Super-dominant left circumflex coronary artery (LCx) — an unusual variant of left dominance

Single coronary artery (SCA) is a rare congenital anomaly of the coronary circulation, the incidence of which has been reported as being from 0.6–1.3% among the population undergoing coronary angiography. The absence of a right coronary artery (RCA) with the origin of the RCA arising from the distal circumflex artery is an exceedingly rare variant of the SCA. The exact incidence of this anomaly is uncertain, with very few cases reported. We here report the case of a 56 year-old diabetic, hypertensive male presenting with acute inferior wall myocardial infarction who was thrombolysed with tenecteplase. Subsequent coronary angiogram demonstrated RCA arising from the distal left circumflex coronary artery (LCx) as its extension, thereby making the LCx super-dominant. RCA had ostial plaquing, and therefore the patient was managed conservatively.