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.