What About PFA Safety?
In the ADVENT randomized trial, safety results were similar, though the one death, caused by cardiac perforation and tamponade, occurred in the PFA arm. In the MANIFEST-17K multinational survey of PFA ablation, safety events were in the range reported with thermal ablation. PFA still involves placing catheters in the heart, and complications such as tamponade, stroke, and vascular damage occur.
The large MANIFEST-17K survey also exposed two PFA-specific complications: coronary artery spasm, which can occur when PFA is delivered close to coronary arteries; and hemolysis-related kidney failure — severe enough to require dialysis in five patients. Supporters of PFA speculate that hemolysis occurs because electrical energy within the atrium can shred red blood cells. Their solution is to strive for good contact and use hydration. The irony of this latter fix is that one of the best advances in thermal ablation has been catheters that deliver less fluid and less need for diuresis after the procedure.
No PFA study has shown a decreased incidence of thermal damage to the esophagus with PFA ablation. Of course, this is because it is such a low-incidence event.
One of my concerns with PFA is brain safety. PFA creates substantial microbubbles in the left atrium, which can then travel north to the brain. In a small series from ADVENT, three patients had brain lesions after PFA vs none with thermal ablation. PFA proponents wrote that brain safety was important to study, but few patients have been systematically studied with brain MRI scans. Asymptomatic brain lesions have been noted after many arterial procedures. The clinical significance of these is not known. As a new technology, and one that creates substantial microbubbles in the left atrium, I agree with the PFA proponents that brain safety should be thoroughly studied — before widespread adoption.
What About Speed and Cost?
Observational studies from European labs report fast procedure times. I have seen PFA procedures in Europe; they’re fast — typically under an hour. A standard thermal ablation takes me about 60-70 minutes.
I am not sure that US operators can duplicate European procedural times. In the ADVENT regulatory trial, the mean procedure time was 105 minutes and that was in experienced US centers. While this still represents early experience with PFA, the culture of US AF ablation entails far more mapping and extra catheters than I have seen used in European labs.
Cost is a major issue. It’s hard to sort out exact costs in the United States, but a PFA catheter costs approximately threefold more than a standard ablation catheter. A recent study from Liverpool, England, found that PFA ablation was faster but more expensive than standard thermal ablation because of higher PFA equipment prices. For better or worse, US patients are not directly affected by the higher procedural costs. But the fact remains that PFA adds more costs to the healthcare system.
What Drives the Enthusiasm for First-Generation PFA?
So why all the enthusiasm? It’s surely not the empirical data. Evidence thus far shows no obvious advantage in safety or efficacy. European use of PFA does seem to reduce procedure time. But in many electrophysiology labs in the United States, the rate-limiting step for AF ablation is not time in the lab but having enough staff to turn rooms around.
The main factor driving early acceptance of PFA relates to basic human nature. It is the fear of missing out. Marketing works on consumers, and it surely works on doctors. Companies that make PFA systems sponsor key opinion leaders to discuss PFA. These companies have beautiful booths in the expo of our meetings; they host dinners and talks. When a hospital in a city does PFA, the other hospitals feel the urge to keep up. It’s hard to be a Top Person in electrophysiology and not be a PFA user.
One of my favorite comments came from a key opinion leader. He told me that he advised his administration to buy a PFA system, promote that they have it, and keep it in the closet until better systems are released.
Iteration in the medical device field is tricky. There are negatives to being too harsh on first-generation systems. Early cardiac resynchronization tools, for instance, were horrible. Now CRT is transformative in selected patients with heart failure.
It’s possible (but not certain) that electrical ablative therapy will iterate and surpass thermal ablation in the future. Maybe.
But for now, the enthusiasm for PFA far outstrips its evidence. Until better evidence emerges, I will be a slow adopter. And I hope that our field gathers evidence before widespread adoption makes it impossible to do proper studies.
Dr. Mandrola, clinical electrophysiologist, Baptist Medical Associates, Louisville, Kentucky, has disclosed no relevant financial relationships.
A version of this article appeared on Medscape.com.