Functional and Electrical Responses to Ventricular Pulsed Field Ablation: First Human Characterization of Myocardial Excitability Kinetics

BACKGROUND: Pulsed field ablation (PFA) is increasingly used for ventricular tachycardia (VT) treatment, yet reliable intraprocedural markers of lesion formation are lacking. Acute voltage attenuation may reflect reversible electroporation rather than cellular death. Human data on excitability kinetics during ventricular PFA are limited. OBJECTIVE: To assess myocardial capture during sequential pulsed electric field (PEF) applications as a marker of progressive tissue inexcitability and to evaluate the relationship between voltage reduction and functional lesion progression. METHODS: Consecutive patients undergoing VT ablation with the lattice-tip catheter were prospectively enrolled. At each site, four consecutive PEF applications were delivered. Myocardial captures during each PEF delivery were quantified by analyzing peaks on invasive arterial pressure waveform. Local voltage was measured before and after each application. Repeated-measures and correlation analyses were performed. RESULTS: Eighty-nine datasets of applications (15 patients; 62 left ventricular, 27 right ventricular sites) were analyzed. Myocardial captures decreased gradually across sequential applications (median 9 [IQR, 5-11] vs. 5 [IQR, 1-8]; P<0.001), with complete loss of capture achieved in 20% of sites. In contrast, voltage showed an immediate 49% reduction after the first application (P<0.0001), followed by an early plateau. Baseline voltage did not predict complete loss of capture (AUC, 0.57). Complete non-capture was more frequent in the right ventricle (P=0.04). CONCLUSIONS: Sequential ventricular PEF applications produce a stepwise reduction in myocardial excitability, whereas voltage attenuation shows an early plateau response. Assessment of myocardial capture during PEF delivery may represent a complementary intraprocedural marker associated with functional tissue response to PFA.