Atrial fibrillation in athletes – CMAJ

Too much exercise can cause atrial fibrillation

Large observational studies have shown that a sedentary lifestyle increases the risk of atrial fibrillation fivefold.1,2 However, high-intensity aerobic exercise, especially for men, also increases the risk of atrial fibrillation at a threshold of more than 15002000 lifetime hours.3 Evidence is less clear for women.3 In the majority of athletes, atrial fibrillation is paroxysmal and symptomatic.2,3

High-intensity aerobic exercise causes increased hemodynamic stress and generates free radicals.4 The atria appear to be particularly susceptible, with resultant dilatation, chronic inflammation and fibrosis.24 Autonomic modulation also plays a role, and athletes commonly describe triggers that are vagally (sleep, meals) or adrenergically (exercise) mediated.2,3

It is important not to miss conditions associated with atrial fibrillation, including cardiomyopathies, channelopathies, pre-excitation, hyperthyroidism and alcohol or drug misuse.2,3 Energy supplements and performance enhancers should also be considered.2,3 Data on stroke risk among athletes are limited, but the use of thromboembolic risk scores (CHADS-65) is recommended.2,3,5

In nonrandomized studies, detraining has been shown to reduce atrial fibrillation, although athletes are often not willing to do this.2 Anti-arrhythmic medications are limited by bradycardia, impaired performance, long-term adverse effects and risk of ventricular arrhythmias during exercise.2,3 High-impact sports are a contraindication to anticoagulation.2,3

Data remain limited to small, nonrandomized studies, but ablation is often the preferred option for symptomatic athletes.2,3 Despite the distinct pathophysiology between symptomatic athletes and nonathletes, success rates appear similar to those of nonathletes: about 60% for the first procedure and > 80% for the second.2,3 Athletes not meeting CHADS-65 criteria must be informed of the need for anticoagulation for at least 2 months owing to the prothrombotic effect of catheter ablation.2,5

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Atrial fibrillation in athletes - CMAJ