Welcome to another episode of The Lead. Today we're recording actually in person at Sydney at the APHRS in Australia and I'm Mike Lloyd. Today we're going to review the article Late Breaker Bipolar Radiofrequency Ablation of Refractory Ventricular Arrhythmias Results from a Multi-Center Network. First author is Pyotr Futima and our discussants today are Wendy Zou from University of Colorado and Jason Jacobson from Westchester New York Medical College. Wendy, Jason, welcome and thank you. I struggle with the term bipolar unipolar everything has a bipolar so Wendy, describe what bipolar ablation really means practically for the EP dummy. There are no dummies in EP but I think that that's a great question and it's confusing because we use those terms both with respect to ablation as well as with mapping and they kind of mean different things. For standard ablation that's a unipolar circuit so that means there's an elective active electrode the completion of the circuit is to connect it to an inactive or passive ground patch typically. That patch is placed in close enough proximity such that the circuit can be completed through the tissue which you know the tissue is comprised of the myocardium that that is being ablated that the circuit is going through as well as all the other intervening tissue. That circuit will create actually heating at the patch level too if especially not all of the parts of the patch are adherent to the skin. The reason that it's a large surface area is to avoid any skin burns you know so I don't know if you've encountered the situation where the patching is not great and not complete and then you know the patient will have a skin burn afterwards and it's because there is heating at the site of that ground patch. So bipolar ablation is this concept where first of all we know that lesion depths are limited in terms of well multiple factors but when we're talking about optimal conditions RF ablation lesions really in the delivered in that unipolar format can go about the most is about seven millimeters of depth. Now you could understand or conceive where you have a mid myocardial source within thick myocardium that is far deeper than just seven millimeters or five millimeters. So the construct of bipolar ablation is you actually replace that ground patch with another catheter another electrode and you actually place it in close enough proximity typically within 15 millimeters actually 15 to 20 is kind of the sweet spot for bipolar ablation. Bring it in close enough proximity connect it to the circuit. Now the connecting it to the circuit part is what involves a trick and that's what's very unique about this paper that is going to be presented but in doing so then you create the ability for heating to occur from both catheters simultaneously even though the active catheter is really the one that's delivering the electrical current to the tissue. The simultaneous heating in close enough proximity actually facilitates this feedback mechanism where you get an antenna effect and you get more likelihood of transmural lesions. So that's a bipolar ablation is. So that second return electrode is actually another ablation catheter we're driving ablation more focally and Jason tell us what this trial set out to do and how and if they did it. Sure so this was a retrospective study from a multi-center registry from 16 centers in Europe and basically these were consecutive patients undergoing bipolar ablation between March 21 and August 24. These were patients that had PVC's or monomorphic VT refractory to at least one standard unipolar radiofrequency ablation attempt. They used all manner of different mapping systems and different catheters for the active electrode and what they called the return electrode. So these could be two irrigated tip catheters or also could be an eight millimeter catheter so a little bit of a mixed bag there. Interestingly as Wendy already alluded to they used a essentially a commercial adapter to allow for that second ablation catheter to be the return electrode to plug that into the reference patch port on whichever mapping system they use. And this was the adapter that the authors that actually created? Correct it's named after the lead author on this paper and it's made by Core System Poland some company that you know I don't believe is available in the United States does have CE mark. Well that sure beats splicing. I would agree. It often makes me a little nervous with that but you know it's been done enough and has been shown safe enough that you know I think the way that we do it in the U.S. is acceptable. But they did use this dedicated adapter that is commercially available. So for the bipolar RF they started at you know a lower wattage and titrated up based on you know a goal impedance drop of 10%. What they looked at was for PVCs they wanted to see acute elimination and for VT non-inducibility and they looked at you know major complications and also at least short-term efficacy over a number of months. They followed up the PVC patients with 24 to 72 hour holters or two-week event monitors at one to three months and in patients with you know ventricular tachycardia devices they followed the the devices. So the results were certainly I think interesting and and helpful because it was a large you know a fairly large number of patients as far as the you know experience that's been published thus far. 91 patients, 94 procedures. Patients on average were 62 years of age you know three-quarters were male and about one and a half prior attempts at ablation. 