Persistent Left Superior Vena Cava in an Adult Presenting With Atrial Fibrillation.

Persistent left-sided superior vena cava (PLSVC) is usually an asymptomatic, rare congenital anomaly, but has been associated with atrial arrhythmias due to remnant pacemaker tissue within the vessel. This report describes a 62-year-old male who presented with new-onset atrial fibrillation (AF) and was incidentally found to have a PLSVC draining into a dilated coronary sinus, along with additional thoracic and vascular abnormalities, including a bovine aortic arch and tracheal diverticulum. Transthoracic echocardiography with agitated saline injection and computed tomography confirmed the diagnosis. The patient's AF self-terminated and was managed medically, with referral for outpatient electrophysiology follow-up given the recognized association between PLSVC and supraventricular arrhythmias. This case highlights the importance of recognizing PLSVC during the evaluation of AF, the utility of multimodality imaging in establishing the diagnosis, and the need for further studies to clarify the arrhythmogenic potential of PLSVC and the role of targeted electrophysiologic intervention in adults.