Left Atrial Voltage Attenuation Beyond Ablation Sites After Unipolar Pulsed‐Field Ablation for Atrial Fibrillation

Abstract

ABSTRACT Introduction Unlike most pulsed‐field ablation (PFA) systems, Affera (Medtronic) delivers unipolar energy between a lattice‐tip catheter and a cutaneous return patch, potentially generating a broader electric field. We hypothesized that this may attenuate voltage beyond ablated regions and tested this using spatially matched pre‐ and post‐ablation maps. Methods and Results We retrospectively studied five consecutive patients undergoing primary atrial fibrillation ablation with the Affera system. Pre‐ and immediate post‐ablation voltage maps were generated using CARTO 3 and OCTARAY (Biosense Webster) with identical settings during right atrial pacing. Because Affera lacks point‐level 3D coordinates for spatial matching, coordinates (x, y, z) and bipolar voltages were extracted from CARTO 3. Pre‐ and post‐ablation points—outside energy delivery sites, excluding the annulus and left atrial appendage—were spatially matched using a 2 mm mutual nearest‐neighbor criterion. This yielded 3772 pairs. Bipolar voltages were averaged by case. Mean bipolar voltage decreased in all cases from 1.01 ± 0.61 to 0.56 ± 0.29 mV, representing a 40.2% reduction (95% CI, 24.6%–55.8%; p = 0.044). In a distance‐stratified analysis, residual bipolar voltage (post/pre × 100) was lowest just beyond the ablated zone and increased progressively with distance from the nearest application tag center (16.5% at 10–15 mm to 57.8% at 25–30 mm; all p < 0.001), becoming numerically comparable to baseline beyond approximately 30 mm. Conclusions Affera‐based unipolar ablation produced acute bipolar voltage attenuation that extended into non‐ablated myocardium adjacent to the lesion set but diminished with distance and was largely confined within approximately 30 mm of the application sites.

The authors' abstract, as published at the source. Journal of Cardiovascular Electrophysiology, 2026 · DOI ↗