Insight into contact force local impedance technology for predicting effective pulmonary vein isolation

BACKGROUND: Highly localized impedance (LI) measurements during atrial fibrillation (AF) ablation have the potential to act as a reliable predictor of the durability of the lesions created. OBJECTIVE: We aimed to collect data on the procedural parameters affecting LI-guided ablation in a large multicenter registry. METHODS: A total of 212 consecutive patients enrolled in the CHARISMA registry and undergoing their first pulmonary vein (PV) isolation for paroxysmal and persistent AF were included. RESULTS: In all, 13,891 radiofrequency (RF) applications of ≥3 s duration were assessed. The first-pass PV isolation rate was 93.3%. A total of 80 PV gaps were detected. At successful ablation spots, baseline LI and absolute LI drop were larger than at PV gap spots (161.4 ± 19 Ω vs. 153.0 ± 13 Ω, p < 0.0001 for baseline LI; 22.1 ± 9 Ω vs. 14.4 ± 5 Ω, p < 0.0001 for LI drop). On the basis of Receiver operating characteristic curve analysis, the ideal LI drop, which predicted successful ablation, was >21 Ω at anterior sites and >18 Ω at posterior sites. There was a non-linear association between the magnitude of LI drop and contact-force (CF) (r = 0.14, 95% CI: 0.13–0.16, p < 0.0001) whereas both CF and LI drop were inversely related with delivery time (DT) (−0.22, −0.23 to −0.20, p < 0.0001 for CF; −0.27, −0.29 to −0.26, p < 0.0001 for LI drop). CONCLUSION: An LI drop >21 Ω at anterior sites and >18 Ω at posterior sites predicts successful ablation. A higher CF was associated with an increased likelihood of ideal LI drop. The combination of good CF and adequate LI drop allows a significant reduction in RF DT. CLINICAL TRIAL REGISTRATION: http://clinicaltrials.gov/, identifier: NCT03793998.