Rare Coronary Artery Anomaly: Single Coronary Artery from Distal Circumflex Detected by CT

BACKGROUND A single coronary artery is a rare congenital anomaly of the coronary arteries distribution, with an incidence of only 0.03% in the general population undergoing coronary angiography. RCA arising from the distal circumflex artery is an extremely rare variety. CASE REPORT We report the case of a 63-year-old man who was admitted in our hospital after an inconclusive treadmill stress test. He had no cardiovascular risk factors. He was initially evaluated for palpitations. A subsequent Holter monitor showed monomorphic premature ventricular beats. His coronary artery disease (CAD) pre-test probability was low. Non-invasive exploration with 64-detector-row multi-slice computed tomography (MSCT) was performed to visualize the coronary arteries. It showed a single left coronary artery (LCA) with no significant stenosis. There was no artery emerging from the right sinus of Valsalva. The right coronary artery (RCA) had an abnormal origin, arising from the distal circumflex artery. The patient remained asymptomatic. CONCLUSIONS This case report describes an accidental discovery of an unusual variety of single coronary artery. Computed tomography angiography, very useful in patients with low pre-test probability of coronary artery disease, showed a right coronary artery from the distal circumflex artery.