56 of these patients were PVC ablation, 20 were monomorphic VT and another 13 were electrical storm and a couple of patients were PVC induced VF. As could be expected the patients with VT had low rejection fractions, more coronary disease and history of PCI and more likely to be on beta blockers and amiodarone. So they looked at these patients some of which had combined unipolar and bipolar ablation during that index procedure. That was about 79 procedures. For the rest of the patients they only had bipolar ablation because they'd already failed a unipolar ablation attempt. And basically what they found was that they had a pretty good success in these patients that previously had failed. So some of these patients you know had different vectors of their bipole depending on what exactly they had ablated. So what were the targets? In about 74% the LV summit was a target and they could either be you know LVOT to a coronary vein, left the pulmonic cusp to the LVOT or RVOT to LVOT depending on where exactly they were trying to target. But about you know 16% of those patients they targeted multiple vectors. Interventricular septum was a target in about 21 patients and one patient had papillary muscle PVC ablated. And one patient had two separate areas, the summit and the interventricular septum. Some of these patients underwent the typical sub xiphoid epicardial access only about 9%. So a lot of the quote-unquote epicardial electrode placement for the one of the catheters was through a coronary vein. So acute success was about 74% with a significant decrease in about 11% of patients mostly PVCs and 15% had no effect. As far as repeat bipolar ablation, three patients did require that and some patients went on to have other modalities such as alcohol ablation or SBRT, one of each. Not a lot of major complications, just 3% had major complications which included LAD occlusion, one was an anticipated AV block event in a patient who already had CRT, and one was just an access complication that was managed conservatively. I want to stop there and ask about the LAD occlusion. What were the, Wendy maybe you could talk about that. I mean sure it's a pretty small complication rate but that's a big deal. Yeah and I think that's an important question to call out. You know we can do some pretty amazing and innovative things but we still have to take safety into consideration. I suspect that this was a case in which energy was delivered with at least one of the electrodes within one of the coronary sinus or great cardiac vein branches, which is you know as you could conceive in close enough proximity to a major arterial vessel that you could cause injury. Even though the setup is such that you know at least theoretically you're driving current between these two electrodes, there can be dispersive effects outside of that direct path that could cause harm. And so that most likely is the reason for that one. I guess the success rate of this trial, 74% Jason, I mean do they, does that seem like a good number to you? In light of the fact that most of these people had already, if not all, had already failed prior ablations? Yeah I think that is significant and you know you always have to take these things you know with a little bit of a grain of salt you know because it's it's hard to know especially with so many patients that underwent unipolar and then bipolar. Is it bipolar alone that was successful? Was the unipolar preconditioning the area? Does it matter? The point is that they did achieve success in patients that were otherwise difficult and you know unresponsive to prior ablation. So I do think that is important and we do describe this for a number of different types of modalities including alcohol ablation and radiotherapy in patients that have previously failed. So I think it is a fair end point. I also, I like to think of you know management of these complex ventricular arrhythmias in particular kind of like a labor of love. It involves a lot of labor and so and I think that ultimately patients do benefit from the effort. It's just, it's hard. So if you had to criticize this paper, Wendy, or if you had to do it over what would you have changed about the trial design or other things, limitations? No that's great. I mean I think first of all I want to commend Dr. Futima as well as the team that you know kind of developed this cable. The splicing that you're describing, that's an understatement for like the actual effort involved in the innovation and kind of creating these cables. Let's let's be honest, that's MacGyvering it. Totally, absolutely and my personal MacGyver is Will Sauer and he the number of cables he's had to construct and send out to people across the world. He's not the only one but I mean that's a pretty resource-intensive you know process. So the fact that they created a cable that could kind of increase access not just to providers care you know ablationists but also that could integrate multiple different ablation systems together that's very unique and special. The other step I think that is important that they took is they made a registry out of it. You know they applied for you know kind of support from the European Heart Rhythm Association and got it which is terrifically commendable because this is the more that we talk about making bigger deeper lesions the more that we have to worry about monitoring it and that's what they're doing and so I think for those reasons this was a really tremendous effort. There are things about it you know just along the lines of safety that you know are things to call out. They in this study didn't see very many complications which is great that the follow-up interval was relatively short you know most of the patients were followed for a seven to eight month period and when you get out to longer follow-up than that it like falls off really to like one or two patients you know. The other relative limitation again with the mind of you know just being very circumspect about doing too much with what we can without completely considering safety in this is that the majority of the patients were PVC you know patients. Usually when we talk about doing this and the other publications that have looked at this in you know collections of patients have really exclusively been in VT patients. You think those are kind of the highest risk where you would be you