Abstract Body (Do not enter title and authors here): Background: Contemporary power-controlled radiofrequency (RF) ablation prioritizes power, force, and time. However, variables such as impedance and current also greatly impact ablation lesion formation. The appropriate current values to target at various pulmonary vein (PV) regions are not well established.

Objective: To characterize 1) the range of current (mA) delivery with standard ablation and impedance (ohms) values at PV ostia, and 2) the impact of maximum current achieved on freedom from atrial fibrillation (AF) at one year.

Methods: One hundred fifteen consecutive paroxysmal AF patients at our institution between 2020-2021 undergoing first-time RF PV isolation were retrospectively analyzed. Baseline impedance (ohms), impedance drop, power, force, and time were compiled and separated by ostial PV site (CARTO®). Current was calculated based on Power=current x resistance. Calculated current was then compared in a small cohort of patients with the displayed current on the Smart Ablate® system.

Results: Of all patients, 27 patients had atrial fibrillation recurrence within one year. Calculated current was lower than the displayed Smart Ablate® current but had reliable correlation. Baseline impedance was higher in the roof and posterior wall compared to anterior/inferior regions. There was a statistically significant difference in the mean maximum current achieved between patients with AF recurrence vs those without in the regions of the left posterior wall (543 mA vs 564 mA, p = 0.049), left roof (556 mA vs 575 mA, p = 0.043), and right roof (559 mA vs 578 mA, p = 0.042).

Conclusion: Current delivery during RF ablation is dependent on baseline impedance and the impedance drop achieved. We noted significant differences in delivered current in those with and without AF recurrence at the left posterior wall/roof and right roof. Titrating ablation parameters to achieve effective current delivery may be a promising intraprocedural strategy for AF ablation success.