Anomalous right coronary artery originating from the left anterior descending artery.

An anomalous right coronary artery (RCA) arising from the left anterior descending artery (LAD) is very rare, and has previously been considered a variant of single coronary artery. This is the first report of an anomalous RCA arising from the LAD with a coexisting proximal RCA. The anomaly was discovered incidentally during cardiac catheterization for severe mitral regurgitation. The incidence, anatomy and clinical associations of anomalous coronary arteries are reviewed here.