Intracardiac Pulsed Field Ablation: Proof of Feasibility in a Chronic Porcine Model.

BACKGROUND: Radiofrequency (RF) has become an accepted energy source for myocardial ablation but may result in discontinuous lesions and non-targeted tissue injury. We examined feasibility and safety of lesion formation using high amplitude, bipolar pulsed electric fields delivered from a multi-electrode array catheter.

OBJECTIVE: Compare duty-cycled RF ablation (RFA) to pulsed field ablation (PFA) in terms of acute electrical effects, two-week lesion formation, and injury to non-targeted tissues.

METHODS: Intracardiac ablations were performed in six pigs using a circular pulmonary vein ablation catheter. The energy source for ablation delivery was randomized to deliver either PFA or RFA to three atrial endocardial sites. Bipolar pace capture and electrogram (EGM) amplitude measurements were recorded at each site. Histopathology and necropsies were performed after two weeks.

RESULTS: The circular pulmonary vein ablation catheter was used to deliver pulsed electric fields to produce cardiac lesions without skeletal muscle stimulation. Evaluating all ablations in each site, EGM amplitudes were reduced to < 0.5 mV in 67.5% of PFA vs. 27.0% of RFA deliveries (p<0.001). Bipolar cardiac capture was lost after 100% vs 92.0% of PFA vs RFA (p=0.005). At two weeks, PFA resulted in consistent transmural and homogenous replacement fibrosis devoid of lingering myocyte "sequesters". RFA lesions showed a stronger inflammatory response extending to the epicardial fat, arterial injury and thrombosis. Neither PFA nor RFA lesions showed endocardial thrombus.

CONCLUSIONS: Intracardiac PFA can be feasibly delivered from a circular catheter to create fibrotic lesions that have acute electrical effects, without injury to non-targeted tissue.