ORCID Profile
0000-0002-1913-6675
Current Organisations
University of Oxford
,
University of Adelaide
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Publisher: Oxford University Press (OUP)
Date: 06-07-2019
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: 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: Springer Science and Business Media LLC
Date: 04-05-2022
DOI: 10.1186/S12872-022-02633-6
Abstract: Atrial fibrillation (AF) is the most common cardiac tachyarrhythmia and has a rising global prevalence. Given the increasing burden of AF-related symptoms and complications, new approaches to management are required. Anemia and iron deficiency are common conditions in patients with AF. Furthermore, emerging evidence suggests that the presence of anemia may be associated with worse outcome in these patients. The role of anemia and iron deficiency has been extensively explored in other cardiovascular states, such as heart failure and ischemic heart disease. In particular, the role of iron repletion amongst patients with heart failure is now an established treatment modality. However, despite the strong bidirectional inter-relationship between AF and heart failure, the implications of anemia and iron-deficiency in AF have been scarcely studied. This area is of mechanistic and clinical relevance given the potential that treatment of these conditions may improve symptoms and prognosis in the increasing number of in iduals with AF. In this review, we summarise the current published literature on anemia and iron deficiency in patients with AF. We discuss AF complications such as stroke, bleeding, and heart failure, in addition to AF-related symptoms such as exercise intolerance, and the potential impact of anemia and iron deficiency on these. Finally, we summarize current research gaps on anemia, iron deficiency, and AF, and underscore potential research directions.
Publisher: Wiley
Date: 02-02-2021
DOI: 10.1111/JCE.14898
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: Wiley
Date: 04-2009
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: Springer Science and Business Media LLC
Date: 29-08-2013
Abstract: Recently pericardial adipose tissue (PAT) has been shown to be an independent predictor of atrial fibrillation (AF). Atrial PAT may influence underlying atrial musculature creating a substrate for AF. This study sought to validate the assessment of total and atrial PAT by standard cardiovascular magnetic resonance (CMR) measures and describe and validate a three dimensional atrial PAT model. 10 merino cross sheep underwent CMR using a 1.5 Tesla system (Siemens, Sonata, Erlangen, Germany). Atrial and ventricular short axis (SA) images were acquired, using ECG -gated steady state free precession sequences. In order to quantify total volume of adipose tissue, a three dimensional model was constructed from consecutive end-diastolic images using semi-automated software. Regions of adipose tissue were marked in each slice followed by linear interpolation of pixel intensities in spaces between consecutive image slices. Total volume of adipose tissue was calculated as a total volume of the three dimensional model and the mass estimated from volume measurements. The sheep were euthanized and pericardial adipose tissue was removed and weighed for comparison to the corresponding CMR measurements. All CMR adipose tissue estimates significantly correlated with autopsy measurements (ICC 0.80 p 0.03). Intra- observer reliability in CMR measures was high, with 95% levels of agreement within 5.5% (ICC = 0.995) for total fat mass and its in idual atrial (95% CI ± 8.3%, ICC = 0.993) and ventricular components (95% CI ± 6.6%, ICC = 0.989). Inter- observer 95% limits of agreement were within ± 10.7% (ICC = 0.979), 7.4% (ICC = 0.991) and 7.2% (ICC = 0.991) for atrial, ventricular and total pericardial adipose tissue, respectively. This study validates the use of a semi-automated three dimensional atrial PAT model utilizing standard (clinical) CMR sequences for accurate and reproducible assessment of atrial PAT. The measurement of local cardiac fat stores via this methodology could provide a sensitive tool to examine the regional effect of fat deposition on atrial substrate which potentially may influence AF ablation strategies in obese patients.
