One Ostium, Three Coronary Arteries: A Rare Coronary Anomaly in a Patient With Secundum Atrial Septal Defect

Atrial septal defects (ASDs) are among the most common congenital heart defects diagnosed in adulthood, with percutaneous device closure being the standard treatment for suitable secundum ASDs. However, the presence of anomalous coronary artery anatomy, particularly a high-risk interarterial course, may complicate procedural planning due to potential myocardial ischemia and sudden cardiac death. Single-ostium coronary artery anomalies are exceptionally rare, and their coexistence with a secundum ASD is even more uncommon, providing distinct diagnostic and treatment issues. We report the case of a 42-year-old woman with a secundum ASD. Her background included obesity, hypertension, and anxiety. Investigations revealed a significant left-to-right shunt (Qp/Qs 1.72:1), raised pulmonary artery pressures, and right-heart dilation. As part of pre-procedural assessment, CT coronary angiography unexpectedly identified a single coronary artery arising from the right coronary sinus. This single ostium gave rise to three branches: a right coronary artery (RCA) with a normal course, a retroaortic left circumflex (LCx), and a left anterior descending (LAD) artery with an interarterial course between the aorta and pulmonary artery. Despite the anatomical anomaly, high-intensity treadmill testing showed no chest pain, electrocardiogram (ECG) changes, or wall-motion abnormalities. Multidisciplinary evaluation confirmed that no coronary intervention was required due to the absence of ischemia. Therefore, percutaneous transcatheter closure was indicated, given the adequate septal rims. The procedure was successfully performed using a 22 mm Amplatzer septal occluder without complications, and complete elimination of the shunt was achieved. Follow-up imaging confirmed normal device position and stability, reduced pulmonary pressures, and preserved coronary artery patency. This case highlights the critical role of multimodality imaging, in particular CT angiography and functional testing, in the pre-procedural evaluation of coronary anatomy prior to device closure in ASD patients. It emphasizes that in the absence of functional ischemia, even a potentially high-risk single-ostium coronary anomaly may not be a contraindication to safe transcatheter ASD closure. It also underlines the value of a multidisciplinary approach in complex congenital presentations where routine pathways may need to be adapted.