ORCID Profile
0000-0001-7753-1318
Current Organisations
Royal Adelaide Hospital
,
University of Adelaide
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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: 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: 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: 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: 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: Elsevier BV
Date: 04-2020
Publisher: Elsevier BV
Date: 11-2018
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2021
Publisher: Wiley
Date: 18-04-2009
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: 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: 06-2015
DOI: 10.1016/J.JACEP.2015.04.004
Abstract: The purpose of this study was to quantify the magnitude of association between incremental increases in body mass index (BMI) and the development of incident, post-operative, and post-ablation atrial fibrillation (AF). Obesity has been estimated to account for one-fifth of all AF and approximately 60% of recent increases in population AF incidence. From a public health perspective, obesity, therefore, is a modifiable risk factor that could be profitably targeted. A systematic review and meta-analysis was conducted. Medline and EMBASE databases were searched for observational studies reporting data on the association between obesity and incident, post-operative, and post-ablation AF. Studies were included if they reported or provided data allowing calculation of risk estimates. Data from 51 studies including 626,603 in iduals contributed to this analysis. There were 29% (odds ratio [OR]: 1.29, 95% confidence interval [CI]: 1.23 to 1.36) and 19% (OR: 1.19, 95% CI: 1.13 to 1.26) greater excess risks of incident AF for every 5-U BMI increase in cohort and case-control studies, respectively. Similarly, there were 10% (OR: 1.10, 95% CI: 1.04 to 1.17) and 13% (OR: 1.13, 95% CI: 1.06 to 1.22) greater excess risks of post-operative and post-ablation AF for every 5-U increase in BMI, respectively. Incremental increases in BMI are associated with a significant excess risk of AF in different clinical settings. For every 5-U increase in BMI, there were 10% to 29% greater excess risks of incident, post-operative, and post-ablation AF. By providing a comprehensive and reliable quantification of the relationship between incremental increases in obesity and AF across different clinical settings, our findings highlight the potential for even moderate reductions in population body mass indexes to have a significant effect in mitigating the rising burden of AF.
Publisher: Elsevier BV
Date: 03-2016
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: Elsevier BV
Date: 03-2019
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
Date: 2017
Publisher: Wiley
Date: 06-2018
DOI: 10.1002/CLC.22967
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.IJCARD.2015.07.057
Abstract: Temporal dynamics of electrical wave propagation during AF is unknown. There are reports of transient linking of atrial activation. We aim to characterize temporal dynamics of wave propagation patterns during AF in an established chronically remodeled substrate. Bi-atrial epicardial mapping of AF (mean duration 62±61s) was performed in 13 sheep with induced hypertension using custom-designed plaques. Wave propagation patterns were classified into periods of repetitive activity termed modes. In total, we identified 9241 distinct depolarization events which were classified as: passing wave (69% occurrence, 68.6% of total time), point source (20.4%, 13.1%), wave collision (4%, 2.8%), re-entrant wave (0.7%, 6.3%), half-rotation (2.9%, 4.4%), wave splitting (2.7%, 4.3%), conduction block (0.05%, 0.03%) and figure of eight reentry (0.05%, 0.05%). Episodes of re-entrant activity had mean length 701±1012ms. A total of 435 modes of distinct periods of repetitive activity were detected (121 in LA and 314 in RA). Looking at temporal changes between modes, we found a preferential transition: change between train of waves propagating from direction of coronary sinus and reentrant activity. High density mapping of the hypertensive fibrillating atria observed 20% point sources and 0.7% of reentrant activation which may have served as drivers of AF. Remaining activations were peripheral waves. Majority of the activation was organized into events of transient linking with existence of preferential types of transitions. These findings support the importance of substrate based regions of anatomically or functionally determined preferential conduction in the maintenance of AF.
Publisher: Elsevier
Date: 2013
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: 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: Elsevier BV
Date: 05-2012
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: 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: 03-2020
Publisher: Elsevier BV
Date: 11-2020
Publisher: Oxford University Press (OUP)
Date: 25-04-2017
Abstract: Besides the inhibition of the sodium inward current, vernakalant also inhibits the ultra rapid rectifier (IKur) and transient outward current (Ito). Inhibition of these currents increases contractility in canine atrial myocytes and goat atria. We investigated the effect of vernakalant on early repolarization and contractility in normal and electrically remodelled atria. Goats were implanted a pressure catheter, piezoelectric crystals, and electrodes to obtain atrial contractility and effective refractory period (ERP). The active component in pressure distance loops was used to compute the atrial work index (AWI). Experiments were performed in normal and electrically remodelled atria at clinically relevant plasma levels of vernakalant. As a positive control, the Ito/IKur blocker AVE0118 was investigated. Monophasic action potentials were recorded in anaesthetized goats and in explanted hearts to determine changes in action potential morphology. Vernakalant did not affect atrial work loops during sinus rhythm. Likewise vernakalant did not increase atrial fractional shortening or AWI during pacing with fixed heart rate and AV-delay. In contrast, AVE0118 did increase AWI, with a positive force frequency relation. Both in normal and remodelled atria, vernakalant strongly increased ERP but did not prolong early repolarization. In goat atria, vernakalant does not have an atrial positive inotropic effect and does not affect early repolarization. At high rates vernakalant may even have a negative inotropic effect.
