An unroofed coronary sinus is an uncommon congenital cardiac anomaly. It leads to a left to right shunt like an atrial septal defect (ASD) and comprises <1% of all ASDs. It can also additionally create a pathway for paradoxical embolization to the brain and other attendant complications. Here, we present the case of an asymptomatic 40-year-old-male with a history of prior surgical closure of an ostium secundum ASD who was referred for preoperative evaluation for non-cardiac surgery. An unroofed coronary sinus with persistent left superior vena cava (PLSVC) was suspected on transthoracic echocardiography and confirmed by transesophageal echocardiography.