with normotensive rats. Mean blood pressure was similarly increased in SHR ‐lean and SHR ‐obese when compared with normotensive rats (178±9 and 180±8 mm Hg [not significant] versus 118±5 mm Hg, P .01 for both), but left ventricular end‐diastolic pressure was more increased in SHR ‐obese than in SHR ‐lean. Impairment of left atrial emptying function, increase in total atrial activation time, and conduction heterogeneity, as well as prolongation of inducible atrial fibrillation durations, were more pronounced in SHR ‐obese as compared with SHR ‐lean. Histological and biochemical examinations revealed enhanced triglycerides and more pronounced fibrosis in the left atrium of SHR ‐obese. Besides increased expression of profibrotic markers in SHR ‐lean and SHR ‐obese, the profibrotic extracellular matrix protein osteopontin was highly upregulated only in SHR ‐obese. In addition to hypertension alone, concomitant obesity and metabolic syndrome add to the atrial arrhythmogenic phenotype by impaired left atrial emptying function, local conduction abnormalities, interstitial atrial fibrosis formation, and increased propensity for atrial fibrillation.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 18-09-2018
Abstract: An association between atrial fibrillation ( AF ), anxiety, and depression is recognized, but the spectrum of psychological distress remains unclear. We aimed to characterize the severity and predictors of distress associated with AF in a tertiary population and its response to AF management. Seventy‐eight patients with symptomatic AF underwent evaluation, including of AF symptom severity, health‐related quality of life, psychological distress, suicidal ideation, and specific personality traits. Twenty participants underwent AF ablation and 58 were managed medically, with repeat assessments at 4, 8, and 12 months. Severe distress (Hospital Anxiety and Depression Scale score, ≥15/42) was identified in 27 of 78 (35%). Independent predictors were a personality marked by vulnerability to stress (Perceived Stress Scale: R 2 , 0.54 β=0.7±0.1 t=7.8 P .001) and 1 marked by negativity/social inhibition (Type D Personality Scale: R 2 , 0.47 β=0.7±0.1 t=6.7 P .001). Suicidal ideation was reported by 16 of 78 (20%) and was predicted by personality traits (Perceived Stress Scale score: R 2 , 0.35 odds ratio, 1.22±0.06 P .001 Type D Personality Scale score: R 2 , 0.48 odds ratio, 1.43±0.14 P .001). Effective AF ablation (median AF burden 1% [0–1%] over 12 months) was associated with significant reductions in distress (Hospital Anxiety and Depression Scale score, 13.9±1.8 to 4.3±1.8 P .05) and prevalence of suicidal ideation (30–5% P =0.02). There was a high prevalence of severe psychological distress (35%) and of suicidal ideation (20%) in a tertiary AF population, with personality traits predicting both. Effective AF ablation was associated with significant improvements, suggesting AF itself may be a treatable causative factor of distress.
Publisher: Elsevier
Date: 2018
Publisher: Oxford University Press (OUP)
Date: 02-08-2021
DOI: 10.1093/EURHEARTJ/EHAB467
Abstract: Dietary intake has been shown to change the composition of gut microbiota and some changes in microbiota (dysbiosis) have been linked to diabetes, hypertension, and obesity, which are established risk factors for atrial fibrillation (AF). In addition, intestinal dysbiosis generates microbiota-derived bioactive metabolites that might exert proarrhythmic actions. Although emerging preclinical investigations and clinical observational cohort studies suggest a possible role of gut dysbiosis in AF promotion, the exact mechanisms through which dysbiosis contributes to AF remain unclear. This Viewpoint article briefly reviews evidence suggesting that abnormalities in the intestinal microbiota play an important and little-recognized role in the pathophysiology of AF and that an improved understanding of this role may open up new possibilities in the management of AF.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2017
DOI: 10.1161/CIRCULATIONAHA.116.024926
Abstract: Since the original description of atrial fibrillation ablation, numerous studies have demonstrated the superiority of catheter ablation over pharmacological therapy for maintenance of sinus rhythm in patients with both paroxysmal and persistent atrial fibrillation. However, to date, no randomized studies have been powered to demonstrate a mortality or stroke reduction benefit of rhythm control with catheter ablation over a rate control strategy. The results of such ongoing studies are not expected until 2018 or 2019. Thus, the only indication for atrial fibrillation ablation in recent guidelines has been the presence of symptoms. However, up to 40% of an atrial fibrillation population may be asymptomatic. In 2017, in the absence of randomized studies, are there nevertheless data that support atrial fibrillation ablation in asymptomatic patients?
Publisher: Oxford University Press (OUP)
Date: 02-06-2021
Abstract: The aim of this study is to determine the association between the coronavirus disease 2019 (COVID-19) pandemic and atrial fibrillation (AF) occurrence in in iduals with cardiac implantable electronic devices (CIEDs). Multi-centre, observational, cohort study over a 100-day period during the COVID-19 pandemic (COVID-19) in the USA. Remote monitoring was used to assess AF episodes in patients with a CIED (pacemaker or defibrillator 20 centres, 13 states). For comparison, the identical 100-day period in 2019 was used (Control). The primary outcomes were the AF burden during the COVID-19 pandemic, and the association of the pandemic with AF occurrence, as compared with 1 year prior. The secondary outcome was the association of AF occurrence with per-state COVID-19 prevalence. During COVID-19, 10 346 CIEDs with an atrial lead were monitored. There were 16 570 AF episodes of ≥6 min transmitted (16 events per 1000 patient days) with a significant increase in proportion of patients with AF episodes in high COVID-19 prevalence states compared with low prevalence states [odds ratio 1.34, 95% confidence interval (CI) 1.21–1.48, P & 0.001]. There were significantly more AF episodes during COVID-19 compared with Control [incident rate ratio (IRR) 1.33, 95% CI 1.25–1.40, P & 0.001]. This relationship persisted for AF episodes ≥1 h (IRR 1.65, 95% CI 1.53–1.79, P & 0.001) and ≥6 h (IRR 1.54, 95% CI 1.38–1.73, P & 0.001). During the first 100 days of COVID-19, a 33% increase in AF episodes occurred with a 34% increase in the proportion of patients with AF episodes observed in states with higher COVID-19 prevalence. These findings suggest a possible association between pandemic-associated social disruptions and AF in patients with CIEDs. Australian New Zealand Clinical Trial Registry: ACTRN12620000692932.
Publisher: Wiley
Date: 06-2003
DOI: 10.1046/J.1540-8167.2003.02152.X
Abstract: Cavotricuspid isthmus (CTI) topography includes ridges, pouches, recesses, and trabeculations. These features may limit the success of radiofrequency ablation (RFA) of typical atrial flutter (AFL). The aim of this study was to assess the utility of phased-array intracardiac echocardiography (ICE) for imaging the CTI and monitoring RFA of AFL. Fifteen patients (mean age 64 +/- 9 years) underwent ICE assessment (imaging frequency 7.5-10 MHz) before and after RFA of AFL. The ICE catheter was positioned at the inferior vena cava-right atrial junction and the following parameters were measured: (1) CTI length from the tricuspid valve to the eustachian ridge (2) extent of CTI pouching and (3) thickness pre ost RFA of the anterior, mid, and posterior CTI. CTI length was 35 +/- 6 mm at end-ventricular systole but shorter (30 +/- 6 mm) and more pouched at end-ventricular diastole (P = 0.02). A pouch or recess was seen in 11 of 15 patients (mean depth 6 +/- 2 mm). The septal CTI was more pouched than the lateral CTI, but the latter had more prominent trabeculations. Trabeculations were seen in 10 of 15 patients, and at these locations the CTI was 4.6 +/- 1 mm thick. Anterior, mid, and posterior CTI thickness pre-RFA was 4.1 +/- 0.8, 3.3 +/- 0.5, and 2.7 +/- 0.9 mm, respectively (P < 0.001 by analysis of variance). ICE guided RFA away from unfavorable CTI features (recesses/thick trabeculations). RFA applications created discrete CTI lesions that coalesced, forming diffuse CTI swelling. Post-RFA thickness was as follows: anterior 4.8 +/- 0.8 mm (P = NS vs pre) mid 3.8 +/- 0.8 mm (P = 0.05 vs pre) and posterior 3.8 +/- 0.8 mm (P = 0.02 vs pre). Phased-array ICE permits novel real-time CTI imaging with excellent endocardial resolution and may facilitate RFA of AFL.
Publisher: Elsevier BV
Date: 09-2019
Publisher: Wiley
Date: 16-11-2006
Publisher: Wiley
Date: 12-2004
DOI: 10.1046/J.1540-8167.2004.04318.X
Abstract: We conducted an acute echocardiographic study comparing hemodynamic and ventricular dyssynchrony parameters during left ventricular pacing (LVP) and biventricular pacing (BVP). We sought to clarify the mechanisms responsible for similar hemodynamic improvement despite differences in electrical activation. Thirty-three patients underwent echocardiography prior to implantation with a multisite pacing device (spontaneous rhythm [SR]) and 2 days after implantation (BVP and LVP). Interventricular dyssynchrony (pulsed-wave Doppler), extent of myocardium displaying delayed longitudinal contraction (%DLC tissue tracking), and index of LV dyssynchrony (pulsed-wave tissue Doppler imaging) were assessed. Compared to SR, BVP and LVP caused similar significant improvement of cardiac output (LVP: 3.2 +/- 0.5, BVP: 3.1 +/- 0.7, SR: 2.3 +/- 0.6 L/min P < 0.01) and mitral regurgitation (LVP: 25.1 +/- 10, BVP: 24.7 +/- 11, baseline: 37.9 +/- 14% jet area/left atria area P < 0.01). LVP resulted in a smaller index of LV dyssynchrony than BVP (29 +/- 10 vs 34 +/- 14 P < 0.05). However, LVP exhibited a longer aortic preejection delay (220 +/- 34 vs 186 +/- 28 msec P < 0.01), longer LV electromechanical delays (244.5 +/- 39 vs 209.5 +/- 47 msec P < 0.05), greater interventricular dyssynchrony (56.6 +/- 18 vs 31.4 +/- 18 P < 0.01), and higher%DLC (40.1 +/- 08 vs 30.3 +/- 09 P < 0.05), leading to shorter LV filling time (387 +/- 54 vs 348 +/- 44 msec P < 0.05) compared to BVP. Although LVP and BVP provide similar hemodynamic improvement, LVP results in more homogeneous but substantially delayed LV contraction, leading to shortened filling time and less reduction in postsystolic contraction. These data may influence the choice of in idual optimal pacing configuration.
Publisher: Wiley
Date: 14-09-2005
DOI: 10.1111/J.1540-8167.2005.00292.X
Abstract: Organized atrial arrhythmias following atrial fibrillation (AF) ablation are typically due to recovered pulmonary vein (PV) conduction or reentry at incomplete ablation lines. We describe the role of nonablated anterior left atrium (LA) in arrhythmias observed after AF ablation. A total of 275 consecutive patients with paroxysmal (n = 200) or chronic (n = 75) AF had PV isolation with/without additional linear ablation at the mitral isthmus (n = 106), LA roof (n = 23), or both (n = 88). Organized arrhythmias occurring after ablation were evaluated utilizing activation and entrainment mapping. Fourteen patients (11 female, 65 +/- 13 years, 10 chronic AF, 10 structural heart disease) demonstrated tachycardia localized to the anterior LA, an area not targeted by prior ablation. Eight had ECG features during sinus rhythm suggestive of impaired anterior LA conduction at baseline. These arrhythmias demonstrated a distinctive ECG flutter morphology in 7 of 10 (70%) with discrete -/+ or +/-/+ aspect in inferior leads. Mapping the anterior LA revealed electrograms spanning the entire tachycardia cycle length (325 +/- 125 msec). Entrainment was possible in all with a postpacing interval exceeding the tachycardia cycle length by 9 +/- 10 msec. Electroanatomic mapping in 6 demonstrated small reentrant circuits rotating clockwise in 4 and counterclockwise in 2. Low- litude, fractionated mid-diastolic potentials with long duration (200 +/- 80 msec) occupying 63 +/- 22% of the cycle length were targeted for ablation resulting in termination and subsequent noninducibility. Organized arrhythmias occurring after AF ablation can be due to reentrant circuits localized to the anterior LA, predominantly in females with chronic AF, structural heart disease, and abnormal atrial conduction. They are characterized by a distinctive surface ECG and highly responsive to RF ablation at the slow conduction area.
Publisher: Elsevier BV
Date: 10-2017
Publisher: Elsevier BV
Date: 07-2016
DOI: 10.1016/J.HRTHM.2016.03.005
Abstract: For clinicians, confidence in atrial fibrillation (AF) episode classification is an important consideration when electing to use insertable cardiac monitors (ICMs). The purpose of this study was to report on the improved AF detection algorithm in the Reveal LINQ ICM. The Reveal LINQ Usability Study is a nonrandomized, prospective, multicenter trial. The ICM has been miniaturized, uses wireless telemetry for remote patient monitoring, and its AF algorithm includes a new p-wave filter. At 1 month post-device insertion, Holter monitor data were collected and annotated for true AF episodes ≥2 minutes, and performance metrics were evaluated by comparing Holter annotations with ICM detections. The study enrolled 151 patients (age 56.6 ± 12.1, male 67%). Reasons for monitoring included AF ablation or AF management in 81.5% (n = 123), syncope in 12.6% (n = 19), and other indications in 5.9% (n = 9) of patients. Of the 138 patients with an analyzable Holter recording, a total of 112 true AF episodes were identified in 38 patients (27.5%). The overall accuracy of the ICM to detect durations of AF or non-AF episodes was 99.4%, and the AF burden measured by the ICM was highly correlated with the Holter (Pearson coefficient 0.995). The new AF detection algorithm in the Reveal LINQ ICM accurately detects the presence or absence of AF. Additionally, it showed high sensitivity in detecting AF duration in patients with a history of intermittent and symptomatic AF.
Publisher: Wiley
Date: 19-10-2018
DOI: 10.1002/CLC.23091
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.HRTHM.2018.07.029
Abstract: Battery longevity is an important factor that may influence the selection of cardiac implantable electronic devices (CIEDs). However, there remains a lack of industry-wide standardized reporting of predicted CIED longevity to facilitate informed decision-making for implanting physicians and payers. The purpose of this study was to compare the predicted longevity of current generation CIEDs using best-matched CIEDs settings to assess differences between brands and models. Data were extracted for current model pacemakers, implantable cardioverter-defibrillators (ICDs), and cardiac resynchronization therapy-defibrillators (CRT-Ds) from product manuals and, where absent, by communication with the manufacturers. Pacemaker longevity estimations were based on standardized pacing outputs (2.5V, 0.40-ms pulse width, 500-Ω impedance) and pacing loads of 50% or 100% at 60 bpm. ICD and CRT-D longevity were estimated at 0% pacing and 15% atrial plus 100% biventricular pacing, with essential capacitor reforms and zero clinical shocks. Mean maximum predicted longevity of single- and dual-chamber pacemakers was 12.0 ± 2.1 and 9.8 ± 1.9 years, respectively. Use of advanced features such as remote monitoring, prearrhythmia electrogram storage, and rate response can result in ∼1.4 years of reduction in longevity. Mean maximum predicted longevity of ICDs and CRT-Ds was 12.4 ± 3.0 and 8.8 ± 2.1 years, respectively. Of note, there were significant variations in predicted CIED longevity according to device manufacturers, with up to 44%, 42%, and 44% difference for pacemakers, ICDs, and CRT-Ds, respectively. Contemporary CIEDs demonstrate highly variable predicted longevity according to device manufacturers. This may impact on health care costs and long-term clinical outcomes.
Publisher: Elsevier BV
Date: 05-2023
Publisher: Springer Science and Business Media LLC
Date: 28-11-2009
DOI: 10.1007/S10554-008-9394-1
Abstract: Heart mapping systems allow approximate reconstruction of the heart chamber geometry which is used as a base for the representation of the spatial distribution of electrophysiological parameters. Main limitation lies in the difficulty of the reconstruction of the geometry of more complicated areas of the heart. Here, we propose a new method of representation of the spatial distribution of the electrophysiological parameters-an integration of the data points collected by a classical mapping system with the geometry reconstructed from a computed tomography (CT) image. CARTO maps of activation and bipolar viability of seven patients undergoing atrial fibrillation ablation were integrated with the geometry of the left atria reconstructed from the CT image. In all cases, integration was successful with the registration error measured as the distance between objects equal to 2.52 +/- 0.25 mm. Bipolar viability and activation maps were reconstructed on the CT geometry. Our method allowed us to create maps of electrophysiological parameters of anatomically complex structures without the need for their detailed mapping.
Publisher: Elsevier BV
Date: 08-2022
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.CCEP.2019.08.007
Abstract: This review focusses on novel findings in atrial fibrillation mechanisms derived from mapping studies. Recent panoramic mapping techniques have identified 2 arrhythmic mechanisms of interest, namely, rotational (rotors) and ectopic focal activations as drivers of atrial fibrillation. Epicardial adipose tissue and fatty infiltration into the myocardium have been described as novel substrates for atrial fibrillation. There is increasing appreciation that the thin atrial walls harbor a complex 3-dimensional electrostructural substrate to contribute to atrial fibrillation sustenance. Further research is warranted to advance the field toward more targeted therapy.
Publisher: Wiley
Date: 23-06-2009
DOI: 10.1111/J.1540-8167.2008.01425.X
Abstract: Measuring the postpacing interval (PPI) and correcting for the tachycardia cycle length (TCL) is an important entrainment response (ER). However, it may be impossible to measure PPI due to electrical noise on the mapping catheter. To overcome this problem, 2 alternative methods for the assessment of ER have been proposed: N+1 difference (N+1 DIFF) and PPIR method. PPI-TCL difference (PPI-TCL) correlates very well with ER assessed by new methods, but the agreement with PPI-TCL was established only in relation to PPIR method. Moreover, it is not known which of these methods is superior in the assessment of ER. We analyzed 155 episodes of ER in 21 patients with heterogeneous reentrant arrhythmias. ER was estimated by PPI-TCL and by both alternative methods. Agreement between methods was assessed by means of the Bland-Altman test, kappa coefficient (kappa), and correlation coefficient (r). Finally, a mathematical comparison of the alternative methods was performed. The agreement between PPI-TCL and alternative methods was very good. For N+1 DIFF the mean difference was -1.86 +/- 7.31 ms kappa = 0.9 r = 0.98 for PPIR method the mean difference was -1.46 +/- 7.65 ms kappa = 0.92 r = 0.99. Agreement between both alternative methods was also very high: the mean difference of 0.5 +/- 6.6 ms kappa = 0.89 r = 0.99. The analysis of the equations used for calculation of ER by these methods revealed that essentially they were mathematically equivalent. Each of the alternative methods may be used for evaluation of ER when PPI-TCL cannot be assessed directly. Results obtained by both alternative methods are comparable.
Publisher: American Medical Association (AMA)
Date: 10-12-2012
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2013
DOI: 10.1161/CIRCEP.113.000768
Abstract: Atrial fibrillation ablation is an established therapy however, limited data are available on associated complications. This systematic review determines the incidence and potential predictors of acute complications. Electronic searches were conducted in MEDLINE and EMBASE for English scientific literature up to the 18th June 2012. A total of 2065 references were retrieved and evaluated for relevance. Reference lists of retrieved studies and review articles were examined to ensure all relevant studies were included. Data were extracted from 192 studies, total of 83 236 patients. The incidence of periprocedural complications for catheter ablation of atrial fibrillation was 2.9% (95% confidence interval, 2.6–3.2). There was a significant decrease in the acute complication rate in 2007 to 2012 compared with 2000 to 2006 (2.6% versus 4.0% P =0.003). The complication rates reported were higher in prospective studies compared with those that retrospectively described complications (3.5% versus 2.7% P =0.03). There were no significant associations among procedure duration, ablation time or ablation strategy, and acute complication rate. Catheter ablation of atrial fibrillation has a low incidence of periprocedural complications. The acute complication rate has decreased significantly in recent years. This may reflect improved catheter technology and experience. The use of different strategies across centers worldwide seems to be safe with no established relationship between procedural variables and complication rate.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 24-01-2006
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-04-2003
DOI: 10.1161/01.CIR.0000058164.68127.F2
Abstract: Background— Adults with an atrial septal defect (ASD) frequently develop late atrial arrhythmias. We sought to characterize the pattern and persistence of atrial electrical remodeling caused by chronic right atrial (RA) stretch in this group. Methods and Results— Thirteen ASD patients without atrial arrhythmia (42±10 years old RA volume, 65±16 mL) and 17 normal control subjects (44±11 years old RA volume, 38±8 mL) had electrophysiological study to measure (1) atrial effective refractory period (AERP) from the low lateral/high lateral/high septal RA and distal coronary sinus (CS), (2) dispersion of AERP, (3) lateral-RA and CS conduction time during constant pacing, (4) conduction delay across the crista terminalis measuring the number of crista catheter bipoles (0–10) recording discrete double potentials during pacing, (5) corrected sinus node recovery time, and (6) P-wave duration. After ASD closure (8.3±5.6 months), follow-up echo studies (n=12) and electrophysiological study (n=4) were performed. The low-lateral AERP, P-wave duration, sinus node recovery time, and extent of conduction delay across the crista terminalis were significantly greater in ASD patients. No differences were found for other measured electrophysiological study parameters. At follow-up, there was incomplete resolution of RA volume (47±12 mL P .01 versus before surgery), a trend toward shortening of the AERP at the lateral RA and an increase at the distal CS and high septal RA, but persisting extensive, widely split crista double potentials. Conclusions— Chronic RA stretch because of ASD causes electrical remodeling with modest increases in RA ERP, conduction delay at the crista terminalis, and sinus node dysfunction. Conduction delay at the crista terminalis persists beyond ASD closure and may contribute to the long-term atrial arrhythmia substrate in this condition.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2014
DOI: 10.1161/CIRCEP.113.000882
Abstract: Surviving myocytes within scar may form channels that support ventricular tachycardia (VT) circuits. There are little data on the properties of channels that comprise VT circuits and those that are non-VT supporting channels. In 22 patients with ischemic cardiomyopathy and VT, high-density mapping was performed with the PentaRay catheter and Ensite NavX system during sinus rhythm. A channel was defined as a series of matching pace-maps with a stimulus (S) to QRS time of ≥40 ms. Sites were determined to be part of a VT channel if there were matching pace-maps to the VT morphology. This was confirmed with entrainment mapping when possible. Of the 238 channels identified, 57 channels corresponded to an inducible VT. Channels that were part of a VT circuit were more commonly located within dense scar than non-VT channels (97% versus 82% P =0.036). VT supporting channels were of greater length (mean±SEM, 53±5 versus 33±4 mm), had higher longest S-QRS (130±12 versus 82±12 ms), longer conduction time (103±14 versus 43±13 ms), and slower conduction velocity (0.87±0.23 versus 1.39±0.21 m/s) than non-VT channels ( P .001). Of all the fractionated, late, and very late potentials located in scar, only 21%, 26%, and 29%, respectively, were recorded within VT channels. High-density mapping shows substantial differences among channels in ventricular scar. Channels supporting VT are more commonly located in dense scar, longer than non-VT channels, and have slower conduction velocity. Only a minority of scar-related potentials participate in the VT supporting channels.
Publisher: BMJ
Date: 11-11-2019
DOI: 10.1136/HEARTJNL-2019-315327
Abstract: The management of atrial fibrillation (AF) has focused on anticoagulation, rhythm control and ventricular rate control. Recently, a fourth pillar of AF management has been incorporated recognising the importance of risk factor management (RFM). There are several risk factors that contribute to the development and progression of AF, these include traditional risk factors such as age, hypertension, heart failure, diabetes and valvular heart disease. However, increasingly it is recognised that obesity, sleep apnoea, hyperlipidaemia, smoking, alcohol, physical inactivity, genetics, aortic stiffness are associated with the development of AF. Importantly, several of these risk factors are modifiable. We have seen the evolution of RFM programmes which have demonstrated promising results. Indeed, the evidence is now so compelling that major clinical guidelines strongly advocate that aggressive treatment of these risk factors as a key component of AF management. Patients with AF who comprehensively managed their risk factors demonstrate greater reduction in symptoms, AF burden, more successful ablations and improved outcomes with greater AF freedom. In this article, we will review the evidence for the association between cardiac risk factors and AF and assess the burgeoning evidence for improved AF outcomes associated with aggressive cardiac RFM.
Publisher: Wiley
Date: 06-03-2022
DOI: 10.1111/JCE.15421
Abstract: Underrepresentation of females in randomized controlled trials (RCTs) limits generalizability and quality of the evidence guiding treatment of females. This study aimed to measure the sex disparities in participants' recruitment in RCTs of atrial fibrillation (AF) and determine associated factors, and to describe the frequency of outcomes reported by sex. MEDLINE was searched to identify RCTs of AF published between January 1, 2011, and November 20, 2021, in 12 top‐tier journals. We measured the enrollment of females using the enrollment disparity difference (EDD) which is the difference between the proportion of females in the trial and the proportion of females with AF in the underlying general population (obtained from the Global Burden of Disease). Random‐effects meta‐analyses of the EDD were performed, and multivariable meta‐regression was used to explore factors associated with disparity estimates. We also determined the proportion of trials that included sex‐stratified results. Out of 1133 records screened, 142 trials were included, reporting on a total of 133 532 participants. The random‐effects summary EDD was −0.125 (95% confidence interval [CI] = −0.143 to −0.108), indicating that females were under‐enrolled by 12.5 percentage points. Female enrollment was higher in trials with higher s le size ( vs. , adjusted odds ratio [aOR] 1.065, 95% CI: 1.008–1.125), higher mean participants' age (aOR: 1.006, 95% CI: 1.002–1.009), and lower in trials conducted in North America compared to Europe (aOR: 0.945, 95% CI: 0.898–0.995). Only 36 trials (25.4%) reported outcomes by sex, and of these 29 (80.6%) performed statistical testing of the sex‐by‐treatment interaction. Females remain substantially less represented in RCTs of AF, and sex‐stratified reporting of primary outcomes is infrequent. These findings call for urgent action to improve sex equity in enrollment and sex‐stratified outcomes' reporting in RCTs of AF.
Publisher: Elsevier BV
Date: 03-2010
Abstract: Studies relating cardiovascular outcomes to dietary or blood measures of various fatty acids rely on the implicit assumptions that dietary change results in changes in blood fatty acids that, in turn, alter cardiac fatty acids. Although dietary intakes of n-3 (omega-3), n-6 (omega-6), and trans fatty acids are reflected in their concentrations in blood, there are few human data on the relation between blood and cardiac concentrations of fatty acids. The objective was to explore relations between blood and myocardial n-3, n-6, trans, monosaturated, and saturated fatty acids over a range of community intakes to evaluate whether blood fatty acids are useful surrogate markers of their cardiac counterparts. Patients undergoing on-pump coronary bypass surgery were recruited. Right atrial appendages and blood were collected at surgery for fatty acid analysis. Atrial appendages and matching blood s les were collected from 61 patients. Highly significant correlations were identified between atrial and erythrocyte or plasma n-3 [eg, eicosapentaenoic acid (erythrocytes: r = 0.93, P < 0.0001 plasma: r = 0.87, P < 0.0001)], some n-6 [eg, arachidonic acid (erythrocytes: r = 0.45, P = 0.0003 plasma: r = 0.39, P = 0.002)], trans [eg, total trans 18:1 (erythrocytes: r = 0.89, P < 0.0001 plasma: r = 0.74, P < 0.0001)], and monounsaturated [eg, oleic acid (erythrocytes: r = 0.37, P = 0.003)] fatty acids. There were no statistical associations between blood and cardiac saturated fatty acids. Erythrocyte- and plasma phospholipid-derived fatty acids can be used to estimate cardiac fatty acid status in humans.
Publisher: Springer Science and Business Media LLC
Date: 09-09-2017
Publisher: Elsevier BV
Date: 07-2022
DOI: 10.1016/J.JACEP.2022.04.015
Abstract: Observational studies report that obstructive sleep apnea (OSA) is associated with an increasingly remodeled atrial substrate in atrial fibrillation (AF). However, the impact of OSA management on the electrophysiologic substrate has not been evaluated. In this study, the authors sought to determine the impact of OSA management on the atrial substrate in AF. We recruited 24 consecutive patients referred for AF management with at least moderate OSA (apnea-hypopnea index [AHI] ≥15). Participants were randomized in a 1:1 ratio to commence continuous positive airway pressure (CPAP) or no therapy (n = 12 CPAP n = 12 no CPAP). All participants underwent invasive electrophysiologic study (high-density right atrial mapping) at baseline and after a minimum of 6 months. Outcome variables were atrial voltage (mV), conduction velocity (m/s), atrial surface area <0.5 mV (%), proportion of complex points (%), and atrial effective refractory periods (ms). Change between groups over time was compared. Clinical characteristics and electrophysiologic parameters were similar between groups at baseline. Compliance with CPAP therapy was high (device usage: 79% ± 19% mean usage/day: 268 ± 91 min) and resulted in significant AHI reduction (mean reduction: 31 ± 23 events/h). There were no differences in blood pressure or body mass index between groups over time. At follow-up, the CPAP group had faster conduction velocity (0.86 ± 0.16 m/s vs 0.69 ± 0.12 m/s P (time × group) = 0.034), significantly higher voltages (2.30 ± 0.57 mV vs 1.94 ± 0.72 mV P < 0.05), and lower proportion of complex points (8.87% ± 3.61% vs 11.93% ± 4.94% P = 0.011) compared with the control group. CPAP therapy also resulted in a trend toward lower proportion of atrial surface area <0.5 mV (1.04% ± 1.41% vs 4.80% ± 5.12% P = 0.065). CPAP therapy results in reversal of atrial remodeling in AF and provides mechanistic evidence advocating for management of OSA in AF.
Publisher: Elsevier BV
Date: 08-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2021
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.HLC.2017.05.120
Abstract: The epidemic of atrial fibrillation (AF) is increasingly recognised as a growing health problem worldwide. Although epidemiological studies on AF in the Asia-Pacific region are scarce, given the increasing age and size of populations in this region, the burden of AF is expected to be far greater than in North America and Europe. This is not only due to the growing, ageing population but also an increased incidence of risk factors for AF, such as hypertension, obesity, metabolic syndrome and diabetes, in the Asia-Pacific region. While further, high quality data on such aspects as risk factors, racial disparities and clinical implications is urgently required, there is an immediate need for increased focus on appropriate stroke prophylaxis and risk factor management to minimise the clinical complications and societal burden of AF.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.HLC.2017.05.125
Abstract: Catheter ablation is now at the forefront of the management of symptomatic atrial fibrillation (AF). Its role in paroxysmal AF is well defined with considerable data supporting its role. Catheter ablation in persistent AF has been less effective and the subject of considerable debate. Mechanistic studies have demonstrated the critical role of pulmonary vein physiology in paroxysmal AF, whereas the mechanisms that sustain persistent AF are not well understood. Additional substrate ablation in persistent AF has not improved long-term outcomes and the use of novel mapping technologies to assess rotor activity remains controversial. This review will focus on the current understanding of the mechanistic basis of paroxysmal and persistent AF, the role of catheter ablation and, recent advances in the management of these complex arrhythmias.
Publisher: Wiley
Date: 11-02-2010
DOI: 10.1111/J.1540-8167.2010.01727.X
Abstract: The goal of this study was to describe mapping and ablation of severe arrhythmias during pregnancy, with minimum or no X-ray exposure. Treatment of tachyarrhythmia in pregnancy is a clinical problem. Pharmacotherapy entails a risk of adverse effects and is unsuccessful in some patients. Radiofrequency ablation has been performed rarely, because of fetal X-ray exposure and potential maternal and fetus complications. GROUP AND METHOD: Mapping and ablation was performed in 9 women (age 24-34 years) at 12-38th week of pregnancy. Three had permanent junctional reciprocating tachycardia, and 2 had incessant atrial tachycardia. Four of them had left ventricular ejection fraction < or =45%. One patient had atrioventricular nodal reciprocating tachycardia requiring cardioversion. Three patients had Wolff-Parkinson-White syndrome. Two of them had atrial fibrillation with ventricular rate 300 bpm and 1 had atrioventricular tachycardia 300 bpm. Fetal echocardiography was performed before and after the procedure. Three women had an electroanatomic map and ablation done without X-ray exposure. The mean fluoroscopy time in the whole group was 42 +/- 37 seconds. The mean procedure time was 56 +/- 18 minutes. After the procedure, all women and fetuses were in good condition. After a mean period of 43 +/- 23 months follow up (FU), all patients were free of arrhythmia without complications related to ablation either in the mothers or children. Ablation can be performed safely with no or minimal radiation exposure during pregnancy. In the setting of malignant, drug-resistant arrhythmia, ablation may be considered a therapeutic option in selected cases.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.HLC.2017.05.123
Abstract: Atrial fibrillation (AF) is a leading cause of cardiovascular morbidity and mortality worldwide. Management of AF is a complex process involving: 1) the prevention of thromboembolic complications with anticoagulation 2) rhythm control and 3) the detection and treatment of underlying heart disease. However, cardiometabolic risk factors, such as obesity, hypertension, diabetes mellitus, and obstructive sleep apnoea, have been proposed as contributors to the expanding epidemic of atrial fibrillation (AF). Thus, a fourth pillar of AF care would include aggressive targeting of interdependent, modifiable cardiovascular risk factors as part of an integrated care model. Such risk factor management could retard and reverse the pathological processes underlying AF and reduce AF burden.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.HLC.2017.05.124
Abstract: Atrioventricular node ablation (AVNA) is generally reserved for patients whose atrial fibrillation (AF) is refractory all other therapeutic options, since the recipients will often become pacemaker dependent. In such patients, this approach may prove particularly useful, especially if a tachycardia-induced cardiomyopathy is suspected. Historically, an "ablate and pace" approach has involved AVNA and right ventricular pacing, with or without an atrial lead. There is also an evolving role for atrioventricular node ablation in patients with AF who require cardiac resynchronisation therapy for treatment of systolic heart failure. A mortality benefit over pharmacotherapy has been demonstrated in observational studies and this concept is being further investigated in multi-centre randomised control trials.
