Pulsed Field Ablation Treats AF With Few Complications

Daniel M. Keller, PhD

April 14, 2022

In an unselected population of patients with paroxysmal or persistent atrial fibrillation (AF), the pentaspline pulsed field ablation (PFA) catheter achieved pulmonary vein isolation with 99.9% success and good procedure times.

Presenting the results of the Multi-national Survey on Methods, Efficacy and Safety on the Post-approval Clinical Use of Pulsed Field Ablation (MANIFEST-PF), Vivek Reddy, MD, Mount Sinai Hospital, New York City, said: "We do see a safety profile consistent with preferential tissue ablation. There were very few other unique complications."

However, the investigators observed what they called a significant rate of generic catheter complications, often seen with other AF catheter procedures.

The pentaspline PFA catheter (Farapulse PFA System, Boston Scientific) is an over-the-wire catheter with variable distal basket and flower shapes. Besides performing pulmonary vein isolation (PVI), the catheter can also treat the left atrial posterior wall (LAPW), often needed in cases of persistent AF.

The relatively new PFA technology uses trains of microsecond-long, high-amplitude electrical pulses. Rather than destroying tissue with heating as with radio frequency ablation or with cold as with cryoablation, PFA creates microscopic pores (electroporation) in the sarcolemma membrane of the myocardium to ablate without significant heating.

Cardiomyocytes are particularly sensitive to the electroporation effect, whereas other cell types are more resistant, sparing adjacent tissues.

Real-World Performance

First in human trials had shown the pentaspline catheter to be safe and effective, but in total the trials involved fewer than 150 patients. With limited market release begun in March 2021, the investigators aimed to assess its real-world use and performance though the MANIFEST-PF survey of 24 European Union centers involving 90 operators and 1758 patients, gathering center-level data.

Most study sites (81%) were academic or semi-academic centers, averaged 3.8 operators per center (range, 2 to 11), performed a mean of 73 study procedures per center out of about 700 AF ablations annually.

Patients had a mean age of 61.6 years, CHA2DS2-VASc score of 2.1 (range, 0 to 9), 59% had hypertension, 12% had congestive heart failure, mean left atrial diameter was 39 mm, and mean left ventricular ejection fraction (LVEF) was 54.7% (5% with reduced LVEF).

The majority of patients (57.5%) had paroxysmal AF, but 35.2% had persistent AF, and 3.9% had long-standing persistent AF. Two-thirds of patients had failed some class of antiarrhythmic drug, and 88% were receiving a non-vitamin K oral anticoagulant drug. For 94% of patients, it was their first ablation procedure.

In 82% of patients, the procedures were done under deep sedation without intubation; the rest received general anesthesia with intubation. All patients had one transseptal puncture, the mean procedure time was 65 minutes (range, 38 to 215 minutes), mean fluoroscopy time was 12.7 minutes (range, 4.5 to 33 minutes), and 16% of patients were discharged the same day.

The lesion sets were standardized: for pulmonary vein isolation, 2 x basket → rotate → 2 x basket → 2 x flower → rotate → 2 x flower; for LAPW, 2 x flower at each location. There was no esophageal monitoring, deviation, or cooling.

"If we look at the effectiveness, the mean acute PVI success rate was quite high, 99.9%. The median was 100%. If you look at the range, the lowest was 98.9%," Reddy told congress attendees. Adverse events were uncommon.

There were no esophageal complications, pulmonary vein stenosis, or persistent phrenic nerve injury. A total of 1.6% of patients experienced a major complication, among which were pericardial tamponade (0.97%); stroke (0.4%), one of whom died; vascular complications requiring surgery (0.23%); and one instance of coronary artery spasm. Minor complications affected 3.87% of patients (3.19% vascular), the most common being hematoma, at 2.45%.

Considering cardiac tamponade, the timing of the incidence appeared to reveal a learning curve. Of the 17 cases of tamponade across all 24 centers, 11 of the cases (65%) occurred during the first 20 procedures that any center performed.

Three centers performed some brain imaging. Among the 114 patients scanned, MRI showed silent cerebral ischemic events among 20 (17.5%).

Study Limitations

Reddy pointed out that the study is a retrospective analysis; all the data were aggregated from each center, so were not patient-level data, and were based on acute effects. So, "we can't make any comments on long-term efficacy," he cautioned, and late complications could not be known.

Study discussant Tom De Potter, MD Cardiac Research Center Aalst, Belgium, remarked on "the speed at which science operates nowadays." PFA technology was introduced only a few years ago, leading to first in human trials, commercial release only about a year ago, and now "we're looking at a pretty impressive registry of 1700 patients, which is also the testimony to the interest in the field for this technology."

New medical technology raises important questions of efficacy and safety. Because of the design of the registry, he said, it is difficult to comment on efficacy, but the data on safety are reassuring, especially regarding "the most devastating complication that exists in PVI, which is an esophageal fistula."

Because fistula is a consequence of thermal ablations, "it's perfectly conceivable that this complication will be eliminated using PFA," if more cases corroborate what was seen in this study, De Potter said. "And if only that observation holds, I think that technology will be promising."

He expressed concern about MRI cerebral imaging, which was quite limited in this study, as well as effects on the autonomic nervous system, and in particular on long-term sinus rates and therefore on long-term clinical efficacy.

There are open questions about how the technology will be applied once widely adopted in the field, such as what strategy and how many applications are delivered, how many lines are deployed, and what regions are targeted, he added.

"I think we've seen the decade of therapy standardization for PV [isolation]. I think this decade will be the decade of therapy expansion, enabled by technologies that are both highly efficient, and hopefully, will keep their extraordinary safety profile," he predicted.

Relevant to this presentation, Reddy has an equity stake in Farapulse, part of Boston Scientific; has served as a consultant for Farapulse, Biosense Webster, Abbott, Ablacon, Acutus Medical, Affera, Apama Medical, Aquaheart, Atacor, Autonomix, Axon Therapeutics, Backbeat, BioSig, Biotronik, Boston Scientific, Cardiac Implants, CardiaCare, Cardiofocus, Cardionomic, CardioNXT/AFTx, Circa Scientific, Corvia Medical, Dinova-Hangzhou Nuomao Medtech, East End Medical, EBR, EPD, Epix Therapeutics, EpiEP, Eximo Fire1, HRT, Impulse Dynamics, Intershunt, Javelin, Kardium, Keystone Heart, LuxMed, Medlumics, Medtronic, Middlepeak, Nuvera, Philips, Pulse Biosciences, Sirona Medical, Thermedical, and Valcare; owns equity in Ablacon, Acutus Medical, Affera, Apama Medical, Aquaheart, Atacor, Autonomix, Axon Therapeutics, Backbeat, BioSig, Cardiac Implants, CardiaCare, Circa Scientific, Corvia Medical, Dinova-Hangzhou Nuomao Medtech, East End Medical, EPD, Epix Therapeutics, EpiEP, Eximo, HRT, Intershunt, Javelin, Kardium, Keystone Heart, LuxMed, Manual Surgical Sciences, Medlumics, Middlepeak, Newpace, Nuvera, Sirona Medical, Surecor, Valcare, and Vizaramed; and owns stock in Farapulse. All fees relating to De Potter’s travel, consulting, or research support go to the Cardiac Research Institute Aalst. He reported no personal disclosures.

European Heart Rhythm Association (EHRA) 2022. Presented April 4, 2022.


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