The causes of sudden and unexpected death in 29 highly conditioned, competitive 
athletes, ages 13-30 years, are summarized. Sudden death occurred during or just 
after severe exertion on the athletic field in 22 of the 29 athletes. Structural 
cardiovascular abnormalities were identified at necropsy in 28 of the 29 
athletes (97%), and in 22 (76%) were almost certainly the cause of death. The 
most common cause of death in this series was hypertrophic cardiomyopathy, which 
was present in 14 athletes. Other cardiovascular abnormalities that occurred in 
more than one athlete were anomalous origin of the left coronary artery from the 
right (anterior) sinus of Valsalva, idiopathic concentric left ventricular 
hypertrophy, coronary heart disease and ruptured aorta. Cardiac disease was 
suspected during life in only seven of the 29 patients, and in only two of the 
seven was the correct diagnosis made clinically. Hence, in this series of young 
athletes, sudden death was usually due to structural cardiovascular disease, and 
hypertrophic cardiomyopathy was a frequent cause of sudden death; 
atherosclerotic coronary heart disease was relatively uncommon.