Abstract Body (Do not enter title and authors here): Background: Pulsed field ablation (PFA) is a promising modality for treatment of cardiac arrhythmias. PFA increases cell permeability, thereby promoting cell apoptosis. Although greater PFA energy may produce larger lesions, it also carries risks of side effects such as arcing, hemolysis, and microbubbles. Chemical ablation using ethanol (EtOH), such as with injection of the Vein of Marshall, has been used to treat atrial myocardium for refractory atrial arrhythmias.

Hypothesis: We hypothesize that PFA in the atria can increase EtOH uptake through PFA-generated pores, thereby augmenting ablation efficacy by utilizing the cell permeability effects of PFA.

Aim: The aim of this study is to investigate the effects of local EtOH infusion after PFA on lesion size in porcine atria.

Methods: The atria of five porcine subjects were ablated in vivo with low PFA power settings (250V, at 20μs for 50 pulses separated by 200 ms) using a focal bipolar irrigated ablation catheter and BTX 830 electroporation generator (Harvard Apparatus). After PFA, 2 ml of 90 % EtOH vs. saline (control) was infused through the catheter tip to the site of ablation. We compared electrogram voltage amplitude reduction and ablation lesion parameters before and after PFA.

Results: A total of 14 control lesions and 14 EtOH lesions were analyzed. There was significant difference in voltage reduction between two groups (Figure 1A-B). On gross pathology, there were significant differences in ablation lesion maximum surface diameter, lesion depth, and volume between the 2 lesion sets (Figure 1C).

Conclusion: Concurrent EtOH infusion after PFA enhanced acute efficacy of electroporation in porcine atria. Adjuvant therapy has the potential to improve efficacy without requiring higher energy parameters, thereby reducing PFA risks. Further studies to assess chronic efficacy are warranted.