Sudden Cardiac Death and the `Athlete's Heart'

OBJECTIVES: To review the current literature pertaining to the cardiovascular adaptations to exercise and the impact on the physical examination, the electrocardiogram, and the echocardiogram, and to distinguish those physiologic changes from pathologic conditions associated with sudden cardiac death in athletes. DATA SYNTHESIS: Specific cardiovascular adaptations occur in response to regular physical exercise. The extent of these changes depend on the type and duration of exercise as well as the gender of the athlete. These cardiac adaptations are morphologically different from those conditions associated with sudden cardiac death. In the athlete younger than 35 years, hypertrophic cardiomyopathy is the most common cardiac condition associated with sudden death. Right ventricular dysplasia, idiopathic left ventricular hypertrophy, coronary anomalies, premature atherosclerosis, and Marfan syndrome compose the majority of the remaining causes of sudden cardiac death in athletes. In the athlete older than 35 years, coronary atherosclerosis is the leading cause of sudden death followed by those conditions responsible for sudden death in the younger athlete. Despite this, regular exercise before or following a myocardial infarction provides a protective effect with respect to overall mortality, cardiovascular mortality, and fatal reinfarction rates. CONCLUSIONS: Cardiovascular adaptation to regular physical exercise leads to morphologic changes in the myocardium that influence the cardiac examination, the electrocardiogram, and the echocardiogram. Knowledge and recognition of those changes can allow the clinician to distinguish normal physiologic changes from cardiac abnormality. Proper detection of athletes at high risk for sudden cardiac death and abstention from vigorous physical activity in these athletes may prevent sudden death.