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: 06-2015
DOI: 10.1016/J.JACC.2015.04.029
Abstract: Remote monitoring (RM) of implantable cardioverter-defibrillators (ICD) is an established technology integrated into clinical practice. One recent randomized controlled trial (RCT) and several large device database studies have demonstrated a powerful survival advantage for ICD patients undergoing RM compared with those receiving conventional in-office (IO) follow-up. This study sought to conduct a systematic published data review and meta-analysis of RCTs comparing RM with IO follow-up. Electronic databases and reference lists were searched for RCTs reporting clinical outcomes in ICD patients who did or did not undergo RM. Data were extracted from 9 RCTs, including 6,469 patients, 3,496 of whom were randomized to RM and 2,973 to IO follow-up. In the RCT setting, RM demonstrated clinical outcomes comparable with office follow-up in terms of all-cause mortality (odds ratio [OR]: 0.83 p = 0.285), cardiovascular mortality (OR: 0.66 p = 0.103), and hospitalization (OR: 0.83 p = 0.196). However, a reduction in all-cause mortality was noted in the 3 trials using home monitoring (OR: 0.65 p = 0.021) with daily verification of transmission. Although the odds of receiving any ICD shock were similar in RM and IO patients (OR: 1.05 p = 0.86), the odds of inappropriate shock were reduced in RM patients (OR: 0.55 p = 0.002). Meta-analysis of RCTs demonstrates that RM and IO follow-up showed comparable overall outcomes related to patient safety and survival, with a potential survival benefit in RCTs using daily transmission verification. RM benefits include more rapid clinical event detection and a reduction in inappropriate shocks.
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: Elsevier BV
Date: 11-2018
Publisher: Wiley
Date: 10-01-2007
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: 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: 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: 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: Wiley
Date: 05-12-2015
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: 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: Wiley
Date: 27-07-2017
Publisher: Elsevier BV
Date: 02-2018
Publisher: Informa UK Limited
Date: 12-2017
DOI: 10.2147/VHRM.S127393
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.JACEP.2015.12.014
Abstract: This study sought to characterize the clinical characteristics, atrial substrate, and prognosis in a subgroup of patients with persistent atrial fibrillation (AF) from the onset (PsAFonset). Patients with AF frequently progress from trigger-driven paroxysmal arrhythmias to substrate-dependent persistent arrhythmias. Patients referred for persistent AF (PsAF) ablation were enrolled from 3 centers. Consecutive patients with PsAFonset (n = 129) were compared with patients with PsAF that progressed from paroxysmal AF (n = 231). In addition, 90 patients (30 patients with PsAFonset and 60 control subjects) were studied with noninvasive mapping to characterize the AF drivers. The degree of fractionation and endocardial voltages were assessed invasively. Patients with PsAFonset were younger (p = 0.047) and more obese (p < 0.001) there were more men (p = 0.034), more patients with hypertension (p = 0.044), and these patients had larger left (p < 0.05) and right atria (p < 0.05). Baseline AF cycle length was shorter in the PsAFonset group (p < 0.01) the degree of fractionation was higher (p < 0.001 for both atria), and the endocardial voltage was lower (p < 0.05 for both atria). Patients with PsAFonset had higher a number of re-entrant driver regions (p < 0.001) and extrapulmonary vein regions that had re-entrant drivers (p < 0.05), whereas control subjects displayed more focal driver regions (p = 0.029). The acute AF termination rate was lower in the PsAFonset group (42% vs. 81% p < 0.001). During a mean follow-up of 17 ± 11 months from the last procedure, patients with PsAFonset had significantly higher AF, atrial tachycardia (AT), and AF/AT recurrence rates (p < 0.01). Patients with PsAFonset represent a distinct subgroup defined by specific demographics, underlying diffuse biatrial substrate disease, and worse clinical outcome. The findings highlight the importance of defining criteria for early detection of atrial substrate disease.
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: 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: Elsevier BV
Date: 02-2019
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: 08-2022
DOI: 10.1016/J.HLC.2022.03.004
Abstract: Requests from the emergency department (ED) for cardiac implantable electronic device (CIED) checks constitute a large workload for cardiac electrophysiology services. We sought to determine the yield of, and clinical characteristics associated with, clinically relevant (remarkable) issues from ED CIED checks. Consecutive CIED checks from our ED over a 12-month period were studied. A remarkable issue (RI) was defined as arrhythmia relating to the presentation or device/lead issue requiring reprogramming or intervention. The association between the presenting complaint and an RI was assessed using regression analysis. Multivariable regression model was used to identify pre-specified patient-level characteristics that were predictive of a RI. A RI was found in 28% (n=98) of 354 ED CIED checks for 306 patients (76±16 yrs 59% male). Most patients had no RI (n=224 73%). One third of checks occurred after-hours and these had a higher yield of RIs than those during routine clinic hours (35% vs 23% p=0.018). Presenting with a perceived ICD shock was predictive of a RI (odds ratio [OR] 6.0 95% CI=1.8-20.0). Syncope resyncope was five-fold less likely to be predictive of a RI (OR 0.19 95% CI=0.13-0.28) despite being the most common indication for CIED check (51% n=180 checks). Only history of AF was predictive of RI while advancing age was predictive of not finding a RI. Almost three-quarters of ED CIED checks did not yield any RI. Patient-reported ICD shock and history of AF were predictive of RI, while syncope resyncope was not. New models of care especially during after-hours, may help to reduce the burden on cardiac electrophysiology services and health care costs.
