Pulmonary vein isolation in AF patients guided by a novel local impedance algorithm: 1-year outcome from the CHARISMA Study.

BACKGROUND Highly localized impedance (LI) measurements during AF ablation have recently emerged as a viable real-time indicator of tissue characteristics and durability of the lesions created. We report the outcomes of acute and long-term clinical evaluation of the new DirectSense™ algorithm in AF ablation. METHODS Consecutive patients undergoing AF ablation were included in the CHARISMA registry. RF delivery was guided by the DirectSense™ algorithm, which records the magnitude and time-course of the impedance drop. The ablation endpoint was pulmonary vein isolation (PVI), as assessed by the entrance and exit block. RESULTS 3556 point-by-point first-pass RF applications of >10sec duration were analyzed in 153 patients (mean age=59±10 years, 70% male, 61% paroxysmal AF, 39% persistent AF). The mean baseline LI was 105±15Ω prior to ablation and 92±12Ω after ablation (p<0.0001). Both absolute drops in LI and the time to LI drop (LI drop/τ) were greater at successful ablation sites (n=3122, 88%) than at ineffective ablation sites (n=434, 12%) (14±8Ω vs 6±4Ω, p<0.0001 for LI; 0.73[0.41-1.25]Ω/s vs 0.35[0.22-0.59]Ω/s, p<0.0001 for LI drop/τ). No major complications occurred during or after the procedures. All PVs had been successfully isolated. During a mean follow-up of 366±130 days, 18 patients (11.8%) suffered an AF/AT recurrence after the 90-day blanking period. CONCLUSION The magnitude and time-course of the LI drop during RF delivery were associated with effective lesion formation. This ablation strategy for PVI guided by LI technology proved safe and effective, and resulted in a very low rate of AF recurrence over 1-year follow-up. CLINICAL TRIAL REGISTRATION Catheter Ablation of Arrhythmias with a High-Density Mapping System in Real-World Practice (CHARISMA). URL: http://clinicaltrials.gov/Identifier: NCT03793998 This article is protected by copyright. All rights reserved.