Background
Catheter ablation for atrial fibrillation (AF) using thermal energy sources (RF, cryo, laser), causes indiscriminate tissue destruction and can injure esophagus, blood vessels and/or nerves. Energy output has to be reduced to minimize collateral damage; this negatively affects lesion formation. Pulsed field ablation (PFA) is a novel nonthermal energy source. In a process called electroporation, millisecond electric fields create pores in cell membranes and cell death occurs. In contrast to surrounding tissue, cardiomyocytes have a low threshold to PFA (tissue-specificity). There is no need to limit ablation energy, thus larger lesions can be created. Only few small clinical studies have been published. We report on the first „real-world“ experience with pulmonary vein isolation (PVI) using PFA for paroxysmal AF (PAF).

Methods

After LAA-thrombus exclusion by CT-angiography and under propofol sedation, an extensive high-density left atrial (LA) bipolar voltage map was created using a multispline catheter (Biosense Webster, Inc.). Pre- and post-ablation, phrenic nerve function was fluoroscopically assessed. After LA mapping, the 8F sheath and catheter were exchanged for a 16.8F outer diameter steerable sheath and a multispline PFA ablation catheter (Farapulse, Inc.). Using fluoroscopy only and an extra stiff guide wire, all PVs were individually isolated using biphasic pulse trains with a power of 1,900 V and a minimum of 8 applications per PV. Additional ablations were left at operator’s discretion. After the last ablation, the LA bipolar voltage map was repeated to document acute lesion formation.

Results

In 30 PAF 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±21 min. Total LA dwell time was 109±22 min. LA dwell time of the PFA catheter was 31±12 min. Fluoroscopy time was 23±7 min. Dose-area product was 4.96±3.54 Gy.cm². Number of applications per patient until complete PVI was 32±1. In 1 patient with roof dependent flutter, a roof line was intentionally created with 8 additional applications. In 2 patients, unintentional bidirectional mitral isthmus block was created. In 10 patients, temporary pacing due to vagal bradycardia after ablation of the LSPV was necessary. There was no phrenic nerve palsy. In 1 patient who had repeated, difficult CS-catheter placement, 6 hours after the procedure a cardiac tamponade with uncomplicated pericardial drainage of 250 ml blood occurred. Further in-hospital stay was uneventful, and all patients were discharged in sinus rhythm.

Conclusions

Pulmonary vein isolation using pulsed field ablation for paroxysmal atrial fibrillation in a „real-world“ setting is safe and feasible. Procedure times are homogeneous and total ablation time is short. Atrial ablation lines can easily be created. However, unintentional ablation of atrial tissue can occur, so that accurate catheter alignment to the PV ostium and PV axis should be ensured.

Picture

Postero-anterior view of a left atrial high-density bipolar voltage 3D electroanatomical map.

Left panel: before PFA ablation. The magenta areas in the PVs are conducting (>0.5 mV).

Right panel: after PFA ablation. The non-magenta (<0.5 mV) and red (<0.1 mV) areas in the PVs are ablated and electrically silent.