A rare right coronary artery arising from the left anterior descending artery with a critical left main lesion: a case report

Background An anomalous right coronary artery (RCA) arising from the left anterior descending artery (LAD) is a very rare coronary variant. When a distal left main/ostial LAD culprit lesion occurs in this setting, the myocardium at risk is substantial and revascularization decisions are time-critical. Case Summary A 40-year-old non-diabetic heavy smoker presented with NSTEMI. Coronary angiography revealed severe distal left main/ostial LAD stenosis (80–90%), and optical coherence tomography (OCT) confirmed plaque rupture with thrombus. An anomalous RCA arising from the proximal LAD was identified without significant stenosis, and the LCx had no significant disease. Heart Team discussion recommended urgent CABG; however, the patient refused surgery and opted for PCI. OCT-guided PCI from the left main into the LAD was performed successfully with an excellent result. At 8-month follow-up, the patient remained asymptomatic, was exercising regularly, and was compliant with medications. ECG and transthoracic echocardiography were normal, with an LVEF of 60%, and CT coronary angiography demonstrated a patent left main stent and a prepulmonic/anterior course of the anomalous RCA. Discussion This case illustrates a very rare coronary anatomy in which a distal left main ACS carries substantial myocardium at risk. It underscores the value of timely Heart Team discussion and patient-centred decision-making when surgery is declined. Early intracoronary imaging–guided PCI can provide effective revascularization, preserve myocardial function, and achieve an excellent clinical outcome.