Complex single ostium coronary artery from the right coronary sinus with unique course of anomalous left circumflex coronary artery

Single ostium coronary artery is a rare coronary artery anomaly. It is reported to occur in only 0.0448% of cases who underwent invasive coronary angiography. It can be associated with angina, arrhythmias, and possibly sudden death and is a clinically important entity to rule out in patients presenting with chest pain. We report the case of a 68-year old man who presented with worsening resting chest pain and underwent invasive coronary angiography and a single ostium coronary artery was identified. Subsequent coronary computed tomography (CT) angiography revealed it to be a unique variation of class R-III of Lipton classification of single ostium coronary artery. Lipton R-III single ostium coronary artery is rare and its incidence is reported to be 0.004% in patients who had invasive coronary angiography. In our case, anomalous left coronary circumflex artery was retroaortic course combined with intramyocardial course. It also divided into multiple obtuse marginal branches in the myocardium and never coursed along the anterior and lateral aspects of the arterioventricular groove. This variation has not been reported in the literature. Coronary CT angiography played an essential role to delineate this complex coronary anomaly.