Sudden Death in Young Athletes

The sudden death of a young, apparently healthy athlete is a great tragedy. While the odds that any given athlete will die suddenly are very small (with estimates ranging from 1 in 50,000 to 1 in 300,000 over 10 years), each sudden death that does occur is devastating to family, friends, and community.

The large majority of these sudden deaths are related to underlying cardiac conditions that were undiagnosed prior to the lethal event.

The lethal event itself is usually a malignant cardiac arrhythmia called ventricular fibrillation. In most of these unfortunate young people intense physical exertion, in the face of their underlying heart condition, trigger the lethal arrhythmia.

Cardiac Conditions That Increase the Risk

The age that seems to divide "young" athletes from "non-young" athletes is 35 years. Above 35 years of age, sudden death in athletes is usually caused by coronary artery disease due to atherosclerosis.

Below 35 years of age, sudden death in athletes is most commonly related to congenital or genetic heart conditions, or less uncommonly, to infections or inflammatory disease.

The cardiac conditions that may increase the risk for sudden death fall into two general categories: Structural heart disease (in which the heart is structurally, or anatomically, abnormal), and non-structural heart disease (in which the heart is structurally normal; these patients have "electrical" heart abnormalities).

Here is a list of cardiac conditions which can increase the risk for sudden death young athletes.

Structural Heart Disease

• Hypertrophic cardiomyopathy
• Congential abnormalities of the coronary arteries
• Mitral valve prolapse
• Myocarditis
• Arrhythmogenic right ventricular cardiomyopathy
• Marfan syndrome
• Congenital heart disease

No Structural Heart Disease

• Long QT syndrome
• Brugada syndrome
• Catecholamine polymorphic ventricular tachycardia

In the United States, the most common underlying cardiac problems found in the post-mortem examinations of young athletes who die suddenly are hypertrophic cardiomyopathy (36%) and congenital abnormalities in the coronary arteries (approx. 20%). The remainder are more or less evenly divided among the other causes on this list. Notably, more than half the young people who die suddenly with hypertrophic cardiomyopathy are African-American.

The relative incidences of these conditions does not appear to hold for other locations. For instance, in Northern Italy, the most common cause of sudden death in young athletes is arrhythmogenic right ventricular cardiomyopathy (22%), while hypertrophic cardiomyopathy only accounts for 2%.

In general, for most of these conditions the risk of sudden death is highest during physical activity that requires a) bursts of extreme exertion, such as sprinting, football, soccer, basketball, and tennis; 2) intensive training programs; or 3) exercise in extreme conditions of heat, humidity, and/or altitude. The exercise recommendations for each condition thus take these features into account.

Screening Young Athletes for Underlying Cardiac Conditions

Whether, and how extensively, to screen young athletes for cardiac conditions that might put them at risk for sudden death turns out to be a difficult and somewhat controversial question.

_Sources:

_{Maron, B, Chaitman, BR, Ackerman, MJ, et al.Recommendations for physical activity and recreational sports participation for young patients with genetic cardiovascular diseases. Circulation 2004; 109:2807.}

_{Pelliccia, A, Fagard, R, Bjornstad, HH, et al. Recommendations for competitive sports participation in athletes with cardiovascular disease: a consensus document from the Study Group of Sports Cardiology of the Working Group of Cardiac Rehabilitation and Exercise Physiology and the Working Group of Myocardial and Pericardial Diseases of the European Society of Cardiology. Eur Heart J 2005; 26:1422.}