Atrial fibrillation in athletes

Derek Crinion; Adrian Baranchuk

doi:10.1503/cmaj.191209

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 1500–2000 lifetime hours.3 Evidence is less clear for women.3 In the majority of athletes, atrial fibrillation is paroxysmal and symptomatic.2^,3

The causes of atrial fibrillation in athletes are multifactorial

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.2^–4 Autonomic modulation also plays a role, and athletes commonly describe triggers that are vagally (sleep, meals) or adrenergically (exercise) mediated.2^,3

Other causes of atrial fibrillation should be considered and thromboembolic risk assessed

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

Management of atrial fibrillation in athletes poses unique challenges

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

Ablation of atrial fibrillation is increasingly offered as first-line therapy

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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Footnotes

CMAJ Podcasts: author interview at https://soundcloud.com/cmajpodcasts/191209-five
Competing interests: None declared.
This article has been peer reviewed.

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