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: 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: Public Library of Science (PLoS)
Date: 03-01-2023
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: 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: 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: Elsevier BV
Date: 02-2023
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: 11-2021
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: Oxford University Press (OUP)
Date: 12-04-2016
Abstract: Atrial fibrillation (AF) produces a hypercoagulable state. Stimulation of protease-activated receptors by coagulation factors provokes pro-fibrotic, pro-hypertrophic, and pro-inflammatory responses in a variety of tissues. We studied the effects of thrombin on atrial fibroblasts and tested the hypothesis that hypercoagulability contributes to the development of a substrate for AF. In isolated rat atrial fibroblasts, thrombin enhanced the phosphorylation of the pro-fibrotic signalling molecules Akt and Erk and increased the expression of transforming growth factor β1 (2.7-fold) and the pro-inflammatory factor monocyte chemoattractant protein-1 (6.1-fold). Thrombin also increased the incorporation of The hypercoagulable state during AF causes pro-fibrotic and pro-inflammatory responses in adult atrial fibroblasts. Hypercoagulability promotes the development of a substrate for AF in transgenic mice and in goats with persistent AF. In AF goats, nadroparin attenuates atrial fibrosis and the complexity of the AF substrate. Inhibition of coagulation may not only prevent strokes but also inhibit the development of a substrate for AF.
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: 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: 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: Ovid Technologies (Wolters Kluwer Health)
Date: 10-06-2014
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: 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: 09-2018
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: 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: Public Library of Science (PLoS)
Date: 17-11-2014
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: 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: Oxford University Press (OUP)
Date: 17-11-2016
Abstract: Intensive research over the last few decades has seen significant advances in our understanding of the complex mechanisms underlying atrial fibrillation (AF). The epidemic of AF and related hospitalizations has been described as a 'rising tide' with estimates of the global AF burden showing no sign of retreat. There is urgency for effective translational programs in this field to facilitate more in idualized and targeted therapy to modify the abnormal atrial substrate responsible for the perpetuation of this arrhythmia. In this review, we chose to focus on several novel aspects of AF pathogenesis whereby practical applications in clinical practice are currently available or potentially not too far away. Specifically, we explored the contribution of atrial fibrosis, epicardial adipose tissue, autonomic nervous system, hyper-coagulability, and focal drivers to adverse atrial remodelling and AF persistence. We also highlighted the potential practical means of monitoring and targeting these factors to achieve better outcomes in patients suffering from this debilitating illness. Emerging data also support a new paradigm for targeting AF substrate with aggressive risk factor management. Finally, multi-disciplinary integrated care approach has shown great promise in improving cardiovascular outcomes of patients with AF along with potential cost savings.
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: Canadian Science Publishing
Date: 05-2016
Abstract: We describe a novel approach for simultaneously determining regional differences in action potential (AP) morphology and tissue electrophysiological properties in isolated atria. The epicardial surface of rat atrial preparations was placed in contact with a multi-electrode array (9 × 10 silver chloride electrodes, 0.1 mm diameter and 0.1 mm pitch). A glass microelectrode (100 MΩ) was simultaneously inserted into the endocardial surface to record intracellular AP from either of 2 regions (A, B) during pacing from 2 opposite corners of the tissue. AP duration at 80% of repolarisation and its restitution curve was significantly different only in region A (p 0.01) when AP was initiated at different stimulation sites. Alternans in AP duration and AP litude, and in conduction velocity were observed during 2 separate arrhythmic episodes. This approach of combining microelectrode array and intracellular membrane potential recording may provide new insights into arrhythmogenic mechanisms in animal models of cardiovascular disease.
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: 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: 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: 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: 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: Elsevier BV
Date: 06-2022
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: 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: 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: 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: Wiley
Date: 03-03-2020
DOI: 10.1002/JOA3.12325
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-04-2018
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.JACC.2015.06.488
Abstract: Obesity begets atrial fibrillation (AF). Although cardiorespiratory fitness is protective against incident AF in obese in iduals, its effect on AF recurrence or the benefit of cardiorespiratory fitness gain is unknown. This study sought to evaluate the role of cardiorespiratory fitness and the incremental benefit of cardiorespiratory fitness improvement 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 risk factor management and participation in a tailored exercise program. After exclusions, 308 patients were included in the analysis. Patients underwent exercise stress testing to determine peak metabolic equivalents (METs). To determine a dose response, cardiorespiratory fitness was categorized as: low ( 100%). Impact of cardiorespiratory fitness gain was ascertained by the objective gain in fitness at final follow-up (≥2 METs vs. <2 METs). AF rhythm control was determined using 7-day Holter monitoring and AF severity scale questionnaire. There were no differences in baseline characteristics or follow-up duration between the groups defined by cardiorespiratory fitness. Arrhythmia-free survival with and without rhythm control strategies was greatest in patients with high cardiorespiratory fitness compared to adequate or low cardiorespiratory fitness (p < 0.001 for both). AF burden and symptom severity decreased significantly in the group with cardiorespiratory fitness gain ≥2 METs as compared to <2 METs group (p < 0.001 for all). Arrhythmia-free survival with and without rhythm control strategies was greatest in those with METs gain ≥2 compared to those with METs gain <2 in cardiorespiratory fitness (p < 0.001 for both). Cardiorespiratory fitness predicts arrhythmia recurrence in obese in iduals with symptomatic AF. Improvement in cardiorespiratory fitness augments the beneficial effects of weight loss. (Evaluating the Impact of a Weight Loss on the Burden of Atrial Fibrillation [AF] in Obese Patients ACTRN12614001123639).
