Pulsed field ablation (PFA), a new nonthermal ablation approach that preferentially ablates myocardial tissue, results in durable pulmonary vein isolation (PVI) and a low rate of recurrence of atrial arrhythmia, according to one-year outcomes of three clinical trials. "We previously demonstrated that pulsed field ablation can safely isolate pulmonary veins to treat patients with paroxysmal atrial fibrillation. We also showed, in a limited number of patients during invasive remapping studies, that the durability of the PV isolation was quite good using an optimized PF waveform," Dr. Vivek Y. Reddy of the Icahn School of Medicine at Mount Sinai, in New York City, told Reuters Health by email. The procedure involves applying ultrarapid electrical pulses to destabilize cell membranes by forming irreversible nanoscale pores, Dr. Reddy and his colleagues explain in JACC: Clinical Electrophysiology. This phenomenon, known as electroporation, culminates in cell death. The propensity for dielectric cell membrane breakdown varies among tissues. Sensitivity appears greater for some tissues such as the myocardium than for others such as blood vessels or nerve fibers suggesting that its use for catheter ablation of atrial fibrillation (AF) may improve safety by decreasing collateral damage. To investigate, the researchers examined data at one year from 121 patients in the IMPULSE and PEFCAT studies, which were prospective, single-arm safety and feasibility trials, and the PEFCAT II study, which was a prospective, single-arm feasibility trial. All used Farapulse devices. The IMPULSE and PEFCAT studies examined use of an over-the-wire, single-shot multielectrode PFA catheter to achieve PVI. The PEFCAT II study used the same catheter for the treatment of the PVs, but also investigated the first-in-human treatment of cavotricuspid isthmus (CTI)-dependent flutter with a novel, deflectable focal PFA catheter. Therapeutic dosing, say the researchers, evolved from a monophasic to biphasic waveform and optimizations were made to the number of applications per vein, spline shape, and other parameters, Acute PVI was achieved in 100% of PVs with PFA alone. PV remapping, performed in 110 patients at a mean of 93.0 days, showed durable PVI in 84.8% of PVs (64.5% of patients). This was true of 84.1% of patients and 96.0% of PVIs treated with the optimized biphasic energy PFA waveform, The procedure was deemed safe, with a primary adverse-event rate of 2.5%. These events consisted of one cardiac tamponade, one pericardial effusion, and one vascular hematoma. One transient ischemic attack was also seen but there were no further major safety events during follow-up. "Prior to this study," the researchers conclude, "it was an open question as to whether durable PVI with PFA would yield the same results as thermal ablation. After all, could its myocardial preferential ablation properties, which are so beneficial on the safety side, hinder efficacy? However, PFA durability did indeed translate to clinical success." "This last point," added Dr. Reddy, "is a very important one: while the acute and durability data demonstrated the technical effectiveness of the procedure, the fact that this was a completely novel energy source left open the very important question as to whether or not PV isolation using this strategy would translate to freedom from recurrent atrial arrhythmias." "This manuscript," he concluded, "provided the scientific and clinical rationale both 1) for clinical utilization to treat patients with paroxysmal atrial fibrillation in Europe (this technology received CE Mark approval earlier this year and is now being commercialized there), and 2) for the ongoing ADVENT randomized clinical trial (NCT04612244) - the FDA pivotal trial comparing pulsed field ablation to conventional thermal ablation (either radiofrequency or cryo)." Dr. David Frankel, an associate professor of medicine at the Perelman School of Medicine at the University of Pennsylvania, in Philadelphia, told Reuters Health y email, "Pulsed field ablation remains a very promising energy source for ablating myocardium without damaging surrounding structures." Dr. Frankel, who was not involved in the study, added, "It is encouraging that the rate of chronic pulmonary vein isolation increased to 96% with use of the optimized biphasic energy PFA waveform. I am optimistic that PFA will assume a larger role in catheter ablation over the coming years." The study was funded by Farapulse. Dr. Reddy has served as a consultant to the company. —David Douglas Source
