Pulse Field Ablation of AF: Current Pitfalls

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Featured is the presentation entitled “Pulse Field Ablation of AF: Current Pitfalls” from Session 1 of WAFib 2023.

Thank you, Nassir, for the invitation and for another fantastic symposium here in Salt Lake City. So, I tend to consider pulse field ablation (PFA) as the second revolution in my professional life. The first one was the pulmonary veins and their role in atrial fibrillation (AF). I think it's really a major change in our field and practice. Yet, nothing is 0% or 100%. Perfection doesn't exist in medicine, so I'll try to review some of the potential pitfalls that go with this. These are my disclosures. When it comes to safety concerns, I think the MANIFEST study, which is a registry, with all attached limitations that Vivek put together, shows that the safety profile is really good. You see in blue the complications that are PFA specific, and apart from a transient phrenic nerve paresis that occurred in 1,700+ patients, nothing really serious was due to the energy. In red, you have the usual complications due to vascular access or pericardial tamponade. The stroke rate is as expected with radiofrequency (RF), so it seems that there is no benefit here but no pitfall either. This was with FARAPULSE, which is the only commercially approved solution in Europe; it is not yet in the US. It is confirmed, I think, by this study, also using a different system with Medtronic; Atul Verma reported the absence of complications. It's a smaller study of 38 patients, but it's a good sign as well. When it comes to esophageal safety, I think, and others have demonstrated, that the safety profile is just amazing with this tissue specificity that is apparently verified with pulse field. You see here the appearance of the inferior vena cava and the esophagus is right next to it, completely intact with PFA as compared to what you get with RF. It’s frightening. This has been confirmed by our group. We've been investigating those patients acutely right after pulmonary vein isolation (PVI) using either PVI or cryo or RF. With cryo and RF, you can see that we have some late gadolinium enhancement, very bright and visible in the interior aspect of the esophagus. It is visible also in the atrial wall, of course. But with PFA, we haven't seen any of the 19 patients investigated with some late gadolinium enhancements, which is very reassuring. But we've seen some lesions in the aortic wall of the descending, so there might be a word of caution here. It was not as frequent as with thermal energies, but yet it was there. So, that's a word of caution. When it comes to the phrenic, and I think these are experiments that have been done with the Medtronic system, if you push the energy high enough, you start to see some reduction in the phrenic nerve function. But in those animals, it was completely recovered after a month with no histological lesions. This perhaps matches the observation that you may have some paresis, but no sequela. Yet, we should always keep in mind that there are very different recipes out there. When it comes to PFA, it's very different from RF from that perspective, so that might be some effect due to each recipe versus a class effect. Coronary arteries have been largely debated over the last few months. Since the early reports, there have been several of them. This one is from Vivek Reddy’s group, where he reported some spasm of the arteries that were in direct proximity with the ablation catheter using the FARAPULSE technology. Now, there are important things that we should keep in mind. Nothing happened in cases where the energy was delivered in the PVs or in the posterior wall because the distance to the coronary arteries where they are is large enough for that not to happen. They observed some spasm during ablation, and I think you can get the same with mitral isthmus ablation. This is definitely a word of caution. Now, there was no ST elevation in those cases, but I think cases with ST elevation have been seen as well. It is, therefore, important to remember that it's not approved outside of the PVs, and yet, the fact that the injection or the deliverance, either intracoronary or intravenous, of nitrates before the deliveries completely prevented those spasms from happening. So, I think we are still in a better situation as compared to RF. You may not have any coronary damage with RF, but I had some in some patients. It's not a spasm, it's an occlusion that you may get. So, it's important to keep that in mind as well. When you look at some previous preclinical work, this was performed by Kars Neven, for example, delivering right on top of coronary arteries may produce some hyperplasia of the intima, but it was associated with an absolute conservation at 3 months. So, it's transient, apparently. Still, we have to be cautious. This is not safety, but I think it's even more important, because, again, I think that the safety profile of PFA is going to be superior to any of the thermal energies we have at the present time. There is one thing that is a real pitfall, in my opinion, which is this massive stunning effect that we have with PFA. It’s a single-shot device. From the first delivery, you typically destroy all the potentials. The point I want to make here is that if you behave the same as with RF and cryo when using PFA, it's not going to work. Because of this massive stunning effect, you cannot rely on the potentials. So, you have to rely on the recipes that are recommended. In this case, you see that after 3 deliveries, there's not much left in that left superior PV. But if you wait 7 minutes, and we had to wait because of some technical issues, then there is a regrowth of the potentials. So, very transient. Now, contact is also probably important with PFA, not as much as with cryo, which is entirely dependent on contact or RF. But this experiment demonstrates a superior outcome with fewer PV reconnections both in animals and probably in patients as well based on the use of some contact or tissue proximity information, because it's based on impedance. Doing a posterior wall lesion with this FARAPULSE technology is pretty easy, simple, and super efficient. I have had no failure in blocking that line. Mitral isthmus is more difficult. It works, but it's good to combine with Marshall vein ablation, in my opinion, in most cases. Finally, we'll get some randomized studies comparing PFA to thermal energies, giving us some better idea of the potential superiority of this energy of thermal. The last pitfall, which may not be one, is the impact on ganglionated plexi. This is a slide from Vivek Reddy, who published that study, where he reported only 8% of durable GP ablation. Is it a problem? I don't think so, because the results at one year are really good. But that's a word of caution possibly as well. Thank you.

The transcripts have been edited for clarity and length.