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: Elsevier BV
Date: 09-2023
Publisher: Wiley
Date: 03-05-2012
DOI: 10.1111/J.1540-8167.2012.02335.X
Abstract: Stability of CFAE. The efficacy of complex fractionated atrial electrograms (CFAE) ablation as additional substrate modification in atrial fibrillation (AF) patients has been shown to be highly variable. Recently, the validity of sequential CFAE mapping has been challenged by concerns regarding temporal stability of CFAE. Existing studies on CFAE stability are small with very different CFAE definitions. Here, we undertook a systematic literature review to address these controversial findings. A systematic search of the scientific literature was performed through to September 1, 2011. From a total of 162 manuscripts, 7 were identified to contain assessment of the temporal stability of CFAE in human AF. These studies included a total of 96 (80 persistent/16 paroxysmal AF) patients (79% male, mean 58 years old). Varying CFAE mapping techniques or definitions were utilized. CFAE stability averaged 81% between 2 high-density sequential fractionation maps over an average time interval of 19 minutes. However, CFAE stability only averaged at 75% from shorter term continuous recordings (mean 15 comparisons within 75 seconds). Although the variability in CFAE cycle length was small (12-15 ms), coefficients of variation in continuous electrical activity were high (up to 300%). The overall spatial distribution of CFAE was found to be stable. Nevertheless, sequential mapping may not capture all CFAE sites given their dynamic characteristics. CFAE are temporally variable in keeping with the erse mechanisms underlying their existence. The dynamic nature of CFAE will continue to pose a challenge for electrophysiologists in search of critical sites requiring ablation to combat AF. (J Cardiovasc Electrophysiol, Vol. 23, pp. 980-987, September 2012).
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: 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: 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: 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: 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: 06-2023
Publisher: No publisher found
Date: 2017
Publisher: Springer Science and Business Media LLC
Date: 03-12-2019
DOI: 10.1038/S41598-019-54342-4
Abstract: Magnetic resonance imaging (MRI) has long been contraindicated in patients with implanted pacemakers, defibrillators, and cardiac resynchronisation therapy (CRT) devices due to the risk of adverse effects through electromagnetic interference. Since many recipients of these devices will have a lifetime indication for an MRI scan, the implantable systems should be developed as ‘MRI-conditional’ (be safe for the MRI environment under predefined conditions). We evaluated the clinical safety of several Biotronik ProMRI (‘MRI-conditional’) defibrillator and CRT systems during head and lower lumbar MRI scans at 1.5 Tesla. The study enrolled 194 patients at 22 sites in Australia, Canada, and Europe. At ≥9 weeks after device implantation, predefined, non-diagnostic, specific absorption rate (SAR)-intensive head and lower lumbar MRI scans (total ≈30 minutes per patient) were performed in 146 patients that fulfilled pre-procedure criteria. Three primary endpoints were evaluated: freedom from serious adverse device effects (SADEs) related to MRI and defibrillator/CRT (leading to death, hospitalisation, life-threatening condition, or potentially requiring implanted system revision or replacement), pacing threshold increase, and sensing litude decrease, all at the 1-month post-MRI clinical visit. No MRI-related SADE occurred. Lead values remained stable, measured in clinic and monitored daily by the manufacturer home monitoring technology.
Publisher: Wiley
Date: 2011
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: 02-2023
DOI: 10.1016/J.HLC.2022.10.005
Abstract: Most modern cardiac implantable electronic device (CIED) systems are now compatible with magnetic resonance imaging (MRI) scans. The requirement for both pre- and post-MRI CIED checks imposes significant workload to the cardiac electrophysiology service. Here, we sought to determine the burden of CIED checks associated with MRI scans. We identified all CIED checks performed peri-MRI scans at our institution over a 3-year period between 1 July 2017 to 30 June 2020, comprising three separate financial years (FY). Device check reports, MRI scan reports and clinical summaries were collated. The workload burden was determined by assessing the occasions and duration of service. Analysis was performed to determine cost burden rojections for this service and identify factors contributing to the workload. A total of 739 CIED checks were performed in the peri-MRI scan setting (370 pre- and 369 post-MRI scan), including 5% (n=39) that were performed outside of routine hours (weekday 5 pm, and weekends). MRIs were performed for 295 patients (75±13 years old, 64% male) with a CIED (88% permanent pacemaker, and 12% high voltage device), including 49 who had more than one MRI scan. The proportion of total MRI scans for patients with a CIED in-situ increased each FY (from 0.5% of all MRIs in FY1, to 0.9% in FY2, to 1.0% in FY3). The weekly workload increased (R There is an increasing workload burden and expense associated with CIED checks in the peri-MRI setting. Appropriate budgeting, staff allocation and standardisation of automated CIED pre-programming features among manufacturers are urgently needed.
