The lead is coming to you live from Heart Rhythm Sessions in San Diego. Just hours ago, the VOLT-AF-IDE trial was released as a late breaker and simultaneously published in Heart Rhythm Journal. With me today are Drs. Chris Chung, Professor of Medicine, University of Toronto, and Dr. Ed Gersenfeld, Director of EP, UCSF. Gentlemen, thank you. Thank you. Thank you. Great to be here, Mike. Chris, tell us about this one of many, this armada of pulse field catheters that are coming. Tell us about the design and the rationale. Yes. Absolutely. And thanks again for the opportunity to join for this discussion. It's exciting to see all these new types of technologies and catheters come into the space. And it's important to see good high-quality studies to validate their effectiveness and also their safety. So the VOLT system is another catheter that's coming onto the space by Abbott, and we're really excited to see these early results. And so for some perspective for the audience, the balloon-type inflatable catheter is something that has been entertained. The VOLT CE mark study was already presented, the early acute results. And this one is the VOLT-IDE study. So it's a large perspective, single-arm study that's evaluating a balloon-inflatable PFA catheter to achieve pulmonary vein isolation only. So this is a PBI-only type of catheter with a balloon-inflatable deployment. This study took place at 38 sites with 392 patients, with approximately a 50-50 split between persistent and paroxysmal atrial fibrillation patients. And the results that we saw today at the high-impact science presentation were the acute findings in terms of acute pulmonary vein isolation, first-pass isolation, as well as safety results from the VOLT-IDE study. So without further ado, I'll jump into some of these results that we saw. We know that the population that studied is quite standard, again, 50% paroxysmal and 50% persistent. I think they had 165 in the paroxysmal and 155 in the persistent, so 50-50 split. The procedural times in this study were often similar to what we see. And again, this is knowing that this is an early first implementation in this VOLT-IDE study. So the procedure time was 100 minutes on average across the groups, fluoroscopy time was 13 minutes, the left atrial dwell time was 43 minutes, the ablation time that they called the transparent ablation time was 33 minutes, and the total number of PF applications was 17 to 18 in total. And so their protocol is to deliver a maximum of eight applications with this balloon delivery per vein, but on average, it's usually typically around two to four, and so the total number of deliveries was 17 to 18, with the average was 17.6 in the paroxysmal a-fib arm and 19.4 in the persistent a-fib arm. And to remind everyone, this is again a PVI-only study. Now the acute results, so this is the acute effectiveness results they reported, are 98.2%, in this case, PV isolation in the paroxysmal a-fib arm and 99.4% isolation of the pulmonary veins in the persistent a-fib arm with a safety event rate of 1.9%. So I just want to take a second to dive into a little bit about the safety of this catheter because we think we always need to know what the safety profile of these new catheters are. They did report a 1.9% safety endpoint, and these predominantly occurred in those with persistent a-fib, 3.9% in persistent, 0% in paroxysmal. This included two events of cardiac tamponade and perforation, one episode of pericarditis, one episode of stroke, one vascular access complication, and one prolonged hospitalization. Can I stop you there, Chris, and ask Dr. Gersen-Meld, two tamponades, one stroke, in 350 patients, is that high? Is it okay? Is it acceptable? Yeah, it's an important question, but I think it is in line with most of the other PFA trials we've seen. When you look at most of the RF trials, you're looking at major complication rates generally around 4% to 5%. So I think, you know, obviously we'd love it to be less than 1%, but I think if you look at ADVENT, PulseElect, you're seeing complications in the 1% to 2% range. I think strokes or embolic events are obviously something we're very cognizant about with any newer technology. So 1 in 300, you know, you're talking about half a percent or so, I think is in line with what you're seeing. I think in this case, it was the day after the procedure, persistent AF. So yeah, certainly none of those, and I'd be curious, you know, it's hard to tell from the paper, the tamponades, exactly what the mechanism was, was it in the transeptal? Or was it the delivery or the catheter? Correct. I think it was the prior or something related to that. But I think the numbers in general, to me, are in line with what we've seen is expected from other studies. What else, Chris? So they also did a lot of safety analysis, looking at potential hemolysis. So I think that one of the advantages of these balloon inflatable catheters is the fact that the energy is directed towards the pulmonary veins and less towards the blood pool, because you have the balloon that's inflated there. So they did look at hemolysis outcomes. So they looked at serofilirubin levels, haptoglobin levels, LDH levels, they saw a small increase in the LDH level. We know that that's not a very specific marker for hemolysis. And hemoglobin levels, which are overall unchanged. So overall, the findings from there, and sorry, adrenal function as well. So overall, the findings from there is that there's no significant hemolysis that takes place from this balloon. Yeah, just looking at when I looked at the