Good afternoon everybody, welcome to the final session of Heart Rhythm and the most exciting session as well. So congratulations for making it. I'm Mohamed Tariq from Toronto, Canada, Dr. Ellen Bogan from Virginia Commonwealth. We'll be introducing our first speaker, Dr. Bo Dey from UPenn, does CRT have an ongoing role for right bundle branch block patients in the area of physiologic pacing? Thank you. Good afternoon, everybody. First, I want to thank the HIS organizer for inviting me and, of course, thank you all of you for being here this late afternoon. So, today I will be discussing whether or not the CRT still has an ongoing role for the ripened branch block patient as we're entering the era of physiologic pacing. My name is Vy Bodhi. I'm from Texas Catechorythmic Institution and in Austin, Texas. So, the ripened branch block is quite a common conduction disorder. It is associated with delayed right ventricular activation. It causes a challenge, a unique challenge, in selecting optimal pacing in patients who are needing ventricular pacing. In two particularly subgroups of patients, the first group is the patient who has the pacemaker indications with the normal left ventricular ejection fraction. We all know that the RV pacing, especially RV apical pacing in this type of patient may worsen the cardiac dyssynchrony over time between the left ventricle and the right ventricle and overall, by times go on, the LVEF can drop for this patient. The other group of the patient is a patient who, again, has the pacemaker indications with the low LVEF. And we know that these patients usually get the CRT, but CRT has traditionally not shown the consistent benefit as it has in the patient with the left bundle branch block patients. Multiple trials have confirmed that the CRT is less effective in the right bundle branch block patients due to limited ventricular resynchronization. As you can see from the table on the left box below, the hazard ratios with the primary endpoint of the heart failure hospitalization or that, although there's a significant improvement in the patient with the left bundle branch block, but there was no improvement in the patient with the right bundle branch block. And you can see also from the left panel of a meta-analysis of CRT in the patient with the right bundle branch block that, again, it did not show any significant improvement. So the question is, do we abundant the CRT completely in this type of patients or can a newer physiologic pacing strategy offer a better solution for this type of patient? So back in 2012, HRS recognized this gap in efficacy of the CRT and gave us limited guidance on the CRT in the right bundle branch block patient. They gave us class 2A indication in the patients with the low LVEF below 35 or equal to 35 with the QRS duration of equal or more than 150 milliseconds with the NYSHA class 4. And also in the patient with having atrial fibrillation who will be undergoing AVJ ablation. And as well as the patient who will be expected to get a high burden pacing, more than 40%. They gave us class 2B indication for the patients who also have low LVEF, have a little bit more symptoms of NYSHA class 3 and 4, and have a shorter QRS duration of 120 to 149. But if the NYSHA class dropped to 2, which is not that symptomatic, the QRS they recommend to be more than 150 or equal. When the patient does not have a lot of symptoms, NYSHA class 1 to 2, and QRS duration less than 150 milliseconds, it is contraindicated. As physiologic pacing technique evolve, we're beginning to re-evaluate how we approach this type of patients. By targeting the his bundle or the left bundle, we can leverage the native conduction to achieve a more natural activation. Transseptal conduction from the left ventricle to the right ventricle may help the fusions with the residual native conduction and cause the earlier septal activation, which can help to promote the RV engagement in this type of patient. And over time, it might help to remodel the resynchronization of the LV and the RV together and may show the benefit. How exactly do this strategy work? In the right bundle branch block, the left bundle usually intact. So if we are able to pace the left septal region early, we can potentially narrow the QRS duration. And there's also evidence of end nodal capture during the left bundle branch pacing, which can simultaneously cause the RV and LV septal activation. A recent publication by Vijay, who is here as well today, in the Heart Rhythm in 2022, outlined these mechanisms quite well. From the paper, it's also suggested that even though we are not really correcting the right bundle branch block per se, we are promoting a better biventricular coordination between the right ventricle and the left ventricle, and also some narrowing of the QRS complex. Let's look at some data. So in 2018, Chama et al have conducted a retrospective observational multicenter study assessing feasibility of the hip bundle pacing in the right bundle branch block patient who has QRS complex more than 120 millisecond, and YSH class 224, average of LVEF was 31%, with