Commotio cordis is a rare phenomenon that can occur when chest wall trauma during the ascending limb of the T wave results in ventricular fibrillation and sudden cardiac death.

Frequently, this occurs in young male athletes. The exact mechanism is unclear, however this is also the basis for using “synchronized cardioversion” during elective cardioversions. Synchronizing the shock with the QRS complex avoids delivering energy on the T wave thus decreasing the risk of ventricular fibrillation.

Other causes of sudden cardiac death in young athletes includes hypertrophic obstructive cardiomyopathy and coronary anomalies. Automated external defibrillators are readily available at most sporting events since early defibrillation is crucial to survival, which is only estimated at 35% in cases of commotio cordis.