Pulsed field ablation shows potential to replace thermal ablation

The biggest issue is that thermal ablation using heat or cold is tissue indiscriminate, so when the energy wave propagates, it ablates all tissue in its way, Reddy explained. 

"This is good for ablating the myocardium, but bad if it effects other structures around the heart. And when you have a complication like atrial esophageal fistula, it can be quite devastating," he said. "But we have learned is there is some degree of tissue preference with pulsed field ablation, so you can ablate the heart tissue with minimal damage to the surrounding structures."

The ADVENT pivotal trial for the Boston Scientific Farapulse system was the first large, randomized study to investigate the safety and efficacy of PFA. It randomized more than 600 patients at 30 hospitals to PFA or thermal ablation using RF or cryo. 

PFA was found to be noninferior to thermal ablation, successfully treating 73.3% of patients compared to 71.3% for the current standard of EP care. 

The primary safety endpoint was the composite of serious events related to the procedure within seven days of the therapy. PFA had an event rate of 2.1% and thermal ablation a 1.5% event rate, which met the criteria for noninferiority. A secondary safety endpoint looked at changes in pulmonary vein dimensions that would indicate the the start of stenosis from baseline out to 90 days. PFA had a rate of 3.3%, while the standard of care had a significant 19.5%, so PFA showed superiority over contemporary care.

"This speaks to the tissue specificity of PFA, where we don't see any sort of narrowing versus thermal ablation," Reddy stressed.
 
The trial did not find any clinical pulmonary vein stenosis or esophageal fistulas in either group. 

"With conventional ablation, we always use various strategies to minimize the change of esophageal damage, whether it's temperature monitoring moving the esophagus out of the way. We always do something. With PFA, we do nothing. We don't monitor, we don't even look at the esophagus, we just do the procedure," Reddy said.

PFA also appears to make the procedure easier. 

"Even though we had operators who had never used PFA before, the overall procedure times were faster, and the left atrial dwell time was faster. I think that speaks to the ease of use of the catheter," Reddy said. "It is a lot easier to do the procedure with PFAn. The procedure is quicker, the number of manipulations is less. What the trial experience and clinical experience in Europe where it is approved has shown us is that it is a very easy procedure."

This is the second late-breaking trial on pulsed field ablation presented in 2023. The nonrandomized PULSED AF study on the Medtronic pulsed field technology was presented at the American College of Cardiology (ACC) annual meeting in Boston. That trial also showed similar clinical results between PFA and thermal ablation and no major adverse events. Experts in EP say PFA studies are being watched closely because many feel this will be a replacement technology for thermal ablation.

"My own opinion is that PFA will be the workhorse technology we use ... my guess is that once it is approved in the United States, it will likely be utilized quite extensively."