Background Congenital left ventricular aneurysm is a poorly understood and potentially lethal entity. Methods and Results In a clinicopathologic study of 7 new cases, the major presenting features in 6 patients were congestive heart failure in ventricular arrhythmias in a 32-week fetus, and multiple congenital anomalies in a fetus with trisomy Accurate diagnosis was achieved in all 3 living patients by echocardiography, angiocardiography, and magnetic resonance imaging. The aneurysm was predominantly apical in 3 and involved most of the left ventricular free wall in Of the 3 living patients, medical management alone sufficed in The third, a newborn boy, underwent a new and successful aneurysm-exclusion left ventriculoplasty.