Novel Technology Combining Pulsed-Field and Radiofrequency Energy Shows Promise in AF Ablation

A novel lattice-tip focal ablation catheter (Affera Inc.) shows promise for combining the best aspects of pulsed-field ablation (PFA) and radiofrequency ablation (RFA) for treatment of atrial fibrillation (AF), according to a first-in-human study. This prospective, international, single-arm investigation was presented virtually as a late-breaking clinical trial during the Annual Scientific Sessions of the Heart Rhythm Society (HRS) and simultaneously published in Circulation: Arrhythmia and Electrophysiology.

“This technology combines PFA and RFA into a single platform, capitalizing on the improved safety of PFA and the many years of experience with RFA,” says Elad Anter, MD, Associate Section Head of Cardiac Electrophysiology at Cleveland Clinic and Director of the Mark Josephson and Andy Wit Translational Electrophysiology Research Laboratory.

Dr. Anter, who was involved in development of the technology and is a coinvestigator in the study, adds that it allows AF ablation to be performed in unprecedentedly short procedural durations and with increased lesion flexibility for patient-specific tailoring.

The rationale for PFA and a combined RFA/PFA approach

PFA is a nonthermal energy with increased selectivity for cardiomyocytes, which suggests that it may provide safety advantages over RFA for AF ablation. In a preclinical study also presented this week at the virtual HRS sessions and published simultaneously in Circulation: Arrhythmia and Electrophysiology, Dr. Anter’s laboratory characterized the biophysical and tissue properties of PFA on cardiac, esophageal and phrenic nerve tissues. The study showed that, in comparison to RFA, PFA has increased selectivity for atrial tissue and, at therapeutic energy doses, has only a minimal effect on the phrenic nerve and esophagus, the main organs at risk during AF ablation with RFA energy.

“However,” Dr. Anter notes, “RFA may still have some advantages, particularly for ablation in thicker tissue such as ablation of ventricular tachycardia. Therefore, the combination of RFA and PFA provides a greater freedom and flexibility of ablation.”

The novel lattice catheter is a 7.5-French bidirectional catheter with a compressible 9-mm nitinol tip that is able to toggle between delivery of RFA or PFA lesions, each lasting 2 to 5 seconds, allowing rapid and flexible energy delivery. Operators can use PFA in the posterior wall, which is close to the esophagus, or throughout the ablation. They may choose to use RFA in thicker tissues or in ablation of arrhythmias where RFA has a longer track record, such as AV-nodal reentrant tachycardia, ventricular tachycardia or arrhythmias associated with Wolff-Parkinson-White syndrome. “The important novelty of this technology is the flexibility to perform focal ablation in a point-by-point fashion with the freedom to choose PFA or RFA, in contrast to other emerging technologies designed for PFA over multielectrode catheters for single-shot pulmonary vein isolation (PVI),” says Dr. Anter.

Study in brief

The current first-in-human, multicenter, single-arm investigation was designed to evaluate the safety and short-term efficacy of this technology in patients with paroxysmal or persistent AF. Patients were prospectively enrolled to undergo PVI and additional linear ablation as required or desired using one of two strategies: either PFA posteriorly and RFA anteriorly (RF/PF) or PFA throughout (PF/PF). The 76-patient cohort included 55 patients with paroxysmal AF and 21 with persistent AF who underwent RF/PF (n = 40) or PF/PF (n = 36) ablation.

PVI was successfully achieved in all patients, with a mean duration time of 22.6 ± 8.3 minutes. Linear lesions included 14 mitral, 34 left atrial roof and 44 cavo-tricuspid isthmus lines, all of which were acutely successful and achieved in relatively short duration (5.1 ± 3.5, 1.8 ± 2.3 and 2.4 ± 2.1 min, respectively). There were no major complications, including stroke, atrio-esophageal fistula, cardiac tamponade or phrenic nerve paralysis.

“While the study started with a combination of RFA and PFA [RF/PF strategy], after the first several patients, operators became more comfortable using PFA for the entire ablation procedure in an effort to potentially further reduce the risk of damage to neighboring structures,” Dr. Anter observes. “That versatility and increased safety is the appeal of this technology as our understanding of PFA continues to evolve.”

What to look for next

“This first-in-human trial demonstrated the safety and efficacy of this technology for treating our patients with AF and potentially other arrhythmias,” says Dr. Anter. The next step, he adds, is to perform an FDA study in a larger group of patients and for additional arrhythmias.

“We are excited to be part of this development and studies that may benefit our patients,” says Oussama Wazni, MD, Section Head of Cardiac Electrophysiology at Cleveland Clinic.