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AF Pulsed-Field Ablation Meets Pivotal Safety, Efficacy Goals

Radiofrequency (RF) catheter ablation has been a standout success in some forms of atrial fibrillation (AF) but not an unqualified success — it doesn’t always work and has safety issues and other limitations. Thus, the continued search for alternative arrhythmia ablation technologies, which has notably produced cryoballoons and lately, an exotic assortment of pulsed-field ablation (PFA) catheters.

Now, in the prospective PULSED-AF study, PFA for pulmonary vein isolation (PVI) successfully and safely abolished atrial arrhythmias over 1 year in about 80% of a cohort of patients with paroxysmal or persistent AF. The 300-patient trial was designed for US Food and Drug Administration consumption as it considers approval of the tested device, Medtronic’s PulseSelect PFA system.

But the study wasn’t randomized or controlled. Instead, PFA met and surpassed prospectively defined performance goals for efficacy and safety on the basis of published electrophysiology society standards for AF ablation.

Whether applied to paroxysmal or persistent AF, PFA “beat the benchmark performance goals in a statistically significant fashion,” said Atul Verma, MD, McGill University Health Centre, Montreal, Canada. “This is very similar or at least as good as results that we would get from thermal ablation.”

Moreover, the study’s less than 1% rate of serious procedural and device-related adverse events “represents one of the lowest complication rates ever reported in a catheter ablation trial globally,” said Verma when presenting PULSED-AF on March 6 at the American College of Cardiology (ACC) Scientific Session/World Congress of Cardiology (WCC) 2023, conducted live and virtually from New Orleans, Louisiana. He is also lead author on the study’s simultaneous publication online in Circulation.

Application of PFA for PVI, as described by Verma, creates the lesions by exposing the myocardial targets to high-gradient electric fields, leading to a nonthermal electroporation process that rapidly renders myocyte membranes “hyperpermeable,” which induces apoptotic cell death.

Although PFA ablation energy is starkly different from the heat of RF ablation or cryoablation’s deep freeze, “the catheters itself, for the most part, are very similar to catheters that have been used in the past,” Verma told | Medscape Cardiology. So if the technology is approved for practice, operator learning curves likely wouldn’t be steep.

For example, operators in PULSED-AF were allowed only one practice case before taking on a patient that would actually be followed in the trial for outcomes, he said, “and yet we saw that efficacy and safety were excellent.”

That may bode well for PFA’s uptake in practice should it be approved, Jim W. Cheung, MD, who is not part of PULSED-AF, told | Medscape Cardiology.

“It’s one thing to have a study with very few centers and highly specialized operators,” but the fact that the trial was international with 67 operators “I think does provide some good evidence that this is a scalable technology,” said Cheung, who is director of clinical electrophysiology research at Weill Cornell Medicine, New York City.

Earlier at a press conference on PULSED-AF, Cheung agreed that the trial’s freedom from arrhythmia outcomes “were very much in line with the results from large clinical trials involving conventional thermal ablation.”

The PULSED-AF trial enrolled 383 adults with symptomatic paroxysmal or persistent AF despite antiarrhythmic meds at 41 centers in North America, Western Europe, Australia, and Japan.

After exclusions (including for prior AF ablation or left-atrial dilatation) and not counting the “roll-in” patients who allowed participating operators to gain experience in the procedure, Verma said, 150 patients with paroxysmal AF and 150 with persistent AF underwent PFA for PVI and were followed for 12 months. About 70% of the 300 patients were men.

After a 90-day post-procedure blanking period, 66.2% of patients with paroxysmal AF met the primary efficacy endpoint, handily meeting the performance goal of more than 50%. For patients with persistent AF, 55.1% met the efficacy endpoint against a performance goal of more than 40%, Verma reported.

The primary efficacy endpoint consisted of freedom from acute procedural failure, AF recurrence, repeat ablation, direct-current cardioversion, left atrial surgery, or escalation of antiarrhythmic drugs.

Also at 1 year, 69.5% of the paroxysmal-AF patients and 62.3% of the persistent-AF group remained free of any recurrent atrial arrhythmia; 79.7% and 80.8%, respectively, met the clinical-success endpoint of freedom from symptomatic atrial arrhythmia recurrence.

Only 0.7% of patients in both AF groups met the primary safety endpoint of serious procedural and device-related adverse events, which included phrenic nerve, esophageal, or pulmonary vein injury or coronary artery spasm. The performance goal had been less than 13.

Of the 45 patients who had undergone cerebral MRI at both baseline and 72 hours, two patients with each type of AF showed evidence of new asymptomatic lesions. That 8.9% rate is “in keeping with other forms of ablation, which have reported rates of 4%-10% for cryoablation and 0%-19% for radiofrequency ablation,” the published PULSED-AF report states.

Verma is confident that the regulators will respond favorably to the results when they consider the PFA device for approval. “I think it will be a positive decision,” he told | Medscape Cardiology. “And if that’s the case, I think you can start to see this technology being available in the US sometime in the next 6 to 12 months or so.”

Medtronic funded PULSED-AF. Verma discloses consulting for and receiving honoraria and research grants from Medtronic and Biosense Webster; consulting for and receiving honoraria from Medlumics; consulting for Kardium; receiving research grants and honoraria from Bayer; and receiving research grants from Biotronik. Disclosures for the other authors are in the report. Cheung reports receiving consulting fees or honoraria from Abbott, Biotronik, and Boston Scientific.

American College of Cardiology (ACC) Scientific Session/World Congress of Cardiology (WCC) 2023. Presented March 6, 2023. Abstract

Circulation. Published online March 6 2023. Full Text

Follow Steve Stiles on Twitter: @SteveStiles2.

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