A Rare Vascular Tangle Unraveled: Multimodal Imaging in Giant Coronary Arteriovenous Fistula

A 63-year-old woman presented with intermittent palpitations. Transoesophageal echocardiography (TEE) identified a high-velocity shunt from a tortuous left circumflex artery into an enlarged coronary sinus, with a 5-mm fistulous orifice. Coronary CT angiography delineated the full course of a congenital coronary arteriovenous fistula (CAVF), associated circumflex aneurysm, and coronary sinus dilatation. Surgical closure was successfully performed, with intraoperative confirmation of shunt resolution. This case highlights the synergistic utility of multimodal imaging: echocardiography for real-time hemodynamic assessment and CT angiography for precise anatomical mapping-which enables accurate diagnosis, optimal surgical planning, and timely intervention in anatomically complex CAVF before irreversible myocardial damage ensues.