Repeated Syncope During Exercise as a Result of Anomalous Origin of Left Coronary Artery With Intramural Aortic Course in a Teenage Boy.

Anomalous origin of the left coronary artery from the opposite sinus of Valsalva with an intramural aortic course (L-ACAOS-IM) can cause syncope, sometimes as a prodrome of lethal events, including sudden cardiac death, in young athletes. The detailed mechanism of syncope in patients with L-ACAOS-IM is still unclear. This case report describes a 17-year-old boy who presented to the hospital because of syncope following chest pain with increasing frequency during exercise, such as playing soccer and running. In a treadmill exercise test, a decrease in blood pressure was seen (from 99/56 mm Hg to 68/38 mm Hg); chest pain and faintness accompanied by ST-segment elevation in lead aVR and ST-segment depression at other leads on electrocardiography were noted. These findings and symptoms disappeared spontaneously within a few minutes while clinicians prepared for emergency medications. Coronary computed tomography angiography (CCTA) showed that the origin of the left coronary artery (LCA) was the opposite sinus of Valsalva, and the course of the LCA was through the aortic wall toward the left coronary sinus. He was diagnosed with L-ACAOS-IM. After surgical treatment by unroofing the intramural part of the LCA and reconstructing a neo-ostium, he no longer experienced syncope during exercise. This case suggests that low cardiac output caused by myocardial ischemia, not life-threatening arrythmia, is a main mechanism of syncope in patients with L-ACAOS-IM. Consideration should be given to performing CCTA before an exercise stress test for young patients with syncope and chest pain to avoid the risk of severe myocardial ischemia.