Publisher: Wiley
Date: 2004
Publisher: Elsevier BV
Date: 05-2012
Publisher: Oxford University Press (OUP)
Date: 22-09-2021
DOI: 10.1093/CVR/CVAB292
Abstract: Recent preclinical and observational cohort studies have implicated imbalances in gut microbiota composition as a contributor to atrial fibrillation (AF). The gut microbiota is a complex and dynamic ecosystem containing trillions of microorganisms, which produces bioactive metabolites influencing host health and disease development. In addition to host-specific determinants, lifestyle-related factors such as diet and drugs are important determinants of the gut microbiota composition. In this review, we discuss the evidence suggesting a potential bidirectional association between AF and gut microbiota, identifying gut microbiota-derived metabolites as possible regulators of the AF substrate. We summarize the effect of gut microbiota on the development and progression of AF risk factors, including heart failure, hypertension, obesity, and coronary artery disease. We also discuss the potential anti-arrhythmic effects of pharmacological and diet-induced modifications of gut microbiota composition, which may modulate and prevent the progression to AF. Finally, we highlight important gaps in knowledge and areas requiring future investigation. Although data supporting a direct relationship between gut microbiota and AF are very limited at the present time, emerging preclinical and clinical research dealing with mechanistic interactions between gut microbiota and AF is important as it may lead to new insights into AF pathophysiology and the discovery of novel therapeutic targets for AF.
Publisher: Elsevier
Date: 2006
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2014
DOI: 10.1161/CIRCEP.113.000876
Abstract: Inflammation has been linked to the genesis of stroke in atrial fibrillation (AF) and is implicated in early recurrent arrhythmia after AF ablation. We aimed to define the time course of inflammation, myocardial injury, and prothrombotic markers after radiofrequency ablation for AF and its relation to AF recurrence. Ninety consecutive AF patients (53% paroxysmal) undergoing radiofrequency ablation were recruited. High-sensitivity C-reactive protein (hs-CRP), Troponin-T, creatine kinase-MB, fibrinogen, and D-Dimer concentrations were measured at baseline, at 1, 2, 3, 7 days, and at 1 month after ablation. AF recurrence was documented at 3 days and at 1, 3, and 6 months follow-up. Troponin-T and creatine kinase-MB peaked at day 1 after procedure (both P .05). Hs-CRP peaked at day 3 after procedure ( P .05). Fibrinogen ( P .05) and D-Dimer ( P .05) concentrations were significantly elevated at 1 week after procedure. Ln hs-CRP elevation correlated with Ln Troponin-T and fibrinogen elevation. The extent of Ln hs-CRP, Ln Troponin-T, and fibrinogen elevation predicted early AF recurrence within 3 days after procedure ( P .05, respectively), but not at 3 and 6 months. Patients undergoing radiofrequency ablation for AF exhibit an inflammatory response within 3 days. The extent of inflammatory response predicts early AF recurrence but not late recurrence. Prothrombotic markers are elevated at 1 week after ablation and may contribute to increased risk of early thrombotic events after AF ablation.
Publisher: Springer Science and Business Media LLC
Date: 29-06-2011
DOI: 10.1007/S10554-010-9657-5
Abstract: Cardiac fibrosis plays an important prognostic role in nonischemic cardiomyopathy (NICM), making it a potential therapeutic target. Although electromechanical mapping has been used to identify myocardial scar and facilitate intramyocardial intervention in the setting of ischemic heart disease, its application has not been described in NICM. We assessed the detection of myocardial fibrosis by endoventricular electromechanical mapping in an experimental model of NICM. The NOGA® XP system was used to perform left ventricular mapping in twelve sheep that had undergone intracoronary doxorubicin dosing to induce NICM and in six healthy control animals. Results for endocardial voltage and mechanical shortening were evaluated against myocardial fibrosis burden, as determined by delayed-enhancement cardiac magnetic resonance and quantitative histomorphometry. Doxorubicin treatment resulted in dilated cardiomyopathy with moderate-severe impairment of left ventricular ejection fraction. Late gadolinium uptake was present in 9/12 doxorubicin animals, while histological fibrosis was approximately doubled compared to controls and was distributed multisegmentally throughout the left ventricle. Cardiomyopathy was associated with widespread reductions in unipolar and bipolar voltage litude and endocardial shortening. Each parameter showed an inverse relationship with the burden of fibrosis. Moreover, unipolar voltage and linear local shortening ratio displayed moderate accuracy for identifying myocardial segments with delayed contrast enhancement or increased fibrosis content, with optimal discriminatory thresholds of 7.5 mV and 11.5%, respectively. In this model of NICM, electromechanical mapping shows potential for delineating segmental differences in fibrosis. Pending clinical evaluation, it may therefore have applicability for directing targeted intramyocardial interventions in nonischemic heart disease.
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.HRTHM.2012.08.043
Abstract: Obesity is associated with atrial fibrillation (AF) however, the mechanisms by which it induces AF are unknown. To examine the effect of progressive weight gain on the substrate for AF. Thirty sheep were studied at baseline, 4 months, and 8 months, following a high-calorie diet. Ten sheep were s led at each time point for cardiac magnetic resonance imaging and hemodynamic studies. High-density multisite biatrial epicardial mapping was used to quantify effective refractory period, conduction velocity, and conduction heterogeneity index at 4 pacing cycle lengths and AF inducibility. Histology was performed for atrial fibrosis, inflammation, and intramyocardial lipidosis, and molecular analysis was performed for endothelin-A and -B receptors, endothelin-1 peptide, platelet-derived growth factor, transforming growth factor β1, and connective tissue growth factor. Increasing weight was associated with increasing left atrial volume (P = .01), fibrosis (P = .02), inflammatory infiltrates (P = .01), and lipidosis (P = .02). While there was no change in the effective refractory period (P = .2), there was a decrease in conduction velocity (P<.001), increase in conduction heterogeneity index (P<.001), and increase in inducible (P = .001) and spontaneous (P = .001) AF. There was an increase in atrial cardiomyocyte endothelin-A and -B receptors (P = .001) and endothelin-1 (P = .03) with an increase in adiposity. In association, there was a significant increase in atrial interstitial and cytoplasmic transforming growth factor β1 (P = .02) and platelet-derived growth factor (P = .02) levels. Obesity is associated with atrial electrostructural remodeling. With progressive obesity, there were changes in atrial size, conduction, histology, and expression of profibrotic mediators. These changes were associated with spontaneous and more persistent AF.
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.HRTHM.2017.09.010
Abstract: Current phase mapping systems for atrial fibrillation create 2-dimensional (2D) maps. This process may affect the accurate detection of rotors. We developed a 3-dimensional (3D) phase mapping technique that uses the 3D locations of basket electrodes to project phase onto patient-specific left atrial 3D surface anatomy. We sought to determine whether rotors detected in 2D phase maps were present at the corresponding time segments and anatomical locations in 3D phase maps. One-minute left atrial atrial fibrillation recordings were obtained in 14 patients using the basket catheter and analyzed off-line. Using the same phase values, 2D and 3D phase maps were created. Analysis involved determining the dominant propagation patterns in 2D phase maps and evaluating the presence of rotors detected in 2D phase maps in the corresponding 3D phase maps. Using 2D phase mapping, the dominant propagation pattern was single wavefront (36.6%) followed by focal activation (34.0%), disorganized activity (23.7%), rotors (3.3%), and multiple wavefronts (2.4%). Ten transient rotors were observed in 9 of 14 patients (64%). The mean rotor duration was 1.1 ± 0.7 seconds. None of the 10 rotors observed in 2D phase maps were seen at the corresponding time segments and anatomical locations in 3D phase maps 4 of 10 corresponded with single wavefronts in 3D phase maps, 2 of 10 with 2 simultaneous wavefronts, 1 of 10 with disorganized activity, and in 3 of 10 there was no coverage by the basket catheter at the corresponding 3D anatomical location. Rotors detected in 2D phase maps were not observed in the corresponding 3D phase maps. These findings may have implications for current systems that use 2D phase mapping.
Publisher: AMPCo
Date: 19-06-2019
DOI: 10.5694/MJA2.50248
Publisher: Oxford University Press (OUP)
Date: 11-2011
Abstract: To determine whether the extent of myocardial fibrosis by late-gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR), and echocardiographic ventricular dyssynchrony are independently associated with response to medical therapy in patients with newly diagnosed idiopathic dilated cardiomyopathy (DCM). Myocardial fibrosis and ventricular dyssynchrony are frequent findings in DCM. Previous studies focused on patients with established cardiomyopathy however, the degree of myocardial fibrosis and ventricular dyssynchrony at presentation and their role in perpetuating left ventricular (LV) dysfunction in DCM remains unclear. Those studies of in iduals with long-standing DCM did not characterize patients early in the disease course, and may not have included those with significant improvement in LV function. Thus factors contributing to LV recovery are uncertain. Consecutive patients with a new diagnosis of DCM [LV ejection fraction (EF) ≤45%] made within the preceding 2 weeks were recruited. Patients underwent LGE-CMR, echocardiography, 6-minute walk testing, cardiopulmonary exercise testing, and blood s ling for measurement of serum amino-terminal pro-brain natiuretic peptide (NT-pro-BNP) concentration at baseline. Baseline patient characteristics were compared with a cohort of healthy volunteers. Myocardial fibrosis by LGE-CMR was quantified, identified by experienced observers blinded to patient outcome. Left ventricular systolic function was reassessed after 5 months of optimal medical therapy. Sixty-eight patients with DCM and 19 healthy volunteers were studied. DCM patients were studied a median 12.5 days following diagnosis. Compared with healthy controls, DCM patients exhibited greater inter- and intra-ventricular dyssynchrony. Twenty-four per cent of DCM patients exhibited LGE at diagnosis. Among DCM patients with LGE, the mean fibrosis mass was 2.2 ± 1.3 g. On multivariate analysis, strain dyssynchrony index, and fibrosis mass were independently associated with change in the LVEF over time (P≤ 0.001). Late-gadolinium enhancement cardiovascular magnetic resonance conferred additive value for modelling change in the LVEF beyond clinical and echocardiographic dyssynchrony parameters. The extent of myocardial fibrosis is independently associated with lack of response to medical therapy in new-presentation DCM, and LGE-CMR may thus be an important risk-stratifying investigation in these patients. Accurate risk stratification may permit more targeted pharmacological and device therapies for patients with newly diagnosed DCM.
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.HRTHM.2017.01.003
Abstract: Early studies demonstrated relatively low success rates for pulmonary vein isolation (PVI) alone in patients with persistent atrial fibrillation (PeAF). However, the advent of new technologies and the observation that additional substrate ablation does not improve outcomes have created a new focus on PVI alone for treatment of PeAF. The purpose of this study was to systematically review the recent medical literature to determine current medium-term outcomes when a PVI-only approach is used for PeAF. An electronic database search (MEDLINE, Embase, Web of Science, PubMed, Cochrane) was performed in August 2016. Only studies of PeAF patients undergoing a "PVI only" ablation strategy using contemporary radiofrequency (RF) technology or second-generation cryoballoon (CB2) were included. A random-effects model was used to assess the primary outcome of pooled single-procedure 12-month arrhythmia-free survival. Predictors of recurrence were also examined and a meta-analysis performed if ≥4 studies examined the parameter. Fourteen studies of 956 patients, of whom 45.2% underwent PVI only with RF and 54.8% with CB2, were included. Pooled single-procedure 12-month arrhythmia-free survival was 66.7% (95% confidence interval [CI] 60.8%-72.2%), with the majority of patients (80.5%) off antiarrhythmic drugs. Complication rates were very low, with cardiac t onade occurring in 5 patients (0.6%) and persistent phrenic nerve palsy in 5 CB2 patients (0.9% of CB2). Blanking period recurrence (hazard ratio 4.68, 95% CI 1.70-12.9) was the only significant predictor of recurrence. A PVI-only strategy in PeAF patients with a low prevalence of structural heart disease using contemporary technology yields excellent outcomes comparable to those for paroxysmal AF ablation.
Publisher: Wiley
Date: 28-07-2020
DOI: 10.1111/JCE.14688
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.COMPBIOMED.2010.07.005
Abstract: Many conditions remodel the heart muscle such that it results in a perturbation of cells coupling. The effect of this perturbation on the stability of the spiral waves of electrochemical activity is not clear. We used the FitzHugh-Nagumo model of an excitable medium to model the conduction of the activation waves in a two-dimensional system with inhomogeneous anisotropy level. Inhomogeneity of the anisotropy level was modeled by adding Gaussian noise to diffusion coefficients corresponding with lateral coupling of the cells. Low noise levels resulted in a stable propagation of the spiral wave. For large noise level conduction was not possible due to insufficient coupling in direction perpendicular to fibers. For intermediate noise intensities, the initial wave broke up into several independent spiral waves or waves circulating around conduction obstacles. At an optimal noise intensity, the number of wavelets was maximized-a form of anti-coherent resonance was obtained. Our results suggest that the inhomogeneity of conduction anisotropy may promote wave breakup and hence play an important role in the initiation and perpetuation of the cardiac arrhythmias.
Publisher: Wiley
Date: 15-02-2006
DOI: 10.1111/J.1540-8167.2005.00414.X
Abstract: We hypothesized that the frequency spectra of fibrillatory electrograms may reflect the complexity of activities perpetuating atrial fibrillation (AF). To test this hypothesis, we evaluated the frequency spectra in patients with paroxysmal AF in relation to catheter ablation. This study comprised two protocols: 25 patients undergoing pulmonary vein (PV) isolation in protocol I, and 20 patients undergoing mitral isthmus linear ablation after PV isolation in protocol II. The mean of dominant frequency (DF) and organization index (the ratio of the area under the DF and its harmonics to the total power) were determined from 32-second recordings in the coronary sinus. In protocol I, a PV was considered "driver" of AF if isolation of the PV resulted in termination or slowing of AF (decrease in DF by > or =0.25 Hz). Twenty-one patients had AF termination during four PV isolation. Among these 21 patients, 13 patients with single driving PV showed significantly higher baseline organization index than eight patients with multiple driving PVs (0.45 +/- 0.08 vs 0.35 +/- 0.07, P = 0.009). Patients with multiple driving PVs showed a significant increase in the organization index to 0.45 +/- 0.11 (P < 0.05) after isolation of the initial driving PVs. In protocol II, the baseline organization index was significantly higher in seven patients who had termination of AF during mitral isthmus ablation than 13 patients who did not (0.50 +/- 0.10 vs 0.38 +/- 0.07, P < 0.008). The baseline DF was not associated with outcomes of ablation in both protocols. A higher organization index of atrial electrograms is associated with termination of AF during limited ablation. This parameter may be useful to anticipate the extent of ablation.
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.AMJCARD.2016.10.043
Abstract: Identifying patients at risk is now important as there are demonstrable ways to alter disease progression which could potentially prevent atrial fibrillation (AF) and its complications. We sought whether impaired functional capacity was associated with risk of AF, independent of myocardial dysfunction. In this community-based study, asymptomatic participants aged ≥65 years were recruited if they had ≥1 risk factor (e.g., hypertension, diabetes mellitus, and obesity). Participants underwent baseline echocardiography (including measurement of myocardial mechanics) and six-minute walk test. The CHARGE-AF score was used to calculate 5-year risk of developing AF. Receiver operating characteristic curves were used to assess for independent risk factors for AF. A total of 607 patients (age 71 ± 5 years, men 47%) were studied at baseline and followed for at least 6 months. Patients in the higher AF risk groups were older and had increased rates of hypertension, diabetes mellitus, and ischemic heart disease (p <0.05). Greater AF risk was associated with lower exercise capacity, independent of lower mean global longitudinal strain, global circumferential strain, greater mean E/e' ratio, indexed left atrial volume and LV mass. Multivariate linear regression confirmed association of LV and functional capacity parameters with AF risk. Although functional capacity is impaired in AF, this association precedes the onset of AF. In conclusion, poor functional status is associated with AF risk, independent of LV function.
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.IJCARD.2014.01.099
Abstract: Electrical and pharmacological cardioversion (ECV, PCV) are important treatment options for symptomatic patients with recent onset atrial fibrillation (AF). RHYTHM-AF is an international registry of present-day cardioversion providing information that is not currently available on country differences and acute and long-term arrhythmia outcomes of ECV and PCV. 3940 patients were enrolled, of whom 75% underwent CV. All patients were followed for 2 months. There were large variations concerning mode of CV used, ECV being heterogeneous. A choice of PCV drug depended on the clinical patient profile. Sinus rhythm was restored in 89.7% of patients by ECV and in 69.1% after PCV. Among patients not undergoing CV during admission, 34% spontaneously converted to sinus rhythm within 24h. ECV was most successful in patients pretreated with antiarrhythmic drugs (mostly amiodarone). PCV was enhanced by class Ic antiarrhythmic drugs conversion rate on amiodarone was similar to that seen with rate control drugs. Female patients and those with paroxysmal and first detected AF as well as those without previous ECV responded well to PCV. The median duration of hospital stay was 16.2 and 24.0 h for ECV and PCV patients, respectively. There were very few CV-related complications regardless of mode of CV. Chronic maintenance of sinus rhythm was enhanced in patients on chronic antiarrhythmic drugs, beta-blockers or inhibitors of the renin-angiotensin system. Mode of CV varied significantly, but both PCV and ECV were safe and effective. Class Ic drugs were most effective conversion drugs, but amiodarone is used most frequently despite providing merely rate control rather than shorten time to conversion.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.HLC.2017.05.119
Abstract: Recent advances in our understanding of the mechanisms underlying atrial fibrillation (AF) have further underscored the complex pathophysiological basis of the arrhythmia. It has become apparent that the current clinical classification of AF does not reflect the severity of the underlying atrial disease. Atrial fibrosis has been identified as the key structural change in different substrates that are responsible for the perpetuation of AF. Three-dimensional electroanatomical mapping and late gadolinium-enhanced magnetic resonance imaging are novel modalities that can be used to facilitate identification and quantitation of atrial fibrosis for improved delineation of the AF substrate. Advances in AF mapping technology using endocardial 'panaromic' basket-type catheter and non-invasive body surface electrodes have facilitated the identification of two major arrhythmic mechanisms of interest, namely rotational ('rotors') and ectopic focal activations ('foci'). Ongoing research on these potential drivers of AF may provide guidance to more mechanistic based therapies to improve outcomes for this complex arrhythmia in the future. Here, we aim to review the differences in AF substrate in those with paroxysmal and more persistent forms of the arrhythmia by evaluating fibrosis, rotors and foci, towards improved AF substrate classification and in idualised substrate based therapies.
Publisher: Springer Science and Business Media LLC
Date: 19-07-2019
DOI: 10.1007/S10067-019-04678-Z
Abstract: Cardiac involvement in idiopathic inflammatory myopathies (IIM) adversely affects prognosis but is commonly sub-clinical. Cardiac magnetic resonance imaging (CMR) is an effective imaging modality for detecting myocardial inflammation and fibrosis but its use as a screening tool for cardiac disease in IIM has not been fully explored. Nineteen patients with IIM without cardiac symptoms underwent CMR using a specific cardiomyopathy protocol including specific sequences detecting focal and diffuse myocardial fibrosis. 9/19 patients demonstrated late gadolinium enhancement (LGE (3/9 right ventricular insertion, 1/9 sub-endocardial, 7/9 mid-wall/sub-epicardial)). T1 mapping was performed in 15 patients. In total, 7/15 had elevated native T1 values, of which four had detected LGE. Myocardial fibrosis was frequently detected in IIM patients without cardiac history. Detection of LGE and elevated T1 values may have negative prognostic implications. Longitudinal studies determining whether early or augmented treatment has a role in patients with sub-clinical cardiac involvement are needed.Key Points• Cardiac involvement in myositis adversely affects prognosis.• Cardiac magnetic resonance imaging is an effective tool for detecting cardiac involvement.• T1 mapping is a technique which detects diffuse myocardial inflammation and fibrosis.• In our study, focal and diffuse myocardial fibrosis was frequently found in myositis patients without cardiac symptoms.
Publisher: BMJ
Date: 09-05-2012
DOI: 10.1136/HEARTJNL-2012-301799
Abstract: The left atrial appendage (LAA) has been suggested to be the dominant location of thrombus in atrial fibrillation (AF) and has led to the development of LAA occlusion as a therapeutic modality to reduce stroke risk. However, the patient populations that would benefit most from this therapy are not well defined. A systematic review was performed to better define subgroups amenable to appendage closure. The English scientific literature was searched using Pubmed through to March 1, 2011. Reference lists of relevant and review articles were screened to retrieve additional articles. Studies were only included if they described the location of thrombus in left atrium. Case reports and case series describing less than 10 thrombi were excluded. Two reviewers independently extracted data and assessed quality of each study. A total of 34 studies reporting on the location of atrial thrombus in patients with AF were included: 17 in valvular AF, 10 non-valvular AF and 8 in mixed valvular and non-valvular AF. Atrial thrombi were located outside the LAA in 56% (95% CI 53, 60) of valvular AF, 22% (95% CI 19, 25) in mixed cohorts and 11% (95% CI 6, 15) non-valvular AF. In non valvular AF, the studies with higher proportion of thrombi in the left atrial cavity had non-anticoagulated patients and a greater proportion of ventricular dysfunction and history of stroke. The location of atrial thrombus in patients with AF is dependent on the underlying substrate. In valvular AF, more than half the thrombi are located in the left atrial cavity. In the non-valvular AF group, a smaller proportion of thrombi were located outside the appendage. However, in certain subgroups (ie. non anti-coagulated, left ventricular dysfunction or prior stroke) the chances of left atrial cavity thrombus are higher.
Publisher: Springer Science and Business Media LLC
Date: 30-09-2014
DOI: 10.1007/S10840-014-9941-8
Abstract: In recent years, there has been a shift away from performing electrophysiologic study (EPS) to guide implantable cardioverter-defibrillator (ICD) implantation with a reliance on left ventricular ejection fraction (LVEF) alone. ICD patients were prospectively recruited from the multicentre COMFORT (Concept of Optimal Management of ventricular Fibrillation Or Very fast ventricular Tachycardia) trial. Primary prevention ICD patients (n = 260, groups 1 and 2) were compared to secondary prevention ICD patients (n = 210, group 3). Primary prevention ICDs were implanted in patients with ischemic cardiomyopathy based on LVEF ≤ 40 % and inducible ventricular tachycardia (VT) at EPS (n = 123, group 1) or impaired LVEF alone (LVEF ≤ 30 % or LVEF ≤ 35 % with NYHA class II or III n = 137, group 2). EPS was performed in 61 % of secondary prevention ICD patients (n = 129). Patients were followed up for >12 months with a primary endpoint of spontaneous VT/ventricular fibrillation (VF). A significantly higher rate of spontaneous VT/VF occurred in secondary versus primary prevention ICD patients (P < 0.001) and in EPS-guided versus LVEF-guided primary prevention ICD patients (P = 0.029). At 2 years, the proportion of patients with ≥1 VT/VF episode was 24.6 ± 4.2 %, 19.9 ± 4.6 % and 37.1 ± 3.9 % for groups 1, 2 and 3, respectively. In the secondary prevention, patients who underwent EPS, VT/VF occurred in 44.4 ± 5.9 % and 14.1 ± 6.6 % with a positive versus negative result, respectively (P = 0.02). Secondary prevention ICD patients have more spontaneous VT/VF than primary prevention ICD patients. Secondary and primary prevention ICD patients with inducible VT at EPS have more VT/VF than patients without inducible VT or impaired LVEF alone.
Publisher: Elsevier BV
Date: 02-2019
Publisher: Wiley
Date: 2004
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.AMJCARD.2016.10.044
Abstract: The Long-term Effect of Goal Directed Weight Management in an Atrial Fibrillation Cohort: A Long-term Follow-up Study (LEGACY) demonstrated that weight reduction in a cohort of Australian patients with atrial fibrillation (AF) resulted in a reduction in AF burden and improvement in AF symptom severity. The applicability of LEGACY in US cardiovascular practice is not known. A cohort of patients with AF from the National Cardiovascular Data Registry Practice Innovation and Clinical Excellence (PINNACLE) registry of US cardiovascular ambulatory care practices was created. The proportion of PINNACLE AF patients meeting enrollment criteria for LEGACY was assessed. Differences between these patients and LEGACY trial patients were qualitatively compared. Treatment for AF among LEGACY eligible and noneligible patients was compared. Among 349,999 US patients with AF from 179 cardiovascular practices in the PINNACLE registry, 197,255 (56.4%) met enrollment criteria for LEGACY. LEGACY-eligible PINNACLE AF had significantly lower rates of tobacco and alcohol abuse than the LEGACY trial population. There were significant differences in drug therapy comparing LEGACY eligible and LEGACY noneligible PINNACLE AF patients. In this cohort of patients in ambulatory practice in the United States with AF, over 1/2 were potential candidates for a weight management program. Differences between patients in practice and those enrolled in the trial could influence the success and impact of the LEGACY weight management intervention. Our study identifies a potential opportunity to improve AF morbidity and costs to the health care system in the United States by implementing a structured weight reduction program, such as that described in LEGACY.
Publisher: SPIE
Date: 21-12-2007
DOI: 10.1117/12.787253
Publisher: Wiley
Date: 23-07-2010
DOI: 10.1111/J.1440-1681.2010.05435.X
Abstract: 1. High-density cardiac electrophysiological study (EPS) of small animal atria has been limited to optical mapping techniques, which require complex and expensive equipment setup. We aim to evaluate the feasibility of carrying out EPS in isolated atrial tissues using a custom made high-density multiple-electrode array (MEA). 2. Isolated rat atrial preparations were studied. The MEA (4 × 5 mm) consisted of 90 silver chloride coated electrodes (0.1 mm diameter, 0.5 mm pitch) and was connected to a conventional EP system yielding 80 bipolar signals. Atrial tissues were placed over the MEA in a dish bubbled with 100% oxygen and superfused with modified HEPES solution at pH 7.35 and 37°C. Then, 1 mmol of 2,3-butanedione monoxime was added to suppress motion artifacts from muscle contractions. Custom plaque analysis software was used for offline conduction analysis. 3. Isolated atrial tissues showed good viability of > 30 min, allowing le time for complete EPS. High quality electrograms with excellent signal to noise ratio were obtained. All electrophysiological parameters showed good reproducibility: effective refractory period, conduction velocity and heterogeneity index. Tachycardia was also inducible in these normal atria. 4. The present study shows the feasibility of performing high-density EPS of small isolated atrial tissues with a conventional electrode-based technique. The MEA system is compatible with standard electrophysiology recording systems and provides a novel, inexpensive option for detailed EPS in small animal models. In particular, it presents new research avenues to further explore the mechanisms of atrial arrhythmias in various transgenic and knockout rodent models.
Publisher: Springer Science and Business Media LLC
Date: 23-05-2009
DOI: 10.1007/S10439-009-9709-Y
Abstract: Phase contrast magnetic resonance imaging is performed to produce flow fields of blood in the heart. The aim of this study is to demonstrate the state of change in swirling blood flow within cardiac chambers and to quantify it for clinical analysis. Velocity fields based on the projection of the three dimensional blood flow onto multiple planes are scanned. The flow patterns can be illustrated using streamlines and vector plots to show the blood dynamical behavior at every cardiac phase. Large-scale vortices can be observed in the heart chambers, and we have developed a technique for characterizing their locations and strength. From our results, we are able to acquire an indication of the changes in blood swirls over one cardiac cycle by using temporal vorticity fields of the cardiac flow. This can improve our understanding of blood dynamics within the heart that may have implications in blood circulation efficiency. The results presented in this paper can establish a set of reference data to compare with unusual flow patterns due to cardiac abnormalities. The calibration of other flow-imaging modalities can also be achieved using this well-established velocity-encoding standard.
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.HRTHM.2011.05.021
Abstract: Complex fractionated atrial electrograms (CFAEs) and regions of high dominant frequency (DF) both may identify sites critical to the maintenance of atrial fibrillation (AF). CFAEs may be defined by either (1) complex multicomponent electrograms (EGMs) and/or continuous electrical activity (multicomponent/continuous EGM) or (2) discrete high-frequency EGMs. The purpose of this study was to test if the 2 definitions of CFAE identify the same arrhythmia substrate and determine the relationship of CFAE to areas of high DF. High-density epicardial mapping of the posterior left atrium was performed in 10 patients with long-lasting persistent AF. Point-by-point analysis was performed to determine the spatial distribution and correlation of CFAE defined as either (1) multicomponent/continuous-EGMs or (2) AF cycle length <120 ms. Additionally, spatial analysis was performed to determine the relationship of high DF sites to CFAE sites defined by each of the 2 definitions. The percentage of sites deemed CFAE varied markedly between patients and was different depending on the definition of CFAE adopted. There was a poor correlation between CFAE defined by multicomponent/continuous EGMs and AF cycle length <120 ms (r = 0.18). High DF sites were arranged in clusters evenly distributed throughout the posterior left atrium, with 4.2 ± 1.0 high DF clusters per patient. Although there was poor point-by-point correlation between multicomponent/continuous EGMs and high DF sites (r = 0.107), spatial analysis revealed that 96% of multicomponent/continuous EGMs were found adjacent to and partially surrounding (≤5 mm) high DF sites. There is poor anatomic overlap between CFAE defined by multicomponent/continuous EGMs and CFAE defined by AF cycle length <120 ms. Multicomponent/continuous EGMs are found adjacent to and surrounding sites of high DF. Further studies are needed to determine the mechanisms responsible for these different signals.
Publisher: Oxford University Press (OUP)
Date: 04-11-2016
Publisher: BMJ
Date: 10-2014
DOI: 10.1136/BMJOPEN-2014-006242
Abstract: To examine the prevalence of atrial fibrillation (AF) and cardiac structural characteristics in Indigenous and non-Indigenous Australians. Retrospective cross-sectional study linking clinical, echocardiography and administrative databases over a 10-year period. A tertiary, university teaching hospital in Adelaide, Australia. Indigenous and non-Indigenous Australians. AF prevalence and echocardiographic characteristics. Indigenous Australians with AF were significantly younger compared to non-Indigenous Australians (55±13 vs 75±13 years, p .001). As a result, racial differences in AF prevalence and left atrial diameter varied according to age. In those under 60 years of age, Indigenous Australians had a significantly greater AF prevalence (2.57 vs1.73%, p .001) and left atrial diameters (39±7 vs 37±7 mm, p .001) compared to non-Indigenous Australians. In those aged 60 years and above, however, non-Indigenous Australians had significantly greater AF prevalence (9.26 vs 4.61%, p .001) and left atrial diameters (39±7 vs 37±7 mm, p .001). Left ventricular ejection fractions were less in Indigenous Australians under 60 years of age (49±14 vs 55±11%, p .001) and not statistically different in those aged 60 years and above (47±11 vs 52±13, p=0.074) compared to non-Indigenous Australians. Despite their younger age, Indigenous Australians with AF had similar or greater rates of cardiovascular comorbidities than non-Indigenous Australians with AF. Young Indigenous Australians have a significantly greater prevalence of AF than their non-Indigenous counterparts. In contrast, older non-Indigenous Australians have a greater prevalence of AF compared to their Indigenous counterparts. These observations may be mediated by age-based differences in comorbid cardiovascular conditions, left atrial diameter and left ventricular ejection fraction. Our findings suggest that AF is likely to be contributing to the greater burden of morbidity and mortality experienced by young Indigenous Australians. Further study is required to elucidate whether strategies to prevent and better manage AF in Indigenous Australians may reduce this burden.