a mean follow-up of 15 months. They found that the hip bundle pacing was successfully done in the patient quite well from 37 from 39 patients, narrow QRS in 78% of patients with improvement of the LVEF, and also in YSH class. This seemed to be quite encouraging data to me. Building onto that, Vijay again in 2022 evaluated the left bundle pacing in a similar cohort of the right bundle branch block patients. We again see the high feasibility of the left bundle branch area pacing that was successfully done in almost 90% of patients with narrow QRS in 78% of patients and improved LVEF and in YSH class. The most notable thing is there was no statistically significant differences in the clinical outcome of death or heart failure hospitalization in the left bundle branch area pacing group and the hip bundle branch pacing group, which suggested to me that both hip bundle and the left bundle branch area pacing are the viable options for physiologic pacing in this type of patient. Here's a case example of what this looked like on the ECG. On the top is the patient with the baseline right bundle branch pattern. On the bottom is after the left bundle branch area pacing. You can appreciate a market narrowed of the QRS complex and a chopper in V1 that you can see a more resynchronized activation. So who are the ideal candidates for this type of pacing? Certainly is AV block patient with the right bundle branch block baseline, patient with the right bundle branch block with heart failure with reduced ejection fraction, patient with the right bundle branch block with the high pacing burden or expected high pacing burden, or the patient who already had pacing in due cardiomyopathy and need an upgrade to have a better pacemaker system. As promising as this strategy are, we still need more data. More randomized control trial, maybe comparing the physiologic pacing both way, or a little bit easier to do left bundle branch area pacing now in comparison to CRT, and also RV epical pacing in the right bundle branch block patient. We still need to define what is the QRS or echo-based response criteria for this type of patient. We need better tools for lead delivery and capture confirmations. And the long-term lead performance data is still needed. In some particular patients such as hypertrophic cardiomyopathy or fibrotic intraventricular septal disease that they may have some limitation with physiologic pacing, we still need to debate which way is better to take care of this patient. To summarize, physiologic pacing offer a promising new pathway for the right bundle branch block with pacing needs. The earlier evidence show improvement in both electrical and clinical outcomes. Physiologic pacing may outperform the CRT in patient with right bundle branch block, but further research is still needed to establish best practices and refine our patient selection strategies. Thank you so much for your attention, and I'm ready to ask questions later. Thank you. Thank you very much. Our next speaker, should all CRT be combined with left bundle and or physiologic pacing from Dr. Srivathan at Mayo Clinic Scottsdale. Thank you, Dr. Allen-Bogan. So it takes a second to load here. All right. So I don't have any disclosures. I just want to start off saying the inciting event like a myocardial infarction or early cardiomyopathy, then subsequently there's remodeling. And correspondingly, the QRS starts narrowing. So you start with a normal EF and then you drop, and you may be asymptomatic here. As you progressively dilate, you become more symptomatic. And that correspondingly, the QRS complex starts widening. The way to look at this is to look at this R wave initially has to be narrow, indicating that the right bundle branch is completely intact. And it's only the peak of the R to the end of the S which widens in left bundle branch block. And anything greater than 110 would suggest that there is going to be dyssynchrony. And people who have 150 milliseconds or greater left bundle branch block have additional local Purkinje disease besides the left bundle branch block. Now, if we look at the velocity of conduction of these, the AV node and the myocardium are very slow. This is a calcium channel. This is between muscles. But you can see these Purkinje systems are about 80 times faster, 80 times faster. So there's nothing we can do to match that kind of conduction. We can capture that conduction tissue. If we capture the epicardium and we depend on that to come into the Purkinje system, which is endocardial, it has some delta, some time. Of course, if you enhance the output, you can have a virtual electrode which is large enough to capture the endocardium. But majority of the time, we are concerned about the amplitude of current and in which case it will take some time. And a lot of the spread, very little spread will occur within the epicardium. Substantial portion will cut through the muscle fibers. And if you look at this, there is nothing that can conduct this faster because of the connexin 43 proteins which drop impedance and they can really conduct exceptionally faster. So