Chronic Total Occlusion of the Left Main Coronary Artery Revealed by an Acute Coronary Syndrome: A Rare Case from Senegal

Introduction: Congenital coronary anomalies are rare but may present as serious clinical events, sometimes mimicking acute coronary syndromes. Chronic total occlusion (CTO) of the left main coronary artery (LMCA) is exceptionally rare and is often discovered incidentally or during evaluation of chest pain. Case Presentation: We report, after informed consent, the case of a 69-year-old hypertensive, dyslipidemia and obese woman presenting with resting angina. ECG and blood tests were consistent with NSTEMI. Transthoracic echocardiography demonstrated a preserved ejection fraction with regional wall motion abnormalities. Coronary angiography revealed a chronic total occlusion of the LMCA with collateral circulation. Cardiac CT confirmed a single coronary artery arising from the right anterior sinus with a normal course, excluding a congenital anomaly of origin (ANOCOR). She was subsequently referred for coronary artery bypass grafting. Discussion: Chronic total occlusion of the LMCA is extremely rare, with an estimated incidence of 0.03% to 0.06%. Atherosclerosis is the principal etiology. This diagnosis requires careful image interpretation, correlation with clinical findings, and assessment of collateral networks. Multimodality imaging, particularly coronary CT angiography, plays a key role in confirming the diagnosis and ruling out congenital variants associated with myocardial ischemia. Conclusion: This case highlights the need to consider LMCA chronic occlusion in the differential diagnosis of acute coronary syndromes, especially in elderly patients. It also underlines the value of multimodal imaging in achieving an accurate diagnosis and guiding management.