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: 04-2016
DOI: 10.1016/J.HRTHM.2015.12.009
Abstract: Vernakalant inhibits several potassium currents and causes a rate- and voltage-dependent inhibition of the sodium current. The aim of this study was to evaluate the antiarrhythmic mechanism of vernakalant in normal and electrically remodeled atria. Fourteen goats were instrumented with electrodes on both atria. Drug effects on refractory period (ERP), conduction velocity (CV), and atrial fibrillation cycle length (AFCL) were determined in normal goats (control) and after 2 (2dAF) or 11 (11dAF) days of pacing-induced atrial fibrillation (AF) in awake goats. To evaluate the contribution of changes in conduction and ERP, the same experiments were performed with flecainide and AVE0118. In a subset of goats, monophasic action potentials were recorded during anesthesia. Vernakalant dose-dependently prolonged ERP and decreased CV in CTL experiments. Both effects were maintained after 2dAF and 11dAF. After 11dAF, conduction slowed down by 8.2 ± 1.5 cm/s and AFCL increased by 55 ± 3 ms, leading to AF termination in 5 out of 9 goats. Monophasic action potential measurements revealed that ERP prolongation was due to enhanced postrepolarization refractoriness. During pacing, vernakalant had comparable effects on CV as flecainide, while effect on ERP was comparable to AVE0118. During AF, all compounds had comparable effects on median AFCL and ERP despite differences in their effects on CV during pacing. The antiarrhythmic effect of vernakalant in the goat, at clinically relevant plasma concentrations, is based on both conduction slowing and ERP prolongation due to postrepolarization refractoriness. These electrophysiological effects were not affected by long-term electrical remodeling of the atria.
Publisher: Elsevier BV
Date: 11-2015
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: Oxford University Press (OUP)
Date: 24-06-2015
Publisher: Elsevier BV
Date: 2016
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: 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: Oxford University Press (OUP)
Date: 07-2015
DOI: 10.5665/SLEEP.4796
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: Oxford University Press (OUP)
Date: 21-01-2022
Abstract: To systematic review and meta-analyse the association and mechanistic links between atrial fibrillation (AF) and cognitive impairment. PubMed, EMBASE, and Cochrane Library were searched up to 27 March 2021 and yielded 4534 citations. After exclusions, 61 were analysed 15 and 6 studies reported on the association of AF and cognitive impairment in the general population and post-stroke cohorts, respectively. Thirty-six studies reported on the neuro-pathological changes in patients with AF of those, 13 reported on silent cerebral infarction (SCI) and 11 reported on cerebral microbleeds (CMB). Atrial fibrillation was associated with 39% increased risk of cognitive impairment in the general population [n = 15: 2 822 974 patients hazard ratio = 1.39 95% confidence interval (CI) 1.25–1.53, I2 = 90.3% follow-up 3.8–25 years]. In the post-stroke cohort, AF was associated with a 2.70-fold increased risk of cognitive impairment [adjusted odds ratio (OR) 2.70 95% CI 1.66–3.74, I2 = 0.0% follow-up 0.25–3.78 years]. Atrial fibrillation was associated with cerebral small vessel disease, such as white matter hyperintensities and CMB (n = 8: 3698 patients OR = 1.38 95% CI 1.11–1.73, I2 = 0.0%), SCI (n = 13: 6188 patients OR = 2.11 95% CI 1.58–2.64, I2 = 0%), and decreased cerebral perfusion and cerebral volume even in the absence of clinical stroke. Atrial fibrillation is associated with increased risk of cognitive impairment. The association with cerebral small vessel disease and cerebral atrophy secondary to cardioembolism and cerebral hypoperfusion may suggest a plausible link in the absence of clinical stroke. PROSPERO CRD42018109185.
