Abstract Body (Do not enter title and authors here): Case
A 23-year-old non-smoking male with no comorbidities or trauma history presented with one year of exertional dyspnea. Physical exam and initial workup (CXR, EKG, CBC, BMP, BNP, TrI, lipids, TPHA) were unremarkable. TTE revealed abnormal continuous flow into the RA with aneurysmal RCA origin (14mm); normal LVEF (63%) and PAPS. Color Doppler showed a significant shunt (5mm). Contrast-enhanced CCTA with 3D reconstructions confirmed an aneurysmal RCA ostium (10 mm) and proximal RCA (11 mm). The SNA originates from the RCA, with a 13mm SNA aneurysm and a 9 mm fistula draining into the RA. A contrast jet was visualized through the fistula. The patient underwent successful open surgical repair with direct intra-atrial closure of the fistulous orifice combined with external fistula ligation. Postoperative recovery was uneventful.

Discussion
Coronary artery fistulas (CAFs) are rare, with a prevalence of 0.002% in general population, most often arising from the RCA (55%) or LAD (35%) and draining into low-pressure cardiac chambers. Rarest of all is the triad of RCA aneurysm, SNA aneurysm, and CAF to the RA. This has been reported in only two prior cases. Our patient is the youngest reported adult to present this.

Clinical presentation varies with the size and hemodynamic impact of the CAF. 50% of patients are asymptomatic. Larger fistulas can cause dyspnea, palpitations, fatigue, and angina. ECG and CXR are often normal unless a large left-to-right shunt is present. TTE may show dilated coronary arteries, enlarged chambers, and turbulent flow. Contrast-enhanced CCTA with 3D reconstruction is crucial for precise anatomical delineation of both aneurysms and the fistulous tract, facilitating surgical planning. Our patient presented with minimal symptoms but significant lesions on imaging, emphasizing the importance of high clinical suspicion and comprehensive imaging.

No formal guideline of CAF management exist. Small CAFs may close spontaneously with excellent prognosis. Larger ones can lead to complications (premature CAD, endocarditis, pulmonary hypertension, heart failure, rupture) and require closure, either percutaneously or surgically. Given the exertional dyspnea and large fistula, surgical closure was indicated in this case. Coil embolization was not chosen due to the complexity of the lesion. Resection of the aneurysm was deferred due to its size, absence of mass effect, and the importance of preserving SNA flow to maintain sinoatrial node function.