Clinical importance of tissue proximity indication during pulsed field ablation for atrial fibrillation: Insights from initial experience.

BACKGROUND

Pulsed field ablation (PFA) for paroxysmal atrial fibrillation (AF) has been gaining worldwide acceptance because of its efficacy and safety. A variable loop circular catheter (VLCC, VARIPULSE, Biosense Webster, Inc) for PFA recently launched in Japan, includes a tissue proximity indication (TPI) feature to monitor catheter-tissue contact via impedance. However, the role of TPI during pulmonary vein isolation (PVI) is unclear.

OBJECTIVE

This study aims to evaluate TPI feasibility during PVI and its relationship with acute pulmonary vein (PV) reconnection.

METHODS

Twenty-one patients with paroxysmal AF underwent PFA (at least 4 ablations per PV) using the VLCC. We evaluated the association between TPI-positive site percentages, voltage, left atrial wall thickness on ADAS 3D software (Adas3D Medical SL, Barcelona Spain), and acute PVI failure sites.

RESULTS

Four of 21 patients (8 failure sites) experienced PVI failure after primary PFA. Failure sites had significantly lower TPI-positive site percentages (0 ± 0% vs 63 ± 27%, P < .001) and higher voltage (3.57 ± 1.35 mV vs 2.06 ± 1.42 mV, P = .003) but not PV wall thickness. We found that a left atrial bipolar voltage amplitude ≥2.24 mV was determinants of PV gaps with an area under the curve of 0.83 calculating receiver operating characteristic curves. TPI-positive site percentages increased significantly (58 ± 29% to 64 ± 26%, P = .009), whereas PV gaps decreased from 3 of 28 PVs (11%) to 2 of 54 PVs (4%, P = .332) between the first 7 and last 14 cases.

CONCLUSION

Acute PVI failure was significantly associated with poor tissue contact and higher voltage. However, acute PVI failure can be prevented with improved TPI-based contact information.