Avoiding Cardiac Tamponade During Catheter Ablation: Left Juxtaposition of the Right Atrial Appendage.

BACKGROUND: Left juxtaposition of the right atrial appendage (RAA) is an extremely rare congenital anomaly in which the RAA is located to the left of the ascending aorta and pulmonary artery. CASE SUMMARY: A 67-year-old woman with persistent atrial fibrillation underwent pulsed-field ablation. Preprocedural cardiac computed tomography (CCT) revealed left juxtaposition of the RAA without any associated cardiac anomalies. During the procedure, the coronary sinus catheter initially advanced toward the anomalous appendage, and the transseptal needle tended to deflect into it. Careful manipulation under CCT-based anatomical guidance prevented cardiac perforation. Pulmonary vein and posterior wall isolation were successfully achieved without complications. DISCUSSION: This case highlights the procedural risk of catheter or transseptal needle misdirection into an anomalously positioned RAA and underscores the critical role of preprocedural CCT in preventing potentially fatal complications. TAKE-HOME MESSAGE: Preprocedural CCT enables safe transseptal access by delineating the rare atrial anatomy and preventing cardiac tamponade.