Anomalous origin of left main coronary artery from right coronary artery in a patient presenting with inferior wall myocardial infarction: a case report and literature review

BACKGROUND: Anomalous origin of the coronary arteries is seen in less than 1% of the general population. Single coronary artery (SCA) is a congenital anatomic abnormality identified by a single coronary ostium giving rise to one coronary artery. We present an extremely rare variant of the left main coronary artery (LMCA) branching off from the right coronary artery (RCA) and following a prepulmonic course. CASE SUMMARY: A 72-year-old woman presented due to ongoing chest pain with associated ST-segment elevation involving the inferior leads. Emergent cardiac catheterization revealed a 99% ulcerated lesion in distal RCA, which was intervened on with angioplasty and stent placement. The RCA was noted giving rise to LMCA, which followed a prepulmonic course (anterior to pulmonary artery) before trifurcating into a small caliber left anterior descending, ramus intermedius, and hypoplastic left circumflex arteries. The non-malignant course of the aberrant LMCA was confirmed on the coronary computed tomography angiogram. The patient was discharged home on guideline-directed medical therapy. DISCUSSION: The patient illustrated congenital SCA with type RIIA pattern of the aberrant vessel based on the Lipton anatomic classification for SCA. The prepulmonic course of SCA is usually benign and can be managed conservatively.