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EP LAB DIGEST. 2026;26(6):5.

Edited by Jodie Elrod

Professor Damijan Miklavčič joins Bradley Knight, MD, to discuss the key takeaways from the 2026 HRS/EHRA Scientific Statement on pulsed field ablation (PFA) for cardiac arrhythmias, including the technology’s rapid evolution, safety profile, and expanding clinical applications. The interview explores how the writing committee navigated differing opinions while developing practical guidance in a fast-moving field where new PFA platforms are entering the market frequently. Professor Miklavčič also addresses the major electrical engineering challenges facing next-generation PFA systems, such as energy delivery precision, tissue selectivity, and lesion durability, while offering his perspective on whether PFA would be his preferred approach if he personally required atrial fibrillation ablation.

Brad Knight, MD: Hi, I'm Brad Knight, editor of EP Lab Digest. I'm here at the annual Heart Rhythm Society meeting in Chicago. Dr Miklavčič is here to share with us the content and some of the controversies surrounding the Heart Rhythm Society’s (HRS) new document on pulsed field ablation (PFA) for cardiac arrhythmias such as atrial fibrillation (AF).

Damijan Miklavčič, DSc: Thank you. Yes, today we presented on the HRS Scientific Statement on PFA. Very briefly, we provide the basics, workflow, and evidence, and we discussed the adverse events, even those that are less debated right now. We also looked into the potential to ablate other cardiac arrhythmias other than AF.

Brad Knight, MD: It's an incredibly important topic right now. I haven't performed an ablation without PFA since a year and a half ago. It has completely taken over, and there is a lot of interest in safety and efficacy, but it's a constantly evolving topic. Tell me how the consensus document handled the issue of new devices being available within months. It's changing at a very rapid pace.

Damijan Miklavčič, DSc: That was a challenge, I have to agree. We debated a little about that, but the final conclusion was that we're going to put in everything we know because we didn't want to focus on what is approved and what is not approved. We wanted to include everything. Plus, we did not know whether we had the right information. So we reached out to all the companies and provided them with an Excel sheet to fill out.

Brad Knight, MD: That was a good way to delegate it.

Damijan Miklavčič, DSc: It's not only that. We filled in whatever we thought we knew, and they had the possibility to check, correct, and provide more information. Some actually did provide more, some provided less. 

Brad Knight, MD: There's a lot of topics to discuss, but in a document like this, people are often looking for class recommendations. Is PFA given a Class I recommendation for AF ablation?

Damijan Miklavčič, DSc: We couldn't use the standard Class I, II, or III recommendations. We did go through a number of questions and provided recommendations. For topics where we did not agree, we wanted to be fully transparent. So we provided statements like "11 out of 11 members agreed." If there was less than unity, then we said "8 out of 11," and we also provided comments on what aspects we did not agree upon. I think that is important because we can’t agree on everything at this stage.

Brad Knight, MD: You didn’t force yourself into some structure that required you to share everything you had, such as “80% of us,” for example.

Damijan Miklavčič, DSc: Exactly. We wanted to be transparent. We also wanted to let people know that at this stage we don't have definitive answers.

Brad Knight, MD: The systems that are currently available and under investigation are so different from each other. It's not like a cryoballoon versus a cryoballoon—these things are vastly different. Can you talk about the differences—dual energy, form factors, pulse duration, etc?

Damijan Miklavčič, DSc: These are all very important things. So we grouped the different technologies—focal catheters, large-footprint devices, and single-shot devices. Of course, there are differences. A couple of things are becoming obvious. There's a need for establishing contact to maximize lesion depth. That means companies are introducing some sort of measure of impedance, temperature, or contact force measurement. This is extremely important.

Brad Knight, MD: We're learning more.

Damijan Miklavčič, DSc: We're learning more. The other thing is that there is a lot of discussion about the waveform. I've been working in the field of electroporation for more than 30 years, and I can guarantee you that you can electroporate every cell with enough energy.

Brad Knight, MD: Specificity is relative.

Damijan Miklavčič, DSc: Yes. Also, whether we're talking about nanoseconds or milliseconds, earlier today we saw a late-breaker session on nanopulse technology. It's not superior, and to be honest, it's sub-microsecond, not really nanoseconds. It's 300 nanoseconds, which is close to most of the systems.

Brad Knight, MD: Nanoseconds in plural.

Damijan Miklavčič, DSc: Yes. Most devices right now are in the microsecond range, with some in the sub-microsecond range. So there's not a big difference.

Brad Knight, MD: That's interesting. If you were a regulatory agency like the FDA and I came to you with a new device, what would you ask me to prove? What should the study design be? Should it be randomized from the very beginning? What's the standard now in PFA, and what endpoints are you looking for? For example, cerebral emboli—what are you concerned about as a regulatory body?

