An 82-year-old female was admitted to the coronary care unit with an anterior wall myocardial infarction and cardiogenic shock. She was in chronic atrial fibrillation without oral anticoagulation. Coronary angiography showed occlusion of the left main coronary artery which originated together with a normal right coronary artery from the right sinus of Valsalva. The advanced age, the presence of chronic atrial fibrillation not anticoagulated and the normal appearance of the remaining coronary arteries suggested a thromboembolic origin. Transthoracic echocardiography showed an abrupt interruption of the myocardial wall, in the apical portion of the interventricular septum, not communicating with the pericardial sac or right ventricular cavity suggesting the presence of an incomplete contained rupture of the myocardial wall at this location. She died in cardiogenic shock due to the extensive left ventricular damage.