Welcome to this episode of The Beat. This is a special episode, a post-session recording here at Sydney, Australia at the APHRS meeting. We're going to be discussing update of conduction system pacing 2024, current controversies. I'm Mike Lloyd of the Digital Education Committee. And with my co-moderator here, Jason Jacobson, I have the pleasure of introducing Dr. Ken Ellenbogen and Martin Stiles, who are both discussants at the webinar. Gentlemen, welcome. I want us to consider this a post-game show of the webinar you just presented, and our opportunity to discuss some of the leftover questions that weren't answered, and there were a lot, and some of the things that you took away from the meeting in general. Jason? Why don't we maybe just start with just a quick synopsis of what you felt the session brought new, and some of the controversies, and then we can start with questions, I guess. Well, we had four speakers today, each sort of talking about one of the controversial areas in conduction system pacing. The first speaker was Dr. C.P. Lau, and he talked a little bit about the guidelines, the joint guidelines by the EP Professional Societies on conduction system pacing, which was chaired by Mina Chung from HRS. So he went over the guidelines, and pretty much thought the guidelines the societies came up with very reasonable. There were a couple questions about programming devices, and questions about what sort of peer intervals are too long. There was some discussion about, well, if you love conduction system pacing so much, why don't you just do it for everyone? But the discussion was pretty balanced. And then the second talk from Dr. Pippin Kajojo was a discussion, a comparison about the role of stylet-driven leads versus luminous leads. And there's a real discussion about the art of putting in stylet-driven leads, some of the concerns about angulation of the tip, risk of fracture, and the lack of long-term data on stylet-driven leads. So that was a very robust discussion, talking upon, touching upon all the different companies that have stylet-driven leads, showing a little bit of data, and all the short-term data looks pretty good. There are a lot of things we can discuss about, Martin and I can discuss about that. The third talk was from Dr. Weijun Wang in Guangzhou, from Guangzhou, China, who really was one of the, in many ways, the father of conduction system pacing, but particularly conduction system pacing moving from his bundle pacing to what we now call distal his bundle pacing, or mostly left bundle branch block pacing. And he talked about the physiology of left bundle branch block area pacing versus just pacing the LV septum. He went over the physiology, hemodynamics, synchrony, data on comparing those two. And the final talk was really another fantastic talk, a tour de force on the physiology, the electrophysiology of conduction system pacing, and some of the pitfalls of all the algorithms, how you can't rely on one thing alone, and you really have to look at the physiology. And of course, there was a lot of discussion about that as well. Great, thank you so much. I thought maybe we could try to hit some of the questions that were posted by some of the listeners that weren't gotten to. And I think one of those questions, kind of getting back to that physiology question, was in patients with cardiomyopathy and IVCD, where you can't really get good left bundle capture, is it okay to just accept left septal pacing in that area? Yeah, so this was a question that was posed and answered to a degree by Weijing Huang. And so I think it was felt that if you were not able to do left bundle branch pacing and capture the left bundle, and you had a really strong indication to resynchronize, that it seemed to me that their advice was to implant a coronary sinus lead. So that you had a combination of our traditional bi-V pacing, but also with that left septal pacing to really maximize it. And the phrase I think Weijing used was, try not to leave anything on the table for the patient. And so I think that was a situation where you could use a little bit about what we have previously done with what we now learn. And I think, you know, one of the things that I was trying to tease out was, you know, how much do you have to strive? You know, how good is good enough? And I think we're still learning a bit. Don't you think, Ken? And I, you know, I said the enemy of good is perfect. And we've all been in situations where we've had an adequate situation and we've striven for better, and it's failed. And I think we learn from those situations. But where that line lies is different. It's probably different for every patient, and maybe every center. And maybe every doctor. I think that's got to be the standout controversy this year, is how much does location matter as compared to how much does penetration matter, given the bifurcating, diffuse network of the Hispokinji system, Ken? So that came up in terms of questions. And of course, in real estate, it's all about location, location, location. So what we heard from our speakers today was physiology, physiology, physiology. In the future, we may have more anatomy, anatomy, anatomy. Techniques are being developed to be able to visualize the conduction system using a CT scan. So when you go to the EP lab, if you happen to have a CT scan, you have a bullseye. You know where the conduction system is. But we don't have that today. And I think one of the points Dr. Vijay Raman made is, you want to do the best possible thing for patients while you're in there. You want to give them your one best possible shot. And he pointed out that, particularly in patients who have IVCDs and cardiomyopathies, where they may have diffuse and distal conduction system disease, that once you put a CS lead in, and then you have some measure of LV septal timing, or, I'm sorry, of LV activation, and then you can sort of fine-tune your LV lead, your lead in the septum, whether it gets conduction system or not. You can see how it brings the timing in. The earlier activation of the LV is always better. So I think we don't have any exact answers, but I think it's clear that you do want to get, capture the conduction system. And sometimes just one or