Publisher: Elsevier BV
Date: 11-2008
DOI: 10.1016/J.CARDFAIL.2008.06.449
Abstract: There is a paucity of published experience investigating novel treatment strategies in preclinical and clinical studies of nonischemic cardiomyopathy. We set out to validate an ovine model of doxorubicin-induced cardiomyopathy, using cardiac magnetic resonance (CMR) to assess cardiac function. Ten Merino sheep (51 +/- 8 kg) underwent intracoronary infusions of doxorubicin (1 mg/kg dose) every 2 weeks. Cardiac magnetic resonance was performed at baseline and at 6 weeks after final doxorubicin dose, along with transthoracic echocardiography, measurement of right heart pressure, and cardiac output. After final CMR examination, heart specimens were harvested for histologic analysis. The total dose of doxorubicin administered per animal was 3.8 +/- 0.5 mg/kg. Two animals died prematurely during the study protocol, with evidence of myocarditis. In the remaining 8 sheep, left ventricular ejection fraction dropped from 46.2 +/- 4.7% to 31.3 +/- 8.5% (P < .001), accompanied by reductions in fractional shortening (31.6 +/- 1.8% baseline versus 18.2 +/- 3.9% final, P < .01), cardiac output (3.8 +/- 0.6 L/min versus 3.0 +/- 0.4 L/min, P < .05) and right ventricular ejection fraction (39.5 +/- 5.6% versus 28.9 +/- 9.6%, P < .05). However, significant end-diastolic dilatation of the left ventricle was not observed. Delayed gadolinium uptake was detected by CMR in 2 sheep, in a typical nonischemic pattern. Widespread, multifocal histologic abnormalities consisted of cardiomyocyte degeneration, vasculopathy, inflammatory infiltrates, and replacement fibrosis. Moderate-severe cardiac dysfunction was reproducibly achieved through high-dose intracoronary doxorubicin, with acceptable animal mortality. CMR provides a powerful tool for assessing myocardial function, structural remodeling, and viability in such models.
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.HRTHM.2015.06.033
Abstract: Chronic kidney disease (CKD) patients undergoing hemodialysis (HD) have a high risk of sudden cardiac death (SCD). A unique risk factor may be a longer interval between HD sessions (interdialytic period). Inherent in conventional HD (thrice-weekly) are two 48-hour short breaks (SIDP) and one 72-hour long break (LIDP) between HD sessions. We used an implantable cardiac monitor (ICM) to define the incidence and timing of significant arrhythmias in an HD population. Fifty CKD patients undergoing HD with left ventricular ejection fraction >35% had an ICM inserted, with intensive follow-up to record SCD events and predefined bradyarrhythmias and tachyarrhythmias. Mean age of the patients was 67 ± 11 years 72% were male, and the mean follow-up was 18 ± 4 months. There were 8 unexpected SCDs (16%), all during the LIDP. The terminal event was severe bradycardia with asystole in each recorded case. No episodes of polymorphic ventricular tachycardia (VT) occurred. A total of 7686 arrhythmia events were recorded in 43 patients (86%), including bradycardia in 15 patients (30%), sinus arrest in 14 (28%), second-degree atrioventricular block in 4 (8%), nonsustained VT in 10 (20%), and new-onset paroxysmal atrial fibrillation in 14 (28%). The LIDP was the highest-risk period for all arrhythmias (P < .001). The arrhythmia event rate per hour was greatest during the first pre-HD period of the week compared with any other peri-HD period (P < .001). Risk of SCD and significant arrhythmias is greatest during the LIDP. SCD was attributable to severe bradycardia and asystole. Interventions to prevent this type of SCD or shorten the LIDP deserve further evaluation. URL: www.anzctr.org.au (Unique identifier: ACTRN12613001326785).
Publisher: Elsevier BV
Date: 11-2017
DOI: 10.1016/J.PBIOMOLBIO.2017.07.010
Abstract: Atrial fibrillation (AF) is the most common sustained arrhythmia and across the developed nations, it contributes to increasing hospitalizations and healthcare burden. Several comorbidities and risk factors including hypertension, heart failure, obstructive sleep apnoea and obesity are known to play an important role in the initiation and perpetuation of AF and atrial stretch or dilatation may play a central mechanistic role. The impact of atrial stretch in the development of AF can vary dependent on the underlying disease. This review focuses on understanding the substrate for AF in conditions of acute and chronic stretch and in the presence of common co-morbidities or risk factors through the review of findings in both animal and human studies. Additionally, the reversibility of atrial remodeling following stretch release will also be discussed. Identification of clinical conditions associated with increased atrial stretch as well as the treatment or prevention of these conditions may help to prevent AF progression and improve sinus rhythm maintenance.
Publisher: Elsevier BV
Date: 04-2023
Publisher: Wiley
Date: 06-2001
DOI: 10.1046/J.1540-8167.2001.00653.X
Abstract: Focal right atrial tachycardia (RAT) arising from the crista terminalis, para-Hisian, and coronary sinus os regions are well described. Less information exists regarding RAT arising from the nonseptal region of the tricuspid annulus (TA). From a consecutive series of 64 patients who had undergone successful radiofrequency ablation (RFA) of 67 RATs, the characteristics of 9 (13%) patients (6 men mean age 50 +/- 20 years) with a TA focus were reviewed. The annular focus was localized to the inferoanterior TA in 7 and the superior TA in 2. Mean tachycardia cycle length was 371 +/- 66 msec. Mean activation time at the site of successful RFA in 9 of 9 patients was -43 +/- 11 msec. At 9.3 +/- 5.6 months of follow-up, 1 of 9 patients had recurrent tachycardia successfully treated with repeat RFA. In 7 of 9 patients with RAT from the inferoanterior TA, the surface ECG P wave morphology was upright in aVL, inverted in III and VI, and either inverted or biphasic with an initial negative deflection from V2 to V6. The TA is an important site of origin of RAT. In the present study, the inferoanterior region of the TA was a preferential site of origin with resulting characteristic P wave morphology. Knowledge of this anatomic distribution and P wave morphology allows targeted mapping and may facilitate successful RFA.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-08-2004
Publisher: Oxford University Press (OUP)
Date: 23-07-2018
Abstract: Antiarrhythmic drugs (AADs) for the treatment of atrial fibrillation (AF) are associated with limited efficacy and adverse effects. Inhibition of the atrial current IKur, absent from the ventricle, is expected to be antiarrhythmic, without adverse cardiac effects, particularly ventricular pro-arrhythmic effects. A randomized clinical trial in symptomatic paroxysmal AF patients being considered for ablation. The primary endpoint was AF burden (AFB) as measured by insertable continuous monitoring (ICM) devices. Screened patients had an ICM implanted and were included if AFB was between 1% and 70% after 4 weeks of recording. They were randomly allocated to 4-week treatment of a selective IKur inhibitor S66913 (5 mg, 25 mg, or 100 mg orally per day) or placebo. The study was to enroll 160 patients. The study was terminated prematurely, due to non-study related preclinical safety concerns, after 58 patients had been enrolled. The median AFB ranged from 4.3% to 10.3% at baseline in the four treatment groups. S66913 had no significant effect on AFB or on AFB plus atrial tachycardia (AT) burden, at any dosage nor on any secondary endpoints including the number and duration of AT or AF episodes, and symptoms. The drug was well tolerated with no safety concern during the treatment or the extended clinical follow-up. DIAGRAF-IKUR was the first study to show that using ICM to assess the effect of an AAD is feasible. The selective IKur inhibitor S66913 was safe but had no clinically meaningful effect at the time of early termination of the study.
Publisher: Wiley
Date: 23-04-2018
DOI: 10.1111/JCE.13494
Abstract: Atrioesophageal fistula (AEF) is a dire complication of atrial fibrillation ablation. The diagnostic yield of computed tomography (CT) chest, the role and timing of repeat testing, and the value of other investigations in the diagnosis of AEF is uncertain. We systematically reviewed published AEF cases to evaluate radiological, bedside, and biochemical investigations for AEF (registered on PROSPERO [CRD42017077493]). Eighty-seven articles with 126 patients (median age, 59 years male, 71%) were included in the analysis. CT chest was performed in 88% (111/126) and was abnormal in 87%. A clear diagnosis of AEF (fistula erforation) was only detected in 35% (34/97). Other major findings included free air in mediastinum (26%), left atrium (LA), or LA wall (24%). In 11 patients with normal/nonspecific initial CT chest, major abnormalities were detected in 91% (10/11) of repeat CT chest performed 6 days (median range, 4-22) after initial scan. Initial CT head was normal in 51% diffuse air emboli was identified in 79% (22/28). Initial transthoracic echocardiography was normal in 61% of cases. The spectrum of radiological abnormalities included Air (mediastinum/LA), Effusion (pleural ericardial), Fistula/Perforation, and Thickening (esophagus/LA) - "AEF-Tests." Esophagram demonstrated contrast extravasation in 87% (13/15). Blood culture was consistently positive (100% 28/28), particularly for streptococcus species (93% 26/28). The diagnosis of AEF remains challenging. Clinicians should be aware of the limitations in the yield of CT chest, the variety of major abnormalities reported, the need for repeat testing, unique brain imaging findings, and the importance of positive blood cultures and raised inflammatory markers.
Publisher: BMJ
Date: 07-04-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2014
DOI: 10.1161/CIRCEP.113.000890
Abstract: This study compared generalized complex fractionated atrial electrograms (CFAE) ablation versus a selective CFAE ablation strategy targeting areas of continuous electric activity. Subjects with symptomatic, persistent/high-burden paroxysmal atrial fibrillation (AF) were enrolled at 6 centers (n=86) and randomized to 1 of 2 arms. For group I, all CFAE regions with an interval confidence level were ablated followed by pulmonary vein isolation (PVI). For group II, only CFAE sites with continuous electric activity were ablated followed by PVI. For PVI, all 4 PV antra were isolated with confirmed entrance block. Subjects were followed for 1 year with a visit, ECG, and 48-hour Holter every 3 months. Symptoms were confirmed by loop recording. The primary end point was freedom from arrhythmia seconds at 1 year. For both group I and II, CFAE ablation prolonged AF cycle length (25±33 versus 23±33 ms P =0.78) and resulted in similar rates of AF termination (37% versus 28% P =0.42). Radiofrequency duration during CFAE ablation was significantly less in group II (23±20 versus 38±20 minutes P =0.002). At 1-year follow-up, freedom from AF/atrial flutter/atrial tachycardia recurrence was significantly higher in group I versus group II after 1 procedure (50% versus 28% P =0.03). There were also significantly fewer repeat procedures in group I (13% versus 36% P =0.021). Continuous electric activity ablation+PVI result in a similar incidence of acute AF termination with significantly less radiofrequency time. However, incidence of repeat procedures and long-term recurrence of AF/atrial flutter/atrial tachycardia are significantly lower using generalized CFAE ablation+PVI. URL: www.clinicaltrials.gov . Unique identifier: NCT00926783
Publisher: Elsevier BV
Date: 06-2020
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.HLC.2017.05.132
Abstract: Exercise has substantial health benefits with pleomorphic vascular, metabolic, psychological and anti-neoplastic actions resulting in improved quality of life and longevity. Despite these many benefits, numerous studies have shown that endurance athletes are more likely to develop atrial fibrillation (AF) than non-athletes. The type, intensity and amount of sport appears to influence the risk of developing AF. Several endurance sport activities have been shown to increase the risk of developing AF but an excess in AF has not been shown in non-endurance sports. Furthermore, lifetime hours of participation appear to increase the risk of developing AF. Intriguingly, women appear relatively protected and an association between endurance sport and AF has not been clearly demonstrated amongst female endurance athletes. The mechanisms by which endurance sport promotes the development of AF are unclear. There are, however, a number of pathophysiological mechanisms which are known to increase the risk of AF in non-athletes which have correlates in athletes. These include structural remodelling of the left atrium, elevated left atrial pressure, inflammation, myocardial fibrosis, vagal tone, sinus bradycardia and genetic predisposition. In this article, we explore how some of these mechanisms may contribute to the development of AF in endurance athletes.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2018
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.AMJCARD.2013.03.014
Abstract: Although most of the additional increases in coronary heart disease morbidity and mortality are estimated to occur outside developed regions such as North America and Europe, few nationwide studies have been published of acute myocardial infarction (MI) epidemiology from other regions. We thus sought to expand the global data regarding MI trends. Nationwide trends of incident MI, ST-segment elevation MI (STEMI), and non-ST-segment MI (non-STEMI) were analyzed during a 17-year period in Australia. We identified 714,262 hospitalizations for MI from 1993 to 2010, representing 331,871,389 person-years. During the study period, the age- and gender-adjusted incidence of all MIs increased from 215 to 251 cases per 100,000 person-years, a relative increase of 76% (p <0.0001 for trend). The adjusted incidence of STEMI decreased from 147 to 70 cases per 100,000 person-years, a relative decrease of 30% (p <0.0001 for trend). In contrast, the adjusted incidence of non-STEMI increased from 67 to 182 cases per 100,000 person-years, a relative increase of 315% (p <0.0001 for trend). Age-specific analyses suggested that statistically significant increases in MI incidence were present in those aged <50 and ≥80 years. In conclusion, although it has previously been suggested that declining trends in MI incidence in North American and European reports might be generalizable given the seemingly consistent observations thus far, the present results highlight the possibility that other global populations might have less favorable trends. The incidence of MI in Australia might not be decreasing as rapidly as that seen in other regions and requires additional exploration.
Publisher: BMJ
Date: 08-2021
DOI: 10.1136/BMJOPEN-2020-047642
Abstract: Atrial fibrillation (AF) is associated with significantly impaired quality-of-life. Iron deficiency (ID) is prevalent in patients with AF. Correction of ID in other patient populations with intravenous iron supplementation has been shown to be a safe, convenient and effective way of improving exercise tolerance, fatigue and quality-of-life. The IRON-AF (Effect of Iron Repletion in Atrial Fibrillation) study is designed to assess the effect of iron repletion with intravenous ferric carboxymaltose in patients with AF and ID. The IRON-AF study is a double-blind, randomised controlled trial that will recruit at least 84 patients with AF and ID. Patients will be randomised to receive infusions of either ferric carboxymaltose or placebo, given in repletion and then maintenance doses. The study will have follow-up visits at weeks 4, 8 and 12. The primary endpoint is change in peak oxygen uptake from baseline to week 12, as measured by cardiopulmonary exercise testing (CPET) on a cycle ergometer. Secondary endpoints include changes in quality-of-life and AF disease burden scores, blood parameters, other CPET parameters, transthoracic echocardiogram parameters, 6-minute walk test distance, 7-day Holter/Event monitor burden of AF, health resource utilisation and mortality. The study protocol has been approved by the Central Adelaide Local Health Network Human Research Ethics Committee, Australia. The results of this study will be disseminated through publications in peer-reviewed journals and conference presentations. Australian New Zealand Clinical Trials Registry (ACTRN12620000285954).
Publisher: Informa UK Limited
Date: 05-2020
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.HRTHM.2014.12.014
Abstract: Preclinical studies suggest that neuromodulation with thoracic spinal cord stimulation (SCS) improves left ventricular (LV) function and remodeling in systolic heart failure (HF). The purpose of this study was to evaluate the safety and efficacy of a SCS system for the treatment of systolic HF. We performed a prospective, multicenter pilot trial in patients with New York Heart Association (NYHA) class III HF, left ventricular ejection fraction (LVEF) 20%-35%, and implanted defibrillator device who were prescribed stable optimal medical therapy. Dual thoracic SCS leads were used at the T1-T3 level. The device was programmed to provide SCS for 24 hours per day (50 Hz at pulse width 200 μs). We enrolled 22 patients from 5 centers:17 patients underwent implantation of a SCS device and 4 patients who did not fulfill the study criteria served as nontreated controls. No deaths or device-device interactions were noted during the 6-month period in the 17 SCS-treated patients. Fifteen of 17 completed the efficacy endpoint assessments: composite score improved by 4.2 ± 1.3, and 11 patients (73%) showed improvement in ≥4 of 6 efficacy parameters. There was significant improvement in NYHA class (3.0 vs 2.1, P = .002 13/17 improved) Minnesota Living with Heart Failure Questionnaire (42 ± 26 vs 27 ± 22, P = .026 12/17 improved) peak maximum oxygen consumption (14.6 ± 3.3 vs 16.5 ± 3.9 mL/kg/min, P = .013 10/15 improved) LVEF (25% ± 6% vs 37% ± 8%, P<.001 14/16 improved) and LV end-systolic volume (174 ± 57 vs 137 ± 37 mL, P = .002 11/16 improved) but not in N-terminal prohormone brain natriuretic peptide. No such improvements were observed in the 4 nontreated patients. The results of this first-in-human trial suggest that high thoracic SCS is safe and feasible and potentially can improve symptoms, functional status, and LV function and remodeling in patients with severe, symptomatic systolic HF.
Publisher: Elsevier BV
Date: 06-2012
DOI: 10.1016/J.HLC.2012.03.122
Abstract: Atrial fibrillation (AF) is the most common clinically important cardiac arrhythmia. It is an important cause of stroke, contributes to the burden of heart failure and is a major contributor to health expenditure. Percutaneous catheter ablation is superior to medical therapy in reducing AF recurrences. It has an important role in treatment of patients with failed drug therapy. Successful catheter ablation improves left ventricular function in patients with heart failure. In addition, it may be appropriate for selected highly symptomatic patients as first line therapy. Catheter ablation for AF has been shown in randomised trials to reduce hospital admissions and improve quality of life. There is evidence from registry data to suggest it reduces the risk of stroke and improves mortality. Cost effectiveness has been demonstrated by modelling studies in both Europe and the United States.
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.AMJCARD.2013.03.016
Abstract: Although conferences are important vehicles for discussing scientific findings, the translation of presented research into peer-reviewed manuscripts is a crucial subsequent step in the research process. Given the evolving subspecialization of cardiology, we sought to characterize the temporal and comparative outcomes of abstracts presented at a subspecialty cardiac electrophysiology conference. Abstracts presented at the Heart Rhythm Society conference (1994 through 2006 HRS abstracts) and abstracts presented at the American Heart Association conference (2003 AHA abstracts) were studied. Subsequent publications, impact factors, and citation rates were determined. A total of 3,850 HRS and 1,000 AHA abstracts were studied. More human abstracts were presented at HRS than AHA (p <0.05). Compared with HRS abstracts, more AHA abstracts were published (p <0.001) and had higher impact factors and citation rates (p <0.001 for both). These differences were attributable in part to the greater proportion of human HRS abstracts. Compared with HRS abstracts, electrophysiology-related AHA abstracts were published less (p <0.001), and these publications had similar impact factors (p = 0.38) although greater citation rates (p = 0.001). The number and publication rate of HRS abstracts increased over the 15-year period, as did their publication impact factors and citation rates (p <0.001 for all). In conclusion, there are significant differences between AHA and HRS abstracts. Although AHA abstracts were more likely to be published overall, the publication rate and impact of electrophysiology abstracts presented at both a subspecialty (HRS) and a major cardiovascular conference (AHA) were comparable. There has also been a growth in the number and impact of cardiac electrophysiology abstracts presented at HRS in recent years.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-04-2018
Publisher: BMJ
Date: 20-05-2014
Publisher: Elsevier BV
Date: 10-2008
DOI: 10.1016/J.IJCARD.2007.06.145
Abstract: The number of patients with implantable cardioverter-defibrillator (ICD) is rapidly increasing due to their expanding indications. Amongst the various types of electromagnetic interferences, little is reported about the effects of radiotherapy. We report a case of electrical reset of a single chamber ICD by scattered irradiation from radiotherapy.
Publisher: Wiley
Date: 10-05-2010
DOI: 10.1111/J.1540-8167.2010.01804.X
Abstract: Long-term right ventricular apical (RVA) pacing has been associated with adverse effects on left ventricular systolic function however, the comparative effects of right ventricular outflow tract (RVOT) pacing are unknown. Our aim was therefore to examine the long-term effects of septal RVOT versus RVA pacing on left ventricular and atrial structure and function. Fifty-eight patients who were prospectively randomized to long-term pacing either from the right ventricular apex or RVOT septum were studied echocardiographically. Left ventricular (LV) and atrial (LA) volumes were measured. LV 2D strain and tissue velocity images were analyzed to measure 18-segment time-to-peak longitudinal systolic strain and 12-segment time-to-peak systolic tissue velocity. Intra-LV synchrony was assessed by their respective standard deviations. Interventricular mechanical delay was measured as the difference in time-to-onset of systolic flow in the RVOT and LV outflow tract. Septal A' was measured using tissue velocity images. Following 29 ± 10 months pacing, there was a significant difference in LV ejection fraction (P < 0.001), LV end-systolic volume (P = 0.007), and LA volume (P = 0.02) favoring the RVOT-paced group over the RVA-paced patients. RVA-pacing was associated with greater interventricular mechanical dyssynchrony and intra-LV dyssynchrony than RVOT-pacing. Septal A' was adversely affected by intra-LV dyssynchrony (P < 0.05). Long-term RVOT-pacing was associated with superior indices of LV structure and function compared with RVA-pacing, and was associated with less adverse LA remodeling. If pacing cannot be avoided, the RVOT septum may be the preferred site for right ventricular pacing.
Publisher: Wiley
Date: 28-09-2005
DOI: 10.1111/J.1540-8167.2005.00307.X
Abstract: The relative contributions of different atrial regions to the maintenance of persistent atrial fibrillation (AF) are not known. Sixty patients (53 +/- 9 years) undergoing catheter ablation of persistent AF (17 +/- 27 months) were studied. Ablation was performed in a randomized sequence at different left atrial (LA) regions and comprised isolation of the pulmonary veins (PV), isolation of other thoracic veins, and atrial tissue ablation targeting all regions with rapid or heterogeneous activation or guided by activation mapping. Finally, linear ablation at the roof and mitral isthmus was performed if sinus rhythm was not restored after addressing the above-mentioned areas. The impact of ablation was evaluated by the effect on the fibrillatory cycle length in the coronary sinus and appendages at each step. Activation mapping and entrainment maneuvers were used to define the mechanisms and locations of intermediate focal or macroreentrant atrial tachycardias. AF terminated in 52 patients (87%), directly to sinus rhythm in 7 or via the ablation of 1-6 intermediate atrial tachycardias (total 87) in 45 patients. This conversion was preceded by prolongation of fibrillatory cycle length by 39 +/- 9 msec, with the greatest magnitude occurring during ablation at the anterior LA, coronary sinus and PV-LA junction. Thirty-eight atrial tachycardias were focal (originating dominantly from these same sites), while 49 were macroreentrant (involving the mitral or cavotricuspid isthmus or LA roof). Patients without AF termination displayed shorter fibrillatory cycles at baseline: 130 +/- 14 vs 156 +/- 23 msec P = 0.002. Termination of persistent AF can be achieved in 87% of patients by catheter ablation. Ablation of the structures annexed to the left atrium-the left atrial appendage, coronary sinus, and PVs-have the greatest impact on the prolongation of AF cycle length, the conversion of AF to atrial tachycardia, and the termination of focal atrial tachycardias.
Publisher: Springer Science and Business Media LLC
Date: 02-10-2012
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.AMJCARD.2007.05.051
Abstract: Evidence from noninvasive studies suggests magnesium has a differential effect on atrioventricular nodal (AVN) pathways. To further explore the electrophysiologic effects of intravenous magnesium sulfate (MgSO(4)) on supraventricular tachycardia, with particular reference to AVN conduction pathways, we studied 23 patients with supraventricular tachycardia at the time of electrophysiologic study. Tachycardia cycle length AH, HV, and VA intervals anterograde and retrograde Wenckebach thresholds slow and fast pathway effective refractory periods (ERPs) accessory pathway ERP right atrial and ventricular ERPs blood pressure and serum magnesium were evaluated before and after administration of MgSO(4) during sustained tachycardia. AVN reentry was induced in 14 patients and atrioventricular reentry was induced in 9 1 of the latter had dual AVN physiology with tachycardia using the slow pathway. Serum magnesium level increased from 0.88 +/- 0.11 to 1.79 +/- 0.14 mmol/L (p <0.0001). Magnesium increased tachycardia cycle length to a greater extent in those with dual AVN physiology than those without: 340 +/- 54 to 370 +/- 57 ms versus 347 +/- 29 to 350 +/- 30 ms (p = 0.01). This was associated with greater increase in AH interval in those with dual AVN physiology than in those without: 241 +/- 59 to 270 +/- 60 ms versus 144 +/- 16 to 140 +/- 20 ms (p = 0.003). Presence of dual AVN physiology was more frequently associated with reversion to sinus rhythm: 5 of 15 versus 0 of 8 (p = 0.06). MgSO(4) did not alter other measured parameters. In conclusion, magnesium increases tachycardia cycle length and AH interval in patients with dual AVN physiology through a dominant effect on the slow AVN pathway.
Publisher: Wiley
Date: 14-08-2006
DOI: 10.1111/J.1540-8167.2006.00585.X
Abstract: Left atrial (LA) linear lesions are effective in substrate modification for atrial fibrillation (AF). However, achievement of complete conduction block remains challenging and conduction recovery is commonly observed. The aim of the study was to investigate the localization of gap sites of recovered LA linear lesions. Forty-eight patients with paroxysmal (n = 26) and persistent ermanent (n = 22) AF underwent repeat ablation after pulmonary vein (PV) isolation and LA linear ablation at the LA roof and/or mitral isthmus due to recurrences of AF or flutter. In 35 patients, conduction through the mitral isthmus line (ML) had recovered whereas roof-line recovery was observed in 30 patients. The gaps within the ML were distributed to the junction between left inferior PV and left atrial appendage in 66%, the middle part of the ML in 20%, and in 8% to the endocardial aspect of the ML while only 6% of lines showed an epicardial site of recovery. The RL predominantly recovered close to the right superior PV (54%) and less frequently in the mid roof or close to the left PV (both 23%). Reablation of lines required significantly shorter RF durations (ML: 7.24 +/- 5.55 minutes vs 24.08 +/- 9.38 minutes, RL: 4.24 +/- 2.34 minutes vs 11.54 +/- 6.49 minutes P = 0.0001). Patients with persistent ermanent AF demonstrated a significantly longer conduction delay circumventing the complete lines than patients with paroxysmal AF (228 +/- 77 ms vs 164 +/- 36 ms, P = 0.001). Gaps in recovered LA lines were predominantly located close to the PVs where catheter stability is often difficult to achieve. Shorter RF durations are required for reablation of recovered linear lesions. Conduction times around complete LA lines are significantly longer in patients with persistent ermanent AF as compared to patients with paroxysmal AF.
Publisher: Oxford University Press (OUP)
Date: 21-12-2012
Abstract: Ablation has substantial evidence base in the management of ventricular arrhythmia (VA). It can be a 'lifesaving' procedure in the acute setting of VA storm. Current reports on ablation in VA storm are in the form of small series and have relative small representation in a large observational series. The purpose of this study was to systematically synthesize the available literature to appreciate the efficacy and safety of ablation in the setting of VA storm. The medical electronic databases through 31 January 2012 were searched. Ventricular arrhythmia storm was defined as recurrent (≥ 3 episodes or defibrillator therapies in 24 h) or incessant (continuous >12 h) VA. Studies reporting data on VA storm patients at the in idual or study level were included. A total of 471 VA storm patients from 39 publications were collated for the analysis. All VAs were successfully ablated in 72% [95% confidence interval (CI) 71-89%] and 9% (95% CI: 3-10%) had a failed procedure. Procedure-related mortality occurred in three patients (0.6%). Only 6% patients had a recurrence of VA storm. The recurrence of VA was significantly higher after ablation for arrhythmic storm of monomorphic ventricular tachycardia (VT) relative to ventricular fibrillation or polymorphic VT with underlying cardiomyopathy (odds ratio 3.76 95% CI: 1.65-8.57 P = 0.002). During the follow-up (61 ± 37 weeks), 17% of patients died (heart failure 62%, arrhythmias 23%, and non-cardiac 15%) with 55% deaths occurring within 12 weeks of intervention. The odds of death were four times higher after a failed procedure compared with those with a successful procedure (95% CI: 2.04-8.01, P < 0.001). Ventricular arrhythmia storm ablation has high-acute success rates, with a low rate of recurrent storms. Heart failure is the dominant cause of death in the long term. Failure of the acute procedure carries a high mortality.
Publisher: Springer Science and Business Media LLC
Date: 04-01-2023
Publisher: Springer Science and Business Media LLC
Date: 2000
DOI: 10.2165/00002018-200023030-00004
Abstract: Minor cardiovascular adverse effects from antipsychotic drugs are extremely common. They include effects such as postural hypotension and tachycardia due to anticholinergic or alpha1-adrenoceptor blockade, and may occur in the majority of patients at therapeutic dosages. There are a number of pharmacological effects that are of uncertain clinical significance, such as blockade of calmodulin, sodium and calcium channels and alpha2-adrenoceptors in the central nervous system. The most serious consequences of treatment, arrhythmias and sudden death, are probably uncommon and are most likely to be caused primarily by blockade of cardiac potassium channels such as HERG. Incomplete evidence suggests that arrhythmias and sudden death are a particular problem with certain drugs (thioridazine and droperidol), high risk populations (elderly, pre-existing cardiovascular disease, inherited disorders of cardiac ion channels or of antipsychotic drug metabolism) or people taking interacting drugs (such as drugs that prolong the QT interval, e.g. tricyclic antidepressants, drugs that inhibit antipsychotic drug metabolism, or diuretics). Clozapine may be unique in also causing death from myocarditis and cardiomyopathy. Much further research is required to more clearly identify high risk drugs and the populations that are at risk of sudden death, as well as the mechanisms involved and the extent of the risk.
Publisher: Oxford University Press (OUP)
Date: 06-11-2022
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.JCIN.2010.05.016
Abstract: This study set out to evaluate the safety and efficacy of allogeneic bone marrow mesenchymal precursor cells (MPC) delivered by multisegmental, transendocardial implantation in the setting of nonischemic cardiomyopathy (NICM). Prospectively isolated MPC have shown capacity to mediate cardiovascular repair in myocardial ischemia. However, their efficacy in NICM remains undetermined. Mesenchymal precursor cells were prepared from ovine bone marrow by immunoselection using the tissue nonspecific alkaline phosphatase, or STRO-3, monoclonal antibody. Fifteen sheep with anthracycline-induced NICM were assigned to catheter-based, transendocardial injections of allogeneic MPC (n = 7) or placebo (n = 8), under electromechanical mapping guidance. Follow-up was for 8 weeks, with end points assessed by cardiac magnetic resonance, echocardiography, and histology. Intramyocardial injections were distributed similarly throughout the left ventricle in both groups. Cell transplantation was associated with 1 death late in follow-up, compared with 3 early deaths among placebo animals. Left ventricular end-diastolic size increased in both cohorts, but MPC therapy attenuated end-systolic dilation and stabilized ejection fraction, with a nonsignificant increase (37.3 ± 2.8% before, 39.2 ± 1.4% after) compared with progressive deterioration after placebo (38.8 ± 4.4% before, 32.5 ± 4.9% after, p < 0.05). Histological outcomes of cell therapy included less fibrosis burden than in the placebo group and an increased density of karyokinetic cardiomyocytes and myocardial arterioles (p < 0.05 for each). These changes occurred in the presence of modest cellular engraftment after transplantation. Multisegmental, transendocardial delivery of cell therapy can be achieved effectively in NICM using electromechanical navigation. The pleiotropic properties of immunoselected MPC confer benefit to nonischemic cardiac disease, extending their therapeutic potential beyond the setting of myocardial ischemia.
Publisher: Elsevier BV
Date: 02-2015
DOI: 10.1016/J.CJCA.2014.10.027
Abstract: The ever-increasing prevalence of obesity poses a significant burden on the health care system with escalating socioeconomic consequences. At the in idual level, obesity is well recognized to increase morbidity and mortality. Not only is obesity an established cardiovascular risk factor, it also increases the risk of sudden cardiac death and atrial fibrillation. Studies have shown that increased adiposity itself and the accompanying metabolic consequences of weight gain contribute to an abnormal arrhythmogenic substrate. In this review, we focus on the erse mechanisms underlying cardiac arrhythmias related to obesity. In particular, we highlight the pathogenic role of adipose depots leading to increased atrial fibrillation and the effect of weight reduction in decreasing atrial fibrillation burden in obese in iduals.
