Giant left atrial appendage with a common ventricular-appendicular wall and an abnormal course of the circumflex coronary artery in an asymptomatic 18-month-old girl.

We present a congenital giant left atrial appendage in an asymptomatic 18-month-old girl featuring two morphological aspects not yet described, namely, a common wall between the giant left atrial appendage and the left ventricle and an abnormal course of the circumflex coronary artery across the surface of the grossly dilated left atrial appendage which prohibited its radical resection. Surgery was performed off-bypass, via anterolateral thoracotomy with plication of the aneurysm, leaving a residual pouch. A patch closure of the communicating os between the left atrium and the residual aneurysm was therefore undertaken later. Radical surgical resection is recommended for giant left atrial appendage if complications are to be avoided, as there is potential for progressive growth, intracardiac thrombosis, systemic embolization, cardiac arrhythmia, and need for life-long anticoagulation.