Averaged Impedance Drop Estimates Conduction Gap During Pulmonary Vein Isolation in Atrial Fibrillation

ABSTRACT Background EnSite X provides a module to filter oscillated generator impedance signals due to cardiac beating/respiration (averaged impedance drop, AID). TactiFlex ablation catheter Sensor Enabled (TFSE) is the latest product to incorporate a contact‐force sensor with a flexible tip but without lesion‐estimating parameters. Methods To examine if AID estimates lesion formation, AID were compared between ablated lesions ( n = 1687) with and without conduction gaps (CGs) after first‐pass pulmonary vein isolation (PVI) using TFSE in atrial fibrillation (AF) patients ( n = 20). The clinical efficacy of AID‐guided PVI was evaluated in another subset of AF patients ( n = 30). Results CGs were observed in 45 points (CG[+]) but not in 1642 points (CG[−]). CG[+] had lower %AID (=absolute AID/initial impedance, p < 0.0001) than CG[−]. Decrease of bipolar voltage amplitude during radiofrequency application was linearly correlated with %AID ( R 2 = 0.785, p < 0.05). In receiver operating curve analysis, the cutoff values of %AID and unfiltered generator impedance drop for predicting CG was 9.33% and 11.0 Ω, respectively; %AID had significantly higher area under the curve than unfiltered generator impedance drop (0.761 vs. 0.627, p < 0.05). In swine heart experiments, %AID was correlated with lesion volume ( R 2 = 0.711, p < 0.05). In another subset of AF patients, success rate of first‐pass isolation in %AID ( ≥ 9%)‐guided PVI was 90% for LPV and 90% for RPV. The 1‐year event‐free rate of atrial tachyarrhythmias was 82%. Conclusion AID would improve the usability of impedance drop as an end point for RF application. %AID‐guided PVI using TFSE would be effective in AF patients.