Differing mechanisms of atrial fibrillation in athletes and non-athletes: alterations in atrial structure and function.
Level 4 - case-series / case-control
Cross-sectional comparative study evaluating four distinct clinical groups
PubMed 32757003 · doi:10.1093/ehjci/jeaa183
What was done
Echocardiographic parameters of left atrial (LA) and left ventricular (LV) structure, volume, strain, and diastolic function were compared across 144 individuals divided into four equal groups (n = 36 each): endurance athletes with paroxysmal atrial fibrillation (AF), endurance athletes without AF, non-athletes with paroxysmal AF, and non-athletic healthy controls.
What was found
Athletes had 35% larger LA volumes and 51% larger LV volumes compared to non-athletes. Non-athletes with AF had impaired LV diastolic function compared to controls, whereas athletes with and without AF preserved normal diastolic function. Compared to athletes without AF, athletes with AF had larger LA minimum volumes (22.6 ± 5.6 vs. 19.2 ± 6.7 mL/m², P = 0.033), lower LA emptying fraction (0.49 ± 0.06 vs. 0.55 ± 0.12, P = 0.02), and lower LA expansion index (1.0 ± 0.3 vs. 1.2 ± 0.5, P = 0.03). LA reservoir and contractile strain were reduced in athletes to levels comparable to non-athletes with AF.
Why it matters
These findings suggest that AF in endurance athletes stems from atrial stretch and dynamic volume overload rather than the ventricular diastolic impairment typical in non-athletes.
Limits
The cross-sectional design cannot establish whether LA remodelling preceded or resulted from paroxysmal AF episodes. The sample size was modest (36 per subgroup), and the abstract provides no information regarding participant sex, age, specific sport types, lifetime training loads, or medical comorbidities.
Cited by
- context Studies by Guido Claessen and André La Gerche show that during exercise, increased heart rate and closed-valve time cause atrial dilation due to blood damming, which increases the risk of atrial fibrillation.