Successful superior vena cava isolation using point-by-point cryothermal ablation after failed radiofrequency ablation.

Pulmonary vein isolation is the cornerstone of catheter ablation for atrial fibrillation (AF), but non-pulmonary vein (non-PV) triggers such as the superior vena cava (SVC) also play an important role. Electrical isolation of the SVC (SVCI) can be limited by anatomical complexity and the risk of phrenic nerve or sinus node injury, particularly with radiofrequency or cryoballoon techniques. We report a 76-year-old woman with recurrent paroxysmal AF after cryoballoon pulmonary vein isolation. During repeat ablation, AF was initially induced from the left atrial posterior wall and successfully treated with radiofrequency ablation. Subsequent provocation revealed AF triggers from the SVC. Despite careful radiofrequency ablation under phrenic nerve pacing, complete SVCI could not be achieved. Point-by-point cryothermal ablation was then performed under continuous phrenic nerve monitoring, resulting in successful SVCI without complications. This case suggests that focal cryothermal ablation may be a practical and safer alternative when SVCI cannot be achieved with radiofrequency energy. Learning objective: To understand that superior vena cava isolation (SVCI) may be challenging with radiofrequency ablation due to anatomical complexity and safety limitations related to phrenic nerve injury. This case highlights point-by-point cryothermal ablation as a feasible alternative strategy, enabling stable catheter contact, precise lesion delivery, and continuous phrenic nerve monitoring, particularly in regions where point-by-point pulsed-field ablation is not yet available.