Nonocclusive Ablation Technique Using a Novel Cryoballoon for Failed Left Superior Pulmonary Vein Isolation Despite Complete Occlusion

Background: An indicator of successful cryoballoon (CB)-assisted pulmonary vein (PV) isolation is complete PV occlusion. However, CBs may exhibit a weaker freezing effect on the equatorial plane. This study investigates the predictors of failed left superior PV (LSPV) isolation despite complete occlusion with novel CBs. Methods: This retrospective analysis enrolled 300 consecutive patients who underwent first-time ablation with POLARx or POLARxFIT between November 2021 and October 2023. Of the total, complete occlusion of the LSPV was achieved in 200 patients. Patients in whom LSPV isolation was achieved with additional nonocclusive freezing of the LSPV roof due to nonisolation of LSPV despite complete occlusion (Group A) were compared with those in whom isolation was achieved with complete PV occlusion alone (Group B). Results: Group A had a larger LSPV diameter (21.5 +/- 4.6 mm vs. 18.8 +/- 3.3 mm, p = 0.052), larger left atrial volume on CT (142.3 +/- 47.8 cc vs. 117.8 +/- 39.0 cc, p = 0.028), higher nadir temperature (-54.1 +/- 5.1 degrees C vs. -60.2 +/- 4.4 degrees C, p < 0.001), and smaller northern latitude of the balloon contact site on the LSPV roof side (20.9 degrees +/- 3.8 degrees vs. 38.9 degrees +/- 6.7 degrees, p < 0.001) compared with Group B. A 27.5 degrees north latitude was observed in most of Group A (sensitivity, 100%; specificity, 96%). Conclusions: Adequate contact positioning of the northern hemisphere to the LSPV is critical for effective isolation, particularly when isolation is challenging despite complete occlusion. In such cases, nonocclusive cryoablation against the LSPV roof might be effective.