Coronary artery anomalies are associated with sudden cardiac death, although individual patient outcomes are highly variable. We performed blinded pathologic analysis of 30 consecutive cases of anomalous right (n = 21) or left (n = 9) coronary artery from the contralateral coronary sinus to determine which, if any, features might aid in risk stratification for sudden cardiac death. We found no significant differences in length of aortic intramural segment, coronary ostial size, degree of displacement of the anomalous coronary artery from the correct coronary sinus, or angle of coronary takeoff between patients with (n = 12) and without (n = 18) sudden cardiac death. All pathologic features showed considerable interpatient variability. Age > or = 30 years was the only variable associated with a decreased incidence of sudden cardiac death. Thus no simple relation exists between variations in the initial coronary artery course and clinical outcome in these anomalies.