Efficacy of nonocclusive separate freezing technique of cryoballoon pulmonary vein isolation: comparison of novel and conventional cryoballoon system

Abstract

Abstract Background/Introduction Complete occlusion of pulmonary vein (PV) with cryoballoon is an important factor to achieve enough temperature drop and successful pulmonary vein isolation (PVI). However, it is sometimes difficult to occlude PV completely because of large diameter or anatomical difference. Distal cryoblloon positioning in the PV can achieve complete occlusion but it may increase risk of phrenic nerve injury or PV stenosis. Nonocclusive separate freezing technique, freezing superior and inferior portion of the PV at proximal side with no complete occlusion, may be useful for that situation but efficacy of the technique is not well elucidated. Purpose The purpose of this study is to investigate efficacy of nonocclusive separate freezing technique and compare procedure details of the POLARx and the Arctic Front Advance Pro (AFA-Pro). Methods We retrospectively analyzed consecutive patients who underwent cryoballoon ablation with nonocclusive separate freezing technique from September 2019 to February 2023. We defined failure of the nonocclusive separate freezing as the case which needed distal complete occlusion with cryoballoon or touch up radiofrequency ablation to achieve PVI. We analyzed success rate of nonocclusive separate freezing and evaluated nadir temperature, freezing time and number of application times. We also explored incidence of stop of freezing due to phrenic nerve injury (PNI) or esophageal temperature drop during the procedure and permanent PNI and gastroesophageal complications after the procedure between the POLARx and the AFA-Pro. Results One-hundred and one patients, 73 were male (72.3%) and mean age was 66.8 ± 10.5 years, were analyzed. Total PVs were 121 (left superior (LS) PV 31, right superior (RS) PV 53, left common (LC) PV 37) and the POLARx was 45 (LSPV 18, RSPV 24, LCPV 3) and the AFA-Pro was 76 (LSPV 13, RSPV 29, LCPV 34). Success rates of the separate freezing of the POLARx was 84.4% and the AFA-Pro was 77.6% (p=0.48). There were no significant differences in freezing time and number of application times but nadir temperature was significantly lower in the POLARx (-52.1 ± 4.7 °C vs -42.9 ± 7.2 °C, p<0.001). The incidence of stop of freezing had no significant difference between the POLARx and the AFA-Pro but nadir temperature of stop of freezing due to esophageal temperature drop was significantly lower in the POLARx (-53.8 ± 4.3 °C vs -44.7 ± 7.7 °C, p=0.039). Permanent PNI was not seen but two gastric hypomotility events occurred in the POLARx. Conclusions There was no significant difference of success rate of the nonocclusive separate freezing technique but it tended to be higher and nadir temperature was significantly lower in the POLARx. There was no obvious complication in the AFA-Pro but two gastric hypomotility events were seen in the POLARx.