Anomalous origin of the left main coronary artery from the pulmonary artery (ALCAPA) is a rare congenital coronary anomaly with high mortality. It is associated with cardiovascular complications and is usually diagnosed soon after birth. Those who survive into adulthood can present with signs of myocardial infarction, heart failure, mitral regurgitation, severe pulmonary hypertension, or sudden cardiac death. We present a 53-year-old female presenting with atrial fibrillation and found to have an incidental diagnosis of ALCAPA who refused surgical correction. We also review the epidemiology, diagnosis, age-based clinical presentations, and treatment options for ALCAPA.