Right coronary artery-right ventricle fistula with a rare giant thrombotic aneurysm: a case report and literature review.

Background: Coronary artery fistula (CAF) is a rare vascular anomaly characterized by an abnormal shunt originating from a coronary artery and terminating at an atypical endpoint, typically involving dilated and tortuous vessels. The increased shunt flow can lead to a "coronary steal" phenomenon, resulting in angina pectoris. At present, the complications of CAF other than fistula steal need to be paid more attention, especially aneurysm rupture, thrombosis, and myocardial infarction. CAF may be accompanied by aneurysms, but it is seldomly reported that the aneurysm is giant with thrombosis and possibly relevant to myocardial infarction.

Case description: A 51-year-old female who presented stomachache, chest pain, and palpitation had been indicated as having right coronary artery (RCA)-right ventricle (RV) fistula by echocardiography four years prior. Echocardiography showed dilatation of the RCA and a hypoechoic mass originating from the RCA, with left-to-right septal shunt at the atrial septum. Coronary computed tomography angiography (CCTA) examinations showed a dilated RCA, and a mass which compressed the RV, together with contrast filling defects. The follow-up CCTA four years later revealed nodular calcification of the aneurysm and cinematic rendering reconstruction showed that the aneurysm appeared as a fruit growing on the coronary artery tree. Further cardiac magnetic resonance (CMR) revealed a mass located at the right atrioventricular sulcus, and deformation of the RV with preserved biventricular ejection fraction. Subendocardial late gadolinium enhancement of the basal inferior wall suggested myocardial infarction. Subsequent surgical procedures confirmed and closed the RCA-RV fistula and an aneurysm, as well as the atrial septal defect (ASD). The patient was free of cardiovascular events during the follow-up of 1 year and 3 months.

Conclusions: This case of CAF accompanied by a giant aneurysm with thrombus formation suggested critical value of multimodal imaging, especially cinematic volume rendering reconstruction and multiparametric CMR imaging in the follow-up, preoperative assessment, and complication evaluation.