figures, there was no overall change in creatinine, but there was one patient where it seemed to be, look at figure two, it jumped from two to four. So I'm not sure what happened with that one case. But that seems to be one of the potential advantages of this balloon design. One is that the balloon, you know, some protections that you don't have as much hemolysis, and also you can turn off some of the electrodes. So if you don't feel some electrodes or a contact blading in other areas, which they didn't do in this case, potentially that also could reduce the hemolysis. We should mention this is an industry-funded trial. This is an Abbott product. How important do you think force sensing, these electrodes have now a measure of contact. Is that, does that account for the good results of the isolation? I think so. I think what we've learned, you know, we hoped sort of PFA was so magical, you can kind of wave a catheter by, but it turns out no contact, no lesion. So I think it is important to get contact. There's obviously controversy about whether contact force, you know, will make a difference to some data that it does. I think with a focal catheter, you may see a difference because you're embedding just deeper in the tissue. But I think in terms of the electric field, as long as you have reasonable contact, it shouldn't make a big difference how much contact you have. So I think it is important to know that you have contact, but I'm not sure that, you know, the traditional sort of level of force matters as much for pulse field ablation. So conclusions, limitations, what, what, what did you like about this? What did you not like? Yeah, absolutely. I think this is a great study. I think it shows that these balloon inflatable catheters to deliver PFA is a effective method to achieve isolation in these veins. And certainly this goes on the coattails of the Bolt CE mark study as well that showed the similar results. So it's exciting to see that we have an increase in our armamentarium to deliver a PVI and PVI alone. So that's exciting. There are, of course, a lot of still unanswered questions. We don't have the long-term follow-up from this Bolt IDE study. And I'll highlight that at the same high impact session, the Bolt CE mark study was the 12 month results were presented as well, and those are very optimistic. So those look good, but we don't have the 12 month follow-up for this IDE study. And so that's still pending, presumably a year from now at next HRS. So that's certainly one limitation. I think, of course, the elephant in the room is what are we doing with these PVI only strategies and where, where does something like this fall with our increasing armamentarium of devices that do PVI alone, but also can also reach other areas? How do we approach this device and what is the niche for this type of device when we have additional tools that may allow us to go beyond the veins? I wondered about their measure and every catheter's measure of success or efficacy, 90, high 90s, but their efficacy is acute isolation of the pulmonary veins. Is that really fixing the atrial fibrillation for the patient? Should we be looking at other things? And is it fair to only check for entrance block and not give adenosine? I mean, I guess they did wait 20 minutes. Yeah. I mean, I think that obviously is the limitation. We know with PulseField, you know, even beyond RF, you get effects that can be reversible. So I would say these, you know, it's reassuring certainly that they have 99% isolation. You know, these days, if you can't isolate pulmonary veins acutely, you're probably in trouble. But I, you know, would like to see, you know, I think with any newer approach, certainly three month remapping data in everyone, just because we don't know what the chronic isolation rate is. And then obviously the ultimate is, you know, the lack yet of any long-term outcome data. So I would say it's the minimal data we need to show that it's working acutely and that it's safe. But certainly one of the limitations is lack of clinical outcome data. Yeah. I guess I was excited to see the, so the same high impact session, Pratchett-Sanders also presented the bold CE mark study. And so we did give an example of one patient that had a redo map. And so, because of course we don't know how much of the acute PFA lesion will regress or change in follow-up. So the one example that he showed, it appeared to show that there was not much regression or not much change in the post, in the map when they went back to do a remap. So that perhaps is optimistic, but that of course is just one example. And so we probably need to systematically evaluate, is there going to be regression beyond after the initial patient. And do you know, Chris, do they plan, you know, obviously with any new technology, we'd like to look at other risks. They talked about no pulmonary vein stenosis, but I didn't see whether they were planning any sort of imaging or in terms of, you know, we're all cognizant of asymptomatic cerebral events. I don't know if they're planning MR or heart imaging in three months and follow-up, you know, if that's part of the study. Not that I'm aware of for this study, but I think that highlights the important point that we should be requesting that for all, so pushing for that for all studies, that we should be more rigorously evaluated for these asymptomatic events or pulmonary vein stenosis outcomes. We should proactively be looking for that because, you know, with the slew of technology available, it's kind of up to us to make sure that they're up to par. I