Giant coronary sinus aneurysm: an incidental discovery in a case of acute coronary syndrome.

Coronary sinus (CS) anomalies, although infrequent, are increasingly diagnosed with advances in interventional procedures and imaging techniques. Most cases are asymptomatic and incidentally diagnosed. We present a case of an elderly male without comorbidities who presented with acute angina. Coronary catheterisation revealed a double-vessel disease, but incidentally, sequential angiograms captured contrast filling in the levophase of CS, revealing a giant CS. Primary percutaneous angioplasty of the right coronary artery was performed successfully. Echocardiography confirmed the aneurysm, and a CT scan showed an aneurysmally dilated CS and other coronary veins alongside a normal-sized persistent left superior vena cava draining to the right atrium through CS. CS aneurysms may lead to complications such as thrombosis, embolic events, arrhythmias and heart failure, stressing the importance of vigilant monitoring and timely intervention. This case underscores the significance of recognising CS anomalies in cardiac procedures, even when asymptomatic, for proper management.