Association Between Contact Force and Acute Lesion Effectiveness in Focal Pulsed Field Ablation

INTRODUCTION: Pulsed field ablation (PFA), based on irreversible electroporation, is a non-thermal modality designed to create myocardial lesions while minimizing collateral injury. The determinants of acute lesion effectiveness in humans remain incompletely understood. We evaluated the association of contact force (CF) and impedance drop (ID) with acute lesion effectiveness during focal PFA index-guided pulmonary vein isolation (PVI). METHODS AND RESULTS: Twenty-four patients undergoing PFA-guided PVI for atrial fibrillation (AF) ablation were included. Electroanatomical mapping was performed in sinus rhythm using high-density catheters. Ablation was delivered using a CF catheter in a point-by-point workflow guided by a PFA index. Lesion effectiveness was defined by acute electrophysiological criteria. CF, ID, and PFA index achievement were analyzed at each ablation point. A total of 1460 ablation points were analyzed (1407 successful, 53 unsuccessful). Median CF was significantly higher in successful compared with unsuccessful lesions (15 vs. 11.3 g, p < 0.001). A CF value of 8 g yielded high sensitivity (90.3%) but low specificity (38.9%) for lesion effectiveness. ID did not differ between groups (p = 0.58). Target PFA index achievement was more frequent in successful lesions (67% vs. 9.4%, p < 0.01). CONCLUSIONS: CF is a significant but imperfect predictor of acute lesion effectiveness in PFA, since averaged CF values may inadequately reflect the instantaneous catheter-tissue interaction at the moment of pulse delivery. These findings support a paradigm in which maintaining sufficient real-time CF, rather than achieving a fixed average threshold, is critical for effective lesion formation.