Wolff-Parkinson-White syndrome case due to a coronary sinus accessory pathway in a patient with unique congenital coronary venous anomaly: a case report.

Background: Catheter ablation for Wolff-Parkinson-White syndrome (WPW) has a failure rate of 1-5%, particularly when accessory pathways (APs) are located in challenging regions like the posteroseptal or left posterior areas. These cases may involve coronary sinus (CS) APs and anomalies in the coronary venous system, especially in those with a previous failed ablation procedure. Imaging of the coronary venous system obtained by cardiac computed tomography (CT) can help the procedural planning in the presence of challenging anatomy. Case summary: We present the case of a 16-year-old male with WPW syndrome due to a posteroseptal AP, referred to our institution after two failed ablation procedures. Cardiac CT performed before the third attempt revealed CS drainage into the left atrium and a CS diverticulum near the basal segment of the left ventricle's inferior wall. During the electrophysiological study, the left atrium was accessed via transseptal catheterization. The target site was identified in the left posteroseptal region, where successful radiofrequency ablation was performed At a six-month follow-up, no supraventricular tachycardia recurrence was noted. Transthoracic echocardiography and cardiac magnetic resonance (CMR) further excluded communication between the diverticulum and the left ventricle, leading to a conservative follow-up strategy instead of surgical intervention. Discussion: A detailed understanding of coronary venous system anatomy, as provided by cardiac CT, could be useful for planning WPW ablation, particularly in complex cases. The combined use of CMR and echocardiography was pivotal in guiding management decisions for this unique congenital anomaly of the coronary venous system.