Postinfarction communication between a left ventricular aneurysm and the right atrium is a rare acquired disease. We report a case of a 72-year-old man who recently had dyspnea on minimal exertion and was found to have left ventricle-to-right atrial shunt by two-dimensional transthoracic echocardiography. This diagnosis was confirmed with transesophageal echocardiography, cardiac catheterization, and angiography. The patient underwent successful repair but died of multisystem failure. This case shows the importance of transthoracic echocardiography for the adequate diagnosis and management of such cases.