Publisher: 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: 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: 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: Elsevier BV
Date: 06-2021
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.AMJCARD.2016.05.041
Abstract: Whether anxiety is a risk factor for a range of cardiovascular diseases is unclear. We aimed to determine the association between anxiety and a range of cardiovascular diseases. MEDLINE and EMBASE were searched for cohort studies that included participants with and without anxiety, including subjects with anxiety, worry, posttraumatic stress disorder, phobic anxiety, and panic disorder. We examined the association of anxiety with cardiovascular mortality, major cardiovascular events (defined as the composite of cardiovascular death, stroke, coronary heart disease, and heart failure), stroke, coronary heart disease, heart failure, and atrial fibrillation. We identified 46 cohort studies containing 2,017,276 participants and 222,253 subjects with anxiety. Anxiety was associated with a significantly elevated risk of cardiovascular mortality (relative risk [RR] 1.41, CI 1.13 to 1.76), coronary heart disease (RR 1.41, CI 1.23 to 1.61), stroke (RR 1.71, CI 1.18 to 2.50), and heart failure (RR 1.35, CI 1.11 to 1.64). Anxiety was not significantly associated with major cardiovascular events or atrial fibrillation although CIs were wide. Phobic anxiety was associated with a higher risk of coronary heart disease than other anxiety disorders, and posttraumatic stress disorder was associated with a higher risk of stroke. Results were broadly consistent in sensitivity analyses. Anxiety disorders are associated with an elevated risk of a range of different cardiovascular events, including stroke, coronary heart disease, heart failure, and cardiovascular death. Whether these associations are causal is unclear.
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: 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: Public Library of Science (PLoS)
Date: 27-08-2013
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: 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: BMJ
Date: 19-01-2016
DOI: 10.1136/BMJ.H7013
Abstract: To determine whether atrial fibrillation is a stronger risk factor for cardiovascular disease and death in women compared with men. Meta-analysis of cohort studies. Studies published between January 1966 and March 2015, identified through a systematic search of Medline and Embase and review of references. Cohort studies with a minimum of 50 participants with and 50 without atrial fibrillation that reported sex specific associations between atrial fibrillation and all cause mortality, cardiovascular mortality, stroke, cardiac events (cardiac death and non-fatal myocardial infarction), and heart failure. Two independent reviewers extracted study characteristics and maximally adjusted sex specific relative risks. Inverse variance weighted random effects meta-analysis was used to pool sex specific relative risks and their ratio. 30 studies with 4,371,714 participants were identified. Atrial fibrillation was associated with a higher risk of all cause mortality in women (ratio of relative risks for women compared with men 1.12, 95% confidence interval 1.07 to 1.17) and a significantly stronger risk of stroke (1.99, 1.46 to 2.71), cardiovascular mortality (1.93, 1.44 to 2.60), cardiac events (1.55, 1.15 to 2.08), and heart failure (1.16, 1.07 to 1.27). Results were broadly consistent in sensitivity analyses. Atrial fibrillation is a stronger risk factor for cardiovascular disease and death in women compared with men, though further research would be needed to determine any causality.
Publisher: Elsevier BV
Date: 10-2023
Publisher: Wiley
Date: 30-01-2012
DOI: 10.1111/J.1440-1681.2011.05647.X
Abstract: Endothelial function is an independent predictor of adverse cardiovascular outcomes. The evaluation of endothelial function via changes in vessel diameter or blood flow may be inaccurate during atrial fibrillation (AF) because of non-uniform stroke volumes. Using peripheral arterial tonometry, 50 patients with AF (25 in AF, 25 in sinus rhythm) had digital pulse litudes assessed at baseline and during reactive hyperaemia. Hyperaemic responses were compared over varying measurement durations (5, 10 and 15beats 30s and 1-10min) to determine optimal measurement duration. Endothelial responses were significantly decreased (indicating endothelial dysfunction) in patients in AF compared with patients in sinus rhythm (1.48±0.60 vs 2.05±1.13, respectively P=0.03). Beat-to-beat pulse litude was highly variable during AF although coefficients of variation (CV) for short measurement durations were large, these decreased with longer measurement durations. Bland-Altman plots revealed that limits of agreement for short measurement durations were poor. Limits of agreement became consistently narrower when measurement durations of at least 1min were used. In contrast, limits of agreement and CV for short measurement durations during sinus rhythm were significantly narrower and smaller, respectively, than during AF over similar measurement durations. Pulse litudes are highly variable owing to the non-uniform stroke volumes in AF. Our results suggest that methods of determining endothelial function via vessel diameters or blood flow during reactive hyperaemia should use measurement durations of at least 1min to ensure accurate and reproducible results.
