Differing mechanisms of atrial fibrillation in athletes and non-athletes: alterations in atrial structure and function.

AIMS: Atrial fibrillation (AF) is more common in athletes and may be associated with adverse left atrial (LA) remodelling. We compared LA structure and function in athletes and non-athletes with and without AF. METHODS AND RESULTS: Individuals (144) were recruited from four groups (each n = 36): (i) endurance athletes with paroxysmal AF, (ii) endurance athletes without AF, (iii) non-athletes with paroxysmal AF, and (iv) non-athletic healthy controls. Detailed echocardiograms were performed. Athletes had 35% larger LA volumes and 51% larger left ventricular (LV) volumes vs. non-athletes. Non-athletes with AF had increased LA size compared with controls. LA/LV volume ratios were similar in both athlete groups and non-athlete controls, but LA volumes were differentially increased in non-athletes with AF. Diastolic function was impaired in non-athletes with AF vs. non-athletes without, while athletes with and without AF had normal diastolic function. Compared with non-AF athletes, athletes with AF had increased LA minimum volumes (22.6 ± 5.6 vs. 19.2 ± 6.7 mL/m2, P = 0.033), with reduced LA emptying fraction (0.49 ± 0.06 vs. 0.55 ± 0.12, P = 0.02), and LA expansion index (1.0 ± 0.3 vs. 1.2 ± 0.5, P = 0.03). LA reservoir and contractile strain were decreased in athletes and similar to non-athletes with AF. CONCLUSION: Functional associations differed between athletes and non-athletes with AF, suggesting different pathophysiological mechanisms. Diastolic dysfunction and reduced strain defined non-athletes with AF. Athletes had low atrial strain and those with AF had enlarged LA volumes and reduced atrial emptying, but preserved LV diastolic parameters. Thus, AF in athletes may be triggered by an atrial myopathy from exercise-induced haemodynamic stretch consequent to increased cardiac output.

Sudden Death and Ventricular Arrhythmias in Athletes: Screening, De-Training and the Role of Catheter Ablation.

Athletes enjoy excellent health outcomes including greater longevity relative to non-athletic counterparts. Paradoxically, however, endurance athletic conditioning is associated with an increase in some arrhythmias. This review discusses the potential mechanisms for this paradox and strategies enabling early identification of potentially serious pathologies. Screening remains contentious due to the challenges of identifying relatively rare entities amongst a healthy cohort. The imperfect diagnostic accuracy of all current tests means that screening strategies have potential for harm through incorrect diagnoses as well as the potential for identification of important sub-clinical pathologies. Management of athletes at risk of ventricular arrhythmias and sudden cardiac death is similarly complex. There is much yet to learn about the specific patterns of ventricular arrhythmias in athletes, and the separation of benign from potentially life-threatening remains imperfect. There are some promising advances, however, such as specialised imaging modalities combined with improved electrophysiological diagnostics and therapeutics. Some unique clinical patterns are emerging to advance our understanding and management of athletes with ventricular arrhythmias, requiring specialised skillsets for evaluation and management.

State of the Art Review: Atrial Fibrillation in Athletes.

Exercise has substantial health benefits with pleomorphic vascular, metabolic, psychological and anti-neoplastic actions resulting in improved quality of life and longevity. Despite these many benefits, numerous studies have shown that endurance athletes are more likely to develop atrial fibrillation (AF) than non-athletes. The type, intensity and amount of sport appears to influence the risk of developing AF. Several endurance sport activities have been shown to increase the risk of developing AF but an excess in AF has not been shown in non-endurance sports. Furthermore, lifetime hours of participation appear to increase the risk of developing AF. Intriguingly, women appear relatively protected and an association between endurance sport and AF has not been clearly demonstrated amongst female endurance athletes. The mechanisms by which endurance sport promotes the development of AF are unclear. There are, however, a number of pathophysiological mechanisms which are known to increase the risk of AF in non-athletes which have correlates in athletes. These include structural remodelling of the left atrium, elevated left atrial pressure, inflammation, myocardial fibrosis, vagal tone, sinus bradycardia and genetic predisposition. In this article, we explore how some of these mechanisms may contribute to the development of AF in endurance athletes.