Publisher: Elsevier BV
Date: 2018
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: 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: 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: 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: 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: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2017
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: Public Library of Science (PLoS)
Date: 27-08-2013
Publisher: Oxford University Press (OUP)
Date: 10-01-2018
Abstract: To determine stroke risk in subclinical atrial fibrillation (AF) and temporal association between subclinical AF and stroke. Pubmed/Embase was searched for studies reporting stroke in subclinical AF in patients with cardiac implantable electronic devices (CIEDs). After exclusions, 11 studies were analysed. Of these seven studies reported prevalence of subclinical AF, two studies reported association between subclinical and clinical AF, seven studies reported stroke risk in subclinical AF, and five studies reported temporal relationship between subclinical AF and stroke. Subclinical AF was noted after CIEDs implant in 35% [interquartile range (IQR) 34-42] of unselected patients with pacing indication over 1-2.5 years. The definition and cut-off duration (for stroke risk) of subclinical AF varied across studies. Subclinical AF was strongly associated with clinical AF (OR 5.7, 95% CI 4.0-8.0, P defined cut-off duration was 1.89/100 person-year (95% CI 1.02-3.52) with 2.4-fold (95% CI 1.8-3.3, P < 0.001, I2 = 0%) increased risk of stroke as compared to patients with subclinical AF < cut-off duration (absolute risk was 0.93/100 person-year). Three studies provided mean CHADS2 score. In these studies, with mean CHADS2 score of 2.1 ± 0.1, subclinical AF was associated with annual stroke rate of 2.76/100 person-years (95% CI 1.46-5.23). After excluding patients without AF, only 17% strokes occurred in presence of ongoing AF. Subclinical AF was noted in 29% [IQR 8-57] within 30 days preceding stroke. Subclinical AF strongly predicts clinical AF and is associated with elevated absolute stroke risk albeit lower than risk described for clinical AF.
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: 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: 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: Elsevier BV
Date: 12-2022
Publisher: Elsevier BV
Date: 07-2015
DOI: 10.1016/J.IJCARD.2015.03.064
Abstract: Atrial fibrillation (AF) is a leading cause of preventable stroke in Australia. Given that anticoagulation therapy can significantly reduce this stroke risk, we sought to characterise anticoagulation use in Indigenous and non-Indigenous Australians with AF. Administrative, clinical and prescription data from patients with AF were linked. Anticoagulation use was characterised according to guideline-recommended risk scores and Indigenous status. 19,613 in iduals with AF were studied. Despite a greater prevalence of other risk factors, Indigenous Australians were significantly younger than their non-Indigenous counterparts (p<0.001) and thus had lower CHADS₂- (1.19±0.32 vs 1.99±0.47, p<0.001) and CHA₂DS₂VASc-scores (1.47 ± 0.03 vs 2.82 ± 0.08, p<0.001). Correspondingly, the percentage of Indigenous Australians with CHADS₂ ≥ 2 (39.6% vs 44.1%, p<0.001) and CHA₂DS₂VASc-scores ≥ 2 (62.9% vs 78.8%, p<0.001) was also lower. Indigenous Australians, however, had greater rates of under- and over-anticoagulation. Overall, 72.1% and 68.9% of Indigenous and non-Indigenous Australians with CHADS₂ scores ≥2, and 76.3% and 71.3% with CHA₂DS₂VASc scores ≥2, were under-anticoagulated. Similarly, 27.4% and 24.1% of Indigenous and non-Indigenous Australians with CHADS₂ scores=0, and 24.0% and 16.7% with CHA₂DS₂VASc-scores=0, were over-anticoagulated. In multivariate analyses, Indigenous Australians were more likely to receive under- or over-anticoagulation according to CHADS₂- or CHA₂DS₂VASc-score (p=0.045 and p<0.001 respectively). Anticoagulation for AF is frequently not prescribed in accordance with guideline recommendations. Under-anticoagulation in those at high stroke risk, and over-anticoagulation in those at low risk, is common and more likely in Indigenous patients with AF. Improving adherence to guideline recommendations for anticoagulation in AF may reduce both ischaemic and haemorrhagic strokes in Indigenous and non-Indigenous Australians.
Publisher: Elsevier BV
Date: 2016
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: Wiley
Date: 2011
Publisher: Oxford University Press (OUP)
Date: 17-02-2015
Abstract: Cardiac electrophysiology has evolved into an important subspecialty in cardiovascular medicine. This is in part due to the significant advances made in our understanding and treatment of heart rhythm disorders following more than a century of scientific discoveries and research. More recently, the rapid development of technology in cellular electrophysiology, molecular biology, genetics, computer modelling, and imaging have led to the exponential growth of knowledge in basic cardiac electrophysiology. The paradigm of evidence-based medicine has led to a more comprehensive decision-making process and most likely to improved outcomes in many patients. However, implementing relevant basic research knowledge in a system of evidence-based medicine appears to be challenging. Furthermore, the current economic climate and the restricted nature of research funding call for improved efficiency of translation from basic discoveries to healthcare delivery. Here, we aim to (i) appraise the broad challenges of translational research in cardiac electrophysiology, (ii) highlight the need for improved strategies in the training of translational electrophysiologists, and (iii) discuss steps towards building a favourable translational research environment and culture.
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: 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: 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: Springer Science and Business Media LLC
Date: 27-05-2021
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.JACEP.2015.03.011
Abstract: This study sought to determine the differences between the prothrombotic properties and chamber characteristics in patients with lone atrial fibrillation (AF) and those with AF and comorbidities. Thromboembolic risk is increased in patients with AF however, whether this is due to AF per se or its comorbidities remains unclear. A total of 87 patients undergoing ablation were prospectively recruited for the study, including 30 patients with lone AF, 30 patients with AF and comorbidities in sinus rhythm, and 27 patients with left-sided accessory pathways as controls. Blood s les were obtained from the left atrium (LA), right atrium (RA), and femoral vein (FV) after transseptal puncture. 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 in the LA was significantly elevated compared to that in the FV in patients with lone AF and those with AF and comorbidities compared with that in the FV (p < 0.05 respectively). Thrombin generation was significantly elevated in the LA compared with RA in AF patients (p < 0.05). There were no significant differences in P-selectin, TAT, and sCD40L among the 3 groups. However, there was a significant stepwise increase in endothelial dysfunction measured by ADMA from controls to lone AF and then to patients with AF and comorbidities (p < 0.001 between the 2 groups). Patients with lone AF and those with AF and comorbidities had a greater propensity for atrial thrombogenesis than controls. Prothrombotic risk is greatest in those with comorbid conditions, in whom enhanced thrombogenesis occurs predominantly through increase in endothelial dysfunction.
