An autopsy image showing accumulation of large quantities of blood in the pericardial space (cardiac tamponade). The patient suffered from myocardial rupture 3 days after a large myocardial infarction (MI). Myocardial rupture tends to occur usually 2 to 4 days after an acute MI when the involved myocardium is at its weakest due to coagulative necrosis and lysis of the myocardial connective tissue. The risk is greatest after the first MI. Fibrotic scarring resulting from the prior MI tends to inhibit myocardial rupture. The most common site of rupture is the antero-lateral free wall.