Coronary Sinus Ostial Atresia With Small Cardiac Vein Drainage Into Right Atrium: A Rare Case With an Unusual Drainage Pathway

This case report describes an 80-year-old man with a history of persistent atrial fibrillation. Echocardiography revealed a severely dilated coronary sinus without a normal opening at the coronary sinus ostium, which communicated with an unusual dilated small cardiac vein. Contrast echocardiography and coronary computed tomography angiography were then utilized for further evaluation. After multimodal imaging, this rare case was diagnosed as coronary sinus ostial atresia with an unusual small cardiac vein draining into the right atrium.