A patient with known pulmonary atresia and intact ventricular septum and ductal stent presented with low cardiac output and arrythmia. Intraoperatively, the patient was found to have an anomalous left coronary artery arising from the pulmonary artery. After reimplantation of the left coronary artery to the aortic root and placement of a central shunt, the patient progressed well and was discharged home. A high index of suspicion and clear diagnostic visualization of both right and left coronary artery origins are needed to diagnose this highly fatal yet treatable lesion properly.