Hypertrophic cardiomyopathy: a common cause of sudden death in the young competitive athlete.

The causes of sudden, unexpected death in highly-conditioned competitive athletes are summarized. In the vast majority of young athletes (less than 35 years of age) sudden death is due to underlying structural cardiovascular disease. Hypertrophic cardiomyopathy appears to be the most common cause of such deaths and may account for about one-half of the sudden deaths in a youthful athletic population. Cardiovascular abnormalities that appear to be less frequent important causes of sudden death include anomalous origin of the left coronary artery from the anterior sinus of Valsalva, ruptured aorta (due to cystic medial necrosis), idiopathic concentric left ventricular hypertrophy and coronary artery atherosclerosis. Other diseases which are probably particularly uncommon causes of sudden death in the young athlete include mitral valve prolapse, aortic valvular stenosis, acute myocarditis, QT interval prolongation syndromes, hypoplasia of the coronary arteries or sarcoidosis. Cardiovascular disease in young athletes is usually unsuspected during life. In only about 25% of those competitive athletes who die suddenly is underlying disease identified prior to participation and rarely is the correct clinical diagnosis made. In contrast, when sudden death occurs in older competitive or recreational athletes (over 35 years of age) it is usually due to coronary artery disease.