"Tina Baykaner: Welcome to the Arrhythmia Academy discussion. We are live at the Boston AF Symposium 2026, recording on-site. We'll be talking about whether PFA will redefine AF ablation strategies in 2026. My name is Tina Baykaner, I'm a cardiac electrophysiologist at Stanford University, and I'm joined by Melanie. Would you introduce yourself?
Melanie Gunawardene: Of course — and thank you for having me here. I'm Melanie Gunawardene from CCB in Frankfurt. I'm a cardiac electrophysiologist from Germany and I've been really involved in the journey of PFA, so I'm very happy to talk about this. Starting off the discussion, Tina — I'd be curious to hear your thoughts on the current landscape and challenges in AF ablation.
Tina Baykaner: We're both happy and worried about AF ablation at the same time. On one side, outcomes are great — especially for a subset of patients, particularly those with paroxysmal atrial fibrillation. But on the other hand, we worry about patients with more persistent AF who've had repeated ablations. The substrate has been treated where we want it treated, yet they continue to have AF, so outcomes in that group remain poor and we need to do better — whether through ablation or through a deeper understanding of AFib itself.
The other part of the problem is that we still don't fully understand atrial fibrillation mechanisms. We've struggled to understand triggers, struggled to understand drivers, and struggled to identify how to target those strategies even when we've made some headway. So in 2026, we're still in a challenging place — outcomes aren't where we want them and our mechanistic understanding of AFib has a long way to go.
Melanie Gunawardene: That's a very valid point — and the gaps in mechanistic understanding are probably contributing to the ceiling we keep hitting on outcomes. When we look at Kaplan-Meier curves over recent years, we average around 80% for paroxysmal AF and 50–60% for persistent AF. With continuous monitoring, those numbers go even lower. And I think thermal ablation has also historically limited our acute procedural success, especially once we move beyond the pulmonary veins.
We're settled on PVI as a good strategy for most paroxysmal AF patients — the pulmonary veins are the trigger and we know how to address them. But in persistent AF, where there's more substrate, atrial remodelling and scarring, the biophysics of thermal ablation work against us. With radiofrequency, it's hard to overcome scarred tissue because the resistive loading is already low and the energy doesn't penetrate effectively. We saw this in the CAPLA study, where posterior wall isolation wasn't even achieved in all patients in the intervention arm. And going further back, the success of linear ablation with radiofrequency in STAR AF2 was extremely poor. So we were never really able to properly test a substrate ablation strategy.
Tina Baykaner: Exactly — and part of that is catheter design too. Single-tip ablation makes it genuinely difficult to create lines that are durable and continuous. It's a combination of the catheter and the energy source. But now we have two separate problems: understanding AF and then actually treating it effectively. You've been deeply focused on the mechanistic side — can you tell us more about those challenges?
Melanie Gunawardene: It follows exactly what we've been discussing. We've made good attempts at mapping atrial fibrillation and fibrillatory conduction in persistent AF patients to identify and target drivers — but we've always been limited by the same struggles. Many studies have set out to map and then target specific areas, but we're always challenged by whether we were truly able to ablate what we identified. In the randomized trials done with radiofrequency, could we really trust the outcomes when our ablation catheters may not have been effective enough at the sites where drivers were found? Should we repeat those studies with more effective catheters and look at the outcomes again?
So — what do you think PFA brings to the table in 2026? Which trials should be redone? And what are you expecting in terms of lesion durability, outcomes, and safety?
Tina Baykaner: Those are great questions and I don't have all the answers yet — the studies are still missing. But what PFA has genuinely brought to the field is that it has been the most rapidly adopted technology ever seen in medtech. We now have a tool that applies ultra-rapid electrical fields to the myocardium with preferential myocardial ablation — we believe we can create more homogeneous, tissue-specific lesions, while also sparing adjacent structures like the oesophagus and the phrenic nerve.
Has this already changed ablation strategies? Yes. The faster procedures, larger footprint catheters and short learning curve mean operators are genuinely able to ablate more if they choose to. We're already seeing a trend towards more posterior wall isolation in both paroxysmal and persistent AF. But do we have the data to say this is definitively the best approach — that just because we can do it, we should? I think those trials are still missing, which is precisely why it's so important to do these studies now, especially given how rapidly PFA is being adopted in clinical practice.
On lesion durability: we were very excited at the beginning — we thought we could block every line and isolate every vein. We're learning that's not entirely true. But the field is evolving rapidly. New catheters are coming, dual-energy combinations of PFA and RF offer the prospect of deeper lesions, and some new waveforms can reach depths of up to 20 millimetres. We are technically getting there. These tools aren't all in clinical routine yet, but they will be soon. Now is the right time to redo those mechanistic studies and revisit the strategic questions.
Melanie Gunawardene: I agree completely. PFA is clearly safer — we can say that with confidence. Whether outcomes are superior is less clear. Studies comparing PVI with thermal energy versus PFA haven't shown superiority, and PVI-plus strategies with this technology are still under evaluation in randomised trials. Which brings me to mapping — does PFA change our mechanistic understanding of AF-based ablation? The OPTIMIZED trial, which is already enrolling, will to my knowledge be the first randomised clinical trial using pulsed field energy to target AF drivers. That should give us the first PFA-based mapping RCT data over the next year or two.
Tina Baykaner: I think it has a real role. We've always felt we could map AF but couldn't fully target and treat what we found. This will be the definitive test of whether we're mapping correctly — and if we truly believe our lesions are durable and effective, whether that actually translates to a difference in clinical outcomes. I think we'll be able to trust the trial results a lot more.
Melanie Gunawardene: And that raises the next challenge — even if we can now ablate these sources, how exactly do we do it? If you identify a source in the middle of the left atrial posterior wall, do you deliver a focal lesion? Do you ablate the whole posterior wall? These are the exciting questions we are now actually in a position to answer — as opposed to worrying about whether thermal ablation of the posterior wall was even achievable in the first place.
Tina Baykaner: Yes — and we have to remember that while the overall safety profile of PFA is great, it comes with energy-specific safety considerations that are genuinely new. Every time we ablate near adjacent structures, we carry a risk of coronary spasm — and we know these can occasionally occur in a delayed fashion. We also know that extensive ablation can cause haemolysis, which can affect kidney function. Now that we have this powerful tool, we need to learn how to titrate it and use it safely.
This is where integrating mechanistic information into the procedure becomes really valuable — not just for improving outcomes, but for protecting patients from harm. Tissue preservation still matters. Even scarred, diseased atrial tissue still has a function, and applying everything we can simply because we can is probably not the most elegant path forward.
Melanie Gunawardene: Well said. That wraps up our discussion here at the AFib Symposium 2026 — thank you so much, Tina.
Tina Baykaner: Thank you.”