An Uncommon Coronary Anomaly: A Single Right Coronary Artery With a Conus Branch Supplying the Left Anterior Descending Artery

Coronary artery anomalies (CAAs) are usually asymptomatic and have a good prognosis. Single coronary artery anomaly (SCA) is a very rare CAA. Its true incidence is unknown. They are usually detected incidentally during coronary imaging and autopsy. Although most are asymptomatic, they can rarely cause clinical conditions such as sudden cardiac death and acute coronary syndrome (ACS). In this case report, a 44-year-old male patient was admitted to the emergency department with chest pain and coronary angiography revealed the absence of the left main coronary artery and a single right coronary artery (RCA). The patient's left system was fed by the posterior left ventricular artery (PLVA) and the conus artery. There was a serious lesion in the proximal PLVA and in the region close to the conus branch of the RCA. The patient underwent coronary artery bypass grafting and was discharged with recovery. In this case, we identified a single RCA in the patient presenting with ACS, and interestingly, the conus branch was supplying the proximal part of the left descending artery branch.