Isolated single coronary artery with dual right coronary artery distribution. A rare anatomical variation.

We present the case of a 76-year-old patient in whom coronary angiography, performed due to non-ST-segment elevation myocardial infarction, revealed an isolated single coronary (SCA) artery with dual right coronary artery (RCA) distribution. One RCA arose from the mid segment of the left anterior descending (LAD) artery and followed a prepulmonic course to the right, while the other RCA arose as the terminal extension of the left circumflex artery beyond the crux cordis. This is the second reported case of the combination of these two variants of SCA and the first such case in which the LAD-derived RCA originated as a single branch. Furthermore, this is the first report presenting a sinus node artery with origin from an ectopic LAD-connected RCA. The clinical implications of this rare coronary artery pattern are discussed.