capturing one of these fibers would really spread the activation much faster. Now, pacing the epicardium is not going to do the same thing. And you can see that, I will show you subsequent papers, majority of the left bundle bench block for QRS less than 150 milliseconds. The block is very proximal in the left bundle. And if you can capture just in the septum beyond in the left bundle, you would activate very quickly. In fact, you could argue what is the point in putting a left bundle lead in patients who already have captured the conduction system. But people who have QRS duration greater than 150 milliseconds, there are additional diseases probably distally, particularly in the charge amplifying cells. Now, if we simply put CRT, we have a wavefront collision between right ventricular activation and left ventricular activation. And we will cause some form of wavefront collision at some point. And some of them may produce more the fusion dyssynchrony, which in rare cases can be worse than the natural dyssynchrony caused by the left bundle bench block. In fact, the myocardium is one of the, unlike skeletal muscle, it is branching, which drops the impedance, which means from the endocardium to epicardium, the impulse spreads faster. But for the branching, that impulse would take a much longer time. So physiologically, the way it has been constructed, unlike skeletal muscle, actually branches, which drops impedance. Now, we all have seen this. When we pace the RV, there's a huge amount of time it takes for the LV electrogram to come, because we are on the epicardium on the postolateral or antolateral wall. And the same thing, and the difference may be different if you pace one same electrode in the opposite direction, because the conduction vectors may be different between these two electrodes, depending upon how the electricity reaches the other side. I also mentioned this, when you have a very low output, you can just capture the local myocardium. But when you have very high output, when you have a high output, you may end up capturing the endocardium. And sometimes you will feel the QRS complex is exceptionally narrow with biventricular spacing, mostly because you're probably capturing the local Purkinje tissue directly. And of course, we would like to make sure that the leads are really positioned in the mid-septum, capturing on the other side, we're producing a QR pattern, and an inter-peak interval, about 40 milliseconds or so, would tell you that we are truly capturing the fascicle on the other side. The left ventricular activation time, about 60 to 80 milliseconds, would indicate the free wall is activated very quickly through the conduction system. If you have QRS duration greater than 150 milliseconds, some of them may even take 90 to 95. But once you cross 110, you're really not capturing the left bundle area. Now, here, so this was one of the other problems that not infrequently occurs. Because the helix is about 0.15 millimeters, and the majority of us are turning it until the impedance is above 450 ohms unipolar, something that can happen is the ring electrode may be touching the septum, and the patient could have anodal capture. And even though you have a good positioning system, when you give a higher output, you may end up anodal capture. But once you lower the output, you come back to your original configuration. So something that either we need to expand the size of the ring electrode to diffuse the current out, or we need to space the distance between the distal and proximal. So we need some additional toolkits that we are needed in terms of facilitating pure left bundle capture. There are a lot of patients with intrahysian block, or just you can see that there is a proximal and a distal hyst. And you can see that it is blocked between this hyst to the distal hyst. So I think in these patients, and as well as I think Rod did, we also have seen in patients with alternating bundle bench block where the HV lengthens, the local activation is very consistent with, it's a very proximal block that is occurring within the conduction system. And so this was, you can see that this was actually Dr. Pugarendi's study that you can see baseline with the AAI based the patient. Here is the left bundle branch. This is pure CRT. And then you have the locked CRT. So progressively the QRS narrows. As EP implanters, the best we can do is to narrow the QRS. The mechanical consequences may have to be assessed at a later point, but not immediately in the lab. But you can see that there is some reduction in QRS complex additionally by putting in the left bundle. And you can see this is also in the QRS duration in a locked CRT. There was a statistically significant difference. You can see this between locked CRT and by V, there is a bigger difference. And whereas the left, even with the pure left bundle area pacing, there is some additional reduction by adding the CRT, particularly in patients with QRS greater than 150 milliseconds to begin with. Now, this is the study I was referring that you can see that even though the left bundle branch