Publisher: Elsevier BV
Date: 12-2004
DOI: 10.1016/J.JACC.2004.08.065
Abstract: We sought to evaluate the relationship between hemodynamic and ventricular dyssynchrony parameters in patients undergoing simultaneous and sequential biventricular pacing (BVP). Various echocardiographic parameters of ventricular dyssynchrony have been proposed to screen and optimize BVP therapy. Forty-one patients with heart failure undergoing BVP implantation were studied. Echocardiography coupled with tissue tracking and pulsed Doppler tissue imaging (DTI) was performed before and after BVP implantation and after three months of optimized BVP. Indexes of inter- or intraventricular dyssynchrony were correlated with hemodynamic changes during simultaneous and sequential BVP (10 intervals of right ventricular [RV] or left ventricular [LV] pre-excitation). Variations in intra-LV delay(peak), intra-LV delay(onset), and index of LV dyssynchrony measured by pulsed DTI were highly correlated with those of cardiac output (r = -0.67, r = -0.64, and r = -0.67, respectively p < 0.001) and mitral regurgitation (r = 0.68, r = 0.63, and r = 0.68, respectively p < 0.001), whereas variations in the extent of myocardium displaying delayed longitudinal contraction (r = -0.48 and r = 0.51, respectively p < 0.05) and the variations in septal-to-posterior wall motion delay (r = -0.41, p < 0.05 and r = 0.24, p = NS, respectively) were less correlated. The changes in interventricular dyssynchrony were not significantly correlated (p = NS). Compared with simultaneous BVP, in idually optimized sequential BVP significantly increased cardiac output (p < 0.01), decreased mitral regurgitation (p < 0.05), and improved all parameters of intra-LV dyssynchrony (p < 0.01). At three months, a significant reverse mechanical LV remodeling was observed with significantly decreased LV volumes (p < 0.01) associated with an increased LV ejection fraction (p = 0.035). Specific echocardiographic measurements of ventricular dyssynchrony are highly correlated with hemodynamic changes and may be a useful adjunct in the selection and optimization of BVP. In idually optimized sequential BVP provided a significant early hemodynamic improvement compared with simultaneous BVP.
Publisher: Wiley
Date: 18-11-2010
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2020
DOI: 10.1161/CIRCOUTCOMES.119.006470
Abstract: Sudden cardiac death (SCD) in the young is devastating. Contemporary incidence remains unclear with few recent nationwide studies and limited data addressing risk factors for causes. We aimed to determine incidence, trends, causes, and risk factors for SCD in the young. The National Coronial Information System registry was reviewed for SCD in people aged 1 to 35 years from 2000 to 2016 in Australia. Subjects were identified by the International Classification of Diseases , Tenth Revision code relating to circulatory system diseases (I00–I99) from coronial reports. Baseline demographics, circumstances, and cause of SCD were obtained from coronial and police reports, alongside autopsy and toxicology analyses where available. During the study period, 2006 cases were identified (median age, 28±7 years men, 75% mean body mass index, 29±8 kg/m 2 ). Annual incidence ranged from 0.91 to 1.48 per 100 000 age-specific person-years, which was the lowest in 2013 to 2015 compared with previous 3-year intervals on Poisson regression model ( P =0.001). SCD incidence was higher in nonmetropolitan versus metropolitan areas (0.99 versus 0.53 per 100 000 person-years P .001). The most common cause of SCD was coronary artery disease (40%), followed by sudden arrhythmic death syndrome (14%). Incidence of coronary artery disease–related SCD decreased from 2001–2003 to 2013–2015 ( P .001). Proportion of SCD related to sudden arrhythmic death syndrome increased during the study period ( P =0.02) although overall incidence was stable ( P =0.22). Residential remoteness was associated with coronary artery disease–related SCD (odds ratio, 1.44 [95% CI, 1.24–1.67] P .001). For every 1-unit increase, body mass index was associated with increased likelihood of SCD from cardiomegaly (odds ratio, 1.08 [95% CI, 1.05–1.11] P .001) and dilated cardiomyopathy (odds ratio, 1.04 [95% CI, 1.01–1.06] P =0.005). Incidence of SCD in the young and specifically coronary artery disease–related SCD has declined in recent years. Proportion of SCD related to sudden arrhythmic death syndrome increased over the study period. Geographic remoteness and obesity are risk factors for specific causes of SCD in the young.
Publisher: Wiley
Date: 02-09-2019
DOI: 10.1111/JCE.14124
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2020
Publisher: Wiley
Date: 2005
DOI: 10.1111/J.1540-8159.2005.00062.X
Abstract: Cardiac t onade complicating catheter ablation of atrial fibrillation (AF) occurs in approximately 1% of pulmonary vein isolation (PVI), and up to 6% of linear ablation procedures. We reviewed 348 consecutive AF ablation (including repeat) procedures over 1 year, which all included PVI, with additional linear lesions at the mitral isthmus in 73%, and cavotricuspid isthmus (CTI) in 76%. An irrigated-tip ablation catheter was used, with power limited to 25-35 W for PVI and 45-60 W for linear lesions. T onade occurred in seven men and three women (2.9% of the population) during the creation of linear ablation lesions. Mechanical perforations occurred in two patients, and "popping" during radiofrequency (RF) energy delivery at the mitral isthmus in six, and at the CTI in two patients. Peak RF power was significantly higher in patients with than without t onade (53 +/- 4 W vs 48 +/- 7 W P = 0.02), and was greater than 48 W in all cases of "popping." In the following year, RF power for linear ablation was limited to </=42 W. Among 398 procedures, t onade occurred in four patients (1.0% P = 0.047 vs first year), three from "popping" and one from mechanical trauma. Procedural success rate remained the same despite reduction of power. Risk of t onade was highest during linear ablation, mainly associated with high energy delivery and "popping." Reducing the energy limited, though did not eliminate this complication.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.IJCARD.2017.05.012
Abstract: A number of cardiovascular diseases have been linked with bone health and an increased risk of osteoporotic fracture. Whether atrial fibrillation (AF) is associated with subsequent fracture risk is not known. Administrative, clinical and hospitalisation information were linked over a 14-year period. From this longitudinal, population-based dataset of 113,600 in iduals, time-dependent exposures using multivariate Cox proportional hazards regression models were employed to determine incidence rates and hazard ratios (HR) for hip fracture according to a history of AF. The annualised incidence rate for hip fracture was 7.4 per 1000 person-years (95% CI 7.1-7.7) in those without AF and 17.5 per 1000 person-years (95% CI 16.8-18.1) in those with AF. Compared to in iduals without AF, those with AF were more likely to develop incident hip fracture in both men (unadjusted HR 2.39 [95% CI 1.96-2.91]) and women (unadjusted HR 2.91 [95% CI 2.55-3.34]). After adjusting for potential confounders, these associations were attenuated but remained statistically significant (adjusted HR 1.97 [95% CI 1.61-2.42] in men adjusted HR 2.08 [95% CI 1.80-2.39] in women). A history of AF was associated with an increased risk of hip fracture in this large, population-based analysis. This association appeared to remain significant even after adjusting for potential confounders such as age, comorbidities and medication use. Patients with a history of AF may represent a clinical population in whom screening for and treatment of osteoporosis may be warranted to reduce the risk of subsequent fracture.
Publisher: Elsevier BV
Date: 11-2017
DOI: 10.1016/J.IJCARD.2017.05.133
Abstract: Whilst high levels of alcohol consumption are known to be associated with atrial fibrillation (AF), it is unclear if any level of alcohol consumption can be recommended to prevent the onset of the condition. The aim of this review is to characterise the association between chronic alcohol intake and incident AF. Electronic literature searches were undertaken using PubMed and Embase databases up to 1 February 2016 to identify studies examining the impact of alcohol on the risk of incident AF. Prospective studies reporting on at least three levels of alcohol intake and published in English were eligible for inclusion. Studies of a retrospective or case control design were excluded. The primary study outcome was development of incident AF. Consistent with previous studies, high levels of alcohol intake were associated with an increased incident AF risk (HR 1.34, 95% CI 1.20-1.49, p<0.001). Moderate levels of alcohol intake were associated with a heightened AF risk in males (HR 1.26, 95% CI 1.04-1.54, p=0.02) but not females (HR 1.03, 95% CI 0.86-1.25, p=0.74). Low alcohol intake, of up to 1 standard drink (SD) per day, was not associated with AF development (HR 0.95, 95% CI 0.85-1.06, p=0.37). Low levels of alcohol intake are not associated with the development of AF. Gender differences exist in the association between moderate alcohol intake and AF with males demonstrating greater increases in risk, whilst high alcohol intake is associated with a heightened AF risk across both genders.
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.JELECTROCARD.2018.11.014
Abstract: The potential utility of entropy (En) for atrial fibrillation (AF) mapping has been demonstrated in previous studies by multiple groups, where an association between high bipolar electrogram (EGM) entropy and the pivot of rotors has been shown. Though En is potentially attractive new approach to ablation, no studies have examined its temporal stability and specificity, which are critical to the application of entropy to clinical ablation. In the current study, we sought to objectively measure the temporal stability and specificity of bipolar EGM entropy in medium to long term recordings using three studies: i) a human basket catheter AF study, ii) a tachypaced sheep AF study and iii) a computer simulation study. To characterize the temporal dynamics and specificity of Approximate, S le and Shannon entropy (ApEn/S En/ShEn) in human (H), sheep (S), and computer simulated AF. 64-electrode basket bi-atria sustained AF recordings (H:15 min S:40 min) were separated into 5 s segments. ShEn/ApEn/S En were computed, and co-registered with NavX 3D maps. Temporal stability was determined in terms of: (i) global pattern stability of En and (ii) the relative stability the top 10% of En regions. To provide mechanistic insights into underlying mechanisms, stability characteristics were compared to models depicting various propagation patterns. To verify these results, cross-validation was performed across multiple En algorithms, across species, and compared with dominant frequency (DF) temporal characteristics. The specificity of En was also determined by looking at the association of En to rotors and areas of wave cross propagation. Episodes of AF were analysed (H:26 epochs, 6040 s S:15 epochs, 14,160 s). The global pattern of En was temporally unstable (CV- H:13.42% ± 4.58% S:14.13% ± 8.13% Friedman- H: p > 0.001 S: p > 0.001). However, within this dynamic flux, the top 10% of ApEn/S En/ShEn regions were relatively temporally stable (Kappa >0.6) whilst the top 10% of DF regions were unstable (Kappa <0.06). In simulated AF scenarios, the experimental data were optimally reproduced in the context of an AF pattern with stable rotating waves surrounded by wavelet breakup (Kappa: 0.610 p < 0.0001). En shows global temporal instability, however within this dynamic flux, the top 10% regions exhibited relative temporal stability. This suggests that high En regions may be an appealing ablation target. Despite this, high En was associated with not just the pivot of rotors but also with areas of cross propagation, which suggests the need for future work before clinical application is possible.
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.JACC.2009.10.046
Abstract: The aim of this report was to study the effect of chronic stretch reversal on the electrophysiological characteristics of the atria in humans. Atrial stretch is an important determinant for atrial fibrillation. Whether relief of stretch reverses the substrate predisposed to atrial fibrillation is unknown. Twenty-one patients with mitral stenosis undergoing mitral commissurotomy (MC) were studied before and after intervention. Catheters were placed at multiple sites in the right atrium (RA) and sequentially within the left atrium (LA) to determine: effective refractory period (ERP) at 10 sites (600 and 450 ms) and P-wave duration (PWD). Bi-atrial electroanatomic maps determined conduction velocity (CV) and voltage. In 14 patients, RA studies were repeated >or=6 months after MC. Immediately after MC, there was significant increase in mitral valve area (2.1 +/- 0.2 cm(2), p < 0.0001) with decrease in LA (23 +/- 7 mm Hg to 10 +/- 4 mm Hg, p < 0.0001) and pulmonary arterial pressures (38 +/- 16 mm Hg to 27 +/- 12 mm Hg, p < 0.0001) and LA volume (75 +/- 20 ml to 52 +/- 18 ml, p < 0.0001). This was associated with reduction in PWD (139 +/- 19 ms to 135 +/- 20 ms, p = 0.047), increase in CV (LA: 1.3 +/- 0.3 mm/ms to 1.7 +/- 0.2 mm/ms, p = 0.006 and RA: 1.0 +/- 0.1 mm/ms to 1.3 +/- 0.3 mm/ms, p = 0.002) and voltage (LA: 1.7 +/- 0.6 mV to 2.5 +/- 1.0 mV, p = 0.005 and RA: 1.8 +/- 0.6 mV to 2.2 +/- 0.7 mV, p = 0.09), and no change in ERP. Late after MC, mitral valve area remained at 2.1 +/- 0.3 cm(2) (p = 0.7) but with further decrease in PWD (113 +/- 19 ms, p = 0.04) and RA ERP (at 600 ms, p < 0.0001), with increase in CV (1.0 +/- 0.1 mm/ms to 1.3 +/- 0.2 mm/ms, p = 0.006) and voltage (1.8 +/- 0.7 mV to 2.8 +/- 0.6 mV, p = 0.002). The atrial electrophysiologic and electroanatomic abnormalities that result from chronic stretch due to MS reverses after MC. These observations suggest that the substrate predisposing to atrial arrhythmias might be reversed.
Publisher: Wiley
Date: 09-05-2020
DOI: 10.1111/PACE.13926
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.JELECTROCARD.2012.09.006
Abstract: An ECG recorded from a patient with an implanted cardiac pacemaker showed a striking high frequency pulsing on the ST-T segments linked with each QRS complex. In this report we present an approach to the clatter on the ECG and discuss various potential diagnoses that can have closely similar pattern.
Publisher: Wiley
Date: 29-11-2006
DOI: 10.1111/J.1540-8167.2006.00682.X
Abstract: High-density three-dimensional (3D) mapping of the pulmonary vein (PV)-left atrial (LA) junction was performed to characterize spontaneous PV activity in humans. The activation patterns of ectopic beats and of the initial 2 seconds of atrial fibrillation (AF) from the PVs were analyzed using a 64-poles basket catheter. A focal mechanism was defined as a discrete site of early and centrifugal activation. Continuous activity was considered as an activation covering > or = 80% of the tachycardia beat-to-beat cycle length within the mapping field. In 35 patients, 123 spontaneous focal ectopic beats that did not induce AF and 95 that did induce AF were mapped. The mean coupling interval of ectopic discharges not inducing AF was 281 +/- 70 msec versus 236 +/- 90 msec for ectopies initiating AF (P < or = 0.01). The first ectopic activity of all 218 arrhythmogenic events showed exclusively a focal mechanism. During the 95 episodes of AF initiation, one or two ectopic beats from the PVs initiated AF in the LA in 39%, a stable focal tachycardia was recorded in 14%, continuous activity with important changes in cycle length (35 +/- 15 msec) suggestive of decremental or fibrillatory conduction was found in 18%, and in 29% the activation pattern could not be classified. No stable and sustained reentrant circuit could be identified by our mapping tool in the PV-LA junction. Arrhythmogenic activity from PVs in humans is predominantly due to discrete focal activity.
Publisher: Wiley
Date: 28-08-2008
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2019
Publisher: BMJ
Date: 17-09-2019
DOI: 10.1136/HEARTJNL-2019-314770
Abstract: The aim of the meta-analysis was to determine the association of obesity and heart failure (HF) and the cardiac impact of intentional weight loss following bariatric surgery on cardiac structure and myocardial function in obese subjects. MEDLINE, Embase and Web of Science were searched up to 3 April 2018. Studies reporting association and prognostic impact of obesity in HF and the impact of intentional weight loss following bariatric surgery on cardiac structure and myocardial function in obesity were included in the meta-analysis. 4959 citations were reviewed. After exclusions, 29 studies were analysed. A ‘J curve’ relationship was observed between body mass index (BMI) and risk of HF with maximum risk in the morbidly obese (1.73 (95% CI 1.30 to 2.31), p .001, n=11). Although ‘obesity paradox’ was observed for all-cause mortality, the overweight group was associated with lower cardiovascular (CV) mortality (OR=0.86 (95% CI 0.79 to 0.94), n=11) with no significant differences across other BMI groups. Intentional weight loss induced by bariatric surgery in obese patients (n=9) without established HF, atrial fibrillation or known coronary artery disease, was associated with a reduction in left ventricular mass index (p .0001), improvement in left ventricular diastolic function (p≤0.0001) and a reduction in left atrial size (p=0.02). Despite the increased risk of HF with obesity, an ‘obesity paradox’ is observed for all-cause mortality. However, the nadir for CV mortality is observed in the overweight group. Importantly, intentional weight loss was associated with improvement in indices of cardiac structure and myocardial function in obese patients. APP 74412.
Publisher: Elsevier BV
Date: 04-2020
Publisher: Elsevier BV
Date: 11-2012
DOI: 10.1016/J.AMJCARD.2012.07.011
Abstract: Recent reports have described that hospitalizations for atrial fibrillation (AF) are continuing to increase. Given that hospitalizations are responsible for most of the economic burden associated with AF, the aim of this study was to characterize the impact of age and how changing procedural practices may be contributing to the increasing rates of AF hospitalizations. The annual age- and gender-specific incidence of hospitalizations for AF, electrical cardioversions, electrophysiologic studies, and radiofrequency ablation procedures in Australia were determined from 1993 to 2007 inclusive. Over this 15-year follow-up period spanning almost 300 million person-years, a total of 473,501 hospitalizations for AF were identified. There was a relative increase in AF hospitalizations of 203% over the study period, in contrast to an increase for all hospitalizations of only 71%. Whereas the gender-specific incidence of hospitalizations remained stable, the age-specific incidence increased significantly over the study period, particularly in older age groups. AF hospitalizations associated with electrical cardioversions decreased from 27% to 14% over the study period. Electrophysiologic studies and radiofrequency ablation procedures contributed minimally to the overall increase in AF hospitalizations observed. In conclusion, in addition to the growing prevalence of AF because of the aging population, there is an increasing age-specific incidence of hospitalizations for AF, particularly in older age groups. In contrast, changing procedural trends have contributed minimally to the increasing number of AF-associated hospitalizations. Greater attention to older patients with AF is required to develop strategies to prevent hospitalizations and contain the growing burden on health care systems.
Publisher: MDPI AG
Date: 04-10-2019
DOI: 10.3390/E21100970
Abstract: Atrial fibrillation (AF) is related to a very complex local electrical activity reflected in the rich morphology of intracardiac electrograms. The link between electrogram complexity and efficacy of the catheter ablation is unclear. We test the hypothesis that the Kolmogorov complexity of a single atrial bipolar electrogram recorded during AF within the coronary sinus (CS) at the beginning of the catheter ablation may predict AF termination directly after pulmonary vein isolation (PVI). The study population consisted of 26 patients for whom 30 s baseline electrograms were recorded. In all cases PVI was performed. If AF persisted after PVI, ablation was extended beyond PVs. Kolmogorov complexity estimated by Lempel–Ziv complexity and the block decomposition method was calculated and compared with other measures: Shannon entropy, AF cycle length, dominant frequency, regularity, organization index, electrogram fractionation, s le entropy and wave morphology similarity index. A 5 s window length was chosen as optimal in calculations. There was a significant difference in Kolmogorov complexity between patients with AF termination directly after PVI compared to patients undergoing additional ablation (p 0.01). No such difference was seen for remaining complexity parameters. Kolmogorov complexity of CS electrograms measured at baseline before PVI can predict self-termination of AF directly after PVI.
Publisher: Wiley
Date: 28-09-2005
DOI: 10.1111/J.1540-8167.2005.00308.X
Abstract: Catheter ablation of atrial fibrillation (AF) is challenging in patients with long-standing persistent AF. The clinical outcome and subsequent arrhythmia recurrence after using an ablation method targeting multiple left atrial sites with the aim of achieving acute AF termination has not been characterized. Sixty patients (mean age: 53 +/- 9 years) with persistent AF (mean duration: 17 +/- 27 months) were prospectively followed after catheter ablation. Catheter ablation targeting the following sites was performed in a random sequence: (i) electrical isolation of all pulmonary veins (PV) (ii) disconnection of other thoracic veins (iii) atrial ablation at sites possessing complex electrical activity, activation gradients, or short cycle lengths. Finally, linear ablation of the LA roof and mitral isthmus was performed if sinus rhythm was not restored following energy delivery to the above sites. At 1, 3, 6, and 12 months after ablation, patients underwent clinical review and 24-hour ambulatory ECG monitoring to identify asymptomatic arrhythmia. Repeat mapping and catheter ablation was performed in any patient experiencing recurrent atrial tachycardia (AT). Clinical success was defined as the absence of any sustained atrial arrhythmia. AF terminated during ablation in 52 patients (87%). The fluoroscopy and procedural durations were 84 +/- 30 minutes and 264 +/- 77 minutes, respectively. Three months after ablation, sustained ATs were documented in 24 patients (associated with AF in 2). Mapping in 23 patients showed a single AT in 7 while multiple ATs were observed in 16. Macroreentry was confirmed to be due to gaps in the ablation lines, while focal ATs originated from discrete sites or isthmuses near the left atrial appendage, coronary sinus, pulmonary veins, or fossa ovalis these sites were similar to those at which the greatest impact was observed on the fibrillatory process during the initial ablation procedure. After repeat ablation, at 11 +/- 6 months of follow-up, 57 patients (95%) were in sinus rhythm and 3 developed recurrent AF or AT. All patients in sinus rhythm demonstrated improved exercise capacity and all but 2 had evidence of atrial transport as assessed by Doppler echocardiography (mitral A wave velocity 34 +/- 17 cm/sec) by 6 months. Catheter ablation of long-lasting persistent AF associated with acute AF termination achieves medium to long-term restoration and maintenance of sinus rhythm in 95% of patients. Arrhythmia recurrence in the majority of patients is AT.
Publisher: Elsevier BV
Date: 06-2017
Publisher: Wiley
Date: 24-04-2023
DOI: 10.1111/ENE.15817
Abstract: Whether carotid artery disease could improve stroke risk stratification tools in patients with atrial fibrillation (AF) remains uncertain. This study was undertaken to investigate the risk of ischemic stroke associated with occlusive and nonocclusive carotid atherosclerotic disease in patients with AF in the prospective population‐based Cardiovascular Health Study. We included participants aged ≥65 years with AF. We used multivariable Cox regression analysis to explore the risk of ischemic stroke associated with the percentage of carotid stenosis, plaque irregularity, echogenicity, and vulnerability (markedly irregular, ulcerated, or hypoechoic plaques). A total of 1398 participants were included (55.2% female, 61.7% aged 65–74 years). The maximum carotid stenosis was %, 50%–99%, and 100% in 94.5%, 5%, and 0.5% of participants, respectively. High‐risk plaques based on echogenicity and plaque irregularity were found in 25.6% and 8.9% of participants, respectively. After a median follow‐up of 10.9 years (interquartile range = 7.5–15.6), 298 ischemic strokes were recorded. There was no difference in the incidence of ischemic stroke according to the degree of carotid artery stenosis ( p = 0.44), plaque echogenicity (low vs. high risk, p = 0.68), plaque irregularity (low vs. high risk, p = 0.55), and plaque vulnerability ( p = 0.86). The CHA₂DS₂‐VASc score was associated with an increased risk of ischemic stroke (adjusted hazard ratio = 1.28, 95% confidence interval = 1.18–1.40, p 0.001). Both maximum grade of stenosis and plaque vulnerability were not associated with incident ischemic stroke (all p 0.05). Neither the degree of carotid stenosis nor the presence of vulnerable plaques was associated with incident ischemic stroke in this cohort of in iduals with AF. This suggests that carotid disease was probably not a significant contributor to ischemic stroke in this population.
Publisher: Oxford University Press (OUP)
Date: 11-01-2018
Abstract: Rotor mapping and ablation have gained favour over the recent years as an emerging ablation strategy targeting drivers of atrial fibrillation (AF). Their efficacy, however, has been a topic of great debate with variable outcomes across centres. The aim of this study was to systematically review the recent medical literature to determine the medium-term outcomes of rotor ablation in patients with paroxysmal atrial fibrillation (PAF) and persistent atrial fibrillation (PeAF). A systematic search of the contemporary scientific literature (PubMed and EMBASE) was performed in August 2017. Only studies assessing arrhythmia-free survival from rotor ablation of AF were included. We used the random-effects model to assess the primary outcome of pooled medium-term single-procedure AF-free survival for both PAF and PeAF. Success rates from multiple procedures and complication rates were also examined. We included 11 observational studies (4 PAF and 10 PeAF) with a total of 556 patients (166 PAF and 390 PeAF). Pooled single-procedure freedom from AF was 37.8% [95% confidence interval 5.6-86.3%] at a mean follow-up period of 13.8 ± 1.8 months for PAF and 59.2% (95% CI 41.4-74.9%) at a mean follow-up period of 12.9 ± 6 months for PeAF. There was a marked heterogeneity between studies (I2 = 93.8% for PAF and 88.3% for PeAF). The mean complication rate of rotor ablation among the reported studies was 3.4%. The wide variability in success rate between different centres performing rotor ablations suggests that the optimal ablation strategy, particularly targeting rotors, is unclear. Results from randomized studies are necessary before this technique can be considered as an established clinical tool.
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.JELECTROCARD.2010.11.004
Abstract: Correlation function analysis applied to endocardial electrograms has earlier been used for analysis of agreement between signals and direction of activation during atrial fibrillation (AF). This study was aimed at evaluating whether preferential activation patterns along the coronary sinus (CS) exist in patients with AF. Twenty-seven patients (57 ± 10 years old) admitted for electrophysiological (EP) study (10 patients) and/or AF ablation (17 patients) were studied, 8 with permanent and 19 with persistent AF. Unipolar signals were recorded during 60 seconds from a 10-pole CS catheter during AF at baseline (BL) and after isolation of left and right pulmonary veins and after additional lines in the left atrium (LA) (End). Correlation function analysis was applied to signals from each pair of adjacent electrodes, and graphs of cumulated time delay were made to enable interpretation of direction of activation. Correlation between paired signals was highest in the distal and middle parts of CS and lowest in the proximal CS. In 21 patients, correlation values greater than 0.8 between closely spaced electrodes suggested uniform propagation of the fibrillatory waves. In 18 of 21 patients, preferential conduction pattern along CS was seen. Of those, 15 patients had left-to-right conduction, and 3 had right-to-left conduction. During ablation, atrial fibrillation cycle length increased from 184 ± 32 milliseconds at BL to 193 ± 39 milliseconds after pulmonary vein isolation and 215 ± 39 milliseconds at the end of ablation (P = .03, BL vs End). Because of ablation, preferential conduction along CS changed in 4 patients from left to right at BL to simultaneous CS activation or right to left. In 1 of 3 patients with simultaneous activation at BL, the direction changed to right to left. No direction change was observed in any of the 3 patients with right-to-left activation at BL. Atrial activation during AF exhibits a high degree of organization in distal and middle CS. Preferential conduction patterns observed in most patients may indicate either relatively dominant stable reentry circuits in the LA or activation spread from a focal source. The changes in preferential conduction during ablation of AF may reflect modification of AF substrate and indicate persistent right atrial sources not affected by ablation in the LA only.
Publisher: Wiley
Date: 21-02-2008
DOI: 10.1111/J.1540-8167.2007.01034.X
Abstract: Sites of complex fractionated atrial electrograms (CFAEs) and highest dominant frequency (DF) have been proposed as critical regions maintaining atrial fibrillation (AF). This study aimed to determine the minimum electrogram recording duration that accurately characterizes CFAE or DF sites for ablation without unduly lengthening the procedure. Fourteen patients with AF undergoing catheter ablation had high-density (498 +/- 174 points) biatrial mapping performed during AF before ablation. At each point, 8-second electrograms were recorded. CFAE characterization using the NavX software provided a representation of electrogram complexity (CFE-mean). CFE-mean for each point from 7-, 6-, 5-, 4-, 3-, 2-, and 1-second subs les were compared with the index 8-second CFE-mean. Offline spectral analysis defined DF as the frequency with greatest power, and DF of subs les were compared with index DF. Index 8-second electrogram CFE-mean was 114 +/- 20 ms for right atria and 102 +/- 17 ms for left atria (P = 0.01) DF was 5.7 +/- 0.8 Hz for right atria and 6.0 +/- 0.8 Hz for left atria (P = 0.02). Means from shorter electrograms were nonsignificantly decreased for CFE-mean and overestimated for DF (P 10% from index values ranged from 2.5 to 56% for CFE-mean and 3.5 to 41% for DF. Intraclass correlation coefficients ranged from 0.992 to 0.788 for CFE-mean and 0.897 to 0.233 for DF. Unacceptable differences from index values were found with CFE-mean and DF from electrograms or=5-second duration are required to accurately characterize CFAE and DF sites for ablation.
Publisher: Springer Science and Business Media LLC
Date: 10-2008
Publisher: Elsevier BV
Date: 11-2001
Publisher: Elsevier BV
Date: 05-2006
DOI: 10.1016/J.JACC.2005.12.068
Abstract: The aim of the present study was to assess the feasibility of identifying sites of focal atrial activity by localized high-density endocardial mapping during atrial fibrillation (AF). Sites of focal activity in the left atrium have been demonstrated by epicardial mapping during AF. Twenty-four patients (15 with paroxysmal, 3 with persistent, and 6 with permanent AF) underwent endocardial mapping during AF. A 20-pole catheter with five radiating spines was used to map both atria for 30 s in each of 10 pre-determined segments. A focal activity was defined as > or =3 atrial cycles with activation spreading from center to periphery of the mapping catheter. Catheter ablation was performed independent of the mapping results. Spontaneous focal activities were observed in 13 sites in the left atrium (9% anterior 1, roof 2, posterior 6, inferior 4) in 12 patients (9 paroxysmal, 3 persistent). Focal activity was observed continuously (two sites) or intermittently (11 sites, median 5 episodes), and associated with shortening of the cycle length (from 183 +/- 33 ms to 172 +/- 29 ms p < 0.05). The mean duration of an intermittent episode was 1.5 s (range 0.4 to 7.1 s). Atrial fibrillation terminated without ablation at the foci in all of 12 patients, but in 2 of them, re-initiated arrhythmia was successfully ablated at these foci. Nine of these 12 patients (75%) were arrhythmia-free without antiarrhythmic drugs during a follow-up period of 7.0 +/- 3.1 months. Termination of AF without ablation at the sites of atrial focal activity suggests that this activity may be triggered by impulses originating from other regions, such as the pulmonary veins.
Publisher: Elsevier BV
Date: 08-2019
Publisher: Elsevier BV
Date: 11-2017
DOI: 10.1016/J.HRTHM.2017.07.001
Abstract: The cardiovascular benefits of regular exercise have been well described, including a significant reduction in cardiovascular morbidity and mortality for those meeting recommended guidelines. Yet the impact of physical activity on the incidence of atrial fibrillation (AF) has been less clear. This review seeks to define the optimal dose and duration for the prevention and treatment of AF. In doing so, we review the evidence that supports a decline in AF risk for those who achieve a weekly physical activity dose slightly above the current recommended guidelines. Furthermore, we identify the reduced AF incidence in those in iduals who attain a cardiorespiratory fitness of 8 METs (metabolic equivalents of task) or more during maximal exercise testing. Finally, we review the evidence that shows an excess of AF among regular participants of endurance exercise.
Publisher: Elsevier BV
Date: 09-2021
Publisher: Springer Science and Business Media LLC
Date: 30-10-2013
Abstract: Randomised controlled trials (RCTs) evaluating the effect of fish oil supplementation on postoperative atrial fibrillation (POAF) following cardiac surgery have produced mixed results. In this study, we examined relationships between levels of red blood cell (RBC) n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) and the incidence of POAF. We used combined data (n=355) from RCTs conducted in Australia and Iceland. The primary end point was defined as POAF lasting >10 min in the first 6 days following surgery. The odds ratios (ORs) for POAF were compared between quintiles of preoperative RBC n-3 LC-PUFA levels by multivariable logistic regression. Subjects with RBC docosahexaenoic acid (DHA) in the fourth quintile, comprising a RBC DHA range of 7.0-7.9%, had the lowest incidence of POAF. Subjects in the lowest and highest quintiles had significantly higher risk of developing POAF compared with those in the fourth quintile (OR=2.36: 95% CI 1.07-5.24 and OR=2.45: 95% CI 1.16-5.17, respectively). There was no association between RBC eicosapentaenoic acid levels and POAF incidence. The results suggest a 'U-shaped' relationship between RBC DHA levels and POAF incidence. The possibility of increased risk of POAF at high levels of DHA suggests an upper limit for n-3 LC-PUFAs in certain conditions.
