Single dominant right coronary artery with hypoplastic left coronary branch: a rare congenital anomaly: a case report.

Background: A right single coronary artery (SCA) and hypoplastic coronary disease represent a rare coronary artery anomaly, which is associated with sudden cardiac death. The clinical manifestations of these anomalies depend on the distribution of collateral vessels. Case summary: A 55-year-old female presented with dyspnoea, mild chest pain during physical activity, and palpitations. Selective coronary angiography revealed a prominent SCA originating from the right coronary sinus. Approximately 2 mm from the ostium, this artery branched into two: a dominant right coronary artery (RCA) and a smaller artery for the anterior wall perfusion. The dominant RCA then moved posteriorly, bifurcating into a posterior descending artery and a posterolateral artery. The latter occupied the expected location of the left circumflex artery and supplied the majority of the coronary circulation, including the left ventricle. Notably, there were no significant atherosclerotic calcifications or stenoses observed. Discussion: We describe a unique case of a SCA that doesn't conform to any category within the modified Lipton's classification. Symptoms are speculated to arise from the compression of the SCA between the aorta and pulmonary artery during physical exertion. Additionally, hypoperfusion from the hypoplastic left coronary branch in the anterior wall warrants consideration. It's paramount to meticulously evaluate the risk of sudden cardiac death when treating patients with a SCA. For high-risk patients, coronary artery bypass grafting should be contemplated.For our patient, given the clinical context, pharmacological treatment optimization was chosen.