block, you can see these are all patients less than 150 millisecond QRS, but you can see the left intrahysion block, or it is at the very proximal location of the left bundle. So left bundle branch block is not farther distal into the conduction system. So I think conduction system pacing tries to overcome this fundamental problem. And in terms of hemodynamics, you can see that LVDPDT by V pacing versus locked CRT. There is, I mean, these two are kind of comparable. And in the, you can see the left pure left bundle area pacing is here. So I think locked CRT definitely is, at least in the DPDT's catches, I mean, is equal to, but there are certain situations if you have a narrower, less than 150 millisecond QRS, you may not even need the LV lead. But in terms of QRS duration, these are acute DPDT measurements. So we don't know what will happen in the long term. But you have the locked CRT produces the narrowest QRS in terms of reducing the QRS duration, which is most of the time, that's what we can actually accomplish in the lab. I think so optimal electrical synchrony is achieved when the paced QRS morphology closely approximates the narrow physiological QRS complex. The epicardial and arbitrarily positioned right ventricular pacing sites often result in wavefront collision and may occasionally even worsen their synchrony. So non-physiological ventricular actuation sequences disrupt normal electromechanical coupling, thereby reducing DPDT and stroke volume. And if you have most of them approximate left bundle bench block, I don't know why we can't use conduction system pacing. So given most of them are proximal, I think this cardiac resynchronization therapy lead offers superior hemodynamic and electrical outcomes. Therefore, left bundle bench block area pacing should be considered as a strategy for all candidates for CRT implantation. I do understand that there are no randomized major trials. Some of them are ongoing, but it is going to be difficult to have 600 patients in each arm because it's not going to be funded by any sources. I mean, it is something that is already existing. But otherwise, I think it makes physiological sense to use this combination. Thank you very much. Thank you very much. Our next talk is a CS lead will remain the mainstay for treating patients with heart failure in the future. Dr. Jacqueline Joseph from McGill University. Just want to make a note that Pugal was trash talking me just now. All right. Thank you again for this great topic. Very excited to discuss and debate. Okay. I know it. So this is Pugol, Dr. Vijayaraman. He doesn't need any introduction, and when he takes an ECG that looks like this, he really makes it look like this. He's really the king, you know? The problem with that is that this is the standard Pugol left bundle branch pacing result. And this is everyone else's left bundle branch pacing result. Is that my ECG? That's your ECG. A standard. So, you know, these are essentially a standard Pugol left bundle branch pacing result, these are how Pugol would have painted it. And this is how everyone else or myself would have painted it. Can keep going. Nice restoration. Everyone else really nailed it here. So, okay. So let's get serious for a little bit though. Okay, so Pugol will tell you about this 30, 40% non-response rate with biventricular pacing as a reason to try new therapy, okay? But is this 30% non-response rate enough to avoid the coronary sinus? In fact, the reasons for non-response apply to both biventricular CRT as well as conduction system pacing CRT. Patient selection, we know that typical left bundle branch block will perform well in both. IVCD, probably better in coronary sinus leads. Pacing configuration certainly will help to optimize that patient, but it's familiar to both CSP and biventricular pacing with the coronary sinus lead. The decreased percent pacing, yeah, both. You can see that for conduction system pacing or bivy, you know, from atrial fibrillation or frequent PVCs, the same treatment applies. Similarly, for optimization of heart failure management and the presence of myocardial scar will prevent optimization and will essentially take that non-response rate to apply to both. And so the results of the eye class study, the early eye class study, I know he presented recently, you know, longer term results, but are these results too good to be true? We saw improvements with left bundle branch pacing as compared to biventricular pacing with the coronary sinus lead. This was retrospective, multi-center observational study. They only included their successful implants. So, you know, there's significant bias there. If you don't include your unsuccessful implants, then who knows if there's really benefit to conduction system pacing versus bivy. So only successful. And 18% of the left bundle branch group received a coronary sinus lead. So it wasn't good enough with the left bundle branch pacing lead. And when we look at the differences, even in small randomized control studies, comparing CSP versus biventricular CRT, you see end systolic volume, change in ejection fraction are