two more turns of the lead goes from LV septal to septal plus conduction system. I think the point that he made, Dr. Wang made, other speakers made was, the goal is to capture the conduction system. And so we should really try to do that if we're doing conduction system based. And I'd just like to make the point that one or two more turns of the lead can also cause preparation. So, you know, this is where I struggle to know about how much is enough and how much is before doing too much. I think another question that's come up is, how proximal do you need to be in the conduction system and is there a trade-off in being more at the distal left bundle and the potential for tricuspid regurgitation? I don't think so. We have very little data on tricuspid regurgitation. We have published and presented some data using a luminous lead and there does not seem to be any increase in tricuspid regurgitation. Possibly because so many patients, their heart failure gets better anyway. But it's a very small lead. It's not very stiff. It doesn't seem to cause a lot of TR. I think the answer is, the more proximal in the conduction system you can get, the better. That's what the message was. Now, that doesn't mean it's going to be easy and, you know, you try to go down a little bit, but the lower you get, the less proximal activation in the conduction system. Ideally, the higher, the more proximal, the better. Dr. Stiles, you mentioned going a little too far and what do you think, what did the panel think of this concept of negative injury or a decline in the RV impedance? We didn't discuss impedance so much, but we did discuss scar and it seemed to me, one of the take-home messages I found was that different outputs tell you a lot. So in a single position, increasing the outputs, decreasing the outputs. We even had mentions about injury current on the proximal ring as being something that you could use, particularly if you were deep in the septum. Yeah, look, my hope is that we're at the sort of technological advancement that CRT was in the early 2000s when we had, you know, single unipolar leads or dipolar leads and terrible CS guide catheters and then look where we are now. We've got these quadripolar leads that we can track anywhere over the ventricle. I personally hope that industry and researchers seize the challenge to improve the tools that we have and improve the techniques that we have so that in five or 10 years, we're sitting having the same conversation. Everyone will go, oh, that's easy. That's my hope. And leadless, perhaps. And leadless, perhaps, is the ultimate combination. Kerner of injury for all active fixation leads is important and we'll see some data coming out in the next couple of months in Heart Rhythm Journal and other journals that particularly a beautiful study from our Polish colleague, Marek Jaworski, which I probably apologize for mispronouncing Marek, looking at Kerner of injury as a way to determine sort of anatomically where you are and to avoid, perhaps, giving those two more turns and ending up in the LV endocardium as opposed to getting subendocardial and getting conduction system capture. As Martin said, it is really important to know when you're in the really good area, you know, the perfect area or a good enough area. And Kerner of injury can be useful, but we need more. We need better tools to determine anatomically where we are, but where we are in relationship to the conduction system. And good enough is different half an hour into the case than 90 minutes to two hours into the case. Can I say that? That's it. Thank you. Absolutely. You mentioned injury, Kerner. Are there other parameters that the proximal pole can tell us, you know, as far as where its location is, such as, you know, impedance or even sensing or capture threshold or these other parameters we can leverage? Well, Vijay was saying that he's moved away from bipolar pacing completely, I think, and unipolar pacing only because of the fact that anodal capture can bring your RV in early and you don't necessarily want that. You mostly don't want that. What other things we were talking about with the different poles? I mean, I think we're learning and the more thresholds you test at, the more you test proximally, distally, I think we learn. I'm still learning, that's for sure. Yeah, I think you summarized very well what you said. I want to wrap up by addressing the elephant in the room that was a big point in the webinar and that's extraction. And the fact that we just don't know, there are reports now of active fixation, stylet-driven defibrillator leads implanted in the LV position. And I wanted both of your thoughts on how hard you think this is going to be and what kind of damage are we going to create? Great question. I don't have an answer. I do know we published a paper in Heart Rhythm on extraction of lumenless leads and the results are excellent. Even many years later, the Medtronic lumenless lead has been around for 17 years, so we have a lot of data on that. I think we just don't know about stylet-driven leads into the septum. We don't know whether extraction will end up with a small hole in the ventricular septum. So I think it'll be one of those things like extracting leadless devices, leadless pacemakers 10 years later. We'll just have to wait and see how that works out. But certainly a reminder to all of us that we have to spread the risk around. When you don't know something, you don't want to put all your eggs in one basket. Yeah, the defibrillators in the septum extracting worries me because of just the size of it, but we don't know. And it's always nice to implant a lead with a thought towards extraction, but sometimes in our enthusiasm to help the patient, in the here and now, we put that to one side. And so it'll remain to see. I haven't put any defibrillators leads in the septum myself, but I'm keen to see what the field tells us. We've been discussing controversies in conduction system pacing 2024. Dr. Ellenbogen and Dr. Stiles have summarized some of the controversies nicely. And on behalf of my colleague, Jason Jacobson, thank you for watching. ♪

conduction system pacing

cardiomyopathy

lead extraction

pacing strategies

technological advancements