Pulmonary vein isolation (PVI) with a “single-shot” pulsed-field ablation (PFA) catheter results in excellent PVI durability and acceptable safety with a low one-year rate of atrial arrhythmia recurrence in paroxysmal atrial fibrillation (AF) patients, according to data pooled from three clinical trials.
These are the conclusion of a paper authored by Vivek Reddy (Icahn School of Medicine at Mount Sinai, New York, USA) and colleagues, published in JACC: Clinical Electrophysiology, documenting one-year outcomes of PFA in patients enrolled in the IMPULSE (A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation), PEFCAT (A Safety and Feasibility Study of the Farapulse Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation), and PEFCAT II (Expanded Safety and Feasibility Study of the Farapulse Endocardial Multi Ablation System to Treat Paroxysmal Atrial Fibrillation) multicentre studies.
Each of the studies assessed the treatment of paroxysmal AF using PVI with a basket or flower catheter (Farapulse). PFA is a non-thermal ablative modality that is able to preferentially ablate myocardial tissue with minimal effect on surrounding tissues, Reddy and colleagues write. Preclinical studies have confirmed the relative tissue selectivity of the technique, the authors note, including the achievement of electrical PVI without adverse effects of thermal ablation including stroke, pulmonary vein (PV) stenosis, phrenic nerve injury, or oesophageal damage.
At present it is unknown whether this translates to freedom from AF recurrence, a fact that the study’s authors sought to determine. The researchers pooled data from the three multicentre trials, in which PFA was employed to perform PVI in 121 paroxysmal AF patients. IMPULSE and PEFCAT studies are prospective, single-arm safety and feasibility trials performed at two sites (Homolka Hospital, Prague, Czech Republic, and Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France), while PEFCAT II study is a prospective, single-arm feasibility trial performed at two sites (Homolka Hospital, Prague, Czech Republic, and CHU Split, Split, Croatia).
The PFA system consists of a generator (Farastar, Farapulse) that delivers high-voltage, high-frequency pulses over multiple channels; an over-the-wire 12-F multielectrode PFA catheter (Farawave, Farapulse); a 12-F steerable focal PFA catheter (Faraflex, Farapulse); and a 13-F steerable sheath (Faradrive, Farapulse).
For PVI, the “single-shot” multielectrode PFA catheter was used, consisting of five splines, with four electrodes per spline and one electrode available for intracardiac electrogram recording or 3D electroanatomic visualisation. When used in conjunction with the PFA generator, an electric field is created that ablates tissue using irreversible electroporation. The catheter shape is changed through the manipulation of a slider mechanism on the handle of the catheter. The diameter of the catheter is measured in the fully deployed “flower” configuration. Energy is delivered through all of the electrodes in a proprietary sequence.
Reddy et al report that in 121 patients, acute PVI was achieved in 100% of PVs with PFA alone. Furthermore, PV remapping performed in 110 patients at 93.0±30.1 days, demonstrated durable PVI in 84.8% of PVs (64.5% of patients), and 96% of PVs (84.1% of patients) treated with the optimised biphasic energy PFA waveform. Primary adverse events occurred in 2.5% of patients (two pericardial effusions or tamponade, one hematoma), Reddy et al note, adding that there was one transient ischaemic attack. The one-year Kaplan-Meier estimates for freedom from any atrial arrhythmia for the entire cohort and for the optimized biphasic energy PFA waveform cohort were 78.5±3.8% and 84.5±5.4%, respectively.
These findings lead the authors to conclude that in paroxysmal AF patients, PVI with a one-shot PFA catheter results in excellent lesion durability and safety. At one year, this translated to low rates of AF and other atrial arrhythmia recurrence. Further to this they note that improvements in PFA dosing and optimisation of the biphasic wave-forms employed in the study results in 96% of PVs remaining durably isolated.
“These data help allay concern that the novel non-thermal ablative mechanism of this energy modality masks undiscovered compromises to clinical success,” they write. “Multicentre, randomised studies comparing PFA with other ablation energy sources are necessary to confirm the favourable findings observed in this study.”
Vivek Reddy discloses that he is a consultant on behalf of and owns stock in Farapulse.