similar between both. So the non-response holds true for both conduction system pacing and biventricular CRT. Although the cohorts, these observational cohorts may suggest differently, randomized studies are starting to show no difference in improvements. So let's look at the RCTs in His bundle pacing CRT. How many do we have? One, two, three. I would say that this one doesn't really apply. You know, it was looking at long PR, narrow QRS. So very small randomized control studies. And overall, the improvements are relatively equivalent. Lots of crossovers as well. Your mouse doesn't show up. Oh, the mouse is not showing up, sorry. So randomized control trials in CRT patients for left bundle branch pacing, these are the randomized control studies we have. The largest one of which, 130 patients, required 27% crossover to biventricular pacing. And overall, the results are quite equivalent between the two groups. That's why Pughall advised the current guidelines from ESC era to ensure that biventricular pacing was the best therapy over conduction system pacing in each subgroup. So let's look at the reality of conduction system pacing, of left bundle branch pacing. This is really the reality. You know, can you imagine trying to put in a left bundle branch or a His bundle pacing lead in this type of patient? Extremely difficult to get good results here. Not just that, but we have significant scar that will prevent the ability to place that lead deep into the septum. And really, you need to go all the way to the LV endocardium to achieve appropriate left bundle branch pacing results. Another example of the reality, you can see here, we're trying to even find the ventricle. Where's the ventricle? You know, maybe down there. Oh, finally, we found it. I don't know what this is, this upgrade. And then, you know, finally we get the lead, you know, to somewhere, but it was, you know, took about 30 or 40 minutes of fluoroscopy time. So really unpleasant, and this is really the reality with conduction system pacing in heart failure patients. We need new sheaths, we don't have them right now. And so we're definitely going to still keep using this coronary sinus for cardiac resynchronization therapy. But, you know, even going through the literature. So what's the literature showing for the success rates of left bundle branch pacing for heart failure patients? When we look at Milos, we are all impressed because there was a left bundle branch capture in 83% of heart failure patients. Then we had Lot-CRT, a small, you know, a small perspective study, observational, of course, around 75% left bundle branch capture, 25% left ventricular septal capture. That's pretty good, so we're all thinking that everybody can do this. And then we start getting the small randomized trials looking at this patient population. Look at that success rate. Not even 60% to implant that left bundle lead. And now, even further, and you know, Pugal showed us very nicely in C-SPOT study that he can only achieve 56% of the time left bundle branch capture. So, you know, the crown is starting to fall. I'm not sure you're gonna win this battle here. And one of the reasons for, well, I'll go back, I'll talk about it after, sorry. So, left bundle branch pacing, I've shown you, is not easy to perform. And in fact, Oscar Kenyo from the Spanish group showed us that in heart failure patients here on the right, when you're attempting to get left bundle branch capture, even then, they can't even get more than 63% of the time left bundle branch capture. And if you don't even try very hard, which sometimes that is the case, you're getting left bundle capture only 37% of the time. And so even when you do demonstrate left bundle branch capture, the results may still be disappointing. So look here on the left, what we have is a non-selective left bundle branch capture. And with unipolar threshold decrement pacing, what we see is selective capture here on the right. But the QRS remains very long, still here, 170, 200 milliseconds. We're demonstrating clear non-selective to selective capture. But why is the R-wave peak time in V6 extending? It should, you know, in selective pacing, we should actually see it remain the same. It's extending because we have such sick conduction system that we have such this delay in activation to the lateral wall. And this is the best result we can have. And you don't even see an R-prime here. And so this is this idea, which is critical to understanding left bundle branch pacing in heart failure patients. This idea of functional deep septal pacing, where we get the tip all the way to the left side, all the way, almost in, you know, at the LV subendocardium, but we don't actually achieve actual capture of the left bundle because there's just such sick tissue, whether it be from scar or what else. And this is really Poogle's worst case scenario because he's able to get that lead there, but he still can't achieve left bundle branch capture. Whereas anatomical deep septal pacing is when you put the lead as far as you can, but you don't really reach the left side. You're just