Anomalous left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital heart defect in which the left coronary artery, responsible for supplying oxygen-rich blood to the heart muscle, originates from the pulmonary artery instead of the aorta. This abnormality can lead to insufficient blood flow to the heart muscle, causing myocardial ischemia, heart failure, and potentially sudden cardiac death if left untreated.