It dominated 2024’s heart rhythm meetings, and it dominates my private electrophysiologist chat groups. My Google alert for “AF ablation” most often includes notices on PFA and the expansion of the atrial fibrillation ablation market.
Yet, the excitement does not match the empirical data.
Despite having strong brains, electrophysiologists adopt new things as if we were emotional shoppers. Our neighbor buys a sports car and we think we need the same car. Left atrial appendage occlusion and subcutaneous defibrillators were past examples.
The most recent example of soft thinking (especially in the United States) is the enthusiasm and early adoption of first-generation PFA systems for the treatment of AF.
Readers of cardiac news (including some of my patients) might think PFA has solved the AF puzzle. It has not.
A true breakthrough in AF would be to find its cause. PFA is simply another way to destroy (ablate) cardiac myocytes. PFA uses electrical energy (think shocks) to create pores in the cell membranes of myocytes. It’s delivered through various types of catheters.
The main theoretical advantage of PFA is cardioselectivity, which is possible because myocytes have lower thresholds for irreversible electroporation than surrounding tissues. The dose of electrical energy that ablates cardiac tissue does not affect surrounding tissues. Cardioselectivity decreases the chance of the most feared complication of standard AF ablation, thermal damage to the esophagus, which is often fatal. The esophagus lies immediately behind the posterior wall of the left atrium and can be inadvertently injured during thermal ablation.
The challenge in assessing this potential advantage is that thermal esophageal damage is, thankfully, exceedingly rare. Its incidence is in the range of 1 in 10,000 AF ablations. But it might be even lower than that in contemporary practice, because knowledge of esophageal injury has led to innovations that probably have reduced its incidence even further.
Proponents of PFA would rightly point to the fact that not having to worry about esophageal injury allows operators to add posterior wall ablation to the normal pulmonary vein isolation lesion set. This ability, they would argue, is likely to improve AF ablation outcomes. The problem is that the strongest and most recent trial of posterior wall isolation (with radiofrequency ablation) did not show better outcomes. A more recent observational analysis also showed no benefit to posterior wall isolation (using PFA) over pulmonary vein isolation alone.
What About PFA Efficacy?
I’ve long spoken and written about the lack of progress in AF ablation. In 1998, the first report on ablation of AF showed a 62% arrhythmia-free rate. Two decades later, in the carefully chosen labs treating patients in the CABANA trial, arrhythmia-free rates after AF ablation remain unchanged. We have improved our speed and ability to isolate pulmonary veins, but this has not increased our success in eliminating AF. The reason, I believe, is that we have made little to no progress in understanding the pathophysiology of AF.
The Food and Drug Administration regulatory trial called ADVENT randomly assigned more than 600 patients to thermal ablation or PFA, and the primary endpoint of ablation success was nearly identical. Single-center studies, observational registries, and single-arm studies have all shown similar efficacy of PFA and thermal ablation.
Proponents of PFA might argue that these early studies used first-generation PFA systems, and iteration will lead to better efficacy. Perhaps, but we’ve had 20 years of iteration of thermal ablation, and its efficacy has not budged.