Genetically Based Atrial Fibrillation: Current Considerations for Diagnosis and Management

Atrial fibrillation (AF) is the most common atrial arrhythmia and is subcategorized into numerous clinical phenotypes. Given its heterogeneity, investigations into the genetic mechanisms underlying AF have been pursued in recent decades, with predominant analyses focusing on early onset or lone AF. Linkage analyses, genome wide association studies (GWAS), and single gene analyses have led to the identification of rare and common genetic variants associated with AF risk. Significant overlap with genetic variants implicated in dilated cardiomyopathy syndromes, including truncating variants of the sarcomere protein titin, have been identified through these analyses, in addition to other genes associated with cardiac structure and function. Despite this, widespread utilization of genetic testing in AF remains hindered by the unclear impact of genetic risk identification on clinical outcomes and the high prevalence of variants of unknown significance (VUS). However, genetic testing is a reasonable option for patients with early onset AF and in those with significant family history of arrhythmia. While many knowledge gaps remain, emerging data support genotyping to inform selection of AF therapeutics. In this review we highlight the current understanding of the complex genetic basis of AF and explore the overlap of AF with inherited cardiomyopathy syndromes. We propose a set of criteria for clinical genetic testing in AF patients and outline future steps for the integration of genetics into AF care. This article is protected by copyright. All rights reserved.

Type 2 diabetes increases the long-term risk of heart failure and mortality in patients with atrial fibrillation

AIMS

Impact of type 2 diabetes mellitus (T2DM) on non-thromboembolic outcomes in atrial fibrillation (AF) is insufficiently explored. This prospective cohort study of AF patients aimed (i) to analyse the association between T2DM and heart failure (HF) events (including new-onset HF), and all-cause and cardiovascular mortality, (ii) to assess the impact of baseline T2DM treatment on outcomes, and (iii) to explore characteristics of new-onset HF phenotypes in relation to T2DM status.

METHODS AND RESULTS

Of 1803 AF patients (515/1288, with/without prior HF), 389 (22%) had T2DM at baseline. After 5 years of median follow-up, T2DM patients had an 85% greater risk of HF events [adjusted hazard ratio (aHR) 1.85; 95% confidence interval (CI) 1.51-2.28; P < 0.001], including a 45% increased risk for new-onset HF (1.45; 1.17-2.28; P = 0.015). T2DM conferred a 56% higher all-cause (1.56, 1.22-2.01; P = 0.003) and a 48% higher cardiovascular mortality (1.48; 1.34-1.93; P = 0.007). Fine-Gray analysis, with mortality as a competing risk, confirmed greater HF risk among T2DM patients. All risks were highest among insulin-treated patients. The prevalence of new-onset HF phenotypes was as follows: 67% preserved ejection fraction (HFpEF), 20% mid-range ejection fraction (HFmrEF) and 13% reduced ejection fraction (HFrEF). On time-dependent Cox regression, adjusted for baseline characteristics and an interim acute coronary event, T2DM increased aHRs for new-onset HFpEF (2.38; 1.30-4.58; P <0.001) and the combined HFmrEF/HFrEF (1.77; 1.11-3.62; P = 0.017).

CONCLUSIONS

Atrial fibrillation patients with T2DM have independently increased risk of new-onset/recurrent HF events, cardiovascular and all-cause mortality, particularly when insulin-treated. The prevailing phenotype of new-onset HF was HFpEF; T2DM conferred higher risk of both HFpEF and HFmrEF/HFrEF.

Type D personality affects health-related quality of life in patients with lone atrial fibrillation by increasing symptoms related to sympathetic activation

BACKGROUND

Health-related quality of life (HRQoL) is impaired in patients with atrial fibrillation (AF), and even more so in patients with a Distressed personality type (Type D). It is unknown whether this extends to patients with 'lone AF'. Since chronic stress is associated with increased arousal, it might affect recurrences and thus HRQoL. The current study examined the influence of Type D on the trajectory of disease-specific and generic HRQoL, compared it with HRQoL in the general population, and assessed the mediating role of arousal symptoms (e.g., tachycardia, sweating).

METHODS

159 patients with 'lone AF' (age: 61.6±0.8, 63% men, 3.3±5.0 years since diagnosis) filled out a survey on personality (Type D: DS14), quality of life (SF-36, AFQoL) and symptoms (ATSSS) of AF at inclusion, and 6, 12, and 18 months later. Linear mixed modeling was used.

RESULTS

Generic HRQoL was reduced as compared to the general population, and all HRQoL scales remained stable across time. Type D personality was a significant predictor of worse disease-specific (estimate= -17.1 ; 95%CI:-23.9 - -10.2; p<.001), and generic HRQoL (estimate_PCS=-5.5; 95%CI:-9.3 - -1.8; p=.004; estimate_MCS=-14.8; 95%CI:-18.9- -10.6; p<.001), with arousal symptoms accounting for substantial change in the Type D estimate, suggesting partially shared variance between Type D and arousal symptoms in predicting HRQoL.

CONCLUSION

HRQoL was stable across time, and systematically poorer in distressed 'lone AF' patients. Arousal symptoms partly explained the relation between Type D and HRQoL. Chronic distress may affect AF patients' HRQoL through sympathetic activation and accompanying complaints.

