Don't Forget Commotio Cordis.

Non-penetrating chest blows can occasionally trigger fatal ventricular tachyarrhythmias and sudden death (commotio cordis). Such events were initially reported in association with sporting activities and projectiles such as baseball/lacrosse balls. However, similar potentially fatal chest blows, seemingly incapable of causing death, can occur during a variety of other circumstances such as when delivered during a fight (by a fist) such as in the accompanying paper. Notably, commotio cordis events can be reversed by resuscitation and defibrillation.