Pulsed Field Ablation for Atrial Fibrillation: Twelve-Month Results Are In

© 2023 HMP Global. All Rights Reserved.

Any views and opinions expressed are those of the author(s) and/or participants and do not necessarily reflect the views, policy, or position of EP Lab Digest or HMP Global, their employees, and affiliates. 

EP LAB DIGEST. 2023;23(4):6.

Dear Readers,

Pulsed field ablation (PFA) is a technology being investigated as a novel energy source for cardiac ablation. The promise is that PFA is a safer and more efficient ablation tool than current techniques of radiofrequency ablation (RFA) and cryoenergy, including cryoballoon ablation (CBA). It is mostly being developed to electrically isolate the pulmonary veins (PVs) to treat patients with atrial fibrillation (AF). Early experiences suggest that PFA is more selective for cardiac tissue than surrounding tissues, leading to a reduced risk of atrial-esophageal fistulas and phrenic nerve injury. It is currently not commercially available in the United States for the treatment of arrhythmias.

On March 6, 2023, the results from the PULSED AF pivotal study were presented by Dr Atul Verma during the late-breaking clinical trials at the 2023 American College of Cardiology’s annual scientific session together with the World Congress of Cardiology.¹ PULSED AF was a single-arm trial sponsored by Medtronic that enrolled 383 patients with drug-refractory recurrent symptomatic paroxysmal AF (pAF) or persistent AF (perAF) who were undergoing a first-time PVI ablation procedure at 41 study locations. Patients with long-standing persistent AF >12 months were excluded. After each of the 67 participating electrophysiologists performed one roll-in procedure, 150 patients with pAF and 150 patients with perAF underwent ablation and were followed for at least 12 months.

The procedure was performed using the PulseSelect PFA System (Medtronic), which delivered PFA from a circular, over-the-wire, deflectable pulmonary vein ablation catheter with gold electrodes that was placed through a 10 French deflectable sheath into the left atrium (LA). PVI was performed, and lesions could be extended to the posterior LA in patients with perAF. Almost all cases were performed with general anesthesia. Transtelephonic monitoring was performed on a weekly basis and with symptoms suggestive of an arrhythmia. The primary efficacy end point at 12 months after a 90-day blanking period was a composite that included successful acute PVI, recurrent atrial arrhythmias, and other factors that reflected recurrence, such as adjustment of antiarrhythmic drugs.

The clinical safety and efficacy outcomes are summarized in the Table. The LA dwell times were 53 minutes for pAF and 60 minutes for perAF. These times included a 20-minute observation period after PVI and optional 3-dimensional remapping. There were no significant esophageal temperature rises detected. Substudy results showed silent cerebral emboli on brain MRIs of 4 of 45 patients and no evidence of PV stenosis. Quality of life scores improved with ablation.

The PULSED AF trial results demonstrate the following:

• PFA with the specific formula and catheter used in this trial can be used to successfully isolate the PVs;
• PVI using this PFA system to treat patients with pAF and perAF results in clinical outcomes such as time to first recurrence of any atrial arrhythmias >30 seconds that are similar to PVI using CBA or point-by-point RFA;
• This PFA system is safe and was associated very few clinical complications in 300 patients;
• This PFA system does not appear to be associated with a high rate of silent cerebral embolism.

Remaining questions about the use of PFA for PVI to treat AF include:

• How durable are PFA lesions using this system?
• Are PFA lesions transmural?
• Exactly how safe is PFA on the esophagus and phrenic nerve in the real world?
• Would outcomes improve if PFA were used beyond PVI?
• Would other complications such as coronary artery spasm occur if PFA were used to ablate the cavotricuspid or mitral isthmus?
• Could the PFA recipe be more aggressive without sacrificing safety?
• How well would PFA be tolerated without general anesthesia?
• How will this system compare to other PFA systems?
• If PFA becomes commercially available in the United States, will it replace CBA and RFA for PVI?
• What will be the costs associated with the PFA console acquisition and catheters?

Disclosures: Dr Knight has served as a paid consultant to Medtronic and was an investigator in the PULSED AF trial. In addition, he has served as a consultant, speaker, investigator, and/or has received EP fellowship grant support from Abbott, AltaThera, AtriCure, Baylis Medical, Biosense Webster, Biotronik, Boston Scientific, CVRx, Philips, and Sanofi; he has no equity or ownership in any of these companies.

Reference

1. Verma A, Haines DE, Boersma LV, et al, on behalf of the PULSED AF Investigators. Pulsed field ablation for the treatment of atrial fibrillation: PULSED AF pivotal trial. Circulation. 2023 March 6. doi:10.1161/CIRCULATIONAHA.123.063988