Coronary sinus diverticulum as a cause of resistant posteroseptal pathway ablation.

Coronary sinus (CS) anomalies such as diverticulum, persistent left superior vena cava or CS ostium dilatation are predominantly found in patients with accessory pathway-related tachycardias. Diverticulum of the proximal CS found in 7-11% of patients with postero-septal or left posterior manifests accessory pathways. We reported a 28 year old gentleman with manifested postero-septal accessory pathway, who underwent repeat electrophysiological study (EPS) and radiofrequency ablation for previously failed ablation. Huge CS diverticulum was identified by angiography as a reason for resistant accessory pathway. Successful RF ablation was achieved at the neck of the diverticulum without complications. Other associated anomalies were ruled out by cardiac computerized tomography (CT) and trans-esophageal echocardiography.