Publisher: Elsevier BV
Date: 08-2022
Publisher: Public Library of Science (PLoS)
Date: 03-01-2023
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: 06-2016
DOI: 10.1016/J.AMJCARD.2016.03.042
Abstract: Atrial fibrillation (AF) is common in patients on dialysis. Although randomized trials of anticoagulation for AF have demonstrated striking reductions in stroke, these trials did not recruit patients on dialysis. We thus undertook this systematic review and meta-analysis of observational studies including patients with AF on dialysis that reported associations of anticoagulation use. Twenty studies involving 529,741 subjects and 31,321 patients with AF on dialysis were identified. Anticoagulation was associated with a 45% (95% CI 13% to 88%) increased risk of any stroke, reflecting a nonsignificant 13% (95% CI -4% to 34%) increased ischemic stroke risk and 38% (95% CI 3% to 85%) increased hemorrhagic stroke risk. There was also a 44% (95% CI 38% to 56%) lower risk of any thromboembolism, and a 31% (95% CI 12% to 53%) increased risk of any bleeding but no clear association with cardiovascular death (relative risk 0.99, 95% CI 0.86 to 1.15) or all-cause mortality (relative risk 0.97, 95% CI 0.90 to 1.04). Incident event rates were similar or worse in patients on anticoagulation. In conclusion, these observational analyses provide little supporting evidence of benefit, and instead suggest harm, from anticoagulation in patients on dialysis with AF. These results raise the possibility that the effects of anticoagulation in patients with AF on dialysis may not be similar to the clear benefit of anticoagulation seen in patients with AF without end-stage renal disease. Randomized trials are required to definitively evaluate the safety and efficacy of anticoagulation for AF in the dialysis setting.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.HRTHM.2010.01.042
Abstract: Atrial fibrillation (AF) is associated with an increased risk of thrombus formation in the left but not the right atrium. The mechanisms underlying this differential effect on the atria are unknown. The purpose of this study was to examine whether atrial-specific differences in platelet activation are present in patients with AF. Nineteen patients (13 men and 6 women age 60 +/- 2 years) with AF undergoing ablation in sinus rhythm were studied. Blood s les from the left atrium, right atrium, and femoral vein were obtained at the start of the procedure and analyzed by whole-blood flow cytometry for expression of platelet P-selectin (CD62P), vitronectin receptor (CD51/61), and active glycoprotein IIb/IIIa receptor (PAC-1). Platelet aggregation was evaluated using adenosine diphosphate (ADP)-induced whole-blood impedance aggregometry. Seven patients with left-sided accessory pathway also were studies as a reference group for the effect of transseptal puncture on platelet reactivity. Platelet P-selectin levels were significantly elevated in the left atrium compared to the right atrium (10.2% +/- 2.5% vs 8.6% +/- 2.3%, P <.05). CD51/61 and PAC-1 levels did not differ between s ling sites. ADP-induced platelet aggregation was significantly higher in the left atrium compared to the right atrium and femoral vein (P <.05 for both). Platelet P-selectin levels and ADP-induced platelet aggregation did not differ between s ling site in the reference group. In patients with AF, left atrial platelet reactivity is increased compared to the right atria and peripheral circulation. The study data suggest that the presence of chamber-specific platelet activation may explain, in part, the propensity for left atrial thrombus formation in patients with AF.
Publisher: Elsevier BV
Date: 06-2011
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: 03-2010
DOI: 10.1016/J.COMPBIOMED.2010.02.001
Abstract: Atrial fibrillation is the most common type of arrhythmia to affect humans. One of the treatment modalities for atrial fibrillation is an electrical cardioversion. Electrical cardioversion can result in one of three outcomes: an immediate termination of arrhythmic activity, a delayed termination or unsuccessful termination. The mechanism of delayed termination is unknown. Here we present a model of an atrial fibrillation as a coexistence of several spiral waves pinned to the inhomogeneities in active media. We show that in inhomogeneous system delayed termination can be explained as the unpinning of a spiral wave from inhomogeneities and its termination after collision with the edge of the system.
