Atrial fibrillation in athletes
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* Derek Crinion
* Adrian Baranchuk

## 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](https://soundcloud.com/cmajpodcasts/191209-five)

*   **Competing interests:** None declared.

*   This article has been peer reviewed.

## References

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    [Abstract/FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6MTQ6ImNpcmN1bGF0aW9uYWhhIjtzOjU6InJlc2lkIjtzOjExOiIxMzEvMjEvMTgyNyI7czo0OiJhdG9tIjtzOjIwOiIvY21hai8xOTIvMi9FNDAuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9) 

2.  Calkins H, Hindricks G, Cappato R, et al. 2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation. Heart Rhythm 2017;14:e445–94.
    
    

3.  Estes NAM III., Madias C. Atrial fibrillation in athletes: a lesson in the virtue of moderation. JACC Clin Electrophysiol 2017;3:921–8.
    
    [Abstract/FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiamNlcCI7czo1OiJyZXNpZCI7czo3OiIzLzkvOTIxIjtzOjQ6ImF0b20iO3M6MjA6Ii9jbWFqLzE5Mi8yL0U0MC5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=) 

4.  Guasch E, Benito B, Qi X, et al. Atrial fibrillation promotion by endurance exercise: demonstration and mechanistic exploration in an animal model. J Am Coll Cardiol 2013;62:68–77.
    
    [FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6MzoiUERGIjtzOjExOiJqb3VybmFsQ29kZSI7czo0OiJhY2NqIjtzOjU6InJlc2lkIjtzOjc6IjYyLzEvNjgiO3M6NDoiYXRvbSI7czoyMDoiL2NtYWovMTkyLzIvRTQwLmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==) 

5.  Andrade JG, Verma A, Mitchell LB, et al.CCS Atrial Fibrillation Guidelines Committee. 2018 focused update of the Canadian Cardiovascular Society guidelines for the management of atrial fibrillation. Can J Cardiol 2018;34:1371–92.