Sudden cardiac death in athletes: causes, symptoms, diagnosis, treatment

An estimated 1 in 200,000 apparently healthy young athletes develop sudden ventricular tachycardia or fibrillation and die suddenly while playing sports. Men are affected 9 times more often. Basketball and football players in the United States and soccer players in Europe have the highest risk.

Sudden cardiac death in young athletes has many causes, but is most often due to unrecognized hypertrophic cardiomyopathy. Athletes with thin, pliable chest walls are at risk for commotio cordis (sudden ventricular tachycardia or fibrillation following cardiac injury), even in the absence of underlying cardiovascular dysfunction. Cardiac dysfunction can result from a moderate impact (eg, baseball, hockey puck, lacrosse ball) or from a collision with another player during the vulnerable phase of myocardial repolarization. Some young athletes die from ruptured aortic aneurysms (in Marfan syndrome).

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Causes of sudden cardiac death in young athletes

• Obstructive hypertrophic cardiomyopathy
• Contusion of the heart (Commotio cordis)
• Coronary artery anomalies (eg, anomalous bypass of the left main coronary artery, anomalous bypass of the right coronary artery, hypoplasia of the coronary arteries)
• Increased heart mass
• Myocarditis
• Ruptured aortic aneurysm
• Arrhythmogenic right ventricular dysplasia
• Tunneled left anterior descending coronary artery
• Aortic stenosis
• Early coronary artery atherosclerosis
• Dilated cardiomyopathy
• Myxomatous degeneration of the mitral valve
• Long Q syndrome
• Brugada syndrome
• Wolff-Parkinson-White syndrome (antegrade conduction only)
• Catecholaminergic polymorphic tachycardia
• Right ventricular outflow tract tachycardia
• Coronary artery spasm
• Sarcoidosis of the heart
• Heart injury
• Rupture of a cerebral artery aneurysm

* Causes are listed in order of decreasing frequency.

Sudden cardiac death in older athletes is most often caused by coronary artery disease. Occasionally, hypertrophic cardiomyopathy, mitral valve prolapse, or acquired valvular disease may be the cause.

In other conditions leading to sudden death in athletes (e.g., asthma, heat stroke, complications associated with the use of illegal or performance-enhancing drugs), ventricular tachycardia or fibrillation is the final rather than the primary event.

Symptoms are similar to those of cardiovascular collapse, and the diagnosis is obvious. Emergency treatment with support of vital organs is successful in less than 20% of cases. This figure may increase as the availability of publicly available automated external defibrillators increases. In survivors, treatment is directed at the underlying disorder.

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Screening

Athletes are routinely screened before participating in competition to identify risk. Screening of all children, adolescents, and young adults (college-age) includes medical and family history and a physical examination (including supine and standing blood pressure and cardiac auscultation). A positive family history, symptoms of hypertrophic cardiomyopathy, or Marfan syndrome are indications for further testing. Diagnosis of any abnormal condition may prohibit participation in the sport. Athletes with near syncope or syncope should be evaluated for coronary artery abnormalities. The use of illicit and performance-enhancing drugs should be avoided. History and examination are neither sensitive nor specific; false-negative and false-positive results are common because the prevalence of cardiac disorders in apparently healthy populations is very low. The use of screening ECG or echocardiography would improve disease detection but would result in a large number of false positive diagnoses in large population settings.