Publisher: Springer Science and Business Media LLC
Date: 14-11-2006
DOI: 10.1007/S10840-006-9045-1
Abstract: Treatment options for atrial fibrillation (AF) have evolved from simple, fluoroscopy-guided pulmonary vein isolation for those patients with paroxysmal AF to complex, multi-modality procedures targeting not only anatomic structures but also electrophysiologic phenomena including complex fractionated electrograms, sites of dominant frequency and local non-venous drivers in patients with persistent and permanent AF. The stepwise ablation approach is a novel technique whereby structures contributing to initiation and maintenance of AF are sequentially targeted by radiofrequency ablation. Broadly ided into pulmonary veins, left atrial (LA) roof, left atrium (incorporating all anatomic regions of the chamber), mitral isthmus and non-LA structures, each region is targeted in sequence and the impact of ablation upon the global fibrillatory process assessed by measurement of AF cycle length (AFCL) at a site remote from the ablation target. In addition to pulmonary vein electrical disconnection and demonstrable complete conduction block across the roof and mitral isthmus lines (when performed), ablation is performed at those sites displaying continuous electrical and complex fractionated activity, with the endpoint of local organization, as well as at sites displaying electrograms consistent with focal sources driving AF. Ablation is accompanied by a cumulative increase in the AFCL prior to termination of AF by conversion either directly to sinus rhythm or to an atrial tachycardia which is then mapped conventionally and ablated. There is a ceiling of ablation within the LA beyond which further ablation is unlikely to result in a clinical benefit and should prompt evaluation of the contribution of the right atrium to maintenance of AF. The stepwise approach benefits from the integration of anatomic and electrophysiologic information to achieve a high level of success in termination of chronic AF by catheter ablation.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 23-09-2003
DOI: 10.1161/01.CIR.0000090688.49283.67
Abstract: Background— Atrial fibrillation (AF) frequently complicates congestive heart failure (CHF). However, the electrophysiological substrate for AF in humans with CHF remains unknown. We evaluated the electrophysiological and electroanatomic characteristics of the atria in patients with CHF. Methods and Results— Twenty-one patients (aged 53.7±13.6 years) with symptomatic CHF (left ventricular ejection fraction 25.5±6.0%) and 21 age-matched controls were studied. The following were evaluated: effective refractory periods (ERPs) from the high and low lateral right atrium (LRA), high septal right atrium, and distal coronary sinus (CS) conduction time along the CS and LRA corrected sinus node recovery times P-wave duration and conduction at the crista terminalis. In a subset, electroanatomic mapping was performed to determine atrial activation, regional conduction velocity, double potentials, fractionated electrograms, regional voltage, and areas of electrical silence. Patients with CHF demonstrated an increase in atrial ERP with no change in the heterogeneity of refractoriness, an increase of atrial conduction time along the LRA and the CS, prolongation of the P-wave duration and corrected sinus node recovery times, and greater number and duration of double potentials along the crista terminalis. Electroanatomic mapping demonstrated regional conduction slowing with a greater number of electrograms with fractionation or double potentials, associated with areas of low voltage and electrical silence (scar). Patients with CHF demonstrated an increased propensity for AF with single extrastimuli, and induced AF was more often sustained. Conclusions— Atrial remodeling due to CHF is characterized by structural changes, abnormalities of conduction, sinus node dysfunction, and increased refractoriness. These abnormalities may be responsible in part for the increased propensity for AF in CHF.
Publisher: Wiley
Date: 17-01-2022
DOI: 10.1111/JCE.15351
Abstract: To summarize data on the prevalence/incidence, risk factors and prognosis of atrial fibrillation (AF) in patients with acute coronary syndromes (ACS). MEDLINE, Embase, and Web of Science were searched to identify all published studies providing relevant data through August 23, 2020. Random-effects meta-analysis method was used to pool estimates. We included 109 studies reporting data from a pooled population of 8 239 364 patients. The prevalence rates were 5.8% for pre-existing AF, 7.3% for newly diagnosed AF, and 11.3% for prevalent (total) AF, in patients with ACS. Predictors of newly diagnosed AF included age (per year increase) (adjusted odds ratio [aOR]: 1.05), C-reactive protein (aOR: 1.49), left atrial (LA) diameter (aOR: 1.08), LA dilatation (aOR: 2.32), left ventricular ejection fraction <40% (aOR: 1.82), hypertension (aOR: 1.87), and Killip ˃ 1 (aOR: 1.85), p < .01 in all analyzes. Newly diagnosed AF was associated with an increased risk of acute heart failure (adjusted hazard ratio [aHR]: 3.20), acute kidney injury (aHR: 3.09), re-infarction (aHR: 1.96), stroke (aHR: 2.15), major bleeding (aHR: 2.93), and mortality (aHR: 1.80) in the short term and with an increased risk of heart failure (aHR: 2.21), stroke (aHR: 1.75), mortality (aHR: 1.67), CV mortality (aHR: 2.09), sudden cardiac death (aHR: 1.53), and a composite of major adverse cardiovascular events (aHR: 1.54) in the long term (beyond 1 month), p < .05 in all analyzes. One in nine patients with ACS has AF, with a high proportion of newly diagnosed AF. AF, in particular newly diagnosed AF, is associated with poor short-term and long-term outcomes in patients with ACS.
Publisher: Elsevier BV
Date: 10-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2021
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.HRTHM.2010.05.037
Abstract: Patients with lone atrial fibrillation (AF) have an abnormal atrial substrate. The purpose of this study was to determine the role of direction-dependent conduction in patients with lone AF. Twenty-four patients with paroxysmal lone AF and 24 reference patients with left-sided accessory pathways were studied. Multipolar catheters placed at the lateral right atrium, crista terminalis, coronary sinus (CS), and left atrial roof were used to determine direction-dependent conduction characteristics. Biatrial electroanatomic maps were created during sinus rhythm and with distal CS pacing to characterize direction-dependent differences in conduction velocities, electrogram complexity, and voltage. Differing wavefront directions caused changes in conduction velocity (P <.001), biatrial activation times (P <.001), electrogram fragmentation (P <.001), site-specific conduction delays (P <.001), and voltage (P <.001) in both lone AF and reference patients. These direction-dependent abnormalities were lified in lone AF patients compared to reference patients, who exhibited greater slowing in conduction velocities (P = .02), prolongation of biatrial activation time (P = .04), increase in number (P <.001) and length (P <.001) of lines of conduction block, increase in proportion of fractionated electrograms (P <.001), and decrease in voltage (P = .03) during distal CS pacing compared to sinus rhythm. This study demonstrates the marked direction-dependent conduction abnormalities present in patients with lone AF. These results provide further insights into the critical interplay between the underlying abnormal substrate and differing wavefront directions. The study suggests that direction-dependent conduction abnormalities may explain in part the greater arrhythmogenicity of ectopic triggers from the left atrium rather than the right atrium.
Publisher: Oxford University Press (OUP)
Date: 17-07-2007
Abstract: Both anti-tachycardia pacing and cardioversion via an implantable cardioverter defibrillator are effective therapies for ventricular tachycardia (VT). We report a case of VT where cardioversion resulted in delayed termination of tachycardia. Potential mechanisms for this observation are discussed.
Publisher: Wiley
Date: 08-09-2019
DOI: 10.1111/JCE.14145
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2020
DOI: 10.1161/CIRCEP.120.008461
Abstract: Recent data demonstrate promising effects on left ventricular dysfunction and left ventricular ejection fraction (LVEF) improvement following ablation for atrial fibrillation (AF) in patients with heart failure. We sought to study the relationship between LVEF, New York Heart Association class on presentation, and the end points of mortality and heart failure admissions in the CASTLE-AF study (Catheter Ablation for Atrial Fibrillation With Heart Failure) population. Furthermore, predictors for LVEF improvement were examined. The CASTLE-AF patients with coexisting heart failure and AF (n=363) were randomized in a multicenter prospective controlled fashion to ablation (n=179) versus pharmacological therapy (n=184). Left ventricular function and New York Heart Association class were assessed at baseline (after randomization) and at each follow-up visit. In the ablation arm, a significantly higher number of patients experienced an improvement in their LVEF to % at the end of the study (odds ratio, 2.17 P .001). Compared with the pharmacological therapy arm, both ablation patient groups with severe ( %) or moderate/severe (≥20% and %) baseline LVEF had a significantly lower number of composite end points (hazard ratio [HR], 0.60 P =0.006), all-cause mortality (HR, 0.54 P =0.019), and cardiovascular hospitalizations (HR, 0.66 P =0.017). In the ablation group, New York Heart Association I/II patients at the time of treatment had the strongest improvement in clinical outcomes (primary end point: HR, 0.43 P .001 mortality: HR, 0.30 P =0.001). Compared with pharmacological treatment, AF ablation was associated with a significant improvement in LVEF, independent from the severity of left ventricular dysfunction. AF ablation should be performed at early stages of the patient’s heart failure symptoms.
Publisher: Elsevier BV
Date: 08-2020
DOI: 10.1016/J.HLC.2019.11.006
Abstract: Studies have shown that suboptimal anticoagulation quality, as measured by time in therapeutic range (TTR), affects a significant percentage of patients with atrial fibrillation (AF). However, TTR has not been previously characterised in Indigenous Australians who experience a greater burden of AF and stroke. Indigenous and non-Indigenous Australians with AF on warfarin anticoagulation therapy were identified from a large tertiary referral centre between 1999 and 2012. Time in therapeutic range was calculated as a proportion of daily international normalised ratio (INR) values between 2 and 3 for non-valvular AF and 2.5 to 3.5 for valvular AF. INR values between tests were imputed using the Rosendaal technique. Linear regression models were employed to characterise predictors of TTR. Five hundred and twelve (512) patients with AF on warfarin were included (88 Indigenous and 424 non-Indigenous). Despite younger age (51±13 vs 71±12 years, p<0.001), Indigenous Australians had greater valvular heart disease, diabetes, and alcohol excess compared to non-Indigenous Australians (p<0.05 for all). Time in therapeutic range was significantly lower in Indigenous compared to non-Indigenous Australians (40±29 vs 50±31%, p=0.006). Univariate predictors of poorer TTR included Indigenous ethnicity, younger age, diuretic use, and comorbidities, such as valvular heart disease, heart failure and chronic obstructive pulmonary disease (p<0.05 for all). Valvular heart disease remained a significant predictor of poorer TTR in multivariate analyses (p=0.004). Indigenous Australians experience particularly poor warfarin anticoagulation quality. Our data also suggest that many non-Indigenous Australians spend suboptimal time in therapeutic range. These findings reinforce the importance of monitoring warfarin anticoagulation quality to minimise stroke risk.
Publisher: Wiley
Date: 2005
DOI: 10.1111/J.1540-8159.2005.00061.X
Abstract: The differentiation of pulmonary vein (PV) electrograms from atrial far-field signals during PV isolation (PVI) for atrial fibrillation (AF) may be difficult. In addition, owing to highly variable PV ostial sizes, current fixed-diameter circular PV mapping catheters may not yield optimal electrograms. We evaluated an expandable, circular 15-25 mm diameter, 20-pole mapping catheter for PV mapping during sustained AF in 25 patients. After selective PV angiography to define the ostial position and size, the catheter was introduced into each PV and withdrawn to the most stable proximal position, with optimal wall contact ensured by progressive loop expansion. At each PV ostium, electrograms recorded at high resolution (HR) were compared with those recorded at a resolution similar to that of a standard 10-pole Lasso catheter. After PVI performed during ongoing AF, the presence of residual far-field potentials (FFP) under both set-ups was compared. We mapped 97 PV, including 4 pairs with common ostia. In the HR recordings, the PV potentials had greater litude (0.5 +/- 0.1 vs 0.3 +/- 0.1 mV, P = 0.001) and fragmentation, whereas left atrial FFP were minimized. After successful isolation of all PV, FFP were observed in 33% of left superior and 28% of left inferior PV on the HR recordings, compared to 66% and 61%, respectively under normal resolution. Catheter stability and optimal wall contact, in combination with HR electrograms can optimize circumferential PV mapping during AF and improve the discrimination of FFP postablation.
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.CJCA.2019.03.020
Abstract: Atrial fibrillation (AF) is a growing global epidemic, with its prevalence expected to significantly rise over coming decades. AF poses a substantial burden on health care systems, largely due to hospitalizations. Home-based clinical characterization has demonstrated improved outcomes in cardiac populations, but its impact on AF remains poorly defined. To test this hypothesis in AF, we developed the Home-Based Education and Learning Program for Patients With Atrial Fibrillation (HELP-AF) study. The HELP-AF study is a prospective multicentre randomized controlled trial that will recruit 620 patients presenting to hospital emergency departments (EDs) with symptomatic AF (ANZCTR Registration: ACTRN12611000607976). Patients will be randomized to either the HELP-AF intervention or usual care. The intervention consists of 2 home visits by a nurse or pharmacist trained in the structured educational visiting (SEV) method. Patients in the control group will receive usual discharge follow-up care. The primary endpoints are total unplanned hospital admissions and quality of life. Secondary endpoints include AF symptom severity and burden score time to first hospital admission total unplanned days in hospital total AF-related hospital admissions (including atrial flutter) total cardiac and noncardiac hospital admissions total AF- or atrial flutter-related cardiac- and noncardiac-related ED presentations and all-cause mortality. An economic evaluation will also be performed. Clinical endpoints will be adjudicated by independent blinded assessors. Follow-up will be at 24 months. This study will assess the efficacy of a home-based structured patient-centred educational intervention in patients with AF.
Publisher: Elsevier BV
Date: 02-2019
Publisher: Oxford University Press (OUP)
Date: 24-07-2023
Abstract: Exercise training reduces recurrence of arrhythmia and symptom severity amongst patients with symptomatic, non-permanent atrial fibrillation (AF). However, there is little evidence on whether this effect is modified by patient sex. In a sub-analysis from the ACTIVE-AF (A Lifestyle-based, PhysiCal AcTIVity IntErvention for Patients With Symptomatic Atrial Fibrillation) randomized controlled trial, we compared the effects of exercise training on AF recurrence and symptom severity between men and women. The ACTIVE-AF study randomized 120 patients (69 men, 51 women) with paroxysmal or persistent AF to receive an exercise intervention combining supervised and home-based aerobic exercise over 6 months or to continue standard medical care. Patients were followed over a 12-month period. The co-primary outcomes were recurrence of AF, off anti-arrhythmic medications and without catheter ablation, and AF symptom severity scores. By 12 months, recurrence of AF was observed in 50 (73%) men and 34 (67%) women. In an intention-to-treat analysis, there was a between-group difference in favour of the exercise group for both men [hazard ratio (HR) 0.52, 95% confidence interval (CI): 0.29–0.91, P = 0.022] and women (HR 0.47, 95% CI: 0.23–0.95, P = 0.035). At 12 months, symptom severity scores were lower in the exercise group compared with controls amongst women but not for men. An exercise-based intervention reduced arrhythmia recurrence for both men and women with symptomatic AF. Symptom severity was reduced with exercise in women at 12 months. No difference was observed in symptom severity for men. Australia and New Zealand Clinical Trials Registry: ACTRN12615000734561
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.HLC.2018.08.026
Abstract: Despite advancements in prevention and treatment, sudden cardiac death (SCD) remains a leading cause of mortality and is responsible for approximately half of all deaths from cardiovascular disease. Outcomes continue to remain poor following a sudden cardiac arrest, with most in iduals not surviving. Although coronary heart disease remains the dominant underlying condition, our understanding of SCD is improving through greater knowledge of clinical risk factors, cardiomyopathies, and primary arrhythmic disorders. However, despite a growing wealth of information from studies in North America, Europe, and Japan, data from other global regions (and particularly from low-and middle-income countries) remains scarce.
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.JACEP.2018.08.014
Abstract: The aims of the study were to characterize: 1) electrical and electroanatomical remodeling in patients with atrial fibrillation (AF) with obesity and 2) the impact of epicardial fat depots on adjacent atrial tissue. Obesity is associated with an increased risk of AF. A total of 115 patients with AF who underwent AF ablation were screened. After exclusion, 26 patients were ided into 2 groups (obese: body mass index [BMI] ≥27 kg/m The BMIs of the obese and reference groups were 30.2 ± 2.6 and 25.2 ± 1.3 kg/m Obesity is associated with electroanatomical remodeling of the atria, with areas of low voltage, conduction slowing, and greater fractionation of electrograms. These changes were more pronounced in regions adjacent to epicardial fat depots, which suggested a role for fat depots in the development of the AF substrate.
Publisher: Elsevier BV
Date: 10-2004
DOI: 10.1016/J.JACC.2004.08.034
Abstract: The goal of this study was to describe the mapping and ablation of polymorphic ventricular tachycardia (VT) after myocardial infarction (MI). The initiating mechanisms of polymorphic VT after MI have not been reported. Five patients (four males age 61 +/- 7 years) with recurrent episodes of polymorphic VT after anterior MI (left ventricular ejection fraction 32 +/- 7%) despite revascularization and antiarrhythmic drugs were studied. All patients demonstrated frequent ventricular premature beats (PBs) initiating polymorphic VT. Pace mapping and activation mapping were used to identify the earliest site of PB activity. The presence of a Purkinje potential preceding PB defined its origin from the Purkinje network. Electroanatomic voltage mapping was performed to delineate the extent of MI. The PBs were observed in all cases to arise from the Purkinje arborization in the MI border zone. These PBs were right bundle-branch block in all five patients, with morphologic variations in the limb leads in four one also had a left bundle-branch block morphology. The coupling interval of the PB to the preceding QRS complex demonstrated significant variations (320 to 600 ms). During PB, the Purkinje potential at the same site preceded the QRS complex by 20 to 160 ms and was associated with different morphologies. Repetitive Purkinje activity was documented during polymorphic VT. Splitting of Purkinje activity and Purkinje to muscle conduction block were also observed. Ablation at these sites eliminated all PBs. At 16 +/- 5 months follow-up using defibrillator memory interrogation, no patient has had recurrence of arrhythmia. The Purkinje arborization along the border-zone of scar has an important role in the mechanism of polymorphic VT in patients after MI. Ablation of the local Purkinje network allows suppression of polymorphic VT.
Publisher: Oxford University Press (OUP)
Date: 23-06-2023
DOI: 10.1093/EURHEARTJ/EHAD375
Abstract: Lifestyle risk factors are a modifiable target in atrial fibrillation (AF) management. The relative contribution of in idual lifestyle risk factors to AF development has not been described. Development and validation of an AF lifestyle risk score to identify in iduals at risk of AF in the general population are the aims of the study. The UK Biobank (UKB) and Framingham Heart Study (FHS) are large prospective cohorts with outcomes measured & years. Incident AF was based on International Classification of Diseases version 10 coding. Prior AF was excluded. Cox proportional hazards regression identified independent AF predictors, which were evaluated in a multivariable model. A weighted score was developed in the UKB and externally validated in the FHS. Kaplan–Meier estimates ascertained the risk of AF development. Among 314 280 UKB participants, AF incidence was 5.7%, with median time to AF 7.6 years (interquartile range 4.5–10.2). Hypertension, age, body mass index, male sex, sleep apnoea, smoking, and alcohol were predictive variables (all P & 0.001) physical inactivity [hazard ratio (HR) 1.01, 95% confidence interval (CI) 0.96–1.05, P = 0.80] and diabetes (HR 1.03, 95% CI 0.97–1.09, P = 0·38) were not significant. The HARMS2-AF score had similar predictive performance [area under the curve (AUC) 0.782] to the unweighted model (AUC 0.802) in the UKB. External validation in the FHS (AF incidence 6.0% of 7171 participants) demonstrated an AUC of 0.757 (95% CI 0.735–0.779). A higher HARMS2-AF score (≥5 points) was associated with a heightened AF risk (score 5–9: HR 12.79 score 10–14: HR 38.70). The HARMS2-AF risk model outperformed the Framingham-AF (AUC 0.568) and ARIC (AUC 0.713) risk models (both P & 0.001) and was comparable to the CHARGE-AF risk score (AUC 0.754, P = 0.73). The HARMS2-AF score is a novel lifestyle risk score which may help identify in iduals at risk of AF in the general community and assist population screening.
Publisher: Wiley
Date: 12-04-2005
DOI: 10.1046/J.1540-8167.2005.40804.X
Abstract: We report a case with paroxysmal atrial fibrillation, in whom multiple foci were identified in the left atrial appendage after pulmonary vein isolation. The patient was successfully treated by catheter ablation to disconnect this structure.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 21-10-2003
DOI: 10.1161/01.CIR.0000091408.45747.04
Abstract: Background— Atrial mechanical “stunning” develops after cardioversion of atrial fibrillation (AF) and is implicated in the genesis of thromboembolic complications. However, the mechanisms responsible for this phenomenon are poorly understood. Whether atrial mechanical dysfunction caused by AF can be reversed by pacing at increased rates or by pharmacological agents is unknown. Methods and Results— Twenty-six patients with AF undergoing cardioversion were dichotomized prospectively on the basis of the duration of arrhythmia as short-duration (1 to 6 months) or long-duration (≥3 years) AF. Left atrial appendage emptying velocities (LAAEVs) and spontaneous echocardiographic contrast (LASEC) were assessed by transesophageal echocardiography during AF, after reversion to sinus rhythm, during atrial pacing at cycle lengths of 750 to 250 ms, after a postpacing pause, and with isoproterenol. In patients with short-duration AF, LAAEV decreased (42.0±2.7 to 18.5±2.0 cm/s P .0001) and LASEC increased (0.9±0.3 to 2.2±0.3 P .01) with termination of AF pacing increased LAAEV (48.3±4.1 cm/s P .0001) and decreased LASEC (1.5±0.3 P .01) isoproterenol increased LAAEV (73.3±7.8 cm/s P .0001) and decreased LASEC (0.3±0.2 P .01) and the postpacing pause increased LAAEV (68.3±3.8 cm/s P .0001). In contrast, patients with long-duration AF demonstrated a significantly attenuated response of atrial mechanical function at each time point. With termination of AF, LAAEV decreased (19.1±2.6 to 8.2±1.0 cm/s P =0.003) and LASEC increased (2.0±0.2 to 3.3±0.2 P .01) pacing increased LAAEV (18.4±2.7 cm/s P .0001) and decreased LASEC (2.3±0.2 P .01) isoproterenol increased LAAEV (26.1±3.9 cm/s P =NS to equivalent atrial rate) and decreased LASEC (1.0±0.3 P .01) and the postpacing pause increased LAAEV (27.2±2.4 cm/s P =0.007). Conclusions— Atrial pacing at increased rates and isoproterenol can reverse atrial mechanical stunning associated with short-duration AF. In contrast, long-duration AF is associated with an attenuated response to these maneuvers. These findings suggest a functional contractile apparatus in the mechanically remodeled atrium caused by AF however, with longer durations of AF, additional factors may determine atrial mechanical function.
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.HLC.2011.07.010
Abstract: Percutaneous transseptal left atrial (LA) access is increasingly becoming a routine procedure in the electrophysiology and cardiac catheterisation laboratories. Our aim was to review an unselected large series of this procedure performed over a period of five years. We clinically characterised difficult cases and presented a method of safe and expeditious LA access. Overall, 543 transseptal punctures were performed. Of those, 10 were classified as difficult, with failure to access the LA in three or more attempts. In all 10 cases, surgical electrocautery was successfully used to facilitate needle puncture of the septum. All patients subsequently underwent an uncomplicated procedure. In conclusion, we describe a method to trouble-shoot the difficult transseptal access procedure, outlining the clinical characteristics, echocardiographic features and special precautions that need to be considered when utilising this method.
Publisher: Elsevier BV
Date: 04-2009
DOI: 10.1016/J.JACC.2008.11.054
Abstract: The purpose of this study was to determine whether patients with paroxysmal "lone" atrial fibrillation (AF) have an abnormal atrial substrate. While "AF begets AF," prompt termination to prevent electrical remodeling does not prevent disease progression. Twenty-five patients with paroxysmal lone AF, without arrhythmia in the week prior, and 25 reference patients with left-sided accessory pathways were studied. Multipolar catheters placed at the lateral right atrium (RA), crista terminalis, coronary sinus, septal RA, and sequentially within the left atrium (LA) determined the effective refractory period (ERP) at 10 sites, conduction time along linear catheters, and conduction characteristics at the crista terminalis. Bi-atrial electroanatomic maps were created to determine regional differences in conduction velocity and voltage. Patients with AF demonstrated the following compared with reference patients: larger atrial volumes (RA: 94 +/- 18 ml vs. 69 +/- 9 ml, p = 0.003 LA: 99 +/- 19 ml vs. 77 +/- 17 ml, p = 0.006) longer ERP (at 600 ms: 255 +/- 25 ms vs. 222 +/- 16 ms, p < 0.001 at 450 ms: 234 +/- 20 ms vs. 212 +/- 14 ms, p = 0.004) longer conduction time along linear catheters (57 +/- 18 ms vs. 47 +/- 10 ms, p = 0.01) longer bi-atrial activation time (128 +/- 17 ms vs. 89 +/- 10 ms, p < 0.001) slower conduction velocity (RA: 1.3 +/- 0.3 mm/ms vs. 2.1 +/- 0.5 mm/ms LA: 1.2 +/- 0.2 mm/ms vs. 2.2 +/- 0.4 mm/ms, p < 0.001) greater proportion of fractionated electrograms (27 +/- 8% vs. 8 +/- 5%, p < 0.001) longer corrected sinus node recovery time (265 +/- 57 ms vs. 185 +/- 60 ms, p = 0.002) and lower voltage (RA: 1.7 +/- 0.4 mV vs. 2.9 +/- 0.4 mV LA: 1.7 +/- 0.7 mV vs. 3.3 +/- 0.7 mV, p < 0.001). Patients with paroxysmal lone AF, remote from arrhythmia, demonstrate bi-atrial abnormalities characterized by structural change, conduction abnormalities, and sinus node dysfunction. These factors are likely contributors to the "second factor" that predisposes to the development and progression of AF.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-1999
Publisher: Elsevier BV
Date: 2005
Publisher: Elsevier BV
Date: 03-2005
DOI: 10.1016/J.HRTHM.2004.12.018
Abstract: The purpose of this study was to evaluate a possible correlation between atrial ECG litude in common atrial flutter (AFL) and radiofrequency (RF) energy required to achieve cavotricuspid isthmus block. The amount of RF delivery required for ablation of typical AFL is variable. This variation has been attributed to the cavotricuspid isthmus anatomy. Atrial ECG litude can be a marker of atrial anatomic variations and therefore may correlate with RF duration required to achieve cavotricuspid isthmus block. Seventy consecutive patients were prospectively studied. Ablation of the cavotricuspid isthmus was performed by creating a line of block between the inferior tricuspid annulus and the inferior caval vein using 8-mm-tip electrode catheters. If more than 20 minutes of RF time was required to achieve conduction block, the catheter was changed to an irrigated-tip catheter. Atrial ECG litude was assessed in leads II, III, aVF, and aVL. A total of 14 +/- 11 minutes of RF energy was delivered to achieve block in all patients 12 patients (8%) required more than 20 minutes. Atrial ECG litude showed highly significant correlations with cumulative RF energy (F and P waves in lead II: r = 0.703 and r = 0.737, P < .001). P-wave litude <0.2 mV and/or flutter wave litude <0.35 mV in lead II have a high negative predictive value to predict <20 min RF delivery (96% and 89% respectively). A significant correlation exists between atrial ECG litude and amount of RF required to ablate typical AFL. Atrial ECG litude may be a surrogate marker of characteristics of isthmus anatomy. These findings may influence the choice of catheter used for cavotricuspid isthmus ablation.
Publisher: Elsevier BV
Date: 12-2011
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 26-08-2003
DOI: 10.1161/01.CIR.0000088781.99943.95
Abstract: Background— The long-QT and Brugada syndromes are important substrates of malignant ventricular arrhythmia. The feasibility of mapping and ablation of ventricular arrhythmias in these conditions has not been reported. Methods and Results— Seven patients (4 men age, 38±7 years 4 with long-QT and 3 with Brugada syndrome) with episodes of ventricular fibrillation or polymorphic ventricular tachycardia and frequent isolated or repetitive premature beats were studied. These premature beats were observed to trigger ventricular arrhythmias and were localized by mapping the earliest endocardial activity. In 4 patients, premature beats originated from the peripheral right (1 Brugada) or left (3 long-QT) Purkinje conducting system and were associated with variable Purkinje-to-muscle conduction times (30 to 110 ms). In the remaining 3 patients, premature beats originated from the right ventricular outflow tract, being 25 to 40 ms ahead of the QRS. The accuracy of mapping was confirmed by acute elimination of premature beats after 12±6 minutes of radiofrequency applications. During a follow-up of 17±17 months using ambulatory monitoring and defibrillator memory interrogation, no patients had recurrence of symptomatic ventricular arrhythmia but 1 had persistent premature beats. Conclusion— Triggers from the Purkinje arborization or the right ventricular outflow tract have a crucial role in initiating ventricular fibrillation associated with the long-QT and Brugada syndromes. These can be eliminated by focal radiofrequency ablation.
Publisher: Wiley
Date: 06-2018
DOI: 10.1002/CLC.22967
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.IJCARD.2018.10.068
Abstract: Due to barriers to accessing timely elective electrical cardioversion (CV) for persistent AF (PeAF), we adopted a policy of instructing patients to present directly to the Emergency Department (ED) for CV. We compare a strategy of Emergency CV (ED-CV) versus Elective CV (EL-CV) for treatment of symptomatic PeAF. Between 2014 and 7, we evaluated 150 patients undergoing CV for PeAF. ED-CV patients were provided an AF action plan for recurrent symptoms and advised to present to ED within 36 h. EL-CV patients followed standard care, including cardiologist referral and placement on an elective hospital waiting list. Follow-up was 12 months. We included 75 consecutive ED-CV patients and 75 consecutive EL-CV patients. ED-CV patients had a significantly shorter median AF duration prior to CV (1 day vs 3 months p < 0.01) and less overall AF-related symptoms at 12 months (modified EHRA symptom score ≥ 2a in 44% vs 72% p = 0.005). Time to next AF recurrence was longer in the ED-CV group (295 ± 15 vs 245 ± 15 days logrank p = 0.001), as was time to AF ablation referral (314 ± 13 vs 276 ± 15 days logrank p = 0.01). Baseline LA area was similar (ED-CV 27 ± 4 cm ED-CV is an acceptable strategy for symptomatic PeAF. In addition to reduced time spent in AF and improved symptom scores, this strategy may also slow progression of atrial substrate & delay onset of next AF episode.
Publisher: Wiley
Date: 04-2003
DOI: 10.1046/J.1540-8167.2003.02521.X
Abstract: We report the case of an accessory pathway in a left inferoposterior erticulum. The pathway masqueraded as a true left lateral pathway due to the direction of activation over a coronary sinus to left atrium connection. The patient had undergone four prior failed ablation attempts at other institutions using both a transseptal and retrograde approach.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-08-2005
DOI: 10.1161/CIRCULATIONAHA.104.517011
Abstract: Background— The identification of sites of dominant activation frequency during atrial fibrillation (AF) in humans and the effect of ablation at these sites have not been reported. Methods and Results— Thirty-two patients undergoing AF ablation (19 paroxysmal, 13 permanent) during ongoing arrhythmia were studied. Electroanatomic mapping was performed, acquiring 126±13 points per patient throughout both atria and coronary sinus. At each point, 5-second electrograms were obtained to determine the highest- litude frequency on spectral analysis and to construct 3D dominant frequency (DF) maps. The temporal stability of the recording interval was confirmed in a subset. Ablation was performed with the operator blinded to the DF maps. The effect of ablation at sites with or without high-frequency DF sites (maximal frequencies surrounded by a decreasing frequency gradient ≥20%) was evaluated by determining the change in AF cycle length (AFCL) and the termination and inducibility of AF. The spatial distribution of the DF sites was different in patients with paroxysmal and permanent AF paroxysmal AF patients were more likely to harbor the DF site within the pulmonary vein, whereas in permanent AF, atrial DF sites were more prevalent. Ablation at a DF site resulted in significant prolongation of the AFCL (180±30 to 198±40 ms P .0001 κ= 0.77), whereas in the absence of a DF site, there was no change in AFCL (169±22 to 170±22 ms P =0.4). AF terminated during ablation in 17 of 19 patients with paroxysmal and 0 of 13 with permanent AF ( P .0001). When 2 patients with nonsustained AF during mapping were excluded, 13 of 15 (87%) had AF termination at DF sites (54% at the initially ablated DF site): 11 pulmonary veins and 2 atrial. In addition, AF could no longer be induced in 69% with termination of AF at a DF site. There were no significant differences in the number or percentage of DF sites detected (5.4±1.6 versus 4.9±2.1 P =0.3) and ablated (1.9±1.0 versus 2.4±1.0 P =0.3) in those with and without AF termination. The duration of radiofrequency ablation to achieve termination was significantly shorter than that delivered in those with persisting AF (34.8±24.0 versus 73.5±22.9 minutes P =0.0002). All patients with persisting AF had additional DF sites outside the ablated zones. Conclusions— Spectral analysis and frequency mapping identify localized sites of high-frequency activity during AF in humans with different distributions in paroxysmal and permanent AF. Ablation at these sites results in prolongation of the AFCL and termination of paroxysmal AF, indicating their role in the maintenance of AF.
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.MEDENGPHY.2009.11.007
Abstract: In a chamber of the heart, large-scale vortices are shown to exist as the result of the dynamic blood flow and unique morphological changes of the chamber wall. As the cardiovascular flow varies over a cardiac cycle, there is a need for a robust quantification method to analyze its vorticity and circulation. We attempt to measure vortex characteristics by means of two-dimensional vorticity maps and vortex circulation. First, we develop vortex component analysis by segmenting the vortices using an data clustering algorithm before histograms of their vorticity distribution are generated. The next stage is to generate the statistics of the vorticity maps for each phase of the cardiac cycle to allow analysis of the flow. This is followed by evaluating the circulation of each segmented vortex. The proposed approach is dedicated to examining vortices within the human heart chamber. The vorticity field can indicate the strength and number of large-scale vortices in the chamber. We provide the results of the flow analysis after vorticity map segmentation and the statistical properties that characterize the vorticity components. The success of the cardiac measurement and analysis is illustrated by a case study of the right atrium. Our investigation shows that it is possible to utilize a data clustering algorithm to segment vortices after vorticity mapping, and that the vorticity and circulation analysis of a chamber vorticity can provide new insights into the blood flow within the cardiovascular structure.
