Anomalous aortic origin of the left coronary artery from an incorrect aortic sinus has been reported as the second most common causes of sudden cardiac arrest in young athletes. Intramural course of the proximal left coronary artery is considered a high-risk morphology. It is associated with a slit-like ostium and elliptical shape of the proximal artery. In this case, all pre-operative cardiac images demonstrated a round ostium and round luminal shape of the left coronary artery, which suggested no evidence of intramural course. On intraoperative inspection, although the ostium and proximal left coronary artery appeared round, the patient had a long intramural course of the left coronary artery which our surgeons performed a successful unroofing procedure. The post-operative images showed a patent new ostium from the correct aortic sinus. These findings are very unusual and proved that we should not exclude intramural course even in the absence of a slit-like ostium and elliptical shape of the proximal left coronary artery.
