Co-occurrence of Anomalous Right Coronary Artery Origin and Subaortic Membrane in an Adult Male

Abstract

Anomalous origin of the right coronary artery (ARCA) represents <3% of congenital coronary anomalies, while the subaortic membrane represents 6.5% of congenital heart anomalies. Symptomatic co-occurrence of ARCA and subaortic membrane in an adult is rare. A 68-year-old man developed a non-ST-elevation myocardial infarction necessitating percutaneous coronary intervention (PCI) four years prior to presentation at our hospital. In the years after his PCI, he developed progressive exertional breathlessness. Following a positive treadmill EKG, he underwent coronary CT angiography that indicated RCA dominance with ARCA arising from the left coronary sinus and coursing between the ascending aorta and pulmonary artery, causing 50-60% intraluminal narrowing at rest without atherosclerotic plaque. Echo showed normal left ventricular ejection fraction (LVEF) and a surprise finding of the subaortic membrane, with a modest gradient. He underwent successful resection of the subaortic membrane and unroofing of the anomalous RCA tunnel with tract marsupialization. The post-operative period was complicated by arrhythmias necessitating electrical cardioversion. At discharge, he was sent home on apixaban, bisoprolol, aspirin, atorvastatin, and an amiodarone taper. The subaortic membrane would not have required intervention independently because it was not associated with a severe gradient. However, surgery is recommended for symptomatic ARCA or subaortic membrane; hence, our patient underwent surgical management. Atrial fibrillation and flutter are the most common arrhythmias following cardiac surgery. Due to the patient's increased risk of complications, cardioversion and anticoagulation were pursued. Although ARCA is congenital, our patient had been asymptomatic for most of his life, suggesting that the development of the subaortic membrane might have triggered symptom onset, combining a modest subaortic gradient with previously asymptomatic exercise-induced right coronary ischemia. Clinicians should consider evaluating for secondary structural heart conditions in newly symptomatic adult patients with ARCA due to the risk of sudden cardiac death, to provide the most complete treatment.