Abstract Body (Do not enter title and authors here): Background: Catheter ablation (CA) is a well-established treatment for atrial fibrillation (AF). The most popular current methods of CA include radiofrequency ablation (RFA) and cryoablation (CRYO) which are thermal methods of ablation known to affect the autonomic nervous system through ablation of cardiac ganglionated plexi (GP). Pulsed[SC1] -field ablation (PFA) is a newer method of CA with demonstrated efficacy that preferentially affects cardiac cells and spares surrounding structures such as GP through irreversible electroporation which does not lead to chronic fibrosis like RFA or CRYO. Elevations in the marker the marker P terminal force (PTF) have been associated with AF/stroke and have been known to correlate with atrial fibrosis, and higher PTF after cryoablation for patients with paroxysmal AF has been associated with an increased risk of recurrence. The differences in P-wave parameters pre and post PFA have not been studied.

Objective: To investigate the differences in P-wave parameters after PFA and compare them to CRYO.

Methods: We identified 40 patients who underwent PFA (20 patients) or CRYO (20 patients) for paroxysmal AF and compared P-wave parameters including duration and amplitude in leads aVF, V1 and the PTF calculated as the duration x amplitude of the terminal negative component of the P-wave in V1. Data were obtained from 12-lead electrocardiograms obtained pre and post ablation.

Results: The mean age of patients in our study was 61 with 75% male and 33% on antiarrythmics. We noticed a significant reduction in PTF for patients who underwent CRYO (54 mVmS at baseline compared to 36.8 mVmS after CRYO, p = 0.04) and no significant reduction in PTF for patients who underwent PFA (46 mVmS at baseline compared to 38 mVmS after PFA, p = 0.27). There was also a significant increase in HR after CRYO (65 bpm at baseline compared to 78 bpm after CRYO, p=0.01) and no significant change in HR after PFA (61 bpm at baseline compared with 60 bpm after PFA, p=0.8). There was no statistical difference in both groups looking at aVF or total V1 duration or amplitude pre and post ablation.

Conclusions: CRYO leads to a significant change in PTF after ablation while PFA does not, consistent with the notion that PFA does not lead to fibrosis and PTF is not a useful marker for measuring risk of recurrence of AF post PFA.