Incidence of Atrial Fibrillation in Elite Athletes.

Importance: Vigorous exercise (particularly endurance sports) might increase the risk of atrial fibrillation (AF), but there is variability in the reported frequency of this condition among elite athletes. The underlying pathophysiologic source remains unclear. Objective: To determine AF incidence in a large cohort of elite athletes and its association with potential risk factors. Design, Setting, and Participants: Retrospective observational cohort of all Spanish athletes (N = 6813) referred to a single center was used to determine AF incidence from January 1, 1997, to December 31, 2017, and cross-sectional analysis was conducted to compare athletes with and without reported AF. The cohort covered most sports disciplines, and the studied athletes were on national teams and competed in major international events. Cardiologists responsible for echocardiographic assessment were not blinded to the condition (AF or no AF) of the athletes. Exposures: All participants underwent at least 1 cardiologic evaluation, including assessment at time of AF diagnosis in those with this condition. Main Outcomes and Measures: Diagnosis of AF based on resting and/or exercise electrocardiogram, and/or 24-hour Holter monitoring and echocardiography-assessed atrial dimensions. Results: A total of 6813 Spanish elite athletes (2385 [35.0%] women) were referred for cardiac evaluation during the study period. Mean (SD) age was 22 (7) years, and mean (SD) time of competition was 8 (5) years. Only 21 athletes (1 woman), participating in different types of sports, had AF (ie, paroxysmal [n = 18], persistent [n = 1], or long-standing persistent [n = 2]) during the 20-year study. In multivariate analysis, increasing values of age (odds ratio [OR], 1.07; 95% CI, 1.00-1.14), years of competition (OR, 1.14; 95% CI, 1.07-1.22), and left atrial anteroposterior diameter (OR, 1.21; 95% CI, 1.10-1.32) were associated with higher AF risk. Conclusions and Relevance: The incidence of AF is low among young Spanish elite athletes, even when considering only endurance athletes. Yet, potential contributors (particularly atrial remodeling) need to be monitored.