Blunt precordial blows triggering ventricular fibrillation (commotio cordis) 
represent a leading cause of sudden death in young athletes. Attention has 
focused on the primary prevention of these tragedies with chest barriers. The 
U.S. Commotio Cordis Registry was accessed to determine the likelihood of sudden 
death in athletes exposed to precordial blows while wearing chest protectors. Of 
182 cases of commotio cordis, 85 (47%) occurred during practice or competition 
in organized sports. In 32 of these 85 competitive athletes (38%), fatal chest 
blows occurred despite the presence of potentially protective equipment. 
Athletes wore standard, commercially available chest barriers made of polymer 
foam covered by fabric or hard shells, generally perceived as protective from 
arrhythmic consequences of the blows. These events occurred in 4 sports: hockey 
(n = 13; 1 goalie), football (n = 10), lacrosse (n = 6; 3 goalies), and baseball 
(n = 3; all catchers). Scenarios included the failure of the padding to cover 
the precordium so that blows circumvented the protective barrier (n = 25) or 
projectiles that struck the chest barrier directly (n = 7). In conclusion, a 
significant proportion (about 40%) of sudden deaths reported in young 
competitive athletes due to blunt chest blows (commotio cordis) occur despite 
the presence of commercially available sports equipment generally perceived as 
protective.