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

## TL;DR

This study shows that averaged impedance drop (AID) can predict successful ablation during heart procedures for atrial fibrillation, improving treatment outcomes.

## Contribution

The study introduces AID as a novel, effective parameter for estimating conduction gaps during pulmonary vein isolation using the TactiFlex ablation catheter.

## Key findings

- Lower %AID values were significantly associated with conduction gaps after ablation.
- %AID had higher predictive accuracy than unfiltered impedance drop for identifying conduction gaps.
- AID-guided ablation achieved high success rates and improved 1-year event-free survival in AF patients.

## Abstract

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.

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).

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%.

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.