Risk factor management and atrial fibrillation

The management of atrial fibrillation (AF) is multifaceted and treatment paradigms have changed significantly in the last century. The treatment of AF requires a comprehensive approach which goes beyond the treatment of the arrhythmia alone. Risk factor management has been introduced as a crucial pillar of AF management. As a result, the landscape of care delivery is changing as well, and novel models of comprehensive care delivery for AF have been introduced. This article reviews the evidence for the role of risk factor management in AF, how this can be integrated and implemented in clinical practice by applying novel models of care delivery, and finally identifies areas for ongoing research and potential healthcare reform to comprehensively manage the burgeoning AF population.

Development and validation of a questionnaire to assess knowledge in patients with Atrial Fibrillation

Funding Acknowledgements

Type of funding sources: None.

OnBehalf

Centre for Heart Rhythm Disorders

Background

Education is critical to empower individuals to self-monitor and manage their condition. Significant variability exists in the provision of education for atrial fibrillation (AF), whilst individual patient factors including health literacy and education level attainment may impact on knowledge levels. Objective assessment of knowledge  may help to target education to areas of need, and result in improved patient outcomes.

Objective

To describe the development and validation of a knowledge questionnaire for AF.

Methods

A multidisciplinary expert team of healthcare professionals developed the questionnaire, in conjunction with consumers, with question content based upon areas deemed most critical to AF and related self-management. The multiple choice questionnaire consists of 20 items, each worth 5 points, to give a total score out of 100. The questionnaire assesses five domains specific to AF: general knowledge, complications, medications, risk factors and action. The questionnaire was developed in English. The questionnaire was tested on 10 randomly selected patients with AF for face validity and 19 healthcare professionals for content validity. The final version was completed by 454 individuals with AF. Exploratory factor analysis was used to determine construct validity with factor loadings of 0.40 and above considered acceptable. Reliability was assessed using Cronbach’s alpha, with a value greater than 0.7 acceptable.

Results

Face and content validity were considered acceptable, after minor changes to wording. The cohort of 454 individuals with AF had a mean age of 66.9 ± 12 years and 43% were female. Mean (SD) total score was 57.7 ± 15.8. Exploratory factor analysis was undertaken using the principal components method. This resulted in a Kaiser–Meyer–Olkin Measure of Sampling Adequacy of .64 and a Bartlett"s Test of Sphericity being significant at 0.00. Seven factors were selected and analysed using principal component analysis with varimax rotation. All items loaded on one of the seven factors. Internal consistency demonstrated a Cronbach’s alpha of 0.65.

Conclusion

The Atrial Fibrillation Knowledge Questionnaire is a valid measure to assess knowledge in individuals with AF.

A meta-analysis of clinical risk factors for stroke in anticoagulant-naïve patients with atrial fibrillation

AIMS

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.

METHODS AND RESULTS

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 1.33, 95% CI 1.15-1.55), but not in those done in Asia (HR 0.95, 95% CI 0.81-1.10).

CONCLUSION

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.

Electrophysiological and Structural Remodeling of the Atria in a Mouse Model of Troponin-I Mutation Linked Hypertrophic Cardiomyopathy: Implications for Atrial Fibrillation

Hypertrophic cardiomyopathy (HCM) is an inherited cardiac disorder affecting one in 500 of the general population. Atrial fibrillation (AF) is the most common arrhythmia in patients with HCM. We sought to characterize the atrial electrophysiological and structural substrate in young and aging Gly203Ser cardiac troponin-I transgenic (HCM) mice. At 30 weeks and 50 weeks of age (n = 6 per strain each group), the left atrium was excised and placed on a multi-electrode array (MEA) for electrophysiological study; subsequent histological analyses and plasma samples were analyzed for biomarkers of extracellular matrix remodeling and cell adhesion and inflammation. Wild-type mice of matched ages were included as controls. Young HCM mice demonstrated significantly shortened atrial action potential duration (APD), increased conduction heterogeneity index (CHI), increased myocyte size, and increased interstitial fibrosis without changes in effective refractory periods (ERP), conduction velocity (CV), inflammatory infiltrates, or circulating markers of extracellular matrix remodeling and inflammation. Aging HCM mice demonstrated aggravated changes in atria electrophysiology and structural remodeling as well as increased circulating matrix metalloproteinases (MMP)-2, MMP-3, and VCAM-1 levels. This model of HCM demonstrates an underlying atrial substrate that progresses with age and may in part be responsible for the greater propensity for AF in HCM.

