Prevalence and Clinical Significance of Left Atrial Remodeling in Competitive Athletes

ObjectivesIn the present study we assessed the distribution and clinical significance of left atrial (LA) size in the context of athlete's heart and the differential diagnosis from structural heart disease, as well as the proclivity to supraventricular arrhythmias.BackgroundThe prevalence, clinical significance, and long-term arrhythmic consequences of LA enlargement in competitive athletes are unresolved.MethodsWe assessed LA dimension and the prevalence of supraventricular tachyarrhythmias in 1,777 competitive athletes (71% of whom were males), free of structural cardiovascular disease, that were participating in 38 different sports.ResultsThe LA dimension was 23 to 50 mm (mean, 37 ± 4 mm) in men and 20 to 46 mm (mean, 32 ± 4 mm) in women and was enlarged (i.e., transverse dimension ≥40 mm) in 347 athletes (20%), including 38 (2%) with marked dilation (≥45 mm). Of the 1,777 athletes, only 14 (0.8%) had documented, symptomatic episodes of either paroxysmal atrial fibrillation (n = 5; 0.3%) or supraventricular tachycardia (n = 9; 0.5%), which together occurred in a similar proportion in athletes with (0.9%) or without (0.8%; p = NS) LA enlargement. Multivariate regression analysis showed LA enlargement in athletes was largely explained by left ventricular cavity enlargement (R2= 0.53) and participation in dynamic sports (such as cycling, rowing/canoeing) but minimally by body size.ConclusionsIn a large population of highly trained athletes, enlarged LA dimension ≥40 mm was relatively common (20%), with the upper limits of 45 mm in women and 50 mm in men distinguishing physiologic cardiac remodeling (“athlete's heart”) from pathologic cardiac conditions. Atrial fibrillation and other supraventricular tachyarrhythmias proved to be uncommon (prevalence