The incidence is probably quite low.
Unrecognized hypertrophic cardiomyopathy (HCM) is one cause of exercise-related sudden cardiac death in young athletes. For 10 years, investigators prospectively analyzed cardiac screening results for 3500 asymptomatic elite athletes (98% white) in the U.K. Each athlete underwent 12-lead electrocardiography and two-dimensional echocardiography (echo). Athletes with family histories of HCM or suggestive findings on ECG or echo underwent 48-hour Holter monitoring, cardiopulmonary exercise testing, and magnetic resonance imaging.
In 53 athletes (1.5%), echo suggested left ventricular hypertrophy (LVH). Fifty of these athletes had associated left-ventricle dilation and normal systolic function, consistent with physiologic LVH. The remaining three — classified as having possible HCM — had no clinically significant arrhythmias, excellent exercise tolerance, and normal MRI on further testing. One athlete agreed to stop training, and ECG and echo abnormalities resolved, which suggested physiologic hypertrophy had been present. Fifteen participants had other abnormalities associated with sudden cardiac death; 11 had minor congenital abnormalities. The authors concluded that HCM is less prevalent among highly trained athletes than among the general population, and that screening with echo was not cost-effective, particularly because all athletes with possible HCM also exhibited abnormal ECGs.
Comment: This report suggests that the incidence of HCM in elite athletes is quite low, but sudden cardiac death in this group remains a high-profile tragedy. Editorialists from Germany disagree about the value of echo, arguing that screening costs are "negligible" in the context of professional sports and suggesting routine screening. For nonelite competitive athletes, they suggest clinical and ECG screening as a minimum.
— Kirsten E. Fleischmann, MD, MPH
Published in Journal Watch General Medicine April 17, 2008
Basavarajaiah S et al. Prevalence of hypertrophic cardiomyopathy in highly trained athletes: Relevance to pre-participation screening. J Am Coll Cardiol 2008 Mar 11; 51:1033.