The changing circumstance of atrial fibrillation - progress towards precision medicine

The prevalence of atrial fibrillation (AF) in the general population is between 1% and 2% in the developed world and is higher in men than in women. The arrhythmia occurs much more commonly in the elderly, and the estimated lifetime risk of developing AF is one in four for men and women aged 40 years and above. Projected data from multiple population-based studies in the USA and Europe predict a two- to threefold increase in the number of AF patients by 2060. The high lifetime risk of AF and increased longevity underscore the important public health burden posed by this arrhythmia worldwide. AF has multiple aetiologies and a broad variety of presentations. The primary pathologies underlying or promoting the occurrence of AF vary more than for any other cardiac arrhythmia, ranging from autonomic imbalance to organic heart disease and metabolic disorders, such as diabetes mellitus, metabolic syndrome, hyperthyroidism and kidney disease, and lifestyle factors such as smoking, alcohol consumption and participation in endurance sports. Biomarkers are increasingly being investigated and, together with clinical and genetic factors, will eventually lead to a clinically valuable detailed classification of AF which will also incorporate pathophysiological determinants and mechanisms of the arrhythmia. In turn, this will allow the development and application of precision medicine to this troublesome arrhythmia.

Catheter Ablation for "Lone" Atrial Fibrillation: Efficacy and Predictors of Recurrence

BACKGROUND

Atrial fibrillation in otherwise healthy young patients has been termed "lone" atrial fibrillation (AF). The best treatment choice is still under discussion. The aim of this study was to report on efficacy and safety of catheter ablation.

METHODS

Among 855 patients referred to our center between 2011 and 2013, 76 (9%) met the diagnostic criteria for lone AF (mean age 45 ± 8 years; mean LA diameter 37 ± 4 mm; paroxysmal AF 82%; persistent AF 18%). The primary endpoint was freedom from any atrial tachycardia after the first ablation; the secondary endpoint was freedom from any atrial tachycardia after the last ablation procedure without antiarrhythmic drugs.

RESULTS

The primary endpoint occurred in 56 patients (74%) after a mean follow-up time of 444 ± 344 days. The secondary endpoint occurred in 73 patients (96%) after a mean of 1.3 ablations/patient during a follow-up time of 459 ± 366 days. The risk of AF recurrence was not influenced by AF duration or by the type of AF (paroxysmal versus persistent). In a multivariate regression analysis smoking (P = 0.001), first degree atrioventricular block (P = 0.001), and early (< 3 months) AF recurrence (P = 0.001) were independently associated with a higher risk of AF recurrence. Major peri-procedural adverse events did not occur.

CONCLUSIONS

Catheter ablation in young healthy patients is highly effective and safe. The outcomes are maintained during long-term follow-up irrespective of preoperative AF duration. Patients with AF recurrence were more likely to smoke, have first degree AV block and early AF recurrence.

EHRA research network surveys: 6 years of EP wires activity

Clinical practice should follow guidelines and recommendations mainly based on the results of controlled trials, which are often conducted in selected populations and special conditions, whereas clinical practice may be influenced by factors different from controlled scientific studies. Hence, the real-world setting is better assessed by the observational registries enrolling patients for longer periods of time. However, this may be difficult, expensive, and time-consuming. In 2009, the Scientific Initiatives Committee of the European Heart Rhythm Association (EHRA) has instigated a series of surveys covering the controversial issues in clinical electrophysiology (EP). With this in mind, an EHRA EP research network has been created, which included EP centres in Europe among which the surveys on 'hot topic' were circulated. This review summarizes the overall experience conducting EP wires over the past 6 years, categorizing and assessing the topics regarding clinical EP, and evaluating the acceptance and feedback from the responding centres, in order to improve participation in the surveys and better address the research needs and aspirations of the European EP community.

Emerging risk factors and the dose-response relationship between physical activity and lone atrial fibrillation: a prospective case-control study

Aims

The role of high-intensity exercise and other emerging risk factors in lone atrial fibrillation (Ln-AF) epidemiology is still under debate. The aim of this study was to analyse the contribution of each of the emerging risk factors and the impact of physical activity dose in patients with Ln-AF.

Methods and results

Patients with Ln-AF and age- and sex-matched healthy controls were included in a 2:1 prospective case–control study. We obtained clinical and anthropometric data transthoracic echocardiography, lifetime physical activity questionnaire, 24-h ambulatory blood pressure monitoring, Berlin questionnaire score, and, in patients at high risk for obstructive sleep apnoea (OSA) syndrome, a polysomnography. A total of 115 cases and 57 controls were enrolled. Conditional logistic regression analysis associated height [odds ratio (OR) 1.06 [1.01–1.11]], waist circumference (OR 1.06 [1.02–1.11]), OSA (OR 5.04 [1.44–17.45]), and 2000 or more hours of cumulative high-intensity endurance training to a higher AF risk. Our data indicated a U-shaped association between the extent of high-intensity training and AF risk. The risk of AF increased with an accumulated lifetime endurance sport activity ≥2000 h compared with sedentary individuals (OR 3.88 [1.55–9.73]). Nevertheless, a history of <2000 h of high-intensity training protected against AF when compared with sedentary individuals (OR 0.38 [0.12–0.98]).

Conclusion

A history of ≥2000 h of vigorous endurance training, tall stature, abdominal obesity, and OSA are frequently encountered as risk factors in patients with Ln-AF. Fewer than 2000 total hours of high-intensity endurance training associates with reduced Ln-AF risk.