Key characteristics for effective acute pulmonary vein isolation when using a novel cryoballoon technology: insights from the CHARISMA registry

Purpose: A new cryoballoon (CB) technology (POLARx™; Boston Scientific) for pulmonary vein (PV) isolation in patients with atrial fibrillation (AF) has recently been introduced. The aim of this study was to evaluate procedural and biophysical parameters resulting in acute PV isolation when using this new CB. Methods: We assessed the first 69 consecutive patients indicated for AF ablation who underwent PV isolation by means of a novel CB system. Procedural metrics were prospectively recorded. Results: A total of 274 PVs were targeted in 69 patients. PV isolation was achieved in all patients by means of cryoablation alone. The median time to isolation (TTI) was 44 [31–68] s (median temperature at TTI = − 49 [− 53 to − 41] °C). The median duration of CB ablation was 180 [180 to 240] s. The median nadir temperature was − 56.0 [− 61 to − 52] °C, and the median thaw time to 0 °C was 18 [15–21] s. The median grade of PV occlusion was 4 [3 to 4]. On the basis of ROC analysis, we defined the following cut-off values for acute PV isolation: − 56 °C for nadir temperature (sensitivity = 73.3%, specificity = 64.6%, AUC = 0.716; positive predictive value = 88.1%), 30 s for TTT (60.2%, 53.3%, 0.578; 79.7%), thaw time > 17 s (65.3%, 70.0%, 0.709; 86.9%), and grade of PV occlusion = 4 (79.4%, 66.7%, 0.738; 88.5%). No major procedure-related adverse events were observed at 30-day post-procedure. Conclusions: The new POLARx™ CB appears to be effective and safe. A nadir temperature of − 56 °C, a thaw time to 0 °C ≥ 17 s, and complete PV occlusion were the best predictors of acute PV isolation. Clinical trial registration: Catheter Ablation of Arrhythmias with a High-Density Mapping System in Real-World Practice (CHARISMA). URL: http://clinicaltrials.gov/Identifier: NCT03793998. Registration date: January 4, 2019.