Background: Pulsed field ablation (PFA) yields a novel ablation technology for atrial fibrillation (AF). PFA lesions promise to be highly durable, however clinical data on lesion characteristics are still limited.

Objective: This study sought to investigate PFA lesion creation with ultra-high-density (UHDx) mapping. 

Methods: Consecutive AF patients underwent PFA-based pulmonary vein isolation (PVI) using a multispline catheter (Farwave, Farapulse Inc). Additional ablation, including left atrial posterior wall isolation (LAPWI) and mitral isthmus isolation (MI) were performed in a subset of persistent AF patients. Extent of PFA-lesions and decrease of LA-voltage were assessed with pre- and post PFA UHDx-mapping (Orion^TM catheter and Rhythmia^TM 3D-mapping system, Boston Scientific).

Results: In 20 patients, acute PVI was achieved in 80/80 PVs, LAPW isolation in 9/9 patients, MI isolation in 2/2 (procedure time: 123±21.6minutes, fluoroscopy time: 19.2±5.5minutes). UHDx-mapping subsequent to PVI revealed early PV-reconnection in 5 case (5/80, 6.25%). Gaps were located at the anterior-superior PV ostia and were successfully targeted with additional PFA. Repeat UHDx mapping after PFA revealed significant decrease of voltage along the PV ostia (1.67±1.36mV vs. 0.053±0.038mV, P<0.0001) with almost no complex electrogram-fractionation at the lesion border zones. PFA-catheter visualization within the mapping system was feasible in 17/19 (84.9%) patients and adequate in 92.9% of ablation sites. There was one transient coronary spasm in a patient, no further complications occurred.

Conclusion: For the first time illustrated by UHDx mapping, PFA creates wide antral circumferential lesions and homogenous LAPW isolation with depression of tissue voltage to a minimum. Although with a low incidence, early PV reconnection can still occur also in the setting of PFA.

 
Figure1: fluoroscopy of the flower configuration of the PFA catheter (left); UHDx voltage map prior to ablation (middle); UDHx map after PVI and LAPW isolation with visualization of the PFA catheter in the mapping system (right).