Background:

Left atrial (LA) catheter ablation is an established therapy for symptomatic atrial fibrillation (AF). While symptomatic thromboembolic events are rare, silent cerebral emboli (SCL) and/or events (SCE) are a common observation after LA ablation, using thermal ablation techniques. Pulsed field ablation (PFA) is a novel, nonthermal ablation modality that is able to ablate myocardial tissue with minimal effect on surrounding tissue. Preclinical data show absence of cerebral emboli after extensive PFA ablation. However, clinical data on SCL/SCE after PFA-ablation are lacking. This study investigates occurrence of neurological deficits and/or SCL/SCE after PF-ablation in paroxysmal AF (PAF) using National Institutes of Health Stroke Scale (NIHSS) scores to objectively quantify the impairment caused by a stroke and magnetic resonance imaging (MRI).

Methods:

In patients with symptomatic paroxysmal AF, pulmonary vein ablation (PVI) using PFA (Farapulse, Inc.) was performed. The LA appendage was assessed for thrombus by pre-procedural computer tomography (CT)-angiography. PVI was performed with interrupted oral anticoagulation at the day of the procedure and intravenous heparin administered before single transseptal puncture (target ACT >325). In all procedures, extensive high-density pre- and post-ablation 3D electroanatomical voltage maps (Biosense Webster, Inc.) were performed to document acute PVI. NIHSS scores were assessed at baseline, days 2 and 30 after PVI. One day after PVI, patients underwent cerebral 1.5 Tesla MRI-scanning using diffusion-weighted imaging (DWI) and FLAIR sequences to document occurrence of SCL/SCE.  

Results:

In 30 patients (age 63 ± 10 years; 47% male; CHA₂DS₂-VASc-Score 2 [IQR 1-3]), uncomplicated PFA was performed, with all PVs acutely isolated. Skin-to-skin procedure time was 120 ± 23 min and left atrial dwell time was 109 ± 22 min. In-hospital and 30-day clinical follow-up was uneventful. No patients showed neurological deficits. All NIHSS scores at all stadiums were the minimum value of 0. Cerebral MRI scans were normal in 29/30 (97%) patients. In 1/30 (3%) patient, a single 7-mm cerebellar lesion was observed. Forty days after the procedure, a second cerebral MRI scan showed complete regression of the lesion. This origin of this single lesion could not be established. Air embolization after multiple catheter exchanges, or embolization of tissue debris after transseptal puncture cannot be ruled out. 

Conclusions:

PVI using PFA in patients with symptomatic PAF causes no neurological deficits and shows absence of SCL/SCE in 97% of patients. In one patient, a single small SCL/SCE of unknown origin occurred with complete regression after 40 days. PFA seems to be a safe ablation modality for the brain.