Persistent left superior vena cava (PLSVC) is a rare but clinically relevant congenital vascular anomaly, occurring in 0.3% of the general population and up to 4.3% in those with congenital heart disease. It is usually asymptomatic and incidentally discovered during imaging, catheterization, or surgery.

We present the case of a 38-year-old hypertensive female who was evaluated for acute chest discomfort, palpitations and near-syncope. Transthoracic echocardiography revealed a dilated coronary sinus, prompting a contrast echocardiography study that demonstrated early opacification of the coronary sinus upon left arm injection confirming the diagnosis of PLSVC.

This case underscores the importance of recognizing coronary sinus dilatation as a potential marker of venous anomalies such as PLSVC. Contrast echocardiography with bilateral injections remains a practical, non-invasive tool in its diagnosis, with significant implications for future invasive procedures.