Feasibility of tissue proximity indication during atrial fibrillation rhythm as an indicator of acute pulmonary vein reconnection using variable-loop pulsed field ablation catheter

AIMS Although Tissue Proximity Indication(TPI) is considered a useful metric for contact assessment using the variable-loop pulsed field ablation catheter, its significance specifically during atrial fibrillation(AF) rhythm has not been sufficiently evaluated. The purpose of this study was to evaluate the utility of TPI during AF rhythm. METHODS AND RESULTS We enrolled 18 patients(9 patients with CARTO3 version8, 9 patients with version8.1) who underwent pulmonary vein(PV) isolation with or without posterior wall isolation during AF using the system. We investigated the association between acute local PV reconnection and TPI status, bipolar voltage, and impedance at each ablation point during AF rhythm. Local acute reconnection was observed in 155 of 3238 total points(4.4%). In the version 8 group, there was no significant difference in the frequency of acute reconnection based on TPI status. However, in the version 8.1 group, the frequency of reconnection was significantly higher at TPI-negative points compared to TPI-positive points(5.3% versus 3.1%, P = 0.03). Bipolar voltage during AF rhythm was significantly associated with reconnection(R = 0.77, P < 0.001), whereas impedance showed no such association. Furthermore, the combination of high bipolar voltage(≥0.35 mV) and negative TPI status was significantly associated with reconnection regardless of the version(10.7% versus 2.5%, P < 0.001). However, the utility of these metrics was slightly site-dependent, with reduced accuracy observed at the roof/floor lines and the anterior region of the left inferior PV and the carina region of right PV. CONCLUSIONS TPI assessment during AF rhythm is useful, particularly with version 8.1 and combined with bipolar voltage, despite a slight site-dependency.