A rare giant congenital left atrial appendage aneurysm in a 1-day-old newborn.

Congenital left atrial appendage aneurysm (LAAA) is a very rare condition and occurs as a result of congenital dysplasia of musculi pectinate. These patients may be asymptomatic and/or may present with dyspnea, and thromboembolic events. The most common complications are life-threatening thromboembolic events and supraventricular tachyarrhythmias. Transthoracic echocardiography plays a very important role in the diagnosis of LAAA. Herein, we present a rare case of giant congenital LAAA.