Multimodality Imaging-Guided Transcatheter Closure of a Tortuous LCX–CS Fistula: A Case Report

Background Coronary artery fistula (CAF) is a rare congenital anomaly often detected incidentally. When large, it may cause significant left-to-right shunting, requiring closure in symptomatic cases or those with a substantial shunt volume. While previously treated surgically, transcatheter fistula closure is recognized as an effective and less invasive approach. We report a case of a large, tortuous CAF between the left circumflex artery (LCX) and the coronary sinus (CS) successfully treated with transcatheter coil embolization guided by multimodality imaging. Case summary A 44-year-old woman presented with exertional dyspnea and a continuous murmur. Contrast-enhanced computed tomography (CT) revealed a markedly dilated and tortuous CAF arising from the LCX and draining into the CS. Cardiac magnetic resonance imaging (MRI) demonstrated a Qp/Qs ratio of 1.50, and myocardial perfusion scintigraphy showed no ischemia. Preprocedural CT revealed a narrowing neck in the distal segment and severe tortuosity of the fistula. Stable access was achieved using a triple coaxial catheter system, which enabled successful coil delivery to the targeted site via an arterial approach. The procedure was completed without complication in a single session. At six-month follow-up, cardiac MRI showed a reduced Qp/Qs ratio of 1.17, and contrast-enhanced CT confirmed occlusion of the target vessel. Discussion Transcatheter coil embolization is a safe and effective treatment option, especially for tortuous lesions. In this case, multimodality imaging enabled accurate anatomical and functional assessment and procedural planning. The use of a triple coaxial catheter system contributed to stable access and successful coil delivery in this anatomically challenging lesion.