Anomalous origin of the left main coronary artery from the pulmonary artery (ALCAPA) is an uncommon congenital condition seen in the adult population, with most patients developing symptoms in infancy. We describe successful closure of an ALCAPA in an adult using a percutaneous transcatheter approach in a patient with evidence of anterior wall ischemia believed to be the consequence of myocardial steal. A 30-year-old female was noted to have continuous flow in the right ventricular septum on transthoracic echocardiography, with subsequent imaging confirming the presence of an ALCAPA. Myocardial perfusion imaging confirmed anterior wall ischemia, and as a strategy to optimize coronary perfusion pressure, the patient underwent percutaneous ALCAPA closure using an Amplatzer vascular plug. The procedure was well tolerated, with no evidence of anterior ischemia or myocardial dysfunction. Follow up perfusion imaging demonstrated no residual anterior wall ischemia. Transcatheter closure of an ALCAPA is a potentially safe and effective alternative treatment strategy in this patient population.