An unusual coronary trinity: single left coronary artery with the right coronary artery originating from the left main coronary artery and following a retro-aortic course.

All three coronary arteries originating from a single coronary ostium is a rarity. Single coronary artery (CA) arising from the left aortic sinus is far more uncommon than one arising from the right sinus. Usually in such cases, the right coronary artery (RCA) arises as a distal continuation of the left circumflex artery. We describe an extremely uncommon anatomic variant, where the RCA arose from the single undivided CA as a branch of the left main coronary artery and followed a retro-aortic course before reaching its designated anatomic territory.