Publisher: Elsevier BV
Date: 03-2015
Publisher: Oxford University Press (OUP)
Date: 16-12-2020
DOI: 10.1093/EURHEARTJ/EHAA893
Abstract: Our objective was to determine the ventricular arrhythmia burden in implantable cardioverter-defibrillator (ICD) patients during COVID-19. In this multicentre, observational, cohort study over a 100-day period during the COVID-19 pandemic in the USA, we assessed ventricular arrhythmias in ICD patients from 20 centres in 13 states, via remote monitoring. Comparison was via a 100-day control period (late 2019) and seasonal control period (early 2019). The primary outcome was the impact of COVID-19 on ventricular arrhythmia burden. The secondary outcome was correlation with COVID-19 incidence. During the COVID-19 period, 5963 ICD patients underwent remote monitoring, with 16 942 episodes of treated ventricular arrhythmias (2.8 events per 100 patient-days). Ventricular arrhythmia burden progressively declined during COVID-19 (P & 0.001). The proportion of patients with ventricular arrhythmias amongst the high COVID-19 incidence states was significantly reduced compared with those in low incidence states [odds ratio 0.61, 95% confidence interval (CI) 0.54–0.69, P & 0.001]. Comparing patients remotely monitored during both COVID-19 and control periods (n = 2458), significantly fewer ventricular arrhythmias occurred during COVID-19 [incident rate ratio (IRR) 0.68, 95% CI 0.58–0.79, P & 0.001]. This difference persisted when comparing the 1719 patients monitored during both the COVID-19 and seasonal control periods (IRR 0.69, 95% CI 0.56–0.85, P & 0.001). During COVID-19, there was a 32% reduction in ventricular arrhythmias needing device therapies, coinciding with measures of social isolation. There was a 39% reduction in the proportion of patients with ventricular arrhythmias in states with higher COVID-19 incidence. These findings highlight the potential role of real-life stressors in ventricular arrhythmia burden in in iduals with ICDs. Australian New Zealand Clinical Trial Registry URL: www.anzctr.org.au/ Unique Identifier: ACTRN12620000641998
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 12-2005
DOI: 10.1016/J.JACC.2005.08.044
Abstract: The goal of this study was to characterize the origin of focal atrial tachycardias (AT). Focal ATs originate from a small area and spread centrifugally however, activation at the AT origin has not been characterized. Twenty patients with AT having failed prior ablation or occurring after atrial fibrillation ablation were studied. After excluding macro-re-entry, AT was mapped using a 20-pole catheter (five radiating spines diameter 3.5 cm), performing vector mapping to identify the earliest activity followed by high-density mapping at the AT origin. Localized re-entry was considered if >85% of the tachycardia cycle length (CL) was observed within the mapping field and was confirmed by entrainment. A total of 27 ATs were mapped to the pulmonary vein ostia (n = 5), and left (n = 16) and right atria (n = 6). A localized focus was evidenced at the site of origin in 19 ATs (70%), whereas in 8 (30%), localized re-entry was evidenced by 95.2 +/- 4.5% of the tachycardia CL recorded within the mapping field and entrainment showed a post-pacing interval <20 ms longer than tachycardia CL (6 of 6 tested). Localized re-entry had a shorter CL (p = 0.009), slowed conduction at its origin (fractionated potential 115 +/- 19 ms vs. 64 +/- 22 ms, representing 49 +/- 10% and 20 +/- 10% of tachycardia CL, respectively p < 0.0001), and were more often contiguous with regions of electrical silence or conduction abnormalities (88% vs. 32% p = 0.01). In addition, mapping documented varying degrees of intra-atrial conduction block, preferential conduction (n = 5), and rapid bursts of myocardial activity (n = 1). At 11 +/- 7 months, none have had recurrence of AT. High-density multielectrode mapping can be used to perform vector mapping to localize complex AT. It provides novel insight into the mechanisms of focal AT, distinguishing focal AT from localized re-entry.
Publisher: Elsevier BV
Date: 09-2012
DOI: 10.1016/J.HRTHM.2012.03.062
Abstract: Atrial premature contractions (APCs) are well described to precede the initiation of paroxysmal atrial fibrillation (pAF). However, whether APC characteristics alter with progression of the arrhythmia is unknown. To determine the APC characteristics in terms of burden and relative coupling interval with progression of the AF disease process. Fifty consecutive patients with pAF, 50 consecutive patients with persistent AF (perAF), and 25 age-matched controls underwent clinical review, transthoracic echocardiography, and ambulatory electrocardiogram monitoring. After excluding 29 patients who had AF for the entire recording (n = 24) or unreliable recordings (n = 5), we analyzed data from 49 patients with pAF, 24 patients with perAF, and 23 healthy controls. All normal morphology R-R intervals with a >25% decrease in R-R coupling compared with the previous R-R interval (coupling interval index) were deemed APCs (n = 95,873). The median APC burden was higher in patients with pAF (2 [1-22] APCs/h P = .004) and perAF (3 [1-6] APCs/h P = .04) than in controls (1 [0-1] APCs/h) but was not different (P = .66) between the AF subgroups. Patients with pAF had a distinct increase in ectopy burden after 7 PM and elevation throughout the night (P = .002) in comparison with a blunted and complementary temporal response in the perAF cohort (P = .01). Patients with pAF demonstrated a greater proportion of shortly coupled APCs (29% [13-45] P = .04) compared with persistent arrhythmia (17% [5-29]). "Real-life" atrial trigger statistics of APC burden, timing, and diurnal rhythms track the transition from a trigger-based, autonomically sensitive paroxysmal arrhythmia to a more substrate-based persistent disease.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.HRTHM.2010.05.010
Abstract: Hypertension accounts for more atrial fibrillation (AF) than any other predisposing factor. The purpose of this study was to characterize the time course, extent, and electrostructural correlation of atrial remodeling in chronic hypertension. Thirty-two sheep were studied: 21 with induced "one-kidney, one-clip" hypertension and 11 controls. Sequential closed-chest electrophysiologic studies were performed in 12 conscious animals (6 hypertensive, 6 controls) to evaluate progressive remodeling over 15 weeks. Additional atrial structural/functional analyses were performed in 5 controls and at 5, 10, and 15 weeks of hypertension (five per time point) via histology/cardiac magnetic resonance imaging to correlate with open-chest electrophysiologic parameters. The hypertensive group developed a progressive increase in mean arterial pressure (P <.001). Mean effective refractory periods were uniformly higher at all time points (P <.001). Progressive biatrial hypertrophy (P = .003), left atrial dysfunction (P <.05) and greater AF inducibility were seen early with increased inflammation from 5 weeks of hypertension. In contrast, significant conduction slowing (P <.001) with increased heterogeneity (P <.001) along with increased interstitial fibrosis resulted in longer and more fractionated AF episodes only from 10 weeks of hypertension. Significant electrostructural correlation was seen in conduction abnormalities and AF inducibility with both atrial inflammation and fibrosis. Hypertension is associated with early and progressive changes in atrial remodeling. Atrial remodeling occurs at different time domains in chronic hypertension with significant electrostructural correlation of the remodeling cascade. Early institution of antihypertensive treatment may prevent formation of substrate capable of maintaining AF.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2021
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2020
Publisher: American Thoracic Society
Date: 10-2013
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.JACC.2017.09.002
Abstract: Both obesity and atrial fibrillation (AF) are increasing in epidemic proportions, and both increase the prevalence of cardiovascular disease events. Obesity has adverse effects on cardiovascular hemodynamics and cardiac structure and function, and increases the prevalence of AF, partly related to electroanatomic remodeling in obese patients. However, numerous studies, including in AF, have demonstrated an obesity paradox, where overweight and obese patients with these disorders have a better prognosis than do leaner patients with the same degree of severity of cardiovascular disease/AF. In this paper, the authors discuss special issues regarding AF in obesity, as well as the evidence that despite the presence of an obesity paradox, there are benefits of weight loss, physical activity/exercise training, and increases in cardiorespiratory fitness on the prognosis of obese patients with AF.
Publisher: Oxford University Press (OUP)
Date: 17-02-2021
Abstract: There are conflicting data as to the impact of procedural volume on outcomes with specific reference to the incidence of major complications after catheter ablation for atrial fibrillation. Questions regarding minimum volume requirements and whether these should be per centre or per operator remain unclear. Studies have reported ergent results. We performed a systematic review and meta-analysis of studies reporting the relationship between either operator or hospital atrial fibrillation (AF) ablation volumes and incidence of complications. Databases were searched for studies describing the relationship between operator or hospital AF ablation volumes and incidence of complications which were published prior to 12 June 2020. Of 1593 articles identified, 14 (315 120 patients) were included in the meta-analysis. Almost two-thirds of the procedures were performed in low-volume centres. Both hospital volume of ≥50 and ≥100 procedures/year were associated with a significantly lower incidence of complications compared to & /year (4.2% vs. 5.5%, OR = 0.58, 95% CI 0.50–0.66, P & 0.001) or & /year (5.5% vs. 6.2%, OR = 0.62, 95% CI 0.53–0.73, P & 0.001), respectively. Hospitals performing ≥50 procedures/year demonstrated significantly lower mortality compared with those performing & procedures/year (0.16% vs. 0.55%, OR = 0.33, 95% CI 0.26–0.43, P & 0.001). A similar relationship existed between proceduralist volume of & /year and incidence of complications [3.75% vs. 12.73%, P & 0.001 OR = 0.27 (0.23–0.32)]. There is an inverse relationship between both hospital and proceduralist AF ablation volume and the incidence of complications. Implementation of minimum hospital and operator AF ablation volume standards should be considered in the context of a broader strategy to identify AF ablation Centers of Excellence.
Publisher: Wiley
Date: 14-05-2020
DOI: 10.1111/EVJ.13265
Publisher: Elsevier BV
Date: 12-2000
DOI: 10.1016/S0002-9149(00)01219-4
Abstract: The efficacy of intravenous magnesium in terminating sustained monomorphic ventricular tachycardia was examined in this study. This therapy was found to be ineffective in aborting monomorphic ventricular tachycardia induced in the electrophysiology laboratory.
Publisher: Elsevier BV
Date: 03-2022
DOI: 10.1016/J.CJCA.2021.10.012
Abstract: Chronological aging is one of the major risk factors of cardiovascular (CV) disease (CVD) however, the effect of biological aging on CVD and outcomes remain poorly understood. Herein, we evaluated the association between leukocyte telomere length (LTL), a marker of biological age, and CV outcomes. We searched PubMed, Embase, Ovid Medline, and Web of Science Core Collection for the studies on the association between LTL and myocardial infarction (MI), CV death, and/or CVD risk factors from inception to July 2020. Extracted data were pooled in a random-effects meta-analysis and summarized as risk ratio (RR) and corresponding 95% confidence interval (CI) per LTL tertile. A total of 32 studies (n = 144,610 participants) were included. In a pooled analysis of MI and LTL in a multivariate-adjusted model, the shortest LTL was associated with a 39% higher risk of MI (RR, 1.39 95% CI, 1.16-1.67 P < 0.001). After adjusting for chronological age and traditional covariance, we showed a 28% increased risk of CV death in the shortest tertile of LTL (RR, 1.28 95% CI, 1.05-1.56 P = 0.01). Analysis of the studies that investigated the association between CV risk factors and LTL (n = 7) showed that diabetes mellitus is associated with a 46% increased risk of LTL attrition (RR, 1.46 95% CI, 1.46-2.09 P = 0.039). This study shows a strong association between LTL, a marker of biological aging, and the risk of MI and CV death. Cardiometabolic risk factors contribute to telomere attrition and therefore accelerates biological aging.
Publisher: Oxford University Press (OUP)
Date: 28-06-2011
Abstract: Mapping of atrial fibrillation (AF) involves identification of low-voltage regions associated with complex fractionated electrograms (CFE) which theoretically represent abnormal substrate and targets for ablation. Whether low-voltage CFE areas also identify abnormal substrate during paced rhythm is unknown. Twelve patients with persistent AF undergoing ablation of AF had high-density three-dimensional electroanatomic maps created during AF and paced rhythm (24 maps) and the mean voltage during AF and paced rhythm was compared for eight segments of the left atrium (LA). The following were correlated during AF and paced rhythm: regional mean voltage %low voltage (defined as <0.5 mV) and extent of CFE. In addition, the relationship between the extent of CFE in AF: (i) %low voltage and (ii) conduction during paced rhythm were determined. Mean voltage was lower during AF than paced rhythm for all regions and globally (0.7 ± 0.2 mV vs. 2.1 ± 0.6 mV, P < 0.001). The regional and overall %low voltage of the LA was greater during AF than paced rhythm (53 ± 19% vs. 9 ± 2%, P < 0.001). There was no correlation between mean voltage or %low voltage during AF and paced rhythm. Complex fractionated electrograms were prevalent throughout all regions during AF, but did not correlate with %low voltage, fractionation, or slowed conduction during paced rhythm. Areas of CFE and low voltage recorded during AF frequently demonstrate normal atrial myocardial characteristics (normal conduction, electrograms, and voltage) during sinus rhythm. Therefore, AF CFE sites do not necessarily identify regions of an abnormal atrial substrate. However, this does not exclude the possibility that CFE might identify a focal driver or source occurring in a region of normal atrial myocardium.
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.IJCARD.2018.11.091
Abstract: Atrial fibrillation is the most common sustained arrhythmia and is associated with significant morbidity and mortality. The autonomic nervous system has a significant role in the milieu predisposing to the triggers, perpetuators and substrate for atrial fibrillation. It has direct electrophysiological effects and causes alterations in atrial structure. In a significant portion of patients with atrial fibrillation, the autonomic nervous system activity is likely a composite of reflex excitation due to atrial fibrillation itself and contribution of concomitant risk factors such as hypertension, obesity and sleep-disordered breathing. We review the role of autonomic nervous system activation, with focus on changes in reflex control during atrial fibrillation and the role of combined sympatho-vagal activation for atrial fibrillation initiation, maintenance and progression. Finally, we discuss the potential impact of combined aggressive risk factor management as a strategy to modify the autonomic nervous system in patients with atrial fibrillation and to reverse the arrhythmogenic substrate.
Publisher: Public Library of Science (PLoS)
Date: 03-01-2023
Publisher: Wiley
Date: 28-10-2012
DOI: 10.1111/J.1540-8167.2011.02203.X
Abstract: We aimed to characterize electrophysiological properties of pulmonary veins (PVs) in patients with Wolff-Parkinson-White (WPW) syndrome and atrial fibrillation (AF), and to compare them to those in patients with WPW without AF. A total of 31 patients (mean age 40 ± 15 years, 23 males) with WPW were recruited: 16 patients with (AF group) and 15 without (controls) a history of AF. The basic electrophysiological (EPS) and echocardiographic data were not different between the 2 groups. Effective refractory periods (ERPs) of PVs were significantly shorter in the AF group compared to controls: left superior (LS) PV ERP 185±29 versus 230 ± 24 ms, P = 0.001 left inferior PV ERP 198 ± 25 versus 219 ± 26 ms, P = 0.04 right superior (RS) PV ERP 207 ± 25 versus 236 ± 19 ms, P = 0.001 right inferior PV ERP 208 ± 30 versus 240 ± 19 ms, P = 0.003. Maximal veno-atrial conduction delay (i.e., the maximal prolongation of interval from stimulus delivered at PV ostia to proximal coronary sinus after extrastimulus compared to the basic drive cycle) was longer in the AF group when pacing from LSPV (69.3 ± 37.9 vs 32.6 ± 16.1 ms, P = 0.01) and RSPV (74.1 ± 25.9 vs 50.2 ± 26.5 ms, P = 0.04). During EPS, AF was induced more often in the AF group (n = 7) compared to controls (n = 1 P = 0.04). Follow-up revealed that AF recurred in 3 patients in the AF group and none of the controls. Patients with WPW syndrome and AF have shorter ERPs of PVs and greater maximal veno-atrial conduction delay compared to patients with WPW without AF. These findings suggest a potential role of PVs in the development of AF in patients with WPW.
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.HLC.2018.09.005
Abstract: Ventricular fibrillation (VF) is a common and life-threatening arrhythmia resulting in sudden cardiac death (SCD). Due to the inherent challenges of mapping VF in humans, the underlying mechanisms that initiate and sustain this common arrhythmia are still poorly understood. In high-risk patients and survivors of SCD, implantable cardioverter defibrillators (ICD) play a central role in treating VF episodes, however, ICDs do not prevent VF recurrences and patients remain at risk of electrical storm and multiple shocks that are often refractory to escalation of medical therapy. More recently, the utility of catheter ablation (CA) has extended to the treatment of VF storms. This review will focus on updates in elucidating the mechanism of VF leading into the role and indication of CA as a treatment strategy.
Publisher: Elsevier BV
Date: 03-2006
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 24-02-2004
DOI: 10.1161/01.CIR.0000116753.56467.BC
Abstract: Background— The left superior vena cava (LSVC) is the embryological precursor of the ligament of Marshall, which has been implicated in the initiation and maintenance of atrial fibrillation (AF). Rarely, the LSVC may persist and has been associated with some organized arrhythmias, though not with AF. We report 5 patients in whom the LSVC was a source of ectopy, initiating AF. Methods and Results— In 5 patients (4 men age, 46±11 years) with symptomatic drug-refractory AF, ectopy from the LSVC resulting in AF was observed after pulmonary vein isolation. The ectopics were spontaneous in 2 and induced by isoproterenol in the others and preceded P-wave onset by 67±13 ms. During multielectrode or electroanatomic mapping, venous potentials were recorded circumferentially at the proximal LSVC near its junction with the coronary sinus (CS), but at the mid-LSVC level, they were recorded only on part of the circumference. The LSVC was electrically connected to the lateral left atrium (LA) and through the CS to the right atrium, with 4.1±2.3 CS-LSVC and 1.6±0.5 LA-LSVC connections per patient. Catheter ablation in the LSVC targeting these connections resulted in electrical isolation in 4 of the 5 patients without complications. After 15±10 months, the 4 patients with successful isolation, including 1 who had successful reablation for LA flutter, remained in sinus rhythm without drugs. Conclusions— The LSVC can be the arrhythmogenic source of AF with connections to the CS and LA. Ablation of these connections resulted in electrical isolation.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2012
DOI: 10.1161/CIRCEP.112.974436
Abstract: Magnetic resonance imaging (MRI)–guided interventional electrophysiology (EP) has rapidly emerged as a promising alternative to x-ray–guided ablation. We aimed to evaluate an externally irrigated MRI-compatible ablation catheter and integrated EP pacing and recording system, testing the feasibility of pulmonary vein and cavo-tricuspid isthmus ablation. Externally irrigated MRI-compatible ablation and diagnostic EP catheters and an integrated EP recording system (Imricor Medical Systems, Burnsville, MN) were tested in n=11 sheep in a 1.5-T MRI scanner. Power-controlled (40 W, 120-second duration) lesions were formed at the pulmonary vein and cavo-tricuspid isthmus. Real-time intracardiac electrograms were recorded during MRI. Steady-state free precession non–breath-hold images were repeatedly acquired to guide catheter navigation. Lesion visualization was performed using noncontrast (T2-weighted turbo spin echo pulse sequence) and gadolinium-diethylene triamine pentaacetic acid–enhanced T1-weighted imaging (inversion-recovery gradient echo pulse sequence). Catheters were able to be visualized and navigated under cardiovascular magnetic resonance guidance. In total, 8±2.5 lesions (radiofrequency time, 16±4.2 minutes) were formed at the pulmonary vein ostia, and 6.5±1.3 lesions (radiofrequency time, 13±2.2 minutes) were formed at the cavo-tricuspid isthmus, with the end point of bidirectional block. The mean procedure time was 150±55 minutes. Lesion visualization with both T2W imaging and contrast-enhanced imaging correlated with sites of injury at autopsy. These data demonstrate the feasibility of using multiple catheters, an integrated EP pacing and recording system, and externally irrigated ablation with cardiovascular magnetic resonance guidance to undertake clinically relevant biatrial mapping and ablation.
Publisher: Oxford University Press (OUP)
Date: 05-12-2018
Publisher: Oxford University Press (OUP)
Date: 10-2021
Abstract: The prevalence of atrial fibrillation (AF) is increasing rapidly with the growing utilization of catheter ablation (CA) as a treatment strategy. Education for in iduals undertaking this procedure is erse, with varying degrees of information provided and little standardization. Many in iduals utilize the internet as an educational resource. However, there is limited regulation of online patient information. To evaluate the quality of web-based patient education resources for patients undergoing CA for AF. A cross-sectional observational study was performed to obtain all freely accessible online educational resources about CA for AF from inception until 1 October 2019. Search engines used: Google, Yahoo!, and Bing. The Patient Education Materials Assessment Tool (PEMAT) was used to evaluate the quality of web-based patient education materials and printable tools. The PEMAT score objectively measures both the understandability and actionability of educational material. A total of 17 websites and 15 printable sources were included in the analysis. Non-government organizations developed 19% of materials and 75% were created by private or university hospitals. Nineteen sources (59.4%) were rated as highly understandable: 9 websites (52.9%) and 10 printable tools (66.7%). Seven sources (21.9%) were rated as highly actionable: 6 (35.3%) websites and 1 (6.7%) printable tool. The overall understandability of educational CA material was high, whilst improvement of actionability is warranted. The addition of summaries, visual aids, and tools, such as checklists may improve quality. These findings have significant implications for the development of patient educational material for CA in AF.
Publisher: Wiley
Date: 28-10-2004
DOI: 10.1046/J.1540-8167.2004.04388.X
Abstract: Ventricular fibrillation (VF) is the main mechanism of sudden cardiac death. The clinical precipitants of sudden cardiac death due to idiopathic VF are poorly characterized. Emerging evidence implicates triggers originating predominantly from the distal Purkinje arborization and the right ventricular outflow tract. We report three patients without structural heart disease or repolarization abnormalities in whom a febrile illness was the only concurrent disease associated with unexpected sudden cardiac death due to VF storm. An automated defibrillator was implanted in all three patients. In one patient with persistent recurrent VF episodes, mapping demonstrated the origin of these triggers was from the Purkinje arborization of the anterior wall of the right ventricle. Ablation at a site of earliest activation during ectopy, where pace mapping was concordant and Purkinje potential preceded the onset of ventriculogram, resulted in suppression of all arrhythmias. After follow-up of 22, 9, and 18 months in the three patients, no ventricular arrhythmias have been recorded. We present a series of patients in whom an apparently benign febrile illness was associated with malignant ventricular arrhythmias in the absence of cardiac disease or other factors known to precipitate sudden cardiac death. Physicians should be aware of this possible phenomenon in cases of febrile illness associated with syncope.
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.IJCARD.2013.03.130
Abstract: Carto-Sound integrates 2D intra-cardiac ultrasound imaging into a 3D environment to allow left atrial mapping from the right atrium without fluoroscopic assistance. We conducted an open randomized controlled study to compare procedural, clinical and accuracy parameters between CT integrated Carto-Sound and electro-anatomic mapping (EAM) for AF ablation. Sixty index AF ablation patients were randomized equally to either the Carto-Sound or EAM mapping/navigation for their procedure performed at a single institution. Procedure and X-ray times, X-ray dose, navigational accuracy and clinical success were assessed. The study was powered to the primary outcome of fluoroscopy time. Total procedure (232 ± 60 vs 223 ± 48 min p = 0.51), ablation (p = 0.84) and mapping times (p = 0.11) were similar in each group. In contrast, Carto-Sound reduced total X-ray time (65 ± 18 vs 51 ± 12 min p = 0.001), via a reduction in both mapping (p 0.17) compared to EAM. Ultra-sound assisted 3D mapping did not improve single procedure drug free clinical success (EAM: 13/30 [43%] vs Carto-Sound: 15/30 [50%]) at a mean of 13 ± 5 months (p = 0.79). In the context of long left atrial procedures with high radiation doses, reduced X-ray and left atrial access times using CT integrated Carto-Sound mapping/navigation may have implications for patients and laboratory staff, albeit at an extra financial cost and the requirement of an additional access site for a right sided catheter. ACTRN12612000089831.
Publisher: Oxford University Press (OUP)
Date: 07-04-2006
Abstract: Elevated blood pressure (EBP) is the most prevalent and potentially modifiable risk factor for AF, yet little is known of its atrial effects. We aimed to characterize the atrial electrical and structural changes in a chronic ovine model of EBP after prenatal corticosteroid exposure. Twelve sheep with chronically EBP (mean arterial pressure 94+/-3 mmHg) and six controls (71+/-4 mmHg, P<0.01) underwent acute open chest electrophysiologic and pathologic studies. We measured refractoriness at the atrial appendages at 3 cycle lengths (CL) conduction velocities at Bachmann's bundle, both atrial appendages and free walls at 4 CLs conduction heterogeneity atrial wavelength and AF duration. We performed light microscopy (LM) and electron microscopy (EM) and collagen and apoptosis studies. EBP was associated with widespread conduction abnormalities, shortening of atrial wavelength, and increased AF. There was no significant change in refractoriness. LM demonstrated atrial myocyte hypertrophy and myolysis in all EBP sheep and focal scarring in six. EM demonstrated mitochondrial and nuclear enlargement and increased collagen fibrils in EBP sheep, findings not present in any controls. Atrial collagen and apoptosis were increased in EBP animals. This study demonstrates that chronically, EBP is associated with significant atrial electrical and structural remodelling. These changes may explain the increased propensity to atrial arrhythmias observed with long-standing EBP.
Publisher: Elsevier BV
Date: 11-2016
DOI: 10.1016/J.IJCARD.2016.08.113
Abstract: Insertable cardiac monitors (ICMs) are increasingly utilized for diagnosis of unexplained syncope and arrhythmia monitoring. The Reveal LINQ is a novel miniaturized ICM with improved algorithms. The feasibility and safety of insertion outside the traditional electrophysiology laboratory is unknown. Here we compare outcomes of Reveal LINQ insertion in different environments. We report on a prospective, single-centre, non-randomized, observational experience of consecutive Reveal LINQ implantation in the electrophysiology laboratory or a procedure room between October 2013 and October 2015. Of 178 consecutive patients who underwent LINQ device insertion, 80 were implanted in the electrophysiology laboratory and 98 in a procedure room. There were no significant differences in baseline patient characteristics. All implants were performed in the recommended manufacturer method with the exception of 1 which required suture closure. Only a minority received peri-procedural antibiotics with a greater number in the electrophysiology laboratory group (11 [14%] versus 1 [1%], p=0.007). Overall, there were 3 (1.7%) complications with no significant difference between the electrophysiology laboratory and the procedure room groups (2 [3%] versus 1 [1%], p=0.45). There was 1 superficial infection in the procedure room group and 1 superficial infection with device extrusion and 1 traumatic extrusion in the electrophysiology laboratory group. Procedure room implantation subjectively improved laboratory efficiency and patient flow. Reveal LINQ insertion can be safely performed outside of the cardiac laboratory provided a sterile technique is followed by the operator using manufacturer recommendations for insertion. These findings have significant resource implications for hospitals undertaking such procedures.
Publisher: Springer Science and Business Media LLC
Date: 27-03-2012
DOI: 10.1007/S00330-012-2417-2
Abstract: To investigate whether grid-tag myocardial strain evaluation can characterise 'border-zone' peri-infarct region and identify patients at risk of ventricular arrhythmia as the peri-infarct myocardial zone may represent an important contributor to ventricular arrhythmia following ST-segment elevation myocardial infarction (STEMI). Forty-five patients with STEMI underwent cardiac magnetic resonance (CMR) imaging on days 3 and 90 following primary percutaneous coronary intervention (PCI). Circumferential peak circumferential systolic strain (CS) and strain rate (CSR) were calculated from grid-tagged images. Myocardial segments were classified into 'infarct', 'border-zone', 'adjacent' and 'remote' regions by late-gadolinium enhancement distribution. The relationship between CS and CSR and these distinct myocardial regions was assessed. Ambulatory Holter monitoring was performed 14 days post myocardial infarction (MI) to estimate ventricular arrhythmia risk via evaluation of heart-rate variability (HRV). We analysed 1,222 myocardial segments. Remote and adjacent regions had near-normal parameters of CS and CSR. Border-zone regions had intermediate CS (-9.0 ± 4.6 vs -5.9 ± 7.4, P < 0.001) and CSR (-86.4 ± 33.3 vs -73.5 ± 51.4, P < 0.001) severity compared with infarct regions. Patients with 'border-zone' peri-infarct regions had reduced very-low-frequency power on HRV analysis, which is a surrogate for ventricular arrhythmia risk (P = 0.03). Grid-tagged CMR-derived myocardial strain accurately characterises the mechanical characteristics of 'border-zone' peri-infarct region. Presence of 'border-zone' peri-infarct region correlated with a surrogate marker of heightened arrhythmia risk following STEMI. • Grid-tagged cardiac magnetic resonance (CMR) offers new insights into myocardial mechanical function. • Grid-tagged CMR identified different characteristics in 'border-zone' and 'adjacent' peri-infarct myocardial regions. • Reduced very-low-frequency (VLF) power is associated with arrhythmic and mortality risk. • The presence of 'border-zone' peri-infarct region correlated with reduced VLF power.
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 03-2018
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.HRTHM.2009.11.031
Abstract: Hypertension is frequently complicated by the development of atrial fibrillation (AF). However, the mechanisms of this link remain poorly understood. In addition, whether short-term hypertension can result in a substrate for AF is not known. The purpose of this study was to characterize the atrial substrate predisposing to AF due to short-duration hypertension. Sixteen sheep were studied: 10 had induced hypertension for 7 +/- 4 weeks via the "one-kidney, one-clip" model, and six were controls. Cardiac magnetic resonance imaging was used to assess functional changes. Open-chest electrophysiological study was performed using a custom-made 128-electrode epicardial plaque applied to both right (RA) and left atria (LA), including the Bachmann's bundle, to determine effective refractory periods (ERPs) and conduction velocity at four pacing cycle lengths from six sites. Tissue specimens were harvested for structural analysis. The hypertensive group demonstrated the following compared with controls: higher blood pressure (P <.0001), enlarged LA (P <.05), reduced LA ejection fraction (P <.05), uniformly higher mean ERP (P <.001), slower mean conduction velocity (P <.001), higher conduction heterogeneity index (P <.0001), greater AF inducibility (P = .03), and increased AF durations (P = .04). Picrosirius red staining of atrial tissues revealed increased interstitial fibrosis (P <.0001). There was also evidence of increased inflammatory cell infiltrates (P <.0001). Short-duration hypertension is associated with significant atrial remodeling characterized by atrial enlargement/dysfunction, interstitial fibrosis, inflammation, slowed/heterogeneous conduction, increased ERP, and greater propensity for AF.
Publisher: Springer Science and Business Media LLC
Date: 05-05-2009
Abstract: Pericardial adipose tissue (PAT) has been shown to be an independent predictor of coronary artery disease. To date its assessment has been restricted to the use of surrogate echocardiographic indices such as measurement of epicardial fat thickness over the right ventricular free wall, which have limitations. Cardiovascular magnetic resonance (CMR) offers the potential to non-invasively assess total PAT, however like other imaging modalities, CMR has not yet been validated for this purpose. Thus, we sought to describe a novel technique for assessing total PAT with validation in an ovine model. 11 merino sheep were studied. A standard clinical series of ventricular short axis CMR images (1.5T Siemens Sonata) were obtained during mechanical ventilation breath-holds. Beginning at the mitral annulus, consecutive end-diastolic ventricular images were used to determine the area and volume of epicardial, paracardial and pericardial adipose tissue. In addition adipose thickness was measured at the right ventricular free wall. Following euthanasia, the paracardial adipose tissue was removed from the ventricle and weighed to allow comparison with corresponding CMR measurements. There was a strong correlation between CMR-derived paracardial adipose tissue volume and ex vivo paracardial mass (R 2 = 0.89, p 0.001). In contrast, CMR measurements of corresponding RV free wall paracardial adipose thickness did not correlate with ex vivo paracardial mass (R 2 = 0.003, p = 0.878). In this ovine model, CMR-derived paracardial adipose tissue volume, but not the corresponding and conventional measure of paracardial adipose thickness over the RV free wall, accurately reflected paracardial adipose tissue mass. This study validates for the first time, the use of clinically utilised CMR sequences for the accurate and reproducible assessment of pericardial adiposity. Furthermore this non-invasive modality does not use ionising radiation and therefore is ideally suited for future studies of PAT and its role in cardiovascular risk prediction and disease in clinical practice.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 21-12-2004
DOI: 10.1161/01.CIR.0000150336.86033.8D
Abstract: Background— Although dual-chamber pacing improves cardiac function in patients with complete congenital atrioventricular block (CCAVB) by restoring physiological heart rate and atrioventricular synchronization, the long-term detrimental effect of asynchronous electromechanical activation induced by apical right ventricular pacing (RVP) has not been well clarified. Methods and Results— Twenty-three CCAVB adults (24±3 years) with a DDD transvenous pacemaker underwent conventional echocardiography before implantation and, after at least 5 years of RVP, an exercise test and echocardiography coupled with tissue Doppler imaging and tissue tracking. They were compared with 30 matched healthy control subjects. After 10±3 years of RVP, CCAVB adults had significantly higher values versus controls in terms of intra-left ventricular (LV) asynchrony (respectively, 59±18 versus 19±9 ms, P .001), extent of LV myocardium displaying delayed longitudinal contraction (39±15% versus 10±7%, P .01), and septal-to-posterior wall-motion delay (84±26 versus 18±9 ms, P .01). The ratio of late-activated posterior to early-activated septal wall thickness was higher after long-term RVP than before (1.3±0.2 vs 1±0.1, P =0.05) and was higher than in controls (1±0.1, P .05). The percentage of patients with increased LV end-diastolic diameter was higher after long-term RVP than before implantation and was higher than in controls (57% versus 13%, P .05, and 57% versus 0%, P .01, respectively). CCAVB patients with long-term RVP had a lower cardiac output than controls (3.8±0.6 versus 4.9±0.8 L/min, P .05) and lower exercise performance (123±24 versus 185±39 W, P .001). Conclusions— Prolonged ventricular dyssynchrony induced by long-term endovenous RVP is associated with deleterious LV remodeling, LV dilatation, LV asymmetrical hypertrophy, and low exercise capacity. These new data highlight the importance of the ventricular activation sequence in all patients with chronic ventricular pacing.