Atrial fibrillation burden during the coronavirus disease 2019 pandemic

Aims

The aim of this study is to determine the association between the coronavirus disease 2019 (COVID-19) pandemic and atrial fibrillation (AF) occurrence in individuals with cardiac implantable electronic devices (CIEDs).

Method and results

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).

Conclusion

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.

Clinical TRIAL registration

Australian New Zealand Clinical Trial Registry: ACTRN12620000692932.

Performance of a Mobile Single-Lead Electrocardiogram Technology for Atrial Fibrillation Screening in a Semirural African Population: Insights From "The Heart of Ethiopia: Focus on Atrial Fibrillation" (TEFF-AF) Study

Background

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.

Objective

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.

Methods

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.

Results

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 individuals 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 (>100 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.

Conclusions

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.

Trial Registration

Australian New Zealand Clinical Trials Registry ACTRN12619001107112; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=378057&isReview=true

Cardiorespiratory fitness and electroanatomical remodelling in patients with atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Introduction

Atrial fibrillation (AF) is the most common clinically-relevant arrhythmia. Its initiation and maintenance is linked to the presence cardiovascular risk factors such as hypertension and obesity. Higher cardiorespiratory fitness (CRF) has been associated with a better prognosis. However, specific electroanatomical features associated with baseline CRF have not been described. 

Purpose

Compare electroanatomical substrate across exercise capacity levels in patients with AF

Methods

Patients referred for de novo AF radiofrequency ablation at the Centre for Heart Rhythm Disorders from August 2017 until June 2020 were screened for inclusion and CRF was evaluated in metabolic equivalents (METs) by a symptom-limited maximal treadmill exercise test using the standard Bruce protocol prior to ablation. Predicted CRF was calculated based on established equations and patients were categorized according to the percentage of predicted CRF achieved; low (&lt;85%), adequate (85-100%) and high (&gt;100%). Total mean and regional peak-to-peak bipolar voltages, percent of low voltage areas (% LVA), conduction velocity (CV) and percent of complex fractionated electrograms (% CFE) in sinus rhythm were compared across groups. 

Results

There were no between-group differences in baseline characteristics, medication use or echocardiographic features. Total mean voltage was significantly lower in the low CRF group compared to both adequate and high CRF. Compared to the high CRF group, roof (3.25 ± 1.2 mV vs 1.9 ± 1.3 mV, p &lt; 0.05), posterior (3.8 ± 1.8 mV vs 1.7 ± 0.9 mV, p &lt; 0.001) and inferior mean voltages (3.4 ± 2 mV vs 1.6 ± 0.7 mV, p &lt; 0.05) were significantly lower in the low CRF group (figure 1A). Furthermore, compared with the adequate CRF group, mean voltages were significantly lower in the posterior (3.7 ± 1.5 mV vs 1.7 ± 0.9 mV, p &lt; 0.001), inferior (3.4 ± 1 mV vs 1.6 ± 0.7 mV, p &lt; 0.001) and lateral (4.2 ± 2.2 mV vs 2.1 ± 1.4 mV, p &lt; 0.05) walls of the low CRF group. Anterior and septal mean voltages were not significantly different across CRF groups (P for trend = 0.07, 0.3 and 0.15, respectively). Conduction velocities were not significantly different across groups. The inferior %LVA was significantly higher in the low CRF (5.6 ± 6%) compared to adequate CRF group (23 ± 18%) (p &lt; 0.05) (figure 1B). Total and regional % CFE was higher in the low CRF compared to adequate and high CRF.

Conclusion

Participants in the lower baseline CRF category showed significant reductions in regional voltages along with higher fractionation with preserved conduction velocities. Research on the effect of physical activity and CRF on left atrial arrhythmogenic substrate is required.