Damijan Miklavčič, DSc: The first question I would ask is: What is the thermal footprint? I think that was the big miss from the beginning because PFA was introduced as non-thermal and selective.

Brad Knight, MD: How do you show that? How do you prove that?

Damijan Miklavčič, DSc: There are several ways. You can do bench testing, even in saline, and observe bubbles. The second is looking at hemolysis. That can also be done in a benchtop model. So those are the 2 things I would ask first. Now, when it comes to clinical trials, I would require mandatory remapping at 2 or 3 months. Because when looking at clinical endpoints, what we see is that PFA is not necessarily superior to radiofrequency in terms of efficacy. That's largely because we're not talking about pulmonary vein isolation (PVI) alone. If we achieve 100% PVI, then we've effectively cured the AF. I think we're looking at a tool that will allow us to be 100% capable of performing durable PVI.

Brad Knight, MD: Let me elaborate on that because it's not easy to do, especially in some countries, to mandate remapping. You can justify it in some patients because if you find reconnection and reablate it, outcomes may improve. Do you think we'll develop better noninvasive imaging tools that could become a surrogate for durability?

Damijan Miklavčič, DSc: You asked me what I would do. Whether it's feasible is another matter. We need to separate the 2 things. One is being efficient at ablating and creating predictable, durable, transmural lesions. The second is understanding why patients recur. Quite often now, when patients come back, all the PVs remain isolated. That means more needs to be done. That's the disease component, and EPs need to work on that.

Brad Knight, MD: With your regulator hat on, what would you require? Let's take silent cerebral emboli. Would you require all patients, or a subset, to have pre- and post-procedure brain MRIs?

Damijan Miklavčič, DSc: For me, the first priority is reducing the thermal footprint. My firm belief is that many issues stem from thermal effects. We are delivering high-voltage pulses and relatively high currents into the blood pool, not just the myocardium. Blood is actually more conductive than tissue. There is current flowing through the blood. Devices like balloons in baskets may provide some shielding.

Brad Knight, MD: If I could prove that I don't create any significant thermal footprint, would MRI requirements still be necessary?

Damijan Miklavčič, DSc: That's where I would start. Because when we talk about the thermal footprint, I need to emphasize one thing. Blood is full of proteins, and temperatures of 40–50 degrees Celsius are sufficient to begin unfolding proteins. Denaturation can occur at relatively low temperatures. We do see temperatures exceeding 40 degrees.

Brad Knight, MD: What about coronary artery injury? Would you require coronary computed tomography scans? Should we be looking at coronary arteries more carefully?

Damijan Miklavčič, DSc: This is important and was largely missed in the first trials because we didn't fully understand it. We need to understand that even beyond the ablation area, we are exciting nerves and muscles. Smooth muscle in coronary arteries can contract. It has been shown in multiple studies, including preclinical work, that delivering pulses near the coronaries can cause coronary narrowing. Whether that translates into clinically significant spasm is another question. So I think we need a better understanding of what PFA does.

Brad Knight, MD: Not just spasm, but potentially long-term fibrosis and other effects.

Damijan Miklavčič, DSc: That's one aspect. We also need to recognize that patients are not all the same. Some are predisposed to certain outcomes because of comorbidities and underlying disease. We need to learn more about that. In this respect, registries are important because, if well designed, they can help us identify subpopulations that may be more susceptible to specific complications. The other concern is that when we ablate near coronary arteries and ablate smooth muscles in the coronaries, it could potentially result in neointimal hyperplasia and narrowing of the vessel.

Brad Knight, MD: You've been doing this for a long time. There are a lot of interesting questions. I could probably talk to you all day. But before we finish, is there anything else in the document that you think is important to highlight?

Damijan Miklavčič, DSc: Yes. I think what we tried to provide is a balanced and critical view. We spent a great deal of time discussing these issues. Different subgroups developed proposals, and then the entire group reviewed and refined the content together. It was an incredibly well-directed process. In that respect, I have to acknowledge Atul Verma as chair and Mélèze Hocini as co-chair. They did tremendous work. Melanie Gunawardene also played a major role as liaison officer with the HRS document process.

Brad Knight, MD: You didn't just have a difficult topic—you also had a group of electrophysiologists to manage.

Damijan Miklavčič, DSc: Well, for me it was a bit of a surprise that I was nominated, because I'm an electrical engineer and a scientist. I think this may be the first time that someone who is not an electrophysiologist has been part of this type of document.

Brad Knight, MD: I'm glad you were part of it. Thank you for your time.

Damijan Miklavčič, DSc: Thank you.

The transcripts have been edited for clarity and length.