The future of electrophysiology: Reviewing key trends in PFA

PFA works differently to kill cardiac cells than thermal ablation, so the depth of penetration is better controlled. This means it can easily avoid the risk of damage to underlying nerves and the esophagus as well as pulmonary vein stenosis. 

However, Reddy warns that the ease of use and fast procedures is both good and bad. 

"It's good because then we can get the procedures done quicker in our patients. But there is a dark side to this ... because it's so easy to ablate, there is a potential for over ablation. In fact, when you think about safety issues, in my mind, I'm less concerned about some of the other safety issues, which are very real, but are workable. I'm more concerned about the potential that will ablate too much and loose atrial contractile function," Reddy warned. 

Reddy briefly explained the outcomes of the late-breaking studies.

Key PFA trial findings at Heart Rhythm 2024

1. PULSE-EU Trial: Reddy presented this first-in-human trial evaluating a novel single-shot map-and-ablate spherical array PFA catheter from Kardium. He said the one-year outcomes were promising, with around 80% success in both paroxysmal and persistent atrial fibrillation (AF) patients. Despite the small sample size of approximately 45 patients, the high durability rates and good clinical outcomes highlighted the potential of this innovative technology.

2. SPHERE PER-AF Trial: This randomized controlled trial compared a new lattice-tip mapping and ablation system from Medtronic capable of delivering both radiofrequency (RF) and pulsed field energy against conventional RF ablation. The study, involving persistent AF patients, demonstrated that the lattice-tip catheter was not only safe, but potentially more effective, showing a trend towards superiority over traditional methods, Reddy explained.

3. FARADISE Registry: This real-world data collection involved the Farapulse PFA system from Boston Scientific. Enrolling over 1,000 patients, the registry aimed to validate the safety and effectiveness of the Farawave catheter post-market. Preliminary results were consistent with previous pivotal trials, affirming the technology's reliability, Reddy said.

4. ADVENT Trial Sub-analysis: Reddy presented this sub-analysis of the ADVENT trial, which compared the Farawave PFA catheter to conventional ablation methods. He said the trial was significant because it used a more relevant measure of AF burden. He said the traditional 30-second cutoff for defining success in previous trials is not ideal; a more nuanced measure of AF burden is needed, which was used in this study. The analysis revealed an 82% success rate with PFA, compared to 75% with thermal ablation, marking a statistically significant difference. Reddy said the outcomes show maybe it is time to move away from the 30-second cutoff criteria in studies.

5. MANIFEST-PF Registry Sub-analysis: This study focused on the safety and effectiveness of PFA in heart failure patients. The findings indicated comparable success rates between heart failure and non-heart failure patients, with no significant safety concerns, suggesting PFA as a viable option for these high-risk patients.

Advantages of PFA

PFA does not require saline to cool the catheter, which has additional safety benefits. Reddy said RF technology, which relies heavily on irrigated catheters that pump saline through the tip to cool it. However, this can sometimes lead to fluid overload in patients.

"I think that's particularly true in the heart failure patients. In the non-heart failure patients, it probably doesn't matter much, but in the heart failure patients, you really want to try to minimize the fluid overload, particularly in the HFrEF patients," Reddy explained.

There was a lot of interest in moving toward cryo-ablation catheters a few years ago because they offered a more efficient procedure. He said PFA will also offer a similar ease of use
    
"With pulse field, there's going to be some catheters that are going to be easier to use, but it may be a little more limited in terms of what they can do. Others that may require a little more expertise, but will allow the operator to do more things and fine tune their ablation. So I think that sort of issue is going to be there with pulse field also. 

Moving PFA from non-inferiority to superiority

Reddy said efficacy is a key measure, but acknowledged the results of PFA trials to date all similar outcomes to thermal ablation. However, there are signals this may change. 

He said changing the way efficacy is measured by eliminating the 30 second cutoff as in the ADVENT sub-analysis may be a first step. 

"When you use a more relevant measure of success, there were advantages with PFA," Reddy said.