would have a lower threshold to do something more dramatic. You know the PVC group also probably did better than the VT group. You know unclear mechanisms for that and you know as acknowledged by the author it's they were a pretty heterogeneous population. And then finally just along the the line of complications you know there was an important publication in Heart Rhythm actually this year of a case series of bipolar ablation patients. Now granted these were recurrent VT ablations, multiple bipolar attempts, multiple adjunctive techniques and VSDs formed in these patients and it wasn't in that seven to eight month window that these patients have been followed thus far. It was you know out to even as far as a couple of years. Human dynamically significant VSDs that required surgical repair. So it's it's not without potential risk but I would say that the the effort to try to help patients that otherwise would have no other option has to be recognized. And it's one thing to tweet a neat case on a bipolar it's a whole nother to organize and rigorously follow a registry. Yes. Yeah I get that. Jason what what patient scenario do you think about bipolar ablation in? Generally I think about it in patients that do have usually intraceptal substrate or intramural substrate somewhere that I haven't been successful with the standard unipolar RF. I haven't been considering it up front unless I really am concerned about intramural substrate. And I do talk to patients about it up front if you know especially patients with cardiomyopathy and in shocks and a fair amount of VT. I will consider it up front if I'm unsuccessful at what I need to do with standard RF. So that's that's generally the patient population right now. I think we need more you know long-term data as Wendy mentioned. They do point out in this paper that there were no VSDs but to your point you know follow-up was about seven plus or minus eight months. So not a huge amount of follow-up. But you know there's so many new techniques available to us that you know you can choose from. Is it bipolar? Is it alcohol? Is it radio ablation? And you know that's really where you start to wonder okay what's the best approach for which patient? And I don't think we really have that answer yet. Wendy is this practice changing for you? You know to be honest no. Not in my practice but I kind of have access to the cables that we were referring to where we could create this bipolar construct. I would say that it is probably practice altering for the global community who may not have had access to something like this. Certainly if you look at the survey from the EHRA about ablation centers within Europe and you know what tools they have available this vastly you know improves access to this technology without the need for buying new mapping or ablation equipment you know. But I think that the concepts that that Jason mentioned that are important to reinforce are you know this is still really kind of a bailout strategy, a bailout tool. I would not necessarily go to it as a go-to for a first time anything especially if we're talking about idiopathic VT or idiopathic PVCs because it's actually it can be quite destructive in that setting. So I think there still has to be reserve exercised in utilizing it but I think that it is an important incremental advance for you know those really refractory patients that exist all over all over the world. Thank you. I'm gonna do something a little unorthodox. These last two minutes or so I'd like to ask our senior author Dr. Peter Futima to comment briefly on what he took home from this trial and how he seems to use bipolar radiofrequency ablation in his practice. Dr. Futima, thanks for joining us. This is a little unusual. You were the you were groundbreaking in that we're inviting the author to comment on his own paper. So talk to us a little bit about the trial and and where you use bipolar most in your patients. Well if you get into a bipolar ablation you need to be prepared for unusual situations. So the issue is that most of these arrhythmias in a regular manner can be manageable with traditional sources. However at some point you meet this boundary which you cannot like go through it and sometimes you just need a couple more of millimeters of lesion depth. I think that bipolar ablation can actually help you achieve that. However you need to be prepared. You need to be aware that these situations can occur during your practice. So I think that it's important for like VT centers to have like access to advanced ablation techniques. Bipolar ablation is of course one of these methods which is can be pretty you know straightforward. You just take another catheter. You just make a connection and you are there. So for many centers find it straightforward. We have other tools. Some centers have experience with alcohol ablation so it can be also beneficial. The other centers look very forward to get their PFA devices for treatment for deeper lesions. It's not yet there in routine practice but perhaps there is also an option for this kind of advanced ablation therapy. So right now we managed to put all these you know centers together to provide their data. I'm very grateful for European Heart Association Scientific Initiatives Committee because their help allowed us to work on this to also to motivate the centers to get deep dive into their data which is maybe not that straightforward to get. You know these are challenging patients. Sometimes these patients are like after multiple ablation attempts. So sometimes it's really really difficult clinical situations you get into it. So yeah. Well that's wonderful. Today we've been talking about bipolar radiofrequency ablation. A late breaker here in Sydney Australia with Jason Jacobson and Wendy Zou and our special guest Dr. Futima. Thank you very much.

bipolar radiofrequency ablation

ventricular arrhythmias

multi-center study

lesion depth

acute success rate

long-term safety