think so. We've seen, you know, again, some of these catheters, depending on the waveform, which is always, you know, a bit of a missed black box, you know, there may be some thermal effects and, you know, just being aware if there are any of these risk factors, even in the subset of patients, you know, is important. We have forgotten about the simple things to check for, like pulmonary vein stenosis, coronary lesions, it came up today in one of the late breakers, late coronary injury. Now we have all of these catheters. I wanted to get both of your opinions on your dream catheter, your dream PFA catheter and what we're restricted for atrial fibrillation. Can I bring up, I was going to bring up one other potential advantage that was sort of a, at least in the paper, a small part of this, which may have a role, and that is obviously, I think all of us have gone to, you know, we hope this could be done in conscious sedation patients. We've all gone to general anesthesia and paralytics. They did have a subset of 20 patients who just had sedation without propofol. And again, I guess one hope potentially with the balloon is, is there less musculoskeletal, you know, stimulation and maybe just because of stability in the pulmonary vein, you know, I think it would certainly be nice if we could do this without having to put patients under paralytics and general anesthesia, you know, whether that'll pan out, I think, you know, we'll have to see, but it's a potential interesting aspect. It's an important point of this trial that I hadn't seen in others and yeah, would, would increase safety, we think. I think so. And, and, and, and efficiency and potentially safety. Yeah. In terms of the ideal catheter, you know, I think one is, you know, as we've all dealt from an administrative standpoint with the additional costs of these catheters, I'd certainly like a catheter that can both map and ablate with a single catheter. So something where you can get your left atrial geometry and a voltage map ablate and then get a post voltage map without using, you know, several expensive catheters. I think we do want something that's, that's versatile that, you know, can be conformable both to do pulmonary vein isolation, but also other areas, you know, of ablation that's needed, including you know, linear ablation, annual lines, things like that. So that's kind of my ideal, like some conformable multi-electrode, you know, catheter that could map in high resolution and also ablate and ablate in the areas outside of the pulmonary veins as well as the pulmonary veins safely, that would be my ideal. And I completely agree. I think we want, that's what we wanted. The only additional thing I would add is that we want something to be very safe. We need to hold it to a very high standard of safety. We heard a very enthusiastic debate about should we ablate asymptomatically during ACRS? And so I think, you know, as we see these technology become more available and as the bar becomes lower, because we can deliver these ablations quickly, effectively, we need to make sure we can do them safely too. And so some of that might be looking for, like you said, TB stenosis or asymptomatic events, but making sure that we have a very high bar for safety as well, because we are going to be doing this in maybe more and more healthy patients, maybe less symptomatic patients as well. And we want to make sure that we don't cause any harm. As far as evidence, so far we have company, single arm, you know, non-randomized prospective trials evaluating acute effects. What would you like to see in terms of high quality data? Randomized trials with RF or head-to-head trials, catheter to catheter? Well, there was obviously ADVENT, which was a randomized trial between RF and one company's PFA. ADVENT aside. Yeah. You know, I think the challenge, I would love, you know, every catheter to every study, obviously to be a randomized trial, obviously from a cost standpoint, it's much more costly. And the question is, you know, we're discussing this with FDA and other meetings. I mean, does every study to validate a catheter need to be a randomized trial? Probably not just from a cost standpoint. So you know, I think we certainly have data. I think we're going to, we're just not going to see another man randomized trial with RF since ADVENT. But I think, you know, again, that's a good question. So are they going to do randomized trials against other competing companies' catheters? I think it's, you know, unless we do it as a field, right, the companies aren't going to necessarily do that. So we would have to set it up. But I think we have to see how, you know, obviously there's, as Chris mentioned, there's so many just different companies' catheters in the space. I think we have to see how things settle out. And then, you know, ultimately when we have a few products that are commonly used, it would be nice to do a head-to-head trial. But for now, I think most of these studies are going to be single-arm trials with, you know, with standards to try and meet the endpoints that we've seen. Chris, last thoughts? Exciting. Very, very exciting findings from the VOLT IDE study. I think we want to see the long-term results, but it's all very positive and it's great to see this excitement and innovation in the EP space. We've been talking about the VOLT AF IDE trial. Thank you, Dr. Ed Gersenfeld, Dr. Chris Chung, for HRS Digital Education. You've been watching The Lead. I'm Mike Lloyd.

VOLT-AF-IDE trial

catheter technology

atrial fibrillation

pulse field ablation

electrophysiology