Publisher: Elsevier BV
Date: 09-2018
Publisher: American College of Physicians
Date: 21-01-2020
DOI: 10.7326/L19-0708
Publisher: Massachusetts Medical Society
Date: 16-12-2010
Publisher: BMJ
Date: 07-11-2022
DOI: 10.1136/HEARTJNL-2022-321393
Abstract: Prior data have shown rising acute myocardial infarction (MI) trends in Australia whether these increases have continued in recent years is not known. This study thus sought to characterise contemporary nationwide trends in MI hospitalisations and coronary procedures in Australia and their associated economic burden. The primary outcome measure was the incidence and time trends of total MI, ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) hospitalisations from 1993 to 2017. The incidence and time trends of coronary procedures were additionally collected, alongside MI hospitalisation costs. Adjusted for population changes, annual MI incidence increased from 216.2 cases per 100 000 to a peak of 270.4 in 2007 with subsequent decline to 218.7 in 2017. Similarly, NSTEMI incidence increased from 68.0 cases per 100 000 in 1993 to a peak of 192.6 in 2007 with subsequent decline to 162.6 in 2017. STEMI incidence decreased from 148.3 cases per 100 000 in 1993 to 56.2 in 2017. Across the study period, there were annual increases in MI hospitalisations of 0.7% and NSTEMI hospitalisations of 5.6%, and an annual decrease in STEMI hospitalisations of 4.8%. Angiography and percutaneous coronary intervention increased by 3.4% and 3.3% annually, respectively, while coronary artery bypass graft surgery declined by 2.2% annually. MI hospitalisation costs increased by 100% over the study period, despite a decreased average length of stay by 45%. The rising incidence of MI hospitalisations appear to have stabilised in Australia. Despite this, associated healthcare expenditure remains significant, suggesting a need for continual implementation of public health policies and preventative strategies.
Publisher: Oxford University Press (OUP)
Date: 06-01-2005
Abstract: Anatomical and wide atrial encircling of the pulmonary veins (PVs) has been proposed as a cure of atrial fibrillation (AF). We evaluated the acute achievement of electrical PV isolation using this approach. In addition, the consequences of wide encircling of the PVs with isolation were assessed. Twenty patients with paroxysmal AF were studied. Anatomically guided ablation was performed utilizing the CARTO system to deliver coalescent lesions circumferentially around each PV to produce a voltage reduction to <0.1 mV, with the operator blinded to recordings of circumferential PV mapping. After achieving the anatomical endpoint, the incidence of residual conduction and the litude and conduction delay of residual PV potentials were determined. Electrical isolation of the PV was then performed and the residual far-field potentials evaluated. In idual PV ablation was performed in all PVs. Anatomically guided PV ablation was performed for 47.3+/-11 min, after which 44 (55%) PVs were electrically isolated. In the remaining 45%, despite abolition of the local potential at the ablation site, PV potentials [ litude 0.2 mV (range 0.09-0.75) and delay of 50.3+/-12.6 ms] were identified by circumferential mapping. After electrical isolation (12.2+/-11.7 min ablation), 55 (69%) PVs demonstrated far-field potentials with a greater incidence (P=0.015) and litude (P=0.021) on the left compared with the right PVs. At 13.2+/-8.3 months follow-up, 13 patients (65%) remained arrhythmia-free without anti-arrhythmics. In four patients (20%), spontaneous sustained left atrial macrore-entry required re-mapping and ablation. Macrore-entry was observed to utilize regions around or bordering the previous ablation as its substrate. Anatomically guided circumferential PV ablation results in apparently coalescent but electrically incomplete lesions with residual conduction in 45% of PVs. Wide encircling of the PVs was associated with left atrial macrore-entry in 20% of patients.
Publisher: Oxford University Press (OUP)
Date: 28-04-2015
Abstract: Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation of atrial fibrillation (AF). The intervenous ridge (IVR) may be incorporated into ablation strategies to achieve PVI however, randomized trials are lacking. We performed a randomized multi-centre international study to compare the outcomes of (i) circumferential antral PVI (CPVI) alone (minimal) vs. (ii) CPVI with IVR ablation to achieve in idual PVI (maximal). Two hundred and thirty-four patients with paroxysmal AF underwent CPVI and were randomized to a minimal or maximal ablation strategy. The primary outcome of recurrent atrial arrhythmia was assessed with 7-day Holter monitoring at 6 and 12 months. PVI was achieved in all patients. Radiofrequency ablation time was longer in the maximal group (46.6 ± 14.6 vs. 41.5 ± 13.1 min P < 0.01), with no significant differences in procedural or fluoroscopy times. At mean follow-up of 17 ± 8 months, there was no difference in freedom from AF after a single procedure between a minimal (70%) and maximal ablation strategy (62% P = 0.25). In the minimal group, ablation was required on the IVR to achieve electrical isolation in 44%, and was associated with a significant reduction in freedom from AF (57%) compared with the minimal group without IVR ablation (80% P < 0.01). There was no statistically significant difference in freedom from AF between a minimal and maximal ablation strategy. Despite attempts to achieve PVI with antral ablation, IVR ablation is commonly required. Patients in whom antral isolation can be achieved without IVR ablation have higher long-term freedom from AF (the Minimax study ACTRN12610000863033).
Publisher: Elsevier BV
Date: 09-2017
Publisher: Elsevier BV
Date: 04-2020
Publisher: Informa UK Limited
Date: 2010
DOI: 10.3109/08037050903576767
Abstract: The aim of this study is to characterize cardiac remodeling in a large animal model of hypertension. 23 sheep were subjected to unilateral nephrectomy followed by cl ing of the remaining renal artery to 60% ("one kidney-one clip", 1K1C) 3 weeks later. Blood pressure (BP) was monitored invasively over 73+/-28 days. Cardiac function was assessed with magnetic resonance imaging and compared with 12 size-matched controls. Detailed atrial histopathological analysis was performed. In the 1K1C animals, BP rose from baseline to reach a plateau by 4 weeks (systolic BP: 107+/-12 to 169+/-27, diastolic BP: 71+/-10 to 118+/-29 mmHg, both p< 0.0001) cardiac hypertrophy was significant when compared with controls with increased left ventricular weight [left ventricular (LV)/body wt: 2.7+/-0.5 vs 2.1+/-0.2 g/kg, p=0.01] as well as bi-atrial enlargement (right atrial, RA: 22.9+/-4.9 vs 15.7+/-2.8g, p=0.003 left atrial, LA: 35.5+/-6.7 vs 20.9+/-4.1g, p=0.0003) cardiac magnetic imaging demonstrated significantly increased LA volumes (end-diastolic volume: 42.9+/-6.8 vs 28.7+/-6.3 ml, p< 0.0001) and reduced LA ejection fraction (24.1+/-3.6 vs 31.6+/-3.0%, p=0.001) while LV function was relatively preserved (42.3+/-4.7 vs 46.4+/-4.1%, p=0.1) degeneration and necrosis of atrial myocytes were evident with increased atrial lymphocytic infiltration and interstitial fibrosis. The ovine 1K1C model produces reliable and reproducible hypertension with demonstrable cardiac end-organ damage.
Publisher: Elsevier BV
Date: 2006
DOI: 10.1016/J.HRTHM.2005.09.019
Abstract: Areas of complex fractionated atrial electrograms (CFAEs) have been implicated in the atrial substrate of atrial fibrillation (AF). The mechanisms underlying CFAE in humans are not well investigated. The purpose of this study was to investigate the regional activation pattern associated with CFAE using a high-density contact mapping catheter. Twenty patients with paroxysmal AF were mapped using a high-density multielectrode catheter. CFAE were mapped at 10 different sites (left atrium [LA]: inferior, posterior, roof, septum, anterior, lateral right atrium [RA]: anterior, lateral, posterior, septum). Local atrial fibrillation cycle length (AFCL) was measured immediately before and after the occurrence of CFAE, and the longest electrogram duration (CFAEmax) was assessed. Longer electrogram durations were recorded in the LA compared with the RA (CFAEmax 118 +/- 21 ms vs 104 +/- 23 ms, P = .001). AFCL significantly shortened before the occurrence of CFAEmax compared with baseline (LA: 174 +/- 32 ms vs 186 +/- 32 ms, P = .0001 RA: 177 +/- 31 ms vs 188 +/- 31 ms, P = .0001) and returned to baseline afterwards. AFCL shortened by >or=10 ms in 91% of mapped sites. Two different local activation patterns were associated with occurrence of CFAEmax: a nearly simultaneous activation in all spines in 84% indicating passive activation, and a nonsimultaneous activation sequence suggesting local complex activation or reentry. Fractionated atrial electrograms during AF demonstrate dynamic changes that are dependent on regional AFCL. Shortening of AFCL precedes the development of CFAE thus, cycle length is a major determinant of fractionation during AF. High-density mapping in AF may help to differentiate passive activation of CFAE from CFAE associated with an active component of the AF process.
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.JACEP.2019.06.002
Abstract: This study sought to determine the impact of rate and direction on left atrial (LA) substrate. The extent to which substrate mapped in sinus rhythm varies according to cycle length and direction of wave front propagation is unknown. A total of 73 consecutive patients with atrial fibrillation (AF) underwent electroanatomic LA mapping before pulmonary vein isolation using multipolar catheter during distal coronary sinus (CS) pacing at 600 ms and 300 ms. Additional maps were created during left superior pulmonary vein pacing at 300 ms. Bipolar voltage, conduction velocity (CV), and complex signals were determined. Mean age was 61 ± 9 years, 67% were men, and 53% had persistent AF. Global mean voltage was lower with CS pacing at 300 ms compared with 600 ms (1.56 ± 0.47 mV vs. 1.74 ± 0.48 mV p < 0.001). This was seen in all LA segments. Global CV was reduced (30.4 ± 13.0 cm/s vs. 38.6 ± 14.0 cm/s p < 0.001) with greater complex signals at 300 ms (8.9% vs. 5.3% p < 0.005). Compared with CS pacing, left superior pulmonary vein pacing demonstrated highly regional changes with decreased voltage (1.04 ± 0.43 mV vs. 1.47 ± 0.53 mV p = 0.01) and CV (24.4 ± 13.0 cm/s vs. 39.9 ± 16.6 cm/s p = 0.008), and greater complex signals posteriorly. Longer AF duration in paroxysmal AF (p = 0.02) and shorter duration in persistent AF (p = 0.015) and left ventricular ejection fraction (p = 0.016) were independent predictors of voltage change. In patients with AF, variation in cycle length and direction of wave front activation produce both generalized and regional changes in voltage, CV, and complex fractionation, resulting in significant changes in substrate maps. This study highlights the potential limitations of static low-voltage maps to identify the AF ablation target zone.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2022
DOI: 10.1161/CIRCEP.121.009925
Abstract: Population studies have demonstrated a range of sex differences including a higher prevalence of atrial fibrillation (AF) in men and a higher risk of AF recurrence in women. However, the underlying reasons for this higher recurrence are unknown. This study evaluated whether sex-based electrophysiological substrate differences exist to account for worse AF ablation outcomes in women. High-density electroanatomic mapping of the left atrium was performed in 116 consecutive patients with AF. Regional analysis was performed across 6 left atrium segments. High-density maps were created using a multipolar catheter (Biosense Webster) during distal coronary sinus pacing at 600 and 300 ms. Mean voltage and conduction velocity was determined. Complex fractionated signals and double potentials were manually annotated. Overall, 42 (36%) were female, mean age was 61±8 years and AF was persistent in 52%. Global mean voltage was significantly lower in females compared with males at 600 ms (1.46±0.17 versus 1.84±0.15 mV, P .001) and 300 ms (1.27±0.18 versus 1.57±0.18 mV, P =0.013) pacing. These differences were seen uniformly across the left atrium. Females demonstrated significant conduction velocity slowing (34.9±6.1 versus 44.1±6.9 cm/s, P =0.002) and greater proportion of complex fractionated signals (9.9±1.7% versus 6.0±1.7%, P =0.014). After a median follow-up of 22 months (Q1–Q3: 15–29), females had significantly lower single-procedure (22 [54%] versus 54 [75%], P =0.029) and multiprocedure (24 [59%] versus 60 [83%], P =0.005) arrhythmia-free survival. Female sex and persistent AF were independent predictors of single and multiprocedure arrhythmia recurrence. Female patients demonstrated more advanced atrial remodeling on high-density electroanatomic mapping and greater post-AF ablation arrhythmia recurrence compared with males. These changes may contribute to sex-based differences in the clinical course of females with AF and in part explain the higher risk of recurrence. A graphic abstract is available for this article.
Publisher: Public Library of Science (PLoS)
Date: 13-05-2010
Publisher: BMJ
Date: 17-07-2023
DOI: 10.1136/HEARTJNL-2023-322412
Abstract: To examine the associations between specific dietary patterns and incident atrial fibrillation (AF). Using data from the UK Biobank, dietary intakes were calculated from 24-hour diet recall questionnaires. Indices representing adherence to dietary patterns (Mediterranean-style, Dietary Approaches to Stop Hypertension (DASH) and plant-based diets) were scored, and ultra-processed food consumption was studied as a percentage of total food mass consumed. Incident AF hospitalisations were assessed in Cox regression models. A total of 121 300 in iduals were included, with 4 579 incident AF cases over a median follow-up of 8.8 years. Adherence to Mediterranean-style or DASH diets was associated with a lower incidence of AF in minimally adjusted analyses (HR for highest vs lowest quintile 0.87 (95% CI 0.80–0.96) and HR 0.78 (95% CI 0.71–0.86), respectively). However, associations were no longer significant after accounting for lifestyle factors (HR 0.95 (95% CI 0.87–1.04) and 0.94 (95% CI 0.86–1.04) respectively), with adjustment for body mass index responsible for approximately three-quarters of the effect size attenuation. Plant-based diets were not associated with AF risk in any models. Greatest ultra-processed food consumption was associated with a significant increase in AF risk even in fully adjusted models (HR 1.13 (95% CI 1.02–1.24)), and a 10% increase in absolute intake of ultra-processed food was associated with a 5% increase in AF risk (HR 1.05 (95% CI 1.01–1.08)). With the possible exception of reducing ultra-processed food consumption, these findings suggest that attention to other modifiable risk factors, particularly obesity, may be more important than specific dietary patterns for the primary prevention of AF.
Publisher: Elsevier BV
Date: 08-2016
Publisher: Springer Science and Business Media LLC
Date: 15-09-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 16-09-2003
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2019
DOI: 10.1161/CIRCEP.118.007005
Abstract: The posterior left atrium is an arrhythmogenic substrate that contributes to the initiation and maintenance of atrial fibrillation (AF) however, the feasibility, safety, and efficacy of posterior wall isolation (PWI) as an AF ablation strategy has not been widely reported. We undertook a systematic review and meta-analysis of studies performing PWI to assess (1) acute procedural success including the ability to achieve PWI and the number of procedure-related complications, (2) Long-term, clinical success including rates of arrhythmia recurrence and posterior wall reconnection, and (3) The efficacy of PWI compared with pulmonary vein isolation on preventing arrhythmia recurrence. MEDLINE, EMBASE, and Web of Science databases were searched in May 2018 to retrieve relevant studies. Results were pooled using a random effects model. Seventeen studies (13 box isolation, 3 single ring isolation, and 1 debulking ablation) comprising 1643 patients (31.3% paroxysmal AF, left atrial diameter 41±3.1 mm) were included in the final analysis. In studies focusing specifically on PWI, the acute procedural success rate for achieving PWI was 94.1% (95% CI, 87.2%–99.3%). Single-procedure 12-month freedom from atrial arrhythmia was 65.3% (95% CI, 57.7%–73.9%) overall and 61.9% (54.2%–70.8%) for persistent AF. Randomized control trials comparing PWI to pulmonary vein isolation (3 studies, 444 patients) yielded conflicting results and could not confirm an incremental benefit to PWI. Fifteen major complications (0.1%), including 2 atrio-esophageal fistulas, were reported. PWI as an end point of AF ablation can be achieved in a large proportion of cases with good rates of 12-month freedom from atrial arrhythmia. Although the procedure-related complication rate is low, it did not eliminate the risk of atrio-esophageal fistula. URL: www.crd.york.ac.uk rospero . PROSPERO registration number: CRD42018107212.
Publisher: Oxford University Press (OUP)
Date: 02-2021
DOI: 10.1093/CVR/CVAB024
Abstract: Obesity, an established risk factor of atrial fibrillation (AF), is frequently associated with enhanced inflammatory response. However, whether inflammatory signaling is causally linked to AF pathogenesis in obesity remains elusive. We recently demonstrated that the constitutive activation of the ‘NACHT, LRR, and PYD Domains-containing Protein 3’ (NLRP3) inflammasome promotes AF susceptibility. In this study, we hypothesized that the NLRP3 inflammasome is a key driver of obesity-induced AF. Western blotting was performed to determine the level of NLRP3 inflammasome activation in atrial tissues of obese patients, sheep, and diet-induced obese (DIO) mice. The increased body weight in patients, sheep, and mice was associated with enhanced NLRP3-inflammasome activation. To determine whether NLRP3 contributes to the obesity-induced atrial arrhythmogenesis, wild-type (WT) and NLRP3 homozygous knockout (NLRP3−/−) mice were subjected to high-fat-diet (HFD) or normal chow (NC) for 10 weeks. Relative to NC-fed WT mice, HFD-fed WT mice were more susceptible to pacing-induced AF with longer AF duration. In contrast, HFD-fed NLRP3−/− mice were resistant to pacing-induced AF. Optical mapping in DIO mice revealed an arrhythmogenic substrate characterized by abbreviated refractoriness and action potential duration (APD), two key determinants of reentry-promoting electrical remodeling. Upregulation of ultra-rapid delayed-rectifier K+-channel (Kv1.5) contributed to the shortening of atrial refractoriness. Increased profibrotic signaling and fibrosis along with abnormal Ca2+ release from sarcoplasmic reticulum (SR) accompanied atrial arrhythmogenesis in DIO mice. Conversely, genetic ablation of Nlrp3 (NLRP3−/−) in HFD-fed mice prevented the increases in Kv1.5 and the evolution of electrical remodeling, the upregulation of profibrotic genes, and abnormal SR Ca2+ release in DIO mice. These results demonstrate that the atrial NLRP3 inflammasome is a key driver of obesity-induced atrial arrhythmogenesis and establishes a mechanistic link between obesity-induced AF and NLRP3-inflammasome activation.
Publisher: Elsevier BV
Date: 2018
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 24-09-2019
DOI: 10.1161/CIRCULATIONAHA.119.041320
Abstract: Atrial arrhythmias are common in patients with implantable cardioverter-defibrillator (ICD). External shocks and internal cardioversion through commanded ICD shock for electrical cardioversion are used for rhythm-control. However, there is a paucity of data on efficacy of external versus internal cardioversion and on the risk of lead and device malfunction. We hypothesized that external cardioversion is noninferior to internal cardioversion for safety, and superior for successful restoration of sinus rhythm. Consecutive patients with ICD undergoing elective cardioversion for atrial arrhythmias at 13 centers were randomized in 1:1 fashion to either internal or external cardioversion. The primary safety end point was a composite of surrogate events of lead or device malfunction. Conversion of atrial arrhythmia to sinus rhythm was the primary efficacy end point. Myocardial damage was studied by measuring troponin release in both groups. N=230 patients were randomized. Shock efficacy was 93% in the external cardioversion group and 65% in the internal cardioversion group ( P .001). Clinically relevant adverse events caused by external or internal cardioversion were not observed. Three cases of pre-existing silent lead malfunction were unmasked by internal shock, resulting in lead failure. Troponin release did not differ between groups. This is the first randomized trial on external vs internal cardioversion in patients with ICDs. External cardioversion was superior for the restoration of sinus rhythm. The unmasking of silent lead malfunction in the internal cardioversion group suggests that an internal shock attempt may be reasonable in selected ICD patients presenting for electrical cardioversion. URL: www.clinicaltrials.gov . Unique identifier: NCT03247738.
Publisher: Wiley
Date: 20-11-2022
DOI: 10.1111/JCE.15742
Abstract: Use of a novel magnetic sensor enabled optical contact force ablation catheter has been established to be safe and effective for treatment of symptomatic drug-refractory paroxysmal atrial fibrillation (AF) but has yet to be demonstrated in the persistent AF (PersAF) population. PERSIST-END was a multicenter, prospective, nonrandomized, investigational study designed to demonstrate the safety and effectiveness of TactiCath™ Ablation Catheter, Sensor Enabled™(SE) (TactiCath SE) for use in the treatment of subjects with documented PersAF refractory or intolerant to at least one Class I/III AAD. The ablation strategy included pulmonary vein isolation and additional targets at physician discretion. Follow-up through 15-months, including a 3-month blanking period and 3-month therapy consolidation period, was performed with cardiac event and Holter monitoring. Primary safety, primary effectiveness, clinical success, and quality of life (QOL) endpoints were analyzed. Of 224 subjects enrolled at 21 investigational sites in the United States and Australia, 223 underwent ablation with the investigational catheter. The primary safety event rate was 3.1% (seven events in seven subjects). The Kaplan-Meier estimate of freedom from AF/atrial flutter/atrial tachycardia recurrence at 15-months was 61.6% and clinical success at 15 months was 89.8%. Subject QOL significantly improved following ablation as assessed via AFEQT (31.6 point increase, p < .0001) and EQ-5D-5L (10.7 point increase, p < .0001) and was met with a 53% reduction in all cause cardiovascular healthcare utilization. The sensor-enabled force-sensing catheter is safe and effective for the treatment of drug refractory recurrent symptomatic PersAF, reducing arrhythmia recurrence while improving QOL and healthcare utilization.
Publisher: Wiley
Date: 11-05-2005
Publisher: Elsevier BV
Date: 09-2017
Publisher: BMJ
Date: 21-09-2019
DOI: 10.1136/HEARTJNL-2017-312932
Abstract: Mitral valve prolapse (MVP) is commonly observed as a benign finding. However, the literature suggests that it may be associated with sudden cardiac death (SCD). We performed a meta-analysis and systematic review to determine the: (1) prevalence of MVP in the general population (2) prevalence of MVP in all SCD and unexplained SCD (3) incidence of SCD in MVP and (4) risk factors for SCD. The English medical literature was searched for: (1) MVP community prevalence (2) MVP prevalence in SCD cohorts (3) incidence SCD in MVP and (4) SCD risk factors in MVP. Thirty-four studies were identified for inclusion. This study was registered with PROSPERO (CRD42018089502). The prevalence of MVP was 1.2% (95% CI 0.5 to 2.0) in community populations. Among SCD victims, the cause of death remained undetermined in 22.1% (95% CI 13.4 to 30.7) of these, MVP was observed in 11.7% (95% CI 5.8 to 19.1). The incidence of SCD in the MVP population was 0.14% (95% CI 0.1 to 0.3) per year. Potential risk factors for SCD include bileaflet prolapse, ventricular fibrosis complex ventricular ectopy and ST-T wave abnormalities. The high prevalence of MVP in cohorts of unexplained SCD despite low population prevalence provides indirect evidence of an association of MVP with SCD. The absolute number of people exposed to the risk of SCD is significant, although the incidence of life-threatening arrhythmic events in the general MVP population remains low. High-risk features include bileaflet prolapse, ventricular fibrosis, ST-T wave abnormalities and frequent complex ventricular ectopy. PROSPERO (CRD42018089502).
Publisher: Oxford University Press (OUP)
Date: 22-12-2018
Abstract: To investigate the composition of nocturnal hypoxaemic burden and its prognostic value for cardiovascular (CV) mortality in community-dwelling older men. We analysed overnight oximetry data from polysomnograms obtained in 2840 men from the Outcomes of Sleep Disorders in Older Men (MrOS Sleep) study (ClinicalTrials.gov Identifier: NCT00070681) to determine the number of acute episodic desaturations per hour (oxygen desaturation index, ODI) and time spent below 90% oxygen saturation (T90) attributed to acute desaturations (T90desaturation) and to non-specific drifts in oxygen saturation (T90non-specific), respectively, and their relationship with CV mortality. After 8.8 ± 2.7 years follow-up, 185 men (6.5%) died from CV disease. T90 [hazard ratio (HR) 1.21, P & 0.001], but not ODI (HR 1.13, P = 0.06), was significantly associated with CV death in univariate analysis. T90 remained significant when adjusting for potential confounders (HR 1.16, P = 0.004). Men with T90 & 12 min were at an elevated risk of CV mortality (HR 1.59 P = 0.006). Approximately 20.7 (5.7–48.5) percent of the variation in T90 could be attributed to non-specific drifts in oxygen saturation. T90desaturation and T90non-specific were in idually associated with CV death but combining both variables did not improve the prediction. In community-dwelling older men, T90 is an independent predictor of CV mortality. T90 is not only a consequence of frank desaturations, but also reflects non-specific drifts in oxygen saturation, both contributing towards the association with CV death. Whether T90 can be used as a risk marker in the clinical setting and whether its reduction may constitute a treatment target warrants further study.
Publisher: Wiley
Date: 02-02-2021
DOI: 10.1111/JCE.14898
Publisher: Wiley
Date: 15-11-2022
DOI: 10.1111/JCE.15744
Abstract: This study aimed to report the real‐world atrial fibrillation (AF) diagnostic yield of the implantable cardiac monitor (ICM) in patients with stroke or transient ischemic attack (TIA), and compare it to patients with an ICM for unexplained syncope. We used patient data from device clinics across the United States of America with ICM remote monitoring via PaceMate™, implanted for stroke or TIA, and unexplained syncope. Patients with known AF or atrial flutter were excluded. The outcome was AF lasting ≥2 min, adjudicated by International Board of Heart Rhythm Examiners certified cardiac device specialists. We included a total of 2469 patients, 51.1% with stroke or TIA (mean age: 69.7 [SD: 12.2] years, 41.1% female) and 48.9% with syncope (mean age: 67.0 [SD: 17.1] years, 59.4% female). The cumulative AF detection rate in patients with stroke or TIA was 5.5%, 8.9%, and 14.0% at 12, 24, and 36 months, respectively. The median episode duration was 73 (interquartile range: 10–456) min, ranging from 2 min to 40.9 days, with 52.3%, 28.6%, and 4.4% of episodes lasting at least 1, 6, and 24 h, respectively. AF detection was increased by age (adjusted hazard ratio [for every 1‐year increase]: 1.024, 95% confidence interval: 1.008–1.040 p = .003), but was not influenced by sex ( p = .089). For comparison, the cumulative detection rate at 12, 24, and 36 months were, respectively, 2.4%, 5.2%, and 7.4% in patients with syncope. Patients with stroke or TIA have a higher rate of AF detection. However, this real‐world study shows significantly lower AF detection rates than what has been previously reported.
Publisher: Elsevier BV
Date: 02-2012
Publisher: Oxford University Press (OUP)
Date: 08-08-2014
Abstract: To characterize the nature of atrial fibrillation (AF) activation in human persistent AF (PerAF) using modern tools including activation, directionality analyses, complex-fractionated electrogram, and spectral information. The mechanism of PerAF in humans is uncertain. High-density epicardial mapping (128 electrodes/6.75 cm(2)) of the posterior LA wall (PLAW), LA and RA appendage (LAA, RAA), and RSPV-LA junction was performed in 18 patients with PerAF undergoing open heart surgery. Continuous 10 s recordings were analysed offline. Activation patterns were characterized into four subtypes (i) wavefronts (broad or multiple), (ii) rotational circuits (≥2 rotations of 360°), (iii) focal sources with centrifugal activation of the entire mapping area, or (iv) disorganized activity [isolated chaotic activation(s) that propagate ≤3 bipoles or activation(s) that occur as isolated beats dissociated from the activation of adjacent bipole sites]. Activation at a total of 36 regions were analysed (14 PLAW, 3 RSPV-LA, 12 LAA, and 7 RAA) creating a database of 2904 activation patterns. In the majority of maps, activation patterns were highly heterogeneous with multiple unstable activation patterns transitioning from one to another during each recording. A mean of 3.8 ± 1.6 activation subtypes was seen per map. The most common patterns seen were multiple wavefronts (56.2 ± 32%) and disorganized activity (24.2 ± 30.3%). Only 2 of 36 maps (5.5%) showed a single stable activation pattern throughout the 10-s period. These were stable planar wavefronts. Three transient rotational circuits were observed. Two of the transient circuits were located in the posterior left atrium, while the third was located on the anterior surface of the LAA. Focal activations accounted for 11.3 ± 14.2% of activations and were all short-lived (≤2 beats), with no site demonstrating sustained focal activity. Human long-lasting PerAF is characterized by heterogeneous and unstable patterns of activation including wavefronts, transient rotational circuits, and disorganized activity.
Publisher: Wiley
Date: 08-01-2022
DOI: 10.1111/JCE.15747
Abstract: Implantable cardioverter defibrillators (ICD) are indicated for primary and secondary prevention of sudden cardiac arrest. Despite enhancements in design and technologies, the ICD lead is the most vulnerable component of the ICD system and failure of ICD leads remains a significant clinical problem. A novel, small diameter, lumenless, catheter delivered, defibrillator lead was developed with the aim to improve long term reliability. The Lead Evaluation for Defibrillation and Reliability (LEADR) study is a multi-center, single-arm, Bayesian, adaptive design, pre-market interventional pivotal clinical study. Up to 60 study sites from around the world will participate in the study. Patients indicated for a de novo ICD will undergo defibrillation testing at implantation and clinical assessments at baseline, implant, pre-hospital discharge, 3 months, 6 months, and every 6 months thereafter until official study closure. Patients may be participating for a minimum of 18 months to approximately 3 years. Fracture-free survival will be evaluated using a Bayesian statistical method that incorporates both virtual patient data (combination of bench testing to failure with in-vivo use condition data) with clinical patients. The clinical subject s le size will be determined using decision rules for number of subject enrollments and follow-up time based upon the observed number of fractures at certain time points in the study. The adaptive study design will therefore result in a minimum of 500 and a maximum of 900 patients enrolled. The LEADR Clinical Study was designed to efficiently provide evidence for short- and long-term safety and efficacy of a novel lead design using Bayesian methods including a novel virtual patient approach. This article is protected by copyright. All rights reserved.
Publisher: Elsevier BV
Date: 03-2012
DOI: 10.1016/J.COMPBIOMED.2011.03.019
Abstract: Pregnancy leads to physiological changes in various parameters of the cardiovascular system. The aim of this study was to investigate longitudinal changes in the structure and complexity of heart rate variability (HRV) and QT interval variability during the second half of normal gestation. We analysed 30-min high-resolution ECGs recorded monthly in 32 pregnant women, starting from the 20th week of gestation. Heart rate and QT variability were quantified using multiscale entropy (MSE) and detrended fluctuation analyses (DFA). DFA of HRV showed significantly higher scaling exponents towards the end of gestation (p<0.0001). MSE analysis showed a significant decrease in s le entropy of HRV with progressing gestation on scales 1-4 (p<0.05). MSE analysis and DFA of QT interval time series revealed structures significantly different from those of HRV with no significant alteration during the second half of gestation. In conclusion, pregnancy is associated with increases in long-term correlations and regularity of HRV, but it does not affect QT variability. The structure of QT time series is significantly different from that of RR time series, despite its close physiological dependence.
