Abstract
Persistent left superior vena cava is a rare congenital venous anomaly, occurring in approximately 0.2–3% of the general population and more frequently (1.3–11%) in patients with congenital heart disease. It results from failed regression of the left superior cardinal vein during embryonic development. We report the case of a 70-year-old asymptomatic male in whom routine transthoracic echocardiography revealed a large, echo-lucent, cystic-like structure projecting into the left atrium, initially mimicking a left atrial mass. Further evaluation with contrast-enhanced computed tomography confirmed the diagnosis of an isolated persistent left superior vena cava draining into a markedly dilated coronary sinus, associated with the absence of the right superior vena cava. Persistent left superior vena cava may coexist with other congenital cardiac anomalies, such as atrial septal defect, bicuspid aortic valve, or cor triatriatum. Recognition of this vascular variation is essential in order to avoid misdiagnosis and to prevent potential complications during invasive cardiac or thoracic procedures. This case highlights the importance of multimodality imaging for accurate diagnosis and the differential diagnostic challenges such anomalies may present.