We report a case of a 38-year-old man who presented with a cryptogenic stroke in whom a persistent left superior vena cava (PLSVC) to the left atrium was established as an isolated anomaly by both echocardiography and magnetic resonance angiography. This rare cardiac abnormality creates a systemic right to left shunt and the potential for cerebral abscess or infarction. Echocardiographic diagnosis may be missed unless intravenous saline contrast is performed using a left upper extremity vein.