Sudden cardiac death of a young athlete is the most tragic event in sports and 
devastates the family, the sports medicine team, and the local community. Such a 
fatality represents the first manifestation of cardiac disease in up to 80% of 
young athletes who remain asymptomatic before sudden cardiac arrest occurs; this 
explains the limited power of screening modalities based solely on history and 
physical examination. The long-running Italian experience showed that 
electrocardiogram (ECG) screening definitively improves the sensitivity of 
pre-participation evaluation for heart diseases and substantially reduces the 
risk of death in the athletic field (primary prevention). However, some cardiac 
conditions, such as coronary artery diseases, present no abnormalities on 
12-lead ECG. Moreover, cardiac arrest due to non-penetrating chest injury 
(commotio cordis) cannot be prevented by screening. This justifies the efforts 
for implementing programmes of early external defibrillation of unpredictable 
arrhythmic cardiac arrest. This article reviews the epidemiology of sudden 
cardiac arrest in the athlete in terms of incidence, sport-related risk, 
underlying causes, and the currently available prevention programmes such as 
pre-participation screening and early external defibrillation by using automated 
external defibrillators. The best strategy is to combine synergistically primary 
prevention of sudden cardiac death by pre-participation identification of 
athletes affected by at-risk cardiomyopathies and secondary prevention with 
back-up defibrillation of unpredictable sudden cardiac arrest on the athletic 
field.