Diagnosing Left Coronary Ostial Atresia: Sometimes the Old Ways Are Best.

A 12-year-old boy with intermittent syncope associated with exercise. Exercise stress testing suggested myocardial ischemia and 2D echocardiography failed to confirm antegrade flow in the left main stem. Advanced imaging techniques including cardiac-gated computed tomography angiography and stress cardiac magnetic resonance imaging were falsely reassuring. Cardiac catheterization demonstrated left coronary artery ostial atresia with a good caliber left coronary system supplied by generous collaterals from the right coronary artery. The patient underwent successful coronary artery bypass grafting.