Abstract
We describe a patient with an asymptomatic complete unroofed coronary sinus (CS) syndrome associated with the CS stenosis in the absence of a persistent left superior vena cava (SVC) as identified on coronary computed tomography angiography. There was a large defect between the CS and the left atrium (i.e. a large left-to-right shunt), but an unusual combination of the absence of a persistent left SVC (i.e. no risk for brain abscess due to the absence of a right-to-left shunt) and the CS stenosis (i.e. a markedly reduced degree of a left-to-right shunt), resulting in an asymptomatic presentation.