Coronary Artery Fistula Aneurysm: Pathological Analysis After Surgery.

An asymptomatic 75-year-old woman was identified with a 40-mm-sized, round-shaped lesion beside the pulmonary artery on computed tomography (CT). Coronary angiography showed a coronary artery fistula (CAF) with an aneurysm branching from the left anterior descending artery toward the pulmonary artery. The CAF aneurysm (CAFA) was resected and coronary artery bypass graft surgery using the left internal thoracic artery was performed successfully. Pathological analysis revealed that medial depletion similar to segmental arterial mediolysis (SAM) may contribute to aneurysm formation.