Publisher: Elsevier BV
Date: 2009
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.AHJ.2019.04.002
Abstract: Cardiac resynchronization therapy (CRT) improves outcomes, functional capacity and quality of life in patients with heart failure. Despite two decades of experience with CRT, the rate of non-response remains approximately 30%. CRT efficacy is impacted by pacing location, which is anatomically limited in conventional systems. A new wireless endocardial left ventricular (LV) pacing system allows CRT without such limitations and has shown promise in open-label studies. The purpose of this study is to evaluate its use in a patient population with poor therapeutic alternatives. The SOLVE CRT study is an international, multi-center, randomized, double-blind, sham-controlled trial of patients with Class I and IIa indications for CRT who have either failed to respond to or have been unable to receive conventional CRT. Enrollment will comprise 350 patients implanted with the wireless CRT system randomized 1:1 to therapy on (Treatment) or therapy off (Control) for the six-month period over which trial primary endpoints will be evaluated. The primary safety endpoint will measure the proportion of patients free from system- and procedure-related complications. Primary efficacy endpoints will assess absolute change in LV end-systolic volume LVESV, proportion of patients reducing LVESV by ≥15% and clinical composite score for Treatment versus Control patients. Primary endpoints will be evaluated on an intention-to-treat basis, though per-protocol and as-treated analysis will also be performed. SOLVE-CRT will quantify the safety and effectiveness of wireless CRT in non-responders to conventional CRT and indicated patients who have been unable to receive CRT via the usual transvenous approach.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 23-03-2004
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.HRTHM.2010.12.009
Abstract: It has been suggested that omega-3 polyunsaturated fatty acids (n-3 PUFAs) may prevent the development of atrial fibrillation (AF). The purpose of this study was to evaluate the impact of these agents on development of the AF substrate in heart failure (HF). In this study, HF was induced by intracoronary doxorubicin infusions. Twenty-one sheep [7 with n-3 PUFAs treated HF (HF-PUFA), 7 with olive oil-treated HF controls (HF-CTL), 7 controls (CTL)] were studied. Open chest electrophysiologic study was performed with assessment of biatrial effective refractory period (ERP) and conduction. Cardiac function was monitored by magnetic resonance imaging. Atrial n-3 PUFAs levels were quantified using chromatography. Structural analysis was also performed. Atrial n-3 PUFAs levels were twofold to threefold higher in the HF-PUFA group. n-3 PUFAs prevented the development of HF-related left atrial enlargement (P = .001) but not left ventricular/atrial dysfunction. Atrial ERP was significantly lower in the HF-PUFA group (P <.001), but ERP heterogeneity was unchanged. In addition, n-3 PUFAs suppressed atrial conduction abnormalities seen in HF of prolonged P-wave duration (P = .01) and slowed (P <.001) and heterogeneous (P <.05) conduction. The duration of induced AF episodes in HF-PUFA was shorter (P = .02), although AF inducibility was unaltered (P = NS). A 20% reduction of atrial interstitial fibrosis was seen in the HF-PUFA group (P <.05). In this ovine HF study, chronic n-3 PUFAs use protected against adverse atrial remodeling by preventing atrial enlargement, fibrosis, and conduction abnormalities leading to shorter AF episodes despite lower ERP.
Publisher: Elsevier BV
Date: 06-2006
Publisher: Oxford University Press (OUP)
Date: 04-2021
Abstract: The management of atrial fibrillation (AF) is multifaceted and treatment paradigms have changed significantly in the last century. The treatment of AF requires a comprehensive approach which goes beyond the treatment of the arrhythmia alone. Risk factor management has been introduced as a crucial pillar of AF management. As a result, the landscape of care delivery is changing as well, and novel models of comprehensive care delivery for AF have been introduced. This article reviews the evidence for the role of risk factor management in AF, how this can be integrated and implemented in clinical practice by applying novel models of care delivery, and finally identifies areas for ongoing research and potential healthcare reform to comprehensively manage the burgeoning AF population.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-08-2017
DOI: 10.1161/CIRCULATIONAHA.116.023163
Abstract: There has been increasing focus on the rising burden of atrial fibrillation (AF) since the turn of the millennium. The AF epidemic is projected not only to have an impact on morbidity and mortality, but also to result in increasing healthcare use and cost. Intensive research over the previous decades has improved our understanding of this complex arrhythmia while unraveling more knowledge gaps and inadequacies of current therapeutic options. Specifically, the advances in catheter ablation technology and strategies have not translated into significant gains in procedural success rates over recent years. Therefore, strategies aiming at lowering the risk of AF development and progression are urgently needed to curtail the AF epidemic and improve outcomes in affected in iduals. Recent research has highlighted the potential beneficial effects of lifestyle and risk factor management for AF as upstream noninvasive therapy. The evidence supporting this treatment paradigm beyond routine clinical AF management argues for change in the delivery of care to patients who have this debilitating arrhythmia. In this review, we highlight the contributory role of risk factors to AF pathogenesis from both bench and bedside studies. Next, we discuss the rationale and potential benefits of risk factor modification for sinus rhythm maintenance. Last, we propose an integrated care model to incorporate risk factor modification as the fourth pillar of AF care in conjunction with established pillars of rate control, rhythm control, and anticoagulation therapy.
Publisher: Wiley
Date: 05-2002
DOI: 10.1046/J.1445-5994.2002.00215.X
Abstract: Background : Atrial fibrillation (AF) is frequently initiated by focal activity originating in the pulmonary veins. We present the early and long‐term results of a focal approach to pulmonary‐vein ablation for cure of paroxysmal AF. Aims : The aim of this study was to establish the effectiveness of focal pulmonary vein radiofrequency ablation (RFA) for cure of paroxysmal AF. Methods : Fifty‐one consecutive patients (35 male 45 ± 11.4 years) were considered for RFA on the following criteria: (i) symptomatic drug refractory AF, (ii) high‐density atrial ectopy, bursts of atrial tachycardia or AF, (iii) absence of structural heart disease and (iv) provision of informed consent. Pulmonary vein mapping and RFA were by single trans‐septal puncture, which was only performed in patients with adequate focal activity at the time of procedure. Focal activity was present spontaneously or was elicited by isoprenaline, burst pacing or AF induction and cardioversion. Results : One patient was excluded from the analysis due to non‐pulmonary vein triggers. Trans‐septal mapping and RFA were not performed in 22 patients (44%) due to: (i) inadequate ectopy (17), (ii) recurrent AF (1), (iii) inability to cross septum (2) and (iv) multiple foci (2). Of 28 patients, RFA was attempted with procedural success in 23 patients (82%), with no acute complications. Mean fluoro‐ scopy time for patients having RFA was 29 ± 11.5 mins. Pulmonary vein stenosis occurred in one case. Ten patients had symptomatic recurrence and, of those, two had further RFA. At a mean follow up of 11 ± 8 months, 15 patients (54% ablated, 30% of the total cohort) remained free of AF without anti‐arrhythmics. Conclusion : This series highlights the low long‐term success rate of RFA to cure AF by targeting pulmonary vein initiators using a focal approach. Electrical pulmonary vein isolation may provide better long‐term results. (Intern Med J 2002 32: 202−207)
Publisher: Elsevier BV
Date: 2018
Publisher: Springer Science and Business Media LLC
Date: 12-2008
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.HRTHM.2009.06.007
Abstract: Abstract presentation at conferences provides the opportunity to rapidly communicate research findings. The outcome and impact of publications arising from cardiac electrophysiology abstracts are not known. The purpose of this study was to examine the characteristics of abstracts presented at the annual scientific sessions of Heart Rhythm Society (HRS), their publication rate, and the indexed impact of subsequent publications. Two independent database searches (MEDLINE and EMBASE) were performed by cross-referencing authors and keywords from abstracts originally presented at HRS in 2003. ISI Web of Knowledge was accessed for impact factors and citation rates. A total of 790 abstracts were presented, of which 377 (47.7%) resulted in publication of an original article. Median time to publication was 1.39 years (interquartile range [IQR] 0.88-2.30 years), and the median impact factor and citation rate of published articles was 4.14 (IQR 3.48-11.05) and 10 (IQR 4-25), respectively. Experimental research abstract category (odds ratio [OR] 2.03, P <.001), randomized study design (OR 0.53, P = .02), and positive findings (OR 0.80, P = .06) were independently predictive of publication by stepwise logistic regression. Independent predictors of higher citation rates were randomized study design (P = .03) and impact factor of the publishing journal (P <.001). Almost half of all abstracts presented at HRS resulted in publication in journals with a high impact factor. Experimental research abstracts, those with a randomized study design, and those demonstrating positive findings were predictors of subsequent publication. Randomized study design and greater impact factor of the publishing journal were found to predict higher citation rates.
Publisher: Springer Science and Business Media LLC
Date: 22-02-2011
Abstract: The term 'ventricular arrhythmias' incorporates a wide spectrum of abnormal cardiac rhythms, from single premature ventricular complexes to sustained monomorphic ventricular tachycardia (VT), polymorphic VT, and ventricular fibrillation. Sustained ventricular arrhythmias are the most common cause of sudden cardiac death. These arrhythmias occur predominantly in patients with structural heart disease, but are also seen in patients with no demonstrable cardiac disease. The diagnosis of VT can be made reliably using electrocardiographic criteria, and a number of algorithms have been proposed. Among patients with VT and a structurally normal heart, the prognosis is usually benign and treatment is predominantly focused on the elimination of symptoms. Patients who have VT in the presence of structural heart disease are often managed with implantable cardioverter-defibrillators. These devices are effective for both primary and secondary prevention of VT and sudden cardiac death. Pharmacological therapy for VT has limited efficacy and is associated with a high incidence of adverse effects. Radiofrequency catheter ablation is useful for controlling recurrent episodes of monomorphic VT however, research is needed to define the role of catheter ablation in the treatment of other ventricular arrhythmias.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2020
DOI: 10.1161/CIRCEP.120.008512
Abstract: Endocardial-epicardial dissociation and focal breakthroughs in humans with atrial fibrillation (AF) have been recently demonstrated using activation mapping of short 10-second AF segments. In the current study, we used simultaneous endo-epi phase mapping to characterize endo-epi activation patterns on long segments of human persistent AF. Simultaneous intraoperative mapping of endo- and epicardial lateral right atrium wall was performed in patients with persistent AF using 2 high-density grid catheters (16 electrodes, 3 mm spacing). Filtered unipolar and bipolar electrograms of continuous 2-minute AF recordings and electrodes locations were exported for phase analyses. We defined endocardial-epicardial dissociation as phase difference of ≥20 ms between paired endo-epi electrodes. Wavefronts were classified as rotations, single wavefronts, focal waves, or disorganized activity as per standard criteria. Endo-Epi wavefront patterns were simultaneously compared on dynamic phase maps. Complex fractionated electrograms were defined as bipolar electrograms with ≥5 directional changes occupying at least 70% of s le duration. Fourteen patients with persistent AF undergoing cardiac surgery were included. Endocardial-epicardial dissociation was seen in 50.3% of phase maps with significant temporal heterogeneity. Disorganized activity (Endo: 41.3% versus Epi: 46.8%, P =0.0194) and single wavefronts (Endo: 31.3% versus Epi: 28.1%, P =0.129) were the dominant patterns. Transient rotations (Endo: 22% versus Epi: 19.2%, P =0.169 mean duration: 590±140 ms) and nonsustained focal waves (Endo: 1.2% versus Epi: 1.6%, P =0.669) were also observed. Apparent transmural migration of rotational activations (n=6) from the epi- to the endocardium was seen in 2 patients. Electrogram fractionation was significantly higher in the epicardium than endocardium (61.2% versus 51.6%, P .0001). Simultaneous endo-epi phase mapping of prolonged human persistent AF recordings shows significant Endocardial-epicardial dissociation marked temporal heterogeneity, discordant and transitioning wavefronts patterns and complex fractionations. No sustained focal activity was observed. Such complex 3-dimensional interactions provide insight into why endocardial mapping alone may not fully characterize the AF mechanism and why endocardial ablation may not be sufficient. A graphic abstract is available for this article.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 15-12-2020
Abstract: The physiology underlying "brain fog" in the absence of orthostatic stress in postural tachycardia syndrome (POTS) remains poorly understood. We evaluated cognitive and hemodynamic responses (cardiovascular and cerebral: heart rate, blood pressure, end‐tidal carbon dioxide, and cerebral blood flow velocity (CBFv) in the middle cerebral artery at baseline, after initial cognitive testing, and after (30‐minutes duration) prolonged cognitive stress test (PCST) whilst seated as well as after 5‐minute standing in consecutively enrolled participants with POTS (n=22) and healthy controls (n=18). Symptom severity was quantified with orthostatic hypotensive questionnaire at baseline and end of study. Subjects in POTS and control groups were frequency age‐ and sex‐matched (29±11 versus 28±13 years 86 versus 72% women, respectively both P ≥0.4). The CBFv decreased in both groups (condition, P =0.04) following PCST, but a greater reduction in CBFv was observed in the POTS versus control group (−7.8% versus −1.8% interaction, P =0.038). Notably, the reduced CBFv following PCST in the POTS group was similar to that seen during orthostatic stress (60.0±14.9 versus 60.4±14.8 cm/s). Further, PCST resulted in greater slowing in psychomotor speed (6.1% versus 1.4%, interaction, P =0.027) and a greater increase in symptom scores at study completion (interaction, P .001) in the patients with POTS, including increased difficulty with concentration. All other physiologic responses (blood pressure and end‐tidal carbon dioxide) did not differ between groups after PCST (all P .05). Reduced CBFv and cognitive dysfunction were evident in patients with POTS following prolonged cognitive stress even in the absence of orthostatic stress.
Publisher: Informa UK Limited
Date: 08-03-2017
DOI: 10.1080/14779072.2017.1299005
Abstract: Recent research has unravelled an increasing list of cardiac conditions and risk factors that may be responsible for the abnormal underlying atrial substrate that predisposes to atrial fibrillation (AF). Atrial fibrosis has been demonstrated as the pivotal structural abnormality underpinning conduction disturbances that promote AF in different disease models. Despite the advancement in our discoveries of the molecular mechanisms involved in the profibrotic milieu, targeted therapeutics against atrial fibrosis remain lacking. Areas covered: This review is focused on detailing the key molecular signalling pathways that contribute to atrial fibrosis including: angiotensin II, transforming growth factor (TGF- ß1), connective tissue growth factor (CTGF) and endothelin-1. We also discussed the potential therapeutic options that may be useful in modulating the abnormal atrial substrate. In addition, we examined the new paradigm of AF care in lifestyle and risk factor management that has been shown to arrest and reverse the atrial remodelling process leading to improved AF outcomes. Expert commentary: The future of AF care is likely to require an integrated approach consisting of aggressive risk factor management in addition to the established paradigm of rate and rhythm management and anticoagulation. Translational studies on molecular therapeutics to combat atrial fibrosis is urgently needed.
Publisher: Elsevier BV
Date: 06-2020
Publisher: Elsevier BV
Date: 07-2020
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2013
DOI: 10.1161/CIRCEP.112.976654
Abstract: The pivot is critical to rotors postulated to maintain atrial fibrillation (AF). We reasoned that wavefronts circling the pivot should broaden the litude distribution of bipolar electrograms because of directional information encoded in these signals. We aimed to determine whether Shannon entropy (ShEn), a measure of signal litude distribution, could differentiate the pivot from surrounding peripheral regions and thereby assist clinical rotor mapping. Bipolar electrogram recordings were studied in 4 systems: (1) computer simulations of rotors in a 2-dimensional atrial sheet (2) isolated rat atria recorded with a multi-electrode array (n=12) (3) epicardial plaque recordings of induced AF in hypertensive sheep (n=11) and (4) persistent AF patients (n=10). In the model systems, rotation episodes were identified, and ShEn calculated as an index of litude distribution. In humans, ShEn distribution was analyzed at AF termination sites and with respect to complex fractionated electrogram mean. We analyzed rotation episodes in simulations (4 cycles) and animals (rats: 14 rotors, duration 80±81 cycles sheep: 13 rotors, 4.2±1.5 cycles). The maximum ShEn bipole was consistently colocated with the pivot zone. ShEn was negatively associated with distance from the pivot zone in simulated spiral waves, rats, and sheep. ShEn was modestly inversely associated with complex fractionated electrogram however, there was no relationship at the sites of highest ShEn. ShEn is a mechanistically based tool that may assist AF rotor mapping.
Publisher: Springer Science and Business Media LLC
Date: 17-01-2023
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.COMPBIOMED.2010.02.001
Abstract: Atrial fibrillation is the most common type of arrhythmia to affect humans. One of the treatment modalities for atrial fibrillation is an electrical cardioversion. Electrical cardioversion can result in one of three outcomes: an immediate termination of arrhythmic activity, a delayed termination or unsuccessful termination. The mechanism of delayed termination is unknown. Here we present a model of an atrial fibrillation as a coexistence of several spiral waves pinned to the inhomogeneities in active media. We show that in inhomogeneous system delayed termination can be explained as the unpinning of a spiral wave from inhomogeneities and its termination after collision with the edge of the system.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-04-2020
Abstract: The association between mitral valve prolapse (MVP) and sudden death remains controversial. We aimed to describe histopathological changes in in iduals with autopsy‐determined isolated MVP ( iMVP ) and sudden death and document cardiac arrest rhythm. The Australian National Coronial Information System database was used to identify cases of iMVP between 2000 and 2018. Histopathological changes in iMVP and sudden death were compared with 2 control cohorts matched for age, sex, height, and weight (1 group with noncardiac death and 1 group with cardiac death). Data linkage with ambulance services provided cardiac arrest rhythm for iMVP cases. From 77 221 cardiovascular deaths in the National Coronial Information System database, there were 376 cases with MVP . In idual case review yielded 71 cases of iMVP . Mean age was 49±18 years, and 51% were women. In iduals with iMVP had higher cardiac mass (447 g versus 355 g P .001) compared with noncardiac death, but similar cardiac mass (447 g versus 438 g P =0.64) compared with cardiac death. In iduals with iMVP had larger mitral valve annulus compared with noncardiac death (121 versus 108 mm P .001) and cardiac death (121 versus 110 mm P =0.002), and more left ventricular fibrosis (79% versus 38% P .001) compared with noncardiac death controls. In those with iMVP and witnessed cardiac arrest, 94% had ventricular fibrillation. In iduals with iMVP and sudden death have increased cardiac mass, mitral annulus size, and left ventricular fibrosis compared with a matched cohort, with cardiac arrest caused by ventricular fibrillation. The histopathological changes in iMVP may provide the substrate necessary for development of malignant ventricular arrhythmias.
Publisher: OMICS Publishing Group
Date: 04-2013
DOI: 10.2217/ICA.13.2
Publisher: Springer Science and Business Media LLC
Date: 12-04-2018
DOI: 10.1007/S00392-018-1248-9
Abstract: Sleep apnea is associated with increased cardiovascular risk and may be important in atrial fibrillation (AF) management. It is present in up to 62% of the AF population and is highly under-recognized and underdiagnosed. Obstructive sleep apnea (OSA) is strongly associated with AF and non-randomized trials have shown that its treatment can help to reduce AF recurrences and maintain sinus rhythm. The 2016 European Society of Cardiology guidelines for the management of AF recommend that AF patients should be questioned regarding the symptoms of OSA and that OSA-treatment should be optimized to improve AF treatment results. However, strategies on how to implement OSA testing in the standard work-up of AF patients are not provided in the guidelines. Additionally, overnight OSA monitoring rather than interrogation for OSA-related clinical signs alone may be necessary to reliably identify OSA in the majority of AF patients. This review summarizes the available clinical data on OSA in AF patients, and discusses the following key questions: Why and When is testing for OSA needed in AF patients? How and Where should it be performed and coordinated? and Who should test for OSA? To implement OSA testing in a cardiology or electrophysiology clinic, we propose a multidisciplinary integrated care approach based on a chronic care model. We describe the tools, infrastructure and coordination needed to test for OSA in the standard workup of patients with symptomatic AF prior to the initiation of directed invasive or pharmacological rhythm control management.
Publisher: Elsevier BV
Date: 02-2015
Publisher: Springer Science and Business Media LLC
Date: 28-05-2020
Publisher: Oxford University Press (OUP)
Date: 06-03-2007
Abstract: To evaluate the contribution of the posterior left atrium (LA) to chronic atrial fibrillation (AF). Twenty-seven patients with chronic-AF were studied. After pulmonary vein (PV) isolation, the posterior-LA was isolated by ablation joining the right- and left-PVs using an irrigated-tip catheter. Isolation was demonstrated by absent/dissociated posterior-LA activity and the inability to pace the region. Ablation impact was determined by the effect on cycle length (CL) and AF termination. Posterior-LA isolation was achieved using 35 +/- 12 min of radiofrequency with total fluoroscopic and procedural durations of 64 +/- 16 and 199 +/- 46 min, resulting in abolition of electrograms (n = 21) or autonomous activity (n = 6 CL 820 +/- 343 ms). AFCL increased from 156 +/- 28 ms to 162 +/- 27 ms with PV-isolation and to 175 +/- 32 ms by posterior-LA exclusion (P < 0.0001). AF persisted in all after PV-isolation and terminated in 5 (19%) during posterior-LA-isolation. After 10 +/- 6 months, 12 patients developed atrial tachycardia (four) or AF (eight) four underwent repeat posterior-LA-isolation, while the others required additional ablation/antiarrhythmics. After 21 +/- 5 months, 17 (63%) were in sinus rhythm following posterior-LA-isolation. This study demonstrates the feasibility of complete posterior-LA exclusion by catheter ablation. This strategy results in maintenance of sinus rhythm in 63% at 2 years follow-up.
Publisher: Wiley
Date: 10-01-2007
DOI: 10.1111/J.1540-8167.2006.00713.X
Abstract: Pulmonary vein (PV) arrhythmogenicity underlying the maintenance of atrial fibrillation (AF) may be explained by three mechanisms: enhanced automaticity, triggered activity, and reentry. There are only a few reports describing sustained PV tachycardias (PVT) following electrical disconnection from the left atrium, in which the electrophysiological features are most consistent with a reentrant mechanism. We describe the case of a patient with paroxysmal AF demonstrating PVT within an isolated PV with high-density mapping revealing two different PVTs interacting in a "ping-pong" manner.
Publisher: Springer Science and Business Media LLC
Date: 13-12-2017
DOI: 10.1007/S10840-017-0299-6
Abstract: Protected channels of surviving myocytes in late postinfarction ventricular scar predispose to ventricular tachycardia (VT). However, only a few patients develop VT spontaneously. We studied differences in electric remodeling and protected channels in late postinfarction patients with and without spontaneous VT. Patients with ischemic cardiomyopathy (ICM) with recurrent sustained monomorphic VT (n = 22) were compared with stable ICM patients without spontaneous VT (control group n = 5). Left ventricular mapping was performed with a 20-pole catheter. Detailed pace mapping was used to identify channels of protected conduction, and confirmed, when feasible, by entrainment. Anatomical and electrophysiological properties of VT channels and non-VT channels in VT patients and channels in controls were evaluated. Seventy-three (median 3) VTs were inducible in VT patients compared to two (median 0) in controls. The VT channels in VT patients (n = 57, 3 ± 1 per patient) were lengthier (mean ± SEM 53 ± 5 vs. 33 ± 4 vs. 24 ± 8 mm), had longer S-QRS (73 ± 4 vs. 63 ± 3 vs. 44 ± 8 ms), longer conduction time (103 ± 13 vs. 33 ± 4 vs. 24 ± 8 ms), and slower conduction velocity (CV) (0.85 ± 0.21 vs. 1.39 ± 0.20 vs. 1.31 ± 0.41 m/s) than non-VT channels in VT patients (n = 183, 8 ± 6 per patient) (p ≤ 0.01) and channels in controls (n = 46, 9 ± 8 per patient) (p ≤ 0.01). Additionally, non-VT channels in VT patients had longer S-QRS (p = 0.02) however, they were similar in length, conduction time, and CV compared to channels in controls. Channels supporting VT are lengthier, with longer conduction times and slower CV compared to channels in patients without spontaneous VT. These observations may explain why some ICM patients have spontaneous VT and others do not.
Publisher: Oxford University Press (OUP)
Date: 24-06-2013
Abstract: Percutaneous coronary intervention (PCI) and catheter ablation are well-accepted therapeutic interventions for treatment of coronary artery disease and atrial fibrillation (AF), respectively. We sought to examine temporal trends in the provision of these services over the past decade in Australia. A retrospective review of the numbers of PCIs and AF ablations from 2000/01 to 2009/10 was performed on data from three sources: the Australian Institute of Health, Welfare and Aging (AIHW), Medicare Australia database (MA), and local records at a high volume tertiary referral centre (RMH) for AF ablation. Linear regression models were fitted comparing trends in population-adjusted procedural numbers over the 10-year period. There was a 5% per year population-adjusted increment in PCIs over 10 years from both the AIHW and MA sources, respectively (P < 0.001). This was similar to the growth rate of all cardiovascular procedures (AIHW: 5.1 vs. 3.8%/year, P = 0.27). Atrial fibrillation ablations showed a 30.9, 23.2, and 39.8% per year population-adjusted increment over 10 years from the AIHW, MA, and RMH sources respectively (P < 0.001 for all). Growth of AF ablations was significantly higher than PCIs (P < 0.001 for AIHW and MA sources) and all cardiovascular procedures (AIHW: 30.9 vs. 3.8%/year, P < 0.001). The provision of catheter-based AF ablation services in Australia has increased exponentially over the past decade. Its annual growth rate exceeded that of PCIs and all cardiovascular procedures. Given the increasing epidemic of AF, these data have critical implications for public health policy assessing the adequacy of infrastructure, training, and funding for AF ablation services.
Publisher: Oxford University Press (OUP)
Date: 03-2005
Abstract: Catheter ablation of atrial fibrillation (AF) is centred on pulmonary vein (PV) ablation with or without additional atrial substrate modification. These procedures may be prolonged with significant fluoroscopy exposure. This study evaluates a new non-fluoroscopic navigation system during ablation of AF. Seventy-two patients undergoing catheter ablation of symptomatic drug refractory AF were prospectively randomized to ablation with (n=35 study group) or without (n=37 control group) non-fluoroscopic navigation. PV isolation was performed in all patients. In patients with persistent or inducible sustained AF after PV isolation linear ablation was performed by joining the superior PVs. PV isolation was achieved in all patients fluoroscopy (15.4+/-3.4 vs. 21.3+/-6.4 min P<0.001) and procedural (52+/-12 vs. 61+/-17 min P=0.02) durations were significantly reduced in the study group. Linear block was achieved in 37 of the 39 patients with a significant reduction in fluoroscopy (5.6+/-2.2 vs. 9.9+/-4.8 min P=0.003) and procedural (14.7+/-5.5 vs. 26.6+/-16.9 min P=0.007) durations in the study group. After a follow-up of 6.9+/-2.9 months (range 3-10), 26 (74%) patients in the non-fluoroscopic navigation group and 29 (78%) patients in the control group were arrhythmia-free after the first procedure. This prospectively randomized study demonstrates significant reduction of fluoroscopy exposure and procedural duration using supplementary non-fluoroscopic imaging system for AF ablation.
Publisher: Elsevier BV
Date: 10-2018
Publisher: Elsevier BV
Date: 12-2020
Publisher: SPIE
Date: 27-12-2007
DOI: 10.1117/12.696691
Publisher: Springer Science and Business Media LLC
Date: 12-10-2018
DOI: 10.1007/S11886-018-1082-8
Abstract: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in humans, affecting more than 33 million people globally. Its association with complex, resource intensive medical conditions such as stroke, heart failure and dementia have had profound impacts across existing health care structures. The global prevalence of AF has enjoyed significant growth despite significant improvement in our armamentarium for arrhythmia treatment. Efforts aimed at curtailing the incidence, prevalence, or progression of AF have prompted re-evaluation of traditional frameworks for understanding and managing this debilitating disease. It is in this context that focus has shifted toward lifestyle-associated factors such as obesity, hypertension, sleep apnoea, exercise, alcohol and diet, as mechanistic drivers and putative targets for therapy. Compelling evidence exists for weight loss and management of associated risk factors to improve outcomes of AF treatment. This review will address the epidemiologic and mechanistic evidence that link lifestyle-associated factors with AF and in light of this analysis evaluate the clinical impacts of their upstream management. Traditional paradigms of AF are shifting in light of emerging evidence, such that risk factor modification has become positioned as the fourth pillar of AF management.
Publisher: Wiley
Date: 02-05-2006
DOI: 10.1111/J.1540-8167.2006.00505.X
Abstract: Nonpulmonary vein sources have been implicated as potential drivers of atrial fibrillation (AF). This observational study describes regions of fibrillating atrial tissue isolated inadvertently from the left atrium (LA) following linear catheter ablation for AF. We report four patients with persistent ermanent AF who underwent pulmonary vein isolation with additional linear lesions and who presented with recurrent AF (mean AF cycle length [AFCL] 175-270 ms). Further catheter ablation resulted in the inadvertent electrical isolation of significant areas of the LA in which AF persisted at the same AFCL as was measured prior to disconnection, despite the restoration of sinus rhythm (SR) in all other left and right atrial areas, strongly suggesting that these islands were driving the remaining atria into fibrillation. The disconnected areas were located in the lateral LA, including the left atrial appendage (LAA) in three patients (limited to the LAA in one) and in the posterior LA in one patient. These isolated fibrillating regions represented 15-24% of the global LA surface, as estimated by electroanatomic mapping. Fibrillation can be maintained within electrically isolated regions of the LA following catheter ablation of AF, demonstrating the importance of atrial drivers in the maintenance of AF. Further mapping of these drivers is needed to characterize their mechanism and thereby allow for a more specific ablation strategy.
Publisher: Wiley
Date: 05-03-2020
DOI: 10.1111/JCE.14422
Publisher: Wiley
Date: 28-02-2018
DOI: 10.1111/JCE.13456
Publisher: Oxford University Press (OUP)
Date: 18-11-2020
DOI: 10.1093/EURHEARTJ/EHAA822
Abstract: Chronic obstructive pulmonary disease (COPD) is highly prevalent among patients with atrial fibrillation (AF), shares common risk factors, and adds to the overall morbidity and mortality in this population. Additionally, it may promote AF and impair treatment efficacy. The prevalence of COPD in AF patients is high and is estimated to be ∼25%. Diagnosis and treatment of COPD in AF patients requires a close interdisciplinary collaboration between the electrophysiologist/cardiologist and pulmonologist. Differential diagnosis may be challenging, especially in elderly and smoking patients complaining of unspecific symptoms such as dyspnoea and fatigue. Routine evaluation of lung function and determination of natriuretic peptides and echocardiography may be reasonable to detect COPD and heart failure as contributing causes of dyspnoea. Acute exacerbation of COPD transiently increases AF risk due to hypoxia-mediated mechanisms, inflammation, increased use of beta-2 agonists, and autonomic changes. Observational data suggest that COPD promotes AF progression, increases AF recurrence after cardioversion, and reduces the efficacy of catheter-based antiarrhythmic therapy. However, it remains unclear whether treatment of COPD improves AF outcomes and which metric should be used to determine COPD severity and guide treatment in AF patients. Data from non-randomized studies suggest that COPD is associated with increased AF recurrence after electrical cardioversion and catheter ablation. Future prospective cohort studies in AF patients are needed to confirm the relationship between COPD and AF, the benefits of treatment of either COPD or AF in this population, and to clarify the need and cost-effectiveness of routine COPD screening.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-11-2004
DOI: 10.1161/01.CIR.0000146917.75041.58
Abstract: Background— This prospective clinical study evaluates the feasibility and efficacy of combined linear mitral isthmus ablation and pulmonary vein (PV) isolation in patients with paroxysmal atrial fibrillation (AF). Methods and Results— One hundred consecutive patients (13 women age 55±10 years) with drug-refractory, symptomatic paroxysmal AF underwent PV isolation and linear ablation of the cavotricuspid isthmus and the mitral isthmus (lateral mitral annulus to the left inferior PV). They were compared with 100 consecutive patients (14 women age, 52±10 years) undergoing PV isolation and cavotricuspid ablation without mitral isthmus ablation. Bidirectional mitral isthmus block was confirmed by demonstrating (1) a parallel corridor of double potentials during coronary sinus (CS) pacing, (2) an activation detour by pacing either side of the line, and (3) differential pacing techniques. Isolation of all PVs and cavotricuspid isthmus ablation were performed successfully in all. Mitral isthmus block was achieved in 92 patients after 20±10 minutes of endocardial radiofrequency application and an additional 5±4 minutes of epicardial radiofrequency application from within the CS in 68, resulting in a conduction delay of 151±26 ms during CS pacing. Thirty-two patients with mitral isthmus ablation compared with 49 without had recurrent atrial arrhythmia ( P =0.02) requiring further ablation. At 1 year after the last procedure, 87 patients with mitral isthmus ablation and 69 without ( P =0.002) were arrhythmia free without antiarrhythmic drugs, mitral isthmus ablation being the only factor associated with long-term success (RR for AF recurrence, 0.2 CI, 0.1 to 0.4 P .001). Conclusions— Catheter ablation of the mitral isthmus results consistently in demonstrable conduction block and is associated with a high cure rate for paroxysmal AF.
Publisher: Massachusetts Medical Society
Date: 23-10-2008
Location: Australia
No related grants have been discovered for Prashanthan Sanders.