C63-34 Coronary CTA Reveals a Rare Right Coronary Artery to SVC Fistula in a Patient With New-onset Arrhythmia

Introduction Coronary artery fistulas are rare congenital or acquired abnormalities that form an anomalous communication between a coronary artery and a cardiac chamber or great vessel. While often incidentally detected and asymptomatic, hemodynamically significant fistulas may cause myocardial ischemia, heart failure, arrhythmias, or cardiac tamponade, necessitating timely recognition and management. Case Presentation A 63-year-old man without significant medical history presented with recurrent palpitations, hypotension, and tachycardia. ECG showed atrial flutter with rapid ventricular response; labs revealed normal electrolytes/TSH and mild troponin elevation. Hemodynamic instability prompted urgent 250-J direct-current cardioversion, restoring sinus rhythm. Echocardiography demonstrated mild global hypokinesis. He was discharged stable on apixaban. Outpatient coronary CTA revealed a large right coronary artery fistula draining into the superior vena cava with severe right-sided chamber dilation. The patient has been scheduled to undergo cardiac magnetic resonance imaging, after which surgical management will be considered based on the findings. Discussion Most coronary artery fistulas arise from the right coronary artery and drain into low-pressure chambers; drainage into the superior vena cava is exceptionally uncommon (<1%). Although atrial flutter is an atypical presentation, right heart dilation may promote atrial arrhythmogenesis. Clinical manifestations vary according to patient age, magnitude of left-to-right shunting, presence of myocardial ischemia, and the resistance of the receiving chamber or vessel. Most adults remain asymptomatic, with fistulas typically identified by cardiac auscultation or incidentally during coronary angiography performed for unrelated indications. Among symptomatic individuals, chest pain is the most frequent presenting feature. Potential complications include myocardial ischemia, heart failure, arrhythmias, and, rarely, cardiac tamponade. Coronary angiography remains the gold standard for diagnosis; however, non-invasive imaging may be employed for diagnosis and follow-up. Coronary CTA and Cardiac MRI provide better anatomical delineation compared to echocardiography. Hemodynamically significant fistulas warrant intervention via surgical closure or transcatheter embolization. Case reports suggest arrhythmias may resolve following definitive repair. In summary, this case advocates the importance of considering coronary artery fistula in the differential diagnosis of new-onset atrial arrhythmias with right heart dilation. Early recognition and intervention are critical to prevent irreversible cardiac remodeling and adverse outcomes. This abstract is funded by: None