Publisher: Elsevier BV
Date: 11-2018
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: Elsevier BV
Date: 10-2015
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: 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: Elsevier BV
Date: 02-2015
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-02-2016
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: 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: 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: 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: Ovid Technologies (Wolters Kluwer Health)
Date: 09-05-2017
Publisher: Elsevier BV
Date: 09-2021
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: 06-2016
Publisher: Wiley
Date: 19-10-2018
DOI: 10.1002/CLC.23091
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: 17-07-2016
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: 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: IEEE
Date: 08-2012
Publisher: Wiley
Date: 13-12-2016
Abstract: Hypertrophic cardiomyopathy (HCM) is a common heritable cardiac disorder with erse clinical outcomes including sudden death, heart failure, and stroke. Depressed heart rate variability (HRV), a measure of cardiac autonomic regulation, has been shown to predict mortality in patients with cardiovascular disease. Cardiac autonomic remodelling in animal models of HCM are not well characterised. This study analysed Gly203Ser cardiac troponin-I transgenic (TG) male mice previously demonstrated to develop hallmarks of HCM by age 21 weeks. 33 mice aged 30 and 50 weeks underwent continuous electrocardiogram (ECG) recording for 30 min under anaesthesia. TG mice demonstrated prolonged P-wave duration (P < 0.001) and PR intervals (P < 0.001) compared to controls. Additionally, TG mice demonstrated depressed standard deviation of RR intervals (SDRR P < 0.01), coefficient of variation of RR intervals (CVRR P < 0.001) and standard deviation of heart rate (SDHR P < 0.001) compared to controls. Additionally, total power was significantly reduced in TG mice (P < 0.05). No significant age-related difference in either strain was observed in ECG or HRV parameters. Mice with HCM developed slowed atrial and atrioventricular conduction and depressed HRV. These changes were conserved with increasing age. This finding may be indicative of atrial and ventricular hypertrophy or dysfunction, and perhaps an indication of worse clinical outcome in heart failure progression in HCM patients.
Publisher: Informa UK Limited
Date: 03-05-2016
DOI: 10.1080/14779072.2016.1179581
Abstract: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia with a one in four lifetime risk in adults over the age of forty. Traditionally, AF management has focused on the three pillars of rate control, rhythm control and appropriate anticoagulation to reduce stroke risk. More recently, the importance of cardiovascular risk factor management in AF has emerged as a fourth and essential pillar with improved patient outcomes. Here, we aim to summarize the current available evidence for the association between various modifiable risk factors and AF, and to identify optimal treatment targets to improve outcomes. Expert Commentary: Care for AF patients utilizing an integrated approach and aggressive lifestyle management may reduce the enormous burden of this arrhythmia.
Publisher: Wiley
Date: 28-02-2018
DOI: 10.1111/JCE.13456
Publisher: Springer Science and Business Media LLC
Date: 20-06-2023
DOI: 10.1007/S10286-023-00955-9
Abstract: The effect of postural orthostatic tachycardia syndrome (POTS) on health-related quality of life (HrQoL) remains poorly studied. Here, we sought to compare the HrQoL in in iduals with POTS to a normative age-/sex-matched population. Participants enrolled in the Australian POTS registry between 5 August 2021 and 30 June 2022 were compared with propensity-matched local normative population data from the South Australian Health Omnibus Survey. The EQ-5D-5L instrument was used to assess HrQoL across the five domains (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression) with global health rating assessed with a visual analog scale (EQ-VAS). A population-based scoring algorithm was applied to the EQ-5D-5L data to calculate utility scores. Hierarchical multiple regression analyses were undertaken to explore predictors of low utility scores. A total of 404 participants ( n = 202 POTS n = 202 normative population median age 28 years, 90.6% females) were included. Compared with the normative population, the POTS cohort demonstrated significantly higher burden of impairment across all EQ-5D-5L domains (all P 0.001), lower median EQ-VAS ( p 0.001), and lower utility scores ( p .001). The lower EQ-VAS and utility scores in the POTS cohort were universal in all age groups. Severity of orthostatic intolerance symptoms, female sex, fatigue scores, and comorbid diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome were independent predictors of reduced HrQoL in POTS. The disutility in those with POTS was lower than many chronic health conditions. This is the first study to demonstrate significant impairment across all subdomains of EQ-5D-5L HrQoL in the POTS cohort as compared with a normative population. ACTRN12621001034820
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: 07-2016
DOI: 10.1016/J.ANAI.2016.04.024
Abstract: The diagnosis of allergic bronchopulmonary aspergillosis (ABPA) in asthma is often made in patients with total serum IgE levels greater than 1,000 IU/mL in conjunction with evidence of Aspergillus sensitization. The specificity of total serum IgE for the diagnosis of ABPA is low even when combined with serum Aspergillus specific IgE. To determine the prevalence of ABPA and to identify alternative clinical predictors for ABPA among asthmatic patients with a total serum IgE level greater than 1,000 IU/ml. This study was conducted in a tertiary hospital in Melbourne, Australia, with a large asthma and allergy service. Patients with asthma and total serum IgE levels greater than 1,000 IU/ml from January 1, 2005, through December 31, 2014, were included. Patients were considered to have concomitant allergic conditions if they had atopic eczema, allergic rhinitis, or both. The diagnosis of ABPA was based on the managing physician's documented diagnosis and referenced to criteria proposed by the International Society for Human and Fungal Mycology. The prevalence of ABPA in our cohort was 15.8%. Older age, elevated total serum IgE level, reduced lung function, and the absence of other concomitant allergic conditions increased the risk of ABPA. After multivariate logistic regression, patients without concomitant allergic conditions had an odds ratio of 4.4 (95% confidence interval, 1.9-10.1 P = .001) for ABPA when compared with patients with allergic conditions. The absence of atopic eczema and allergic rhinitis in these patients increases the likelihood of ABPA. Eliciting an accurate allergy history may be a useful bedside clinical tool when considering the diagnosis of ABPA.
