Atrial fibrillation ablation with the second generation cryoballoon: Multicenter propensity score matched comparison between freezing strategies.
Second generation cryoballoon (CB-A) ablation is highly effective in achieving pulmonary vein (PV) isolation and freedom from atrial fibrillation (AF). However, the ideal freezing strategy is still under debate. Our objective was to investigate the efficacy and outcome between different freezing strategies used with the CB-A in a multicenter, matched population. From a total cohort of 1018 patients having undergone CB-A ablation for drug-refractory AF, 673 patients with follow-up ≥6months were included and stratified according to the applied freezing strategy: bonus freeze (BF) versus single freeze (SF). Final population of 256 BF patients was compared with 256 propensity-score matched SF patients. BF strategy consisted of 3 different protocols: 3cycles of 180s; 2cycles of 240s; and cycles of 240s followed by 180s in 99/256 (39%); 42/256 (16%); and 115/256 (45%) patients, respectively. SF approach included cycles of 240s in 23/256 (9%), and 180s in 233/256 (91%) patients. Electrical isolation could be achieved in all PVs by both protocols, with shorter procedure and fluoroscopy times in the SF group (mean 106 vs 65min, and 18 vs 14min, respectively, P<0.001). Phrenic nerve palsy persisted after discharge in a total of 11 patients (2.1%): 4 (1.6%) in the BF group vs 7 (2.7%) in the SF group, P=0.5. AF-free survival was similar between the 2 groups during follow-up (mean 18±10months) (log rank, P=0.6). CB-A ablation showed equal efficacy and outcome between SF and BF strategy.