Pacing and Ablation Technique Using Microelectrode for Pulmonary Vein Isolation Using a Local Impedance-Guided Catheter.

Background: The IntellaNav MiFi OI catheter (MiFi) is equipped with a sensor for local impedance (LI) monitoring and three mini-electrodes. In this study, we investigated the target LI values for a successful pulmonary vein isolation (PVI) under the pacing and ablation technique using the MiFi catheter.

Methods: Twenty-seven patients underwent PVI using the MiFi catheter under mini electrode pacing from the MiFi catheter. The local impedance (LI) changes, generator impedance (GI) changes, and the time to capture loss were evaluated.

Results: First-pass isolations were obtained in 15 patients (57.7 %) for right PVs and in 22 patients (84.6 %) for left PVs. At gap sites, the impedance decrease was smaller than at non-gap sites (non-gap sites vs. gap sites; LI drop, 23.2 [±10.3] vs. 15.6 [±7.7] Ω, p < 0.0001; GI drop, 4.8 [±4.1] vs. 2.7 [3.9] Ω, p = 0.0026; %LI drop, -19.3 [±7.4] vs. -13.1 [±6.1] %, p < 0.0001; % GI drop, -5.1 [±4.2] vs. -2.9 [±4.2] %, p = 0.0020), suggesting that changes in impedance could be useful for predicting gaps. The cutoff values for predicting no gaps were identified as 15.0 Ω for the LI drop and -13.74% for the %LI drop.

Conclusion: The LI showed greater changes than the GI and was also useful for predicting gaps. The cutoff values of 15.0 Ω for the LI drop and -13.74% for the %LI drop could predict conduction gaps. Under the monitoring of the LI, the pacing and ablation technique proved useful for PVI, even though the MiFi catheter does not have a CF sensor or ablation indices.