BACKGROUND: Anomalous aortic origin of the left coronary artery (AAOLCA) confers a rare, but significant, risk of sudden cardiac death in children. Surgery is recommended for interarterial AAOLCA, and other subtypes considered benign. We aimed to determine the clinical characteristics and outcomes of 3 AAOLCA subtypes. METHODS: All patients with AAOLCA <21 years old were prospectively enrolled (December 2012-November 2020), including group 1: AAOLCA from the right aortic sinus with interarterial course, group 2: AAOLCA from the right aortic sinus with intraseptal course, and group 3: AAOLCA with a juxtacommissural origin between the left and noncoronary aortic sinus. Anatomic details were assessed using computed tomography angiography. Provocative stress testing (exercise stress testing and stress perfusion imaging) was performed in patients >8 years old or younger if concerning symptoms. Surgery was recommended for group 1 and in select cases in group 2 and group 3. RESULTS: We enrolled 56 patients (64% males) with AAOLCA (group 1, 27; group 2, 20; group 3, 9) at median age of 12 years (interquartile range, 6-15). Intramural course was common in group 1 (93%) compared with group 3 (56%) and group 2 (10%). Seven (13%) presented with aborted sudden cardiac death (group 1, 6/27; group 3, 1/9); 1 (group 3) with cardiogenic shock. Fourteen/42 (33%) had inducible ischemia on provocative testing (group 1, 32%; group 2, 38%; group 3, 29%). Surgery was recommended in 31/56 (56%) patients (group 1, 93%; group 2, 10%; and group 3, 44%). Surgery was performed in 25 patients at a median age 12 (interquartile range, 7-15) years; all have been asymptomatic and free from exercise restrictions at median follow-up of 4 (interquartile range, 1.4-6.3) years. CONCLUSIONS: Inducible ischemia was noted in all 3 AAOLCA subtypes while most aborted sudden cardiac deaths occurred in interarterial AAOLCA (group 1). Aborted sudden cardiac death and cardiogenic shock may occur in AAOLCA with left/nonjuxtacommissural origin and intramural course, thus also deemed high-risk. A systematic approach is essential to adequately risk stratify this population.