Publisher: Wiley
Date: 18-04-2012
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: John Wiley & Sons, Ltd
Date: 16-03-2011
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-06-2014
Publisher: Elsevier BV
Date: 04-2020
Publisher: BMJ
Date: 06-09-2016
DOI: 10.1136/BMJ.I4482
Abstract: To quantify the association between atrial fibrillation and cardiovascular disease, renal disease, and death. Systematic review and meta-analysis. Medline and Embase. Cohort studies examining the association between atrial fibrillation and cardiovascular disease, renal disease, and death. Two reviewers independently extracted study characteristics and the relative risk of outcomes associated with atrial fibrillation: specifically, all cause mortality, cardiovascular mortality, major cardiovascular events, any stroke, ischaemic stroke, haemorrhagic stroke, ischaemic heart disease, sudden cardiac death, congestive heart failure, chronic kidney disease, and peripheral arterial disease. Estimates were pooled with inverse variance weighted random effects meta-analysis. 104 eligible cohort studies involving 9 686 513 participants (587 867 with atrial fibrillation) were identified. Atrial fibrillation was associated with an increased risk of all cause mortality (relative risk 1.46, 95% confidence interval 1.39 to 1.54), cardiovascular mortality (2.03, 1.79 to 2.30), major cardiovascular events (1.96, 1.53 to 2.51), stroke (2.42, 2.17 to 2.71), ischaemic stroke (2.33, 1.84 to 2.94), ischaemic heart disease (1.61, 1.38 to 1.87), sudden cardiac death (1.88, 1.36 to 2.60), heart failure (4.99, 3.04 to 8.22), chronic kidney disease (1.64, 1.41 to 1.91), and peripheral arterial disease (1.31, 1.19 to 1.45) but not haemorrhagic stroke (2.00, 0.67 to 5.96). Among the outcomes examined, the highest absolute risk increase was for heart failure. Associations between atrial fibrillation and included outcomes were broadly consistent across subgroups and in sensitivity analyses. Atrial fibrillation is associated with an increased risk of death and an increased risk of cardiovascular and renal disease. Interventions aimed at reducing outcomes beyond stroke are warranted in patients with atrial fibrillation.
Publisher: Wiley
Date: 02-05-2012
DOI: 10.1111/J.1445-2197.2012.06086.X
Abstract: A substantial percentage of patients with colorectal cancer present with obstructive symptoms. In such patients, surgery is often required and is associated with significant morbidity and mortality. Colorectal stenting is an increasingly commonplace alternative with potentially fewer risks than open surgery. We present our clinical experience over an 8-year period with colorectal stenting in a major tertiary Australian hospital. From 2000 to 2008, patients undergoing colorectal stenting were identified via medical records. Clinical data collected included patient demographics, tumour type, extent of metastatic disease, stent characteristics, technical and clinical success, acute and chronic complications, and long-term follow-up status. Thirty-five patients (69 ± 13 years, 25 male) received a total of 39 stents. Technical success was achieved in 37 (95%), and clinical relief of obstruction was achieved in 34 (89%). One case was complicated by perforation at the time of procedure and three cases experienced delayed perforation. Reintervention was required in 17% of patients, all of whom had less than 50% hepatic volume replacement by metastatic disease. Colorectal stenting is a feasible and safe alternative for patients presenting with obstructive symptoms but the benefit may be restricted to patients with a short expected survival.
