Coronary sinus to left atrium communication.

Coronary sinus anomalies are rare. They can be associated with other vascular anomalies such as persistent left superior vena cava or can occur in isolation. We present a rare case of an isolated coronary sinus communication to the left atrium. This anomaly may be clinically relevant in the setting of significant left-to-right shunting or when shunt reversal results from right-sided heart failure. It may also be significant in cases of persistent atrial fibrillation after attempted pulmonary vein isolation.