Abstract Figure. Global and regional mV and % LVA by CRF

Role of Indices Incorporating Power, Force and Time in AF Ablation: A Systematic Review of Literature

INTRODUCTION

Successful pulmonary vein isolation (PVI) for atrial fibrillation (AF) depends on the formation of durable transmural lesions. Recently, novel indices have emerged to guide lesion delivery. The aim of the systematic review of literature was to determine AF recurrence following ablation guided by indices incorporating force, power and time, and compare acute procedural outcomes and 12-month AF recurrence with ablation guided by contact force (CF) guided only.

METHODS

PubMed, EMBASE, and Web of Science Core Collection databases were searched on 27 January 2020 using the keywords; catheter ablation, ablation index (AI), lesion size index (LSI), contact force, atrial fibrillation.

RESULTS

After exclusions, seven studies were included in the analysis. AI-guided catheter ablation was associated with a 91% (n=5, 0.91 95% CI; 0.88-0.93) and 80% (n=5, 0.80, 95% CI; 0.77-0.84) freedom from AF at 12 months with and without the use of anti-arhythmic drugs respectively. As compared to CF guided ablation, AI-guided catheter ablation was associated with a 49% increase in successful first pass isolation (n=3; RR: 1.49, 95% CI; 1.38, 1.61), a 50% decrease in number of acute reconnections (n=4; RR: 0.50, 95% CI; 0.39-0.65) and a 22% (n=4, RR: 1.22, 95% CI; 1.10-1.35) increase in AF freedom without anti-arrhythmic drugs at 12 months.

CONCLUSIONS

Radiofrequency ablation guided by AI was associated with higher successful first pass isolation and lower rates of acute reconnection which translates to greater freedom from AF at 12 months [CRD42019131469].

Atrial Fibrillation and Obesity: Reverse Remodeling of Atrial Substrate With Weight Reduction

OBJECTIVES

This study sought to evaluate the effect of weight loss on the atrial substrate for atrial fibrillation (AF).

BACKGROUND

Whether weight loss can reverse the atrial substrate of obesity is not known.

METHODS

Thirty sheep had sustained obesity induced by ad libitum calorie-dense diet over 72 weeks. Animals were randomized to 3 groups: sustained obesity and 15% and 30% weight loss. The animals randomized to weight loss underwent weight reduction by reducing the quantity of hay over 32 weeks. Eight lean animals served as controls. All were subjected to the following: dual-energy x-ray absorptiometry, echocardiogram, cardiac magnetic resonance, electrophysiological study, and histological and molecular analyses (fatty infiltration, fibrosis, transforming growth factor β1, and connexin 43).

RESULTS

Sustained obesity was associated with increased left atrium (LA) pressure (p < 0.001), inflammation (p < 0.001), atrial transforming growth factor β1 protein (p < 0.001), endothelin-B receptor expression (p = 0.04), atrial fibrosis (p = 0.01), epicardial fat infiltration (p < 0.001), electrophysiological abnormalities, and AF burden (p = 0.04). Connexin 43 expression was decreased in the obese group (p = 0.03). In this obese ovine model, 30% weight reduction was associated with reduction in total body fat (p < 0.001), LA pressure (p = 0.007), inflammation (p < 0.001), endothelin-B receptor expression (p = 0.01), atrial fibrosis (p = 0.01), increase in atrial effective refractory period (cycle length: 400 and 300 ms; p < 0.001), improved conduction velocity (cycle length: 400 and 300 ms; p = 0.01), decreased conduction heterogeneity (p < 0.001), and decreased AF inducibility (p = 0.03). Weight loss was associated with a nonsignificant reduction in epicardial fat infiltration in posterior LA (p = 0.34).

CONCLUSIONS

Weight loss in an obese ovine model is associated with structural and electrophysiological reverse remodeling and a reduced propensity for AF. This provides evidence for the direct role of obesity in AF substrate and the role of weight reduction in patients with AF.

Lifestyle as a Risk Factor for Atrial Fibrillation

The growing burden of atrial fibrillation health care resource utlization has created an urgent need to develop preventative strategies and opportunities to improve outcomes in the prevalent population. Modifiable risk factors contribute to both disease development and progression. In the prevalent atrial fibrillation population, modifying cardiovascular risk factors has decreased disease burden and progression. However, further research is required to determine the role of comprehensive cardiovascular risk factor modification programs in primary prevention. An understanding of strategies required to facilitate health behavior change is crucial to the effective implementation of cardiovascular risk factor management programs.