Publisher: Elsevier BV
Date: 07-2015
DOI: 10.1016/J.JACC.2015.04.058
Abstract: Obesity and atrial fibrillation (AF) are public health issues with significant consequences. This study sought to delineate the development of global electrophysiological and structural substrate for AF in sustained obesity. Ten sheep fed ad libitum calorie-dense diet to induce obesity over 36 weeks were maintained in this state for another 36 weeks 10 lean sheep with carefully controlled weight served as controls. All sheep underwent electrophysiological and electroanatomic mapping hemodynamic and imaging assessment (echocardiography and dual-energy x-ray absorptiometry) and histology and molecular evaluation. Evaluation included atrial voltage, conduction velocity (CV), and refractoriness (7 sites, 2 cycle lengths), vulnerability for AF, fatty infiltration, atrial fibrosis, and atrial transforming growth factor (TGF)-β1 expression. Compared with age-matched controls, chronically obese sheep demonstrated greater total body fat (p < 0.001) LA volume (p < 0.001) LA pressure (p < 0.001), and PA pressures (p < 0.001) reduced atrial CV (LA p < 0.001) with increased conduction heterogeneity (p < 0.001) increased fractionated electrograms (p < 0.001) decreased posterior LA voltage (p < 0.001) and increased voltage heterogeneity (p 0.8) or ERP heterogeneity (p > 0.3). Obesity was associated with more episodes (p = 0.02), prolongation (p = 0.01), and greater cumulative duration (p = 0.02) of AF. Epicardial fat infiltrated the posterior LA in the obese group (p < 0.001), consistent with reduced endocardial voltage in this region. Atrial fibrosis (p = 0.03) and TGF-β1 protein (p = 0.002) were increased in the obese group. Sustained obesity results in global biatrial endocardial remodeling characterized by LA enlargement, conduction abnormalities, fractionated electrograms, increased profibrotic TGF-β1 expression, interstitial atrial fibrosis, and increased propensity for AF. Obesity was associated with reduced posterior LA endocardial voltage and infiltration of contiguous posterior LA muscle by epicardial fat, representing a unique substrate for AF.
Publisher: Oxford University Press (OUP)
Date: 21-07-2018
Abstract: In 2014, a joint consensus document dealing with the management of antithrombotic therapy in atrial fibrillation (AF) patients presenting with acute coronary syndrome (ACS) and/or undergoing percutaneous coronary or valve interventions was published, which represented an effort of the European Society of Cardiology Working Group on Thrombosis, European Heart Rhythm Association (EHRA), European Association of Percutaneous Cardiovascular Interventions (EAPCI), and European Association of Acute Cardiac Care (ACCA) endorsed by the Heart Rhythm Society (HRS) and Asia-Pacific Heart Rhythm Society (APHRS). Since publication of this document, additional data from observational cohorts, randomized controlled trials, and percutaneous interventions as well as new guidelines have been published. Moreover, new drugs and devices/interventions are also available, with an increasing evidence base. The approach to managing AF has also evolved towards a more integrated or holistic approach. In recognizing these advances since the last consensus document, EHRA, WG Thrombosis, EAPCI, and ACCA, with additional contributions from HRS, APHRS, Latin America Heart Rhythm Society (LAHRS), and Cardiac Arrhythmia Society of Southern Africa (CASSA), proposed a focused update, to include the new data, with the remit of comprehensively reviewing the available evidence and publishing a focused update consensus document on the management of antithrombotic therapy in AF patients presenting with ACS and/or undergoing percutaneous coronary or valve interventions, and providing up-to-date consensus recommendations for use in clinical practice.
Publisher: Elsevier BV
Date: 02-2023
No related grants have been discovered for Dennis H Lau.