somewhere in the mid septum. This idea of anatomical deep septal pacing is everyone else's worst case scenario. So even when we have, so at the top left bundle branch pacing, which we showed confirmed transition, we had to add an additional coronary sinus leads to actually make some sort of resynchronization for this patient. So a CS lead to the rescue. So is this CSP or BIV pacing? And I'll just spend a little bit more time on this. So this is a very important study, the C-SPOT study. And you can see Poogle is part of this study. And you can see here, particularly on the right, when we're looking at the acute hemodynamic, the DPDT, where they measured the acute hemodynamic changes during biventricular pacing, unipolar left bundle, bipolar, or with lot CRT. So all of these patients received a left bundle and a coronary sinus lead. You can see that the addition of the coronary sinus lead is what actually improves the hemodynamics. And overall, lot CRT was even very similar to biventricular pacing. And again, similar, if you never even were able to even get more than a left bundle branch, so if you still had deep septal pacing, the addition of a coronary sinus lead further improved your hemodynamics. And I think that that's kind of, I'm gonna hit the nail in the coffin for you. Sorry, Poogle. So this is a baseline left bundle branch block. This is the after effects of a biventricular CRT. So, sorry. And that's my conclusions. The so-called non-responder rate also applies to CSP-CRT. Current data still favor CSP-CRT over biv CRT. Although Poogle makes it look easy, performing it is not very simple. Functional deep septal pacing is not enough to properly resynchronize a heart failure patient. And despite the progress we were making with CRSP, still at this moment, we still need the coronary sinus lead. Thank you. Well, that's gonna be tough to rebut, but a CS lead will no longer be the future of treating patients with heart failure. By Poogle Vijayraman from Geisinger. Can I not use slides at all? Your choice. So, I had a debate last year with a good friend of mine, Miguel. And I had prepared extensive video slides because I watched others debate, Andrea Natale, Dr. Parker. I said, I have to go with my boxing gloves on. And Miguel was so nice. He had nothing negative to say. And I had all this negative ads and pictures and videos. I said, this time I'm debating Jacqueline, who was with me just yesterday, the day before, the previous day, in all of the CSP sessions, talking about how good CSP is, how easy it is, how well she can do it, how well you can do it. And so I left my boxing gloves at home. I didn't prepare any pictures, any slides. You can have the crown. And the two speakers before me gave you all the information that you needed to know about why CSP is better. But unfortunately, the topic is different. A CS lead will no longer be the future for treating patients with heart failure. And very clearly, very nicely, Jacqueline showed us why we may need both. So I want to concede it right up front. You have to choose what is right for the patient and what you can achieve. The goal is to get the best therapy for the patient. Right? Obviously, there are a lot of advantages for by we. And that's why it's still a class one indication. So I concede right there. It's a class one indication because we have 10 years, 20 years of data, tens of thousands of patients that has shown all these benefits. So it still remains class one. And because we don't have enough data, because we have good amount of information showing the physiology is good, early evidence suggests that it's a reasonable alternative. And it's a class two indication for conduction system pacing. But when you look at biventricular pacing, and the reason we have gone in search of more physiologic alternative is because when you do biv pacing, even in patients with really wide left bundle branch block, you don't completely resynchronize. For the reason, very nicely explained by Srivatsan earlier. And he showed that epicardial to endocardial activation, there's slow conduction. So there's a lot of resynchronization left behind. And if you take patients with AV block, patients undergoing AV neural ablation, patients with pacing induced LV dysfunction, those who had narrow QRS at baseline, biv pacing adds a new element of this synchrony. Why do that when you have a better option? So we've shown previously, some of these slides have been shown before, so we can go from 190 to 95 milliseconds. Jackie tried to tell you that I can do it. But you can't do it. I don't think that's true. Anybody can do it. It may be challenging in the beginning. The more you do it, you're gonna get better at it. And you're definitely gonna be able to do it. If we left our abilities, didn't challenge ourself, we would still be doing Cox-Mays procedure for AV ablations. And now we are debating how fast they can do AV ablation. I can do five by five or something like that. Is that the social media thing? So the reason we are trying to use his spinal pacing is that because when compared directly to biventricular pