Multiple Coronary-Cameral Fistulae Draining Exclusively Into the Left Atrium Associated With Atrial Thrombosis

Coronary artery fistulae (CAF) represent uncommon anomalous connections linking the coronary arterial tree directly to cardiac chambers or great thoracic vessels. Termination into the left atrium is extraordinarily rare, especially when presenting as multiple fistulous tracts. We describe the case of a 60-year-old woman with permanent atrial fibrillation, previous mechanical mitral valve replacement, recurrent systemic thromboembolism, and prosthetic valve thrombosis. Coronary angiography incidentally revealed two coronary-cameral fistulae arising from the proximal left circumflex artery and a third fistula originating from the right coronary artery's distal conus branch, with all channels draining exclusively into the left atrial cavity. Transesophageal echocardiography confirmed continuous turbulent flow entering the left atrium, accompanied by dense spontaneous echocardiographic contrast (SEC) and an organized mural left atrial thrombus. The combination of permanent atrial fibrillation, chronic left atrial volume overload driven by the fistulous shunt, prior mitral valve pathology, and inadequate anticoagulation likely generated a highly prothrombotic environment. This case emphasizes the critical role of multimodality cardiac imaging in characterizing intricate coronary-cameral architecture. Furthermore, it demonstrates that left atrial drainage fistulae may have contributed to atrial flow disturbance and thrombotic propensity in the context of multiple established thromboembolic risk factors, even without achieving conventional thresholds for a hemodynamically significant shunt.