EKG-gated cardiac CT revealed a variant vein in a 44-year-old man that was misinterpreted as a mass on echocardiography. The variant vein was an extension of the confluence of the left internal jugular vein and left subclavian vein and coursed anterior to the right ventricle. It connected to the right atrium directly at the inferior surface of the heart. The variant vein was likely a persistent left superior vena cava, a variant that has never been reported.