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: American Medical Association (AMA)
Date: 14-05-2012
Publisher: Oxford University Press (OUP)
Date: 24-06-2013
Abstract: Percutaneous coronary intervention (PCI) and catheter ablation are well-accepted therapeutic interventions for treatment of coronary artery disease and atrial fibrillation (AF), respectively. We sought to examine temporal trends in the provision of these services over the past decade in Australia. A retrospective review of the numbers of PCIs and AF ablations from 2000/01 to 2009/10 was performed on data from three sources: the Australian Institute of Health, Welfare and Aging (AIHW), Medicare Australia database (MA), and local records at a high volume tertiary referral centre (RMH) for AF ablation. Linear regression models were fitted comparing trends in population-adjusted procedural numbers over the 10-year period. There was a 5% per year population-adjusted increment in PCIs over 10 years from both the AIHW and MA sources, respectively (P < 0.001). This was similar to the growth rate of all cardiovascular procedures (AIHW: 5.1 vs. 3.8%/year, P = 0.27). Atrial fibrillation ablations showed a 30.9, 23.2, and 39.8% per year population-adjusted increment over 10 years from the AIHW, MA, and RMH sources respectively (P < 0.001 for all). Growth of AF ablations was significantly higher than PCIs (P < 0.001 for AIHW and MA sources) and all cardiovascular procedures (AIHW: 30.9 vs. 3.8%/year, P < 0.001). The provision of catheter-based AF ablation services in Australia has increased exponentially over the past decade. Its annual growth rate exceeded that of PCIs and all cardiovascular procedures. Given the increasing epidemic of AF, these data have critical implications for public health policy assessing the adequacy of infrastructure, training, and funding for AF ablation services.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2023
DOI: 10.1161/CIRCEP.122.011771
Abstract: Confirming the presence and participation of concealed nodo-ventricular (cNV) or concealed His-ventricular (cHV) pathways in tachyarrhythmias is challenging. We describe novel observations to aid in diagnosing cNV or cHV pathways. We present 7 cases of cNV and cHV pathway-mediated arrhythmias and focus on several laboratory observations: (1) differential ventricular overdrive pacing (VOD) from the base versus apex, (2) response to His refractory premature ventricular complexes, (3) paradoxical atriohisian response (shorter atriohisian interval during tachycardia than that during sinus rhythm) in long RP tachycardia, and (4) the role of adenosine to aid in the diagnosis. Three cases underwent differential VOD during tachycardia. All demonstrated a shorter postpacing interval minus tachycardia cycle length during basal pacing than apical pacing with one case exhibiting apical VOD results compatible with atrioventricular nodal reentrant tachycardia. Basal VOD was useful for localizing the ventricular connection in a case with cHV pathway. In 3 cases, His refractory premature ventricular complexes reset the tachycardia without conduction to the atrium, which excluded the involvement of an atrioventricular pathway or atrial tachycardia, or atrioventricular nodal reentrant tachycardia alone. One case had His refractory premature ventricular complexes followed by subsequent constant AA interval and then tachycardia termination, suggesting a bystander cNV pathway involvement. Two cNV pathway cases presented with long RP tachycardia had paradoxical atriohisian shortening of ms, suggesting parallel activation of the atrium and the atrioventricular node. Adenosine terminated the tachycardia with retrograde block in 2 cases with cNV pathways but had no response on a cHV pathway. cNV and cHV pathways mediated tachyarrhythmias can present with variable clinical presentations. We emphasize the important role of differential VOD sites, His refractory premature ventricular complexes that reset or terminate the tachycardia without conduction to the atrium, paradoxical atriohisian response in long RP tachycardia, and the use of adenosine for diagnosing cNV and cHV pathways.
Publisher: BMJ
Date: 07-11-2022
DOI: 10.1136/HEARTJNL-2022-321393
Abstract: Prior data have shown rising acute myocardial infarction (MI) trends in Australia whether these increases have continued in recent years is not known. This study thus sought to characterise contemporary nationwide trends in MI hospitalisations and coronary procedures in Australia and their associated economic burden. The primary outcome measure was the incidence and time trends of total MI, ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) hospitalisations from 1993 to 2017. The incidence and time trends of coronary procedures were additionally collected, alongside MI hospitalisation costs. Adjusted for population changes, annual MI incidence increased from 216.2 cases per 100 000 to a peak of 270.4 in 2007 with subsequent decline to 218.7 in 2017. Similarly, NSTEMI incidence increased from 68.0 cases per 100 000 in 1993 to a peak of 192.6 in 2007 with subsequent decline to 162.6 in 2017. STEMI incidence decreased from 148.3 cases per 100 000 in 1993 to 56.2 in 2017. Across the study period, there were annual increases in MI hospitalisations of 0.7% and NSTEMI hospitalisations of 5.6%, and an annual decrease in STEMI hospitalisations of 4.8%. Angiography and percutaneous coronary intervention increased by 3.4% and 3.3% annually, respectively, while coronary artery bypass graft surgery declined by 2.2% annually. MI hospitalisation costs increased by 100% over the study period, despite a decreased average length of stay by 45%. The rising incidence of MI hospitalisations appear to have stabilised in Australia. Despite this, associated healthcare expenditure remains significant, suggesting a need for continual implementation of public health policies and preventative strategies.
Publisher: 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: 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: 07-2013
DOI: 10.1016/J.AMJCARD.2013.03.014
Abstract: Although most of the additional increases in coronary heart disease morbidity and mortality are estimated to occur outside developed regions such as North America and Europe, few nationwide studies have been published of acute myocardial infarction (MI) epidemiology from other regions. We thus sought to expand the global data regarding MI trends. Nationwide trends of incident MI, ST-segment elevation MI (STEMI), and non-ST-segment MI (non-STEMI) were analyzed during a 17-year period in Australia. We identified 714,262 hospitalizations for MI from 1993 to 2010, representing 331,871,389 person-years. During the study period, the age- and gender-adjusted incidence of all MIs increased from 215 to 251 cases per 100,000 person-years, a relative increase of 76% (p <0.0001 for trend). The adjusted incidence of STEMI decreased from 147 to 70 cases per 100,000 person-years, a relative decrease of 30% (p <0.0001 for trend). In contrast, the adjusted incidence of non-STEMI increased from 67 to 182 cases per 100,000 person-years, a relative increase of 315% (p <0.0001 for trend). Age-specific analyses suggested that statistically significant increases in MI incidence were present in those aged <50 and ≥80 years. In conclusion, although it has previously been suggested that declining trends in MI incidence in North American and European reports might be generalizable given the seemingly consistent observations thus far, the present results highlight the possibility that other global populations might have less favorable trends. The incidence of MI in Australia might not be decreasing as rapidly as that seen in other regions and requires additional exploration.
Publisher: BMJ
Date: 08-2021
DOI: 10.1136/BMJOPEN-2020-047642
Abstract: Atrial fibrillation (AF) is associated with significantly impaired quality-of-life. Iron deficiency (ID) is prevalent in patients with AF. Correction of ID in other patient populations with intravenous iron supplementation has been shown to be a safe, convenient and effective way of improving exercise tolerance, fatigue and quality-of-life. The IRON-AF (Effect of Iron Repletion in Atrial Fibrillation) study is designed to assess the effect of iron repletion with intravenous ferric carboxymaltose in patients with AF and ID. The IRON-AF study is a double-blind, randomised controlled trial that will recruit at least 84 patients with AF and ID. Patients will be randomised to receive infusions of either ferric carboxymaltose or placebo, given in repletion and then maintenance doses. The study will have follow-up visits at weeks 4, 8 and 12. The primary endpoint is change in peak oxygen uptake from baseline to week 12, as measured by cardiopulmonary exercise testing (CPET) on a cycle ergometer. Secondary endpoints include changes in quality-of-life and AF disease burden scores, blood parameters, other CPET parameters, transthoracic echocardiogram parameters, 6-minute walk test distance, 7-day Holter/Event monitor burden of AF, health resource utilisation and mortality. The study protocol has been approved by the Central Adelaide Local Health Network Human Research Ethics Committee, Australia. The results of this study will be disseminated through publications in peer-reviewed journals and conference presentations. Australian New Zealand Clinical Trials Registry (ACTRN12620000285954).
Publisher: American Medical Association (AMA)
Date: 10-12-2012
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: 2017
DOI: 10.1016/J.CARDFAIL.2016.08.005
Abstract: Atrial fibrillation (AF) is common among adults with congestive heart failure (CHF). We conducted a meta-analysis to summarize the risk of mortality and cardiovascular disease associated with AF in CHF and stratified our analyses by AF timing and pattern. We searched MEDLINE and EMBASE for observational studies examining the association of AF with cardiovascular disease and death. Eligible studies had a minimum of 50 participants with AF and 50 participants without AF, and a median follow-up of 6 months. Thirty-three studies involving 114,204 adults (43,549 with AF) were included in this meta-analysis. AF was associated with an increased risk of mortality and this risk varied between incident and prevalent AF (relative risk 2.21, 95% confidence interval 1.96-2.49 vs relative risk 1.19, 95% confidence interval 1.03-1.38, respectively P < .001 for interaction). The risk of mortality associated with incident AF was consistent in adults with CHF with reduced and preserved ejection fraction. The relative risk of mortality did not vary between paroxysmal and chronic AF. Finally, AF was associated with an increased risk of cardiovascular mortality and stroke. Use of anticoagulation was infrequently reported in included studies. AF was associated with an increased risk of cardiovascular disease and death and, notably, the risk of mortality varied by AF timing.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Christopher Wong.