An estimated 1/200,000 apparently healthy young athletes develops abrupt-onset ventricular tachycardia or fibrillation and dies suddenly during exercise. Males are affected 10 times more often than females. Basketball and football players in the US and soccer players in Europe may be at highest risk.

In young athletes, sudden cardiac death has many causes (see Table 1: Sports and the Heart: Causes of Sudden Cardiovascular Death in Young Athletes*) but the most common is

• Undetected hypertrophic cardiomyopathy

Athletes with thin, compliant chest walls are at risk of commotio cordis (sudden ventricular tachycardia or fibrillation after a blow to the precordium) even when no cardiovascular disorder is present. The blow may involve a moderate-force projectile (eg, baseball, hockey puck, lacrosse ball) or impact with another player during a vulnerable phase of myocardial repolarization. Other causes include inherited arrhythmia syndromes (eg, long QT syndrome, Brugada syndrome). Some young athletes die of aortic aneurysm rupture (in Marfan syndrome).

In older athletes, sudden cardiac death is typically caused by

• Coronary artery disease

Occasionally, hypertrophic cardiomyopathy, mitral valve prolapse, or acquired valvular disease is involved.

In other conditions underlying sudden death in athletes (eg, asthma, heatstroke, illicit or performance-enhancing drug-related complications), ventricular tachycardia or fibrillation is a terminal, not a primary event.

Symptoms and signs are those of cardiovascular collapse; diagnosis is obvious. Immediate treatment with advanced cardiac life support is successful in < 20%; the percentage may increase as distribution of community-based, automated external defibrillators expands. For survivors, treatment is management of the underlying condition. In some cases, an implanted cardioverter-defibrillator may ultimately be required.

Table 1
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Causes of Sudden Cardiovascular Death in Young Athletes* Obstructive hypertrophic cardiomyopathy Commotio cordis Coronary artery anomalies (eg, anomalous left main coronary artery origin, anomalous right coronary artery origin, coronary arterial hypoplasia) Increased cardiac mass Myocarditis Ruptured aortic aneurysm Arrhythmogenic right ventricular dysplasia Tunneled left anterior descending coronary artery Aortic stenosis Premature atherosclerotic coronary artery disease Dilated cardiomyopathy Myxomatous degeneration of mitral valve Long QT syndrome Brugada syndrome Wolff-Parkinson-White syndrome (anterograde conduction only) Catecholaminergic polymorphic tachycardia Right ventricular outflow tract tachycardia Coronary vasospasm Cardiac sarcoidosis Cardiac trauma Ruptured cerebral artery aneurysm *Causes are listed in approximate order of frequency. Causes of Sudden Cardiovascular Death in Young Athletes* Obstructive hypertrophic cardiomyopathy Commotio cordis Coronary artery anomalies (eg, anomalous left main coronary artery origin, anomalous right coronary artery origin, coronary arterial hypoplasia) Increased cardiac mass Myocarditis Ruptured aortic aneurysm Arrhythmogenic right ventricular dysplasia Tunneled left anterior descending coronary artery Aortic stenosis Premature atherosclerotic coronary artery disease Dilated cardiomyopathy Myxomatous degeneration of mitral valve Long QT syndrome Brugada syndrome Wolff-Parkinson-White syndrome (anterograde conduction only) Catecholaminergic polymorphic tachycardia Right ventricular outflow tract tachycardia Coronary vasospasm Cardiac sarcoidosis Cardiac trauma Ruptured cerebral artery aneurysm *Causes are listed in approximate order of frequency.

Screening

Athletes are commonly screened to identify risk before participation in sports, and they are reevaluated every 2 yr (if high school age) or every 4 yr (if college age or older).

Screening recommendations for all children, adolescents, and college-age young adults include

• Medical, family, and drug history (including use of performance-enhancing drugs and drugs that predispose to long QT syndrome)
• Physical examination (including BP and supine and standing cardiac auscultation)
• Selected testing based on findings on history and physical examination

Clinical Calculator

Screening for older adults also includes incremental symptom-limited exercise testing.

Athletes with a family history or symptoms or signs of hypertrophic cardiomyopathy (see Cardiomyopathies: Hypertrophic Cardiomyopathy), long QT syndrome (see Arrhythmias and Conduction Disorders: Long QT Syndrome and Torsades de Pointes Ventricular Tachycardia), or Marfan syndrome (see Connective Tissue Disorders in Children: Marfan Syndrome) require further evaluation, typically with ECG, echocardiography, or both. Confirmation of any of these disorders may preclude sports participation. Athletes with presyncope or syncope should also be evaluated for anomalous coronary arteries (eg, by cardiac catheterization). If ECG reveals Mobitz type II heart block, complete heart block, true right bundle branch block, or left bundle branch block, a search for cardiac disease is required. Athletes should be counseled against use of illicit and performance-enhancing drugs.

History and examination are neither sensitive nor specific; false-negative and false-positive findings are common because prevalence of cardiac disorders in an apparently healthy population is very low. Use of screening ECG or echocardiography would improve disease detection but would produce even more false-positive diagnoses and is impractical at a population level.

Genetic testing for hypertrophic cardiomyopathy or long QT syndrome is not recommended or even feasible for the screening of athletes.

Key Points

• Sudden cardiac death during exercise is rare and is most commonly due to hypertrophic cardiomyopathy (younger athletes) and coronary artery disease (older athletes).
• Screen younger participants (children through young adults) with history and physical examination; those with abnormal findings or positive family history typically have ECG and/or echocardiography.
• Screen older participants with history, physical examination, and usually an exercise stress test.

Last full review/revision January 2013 by Robert S. McKelvie, MD, PhD, MSc