Patients with ventricular septal (VS) rupture (n = 96) or left ventricular (LV) free wall rupture (n = 97) during acute myocardial infarction had comparable clinical, angiographic, and electrocardiographic features, suggesting similar underlying mechanisms, although the 2 groups differed in the rate of bundle branch block, complete atrioventricular block, atrial fibrillation, and culprit artery. In 20 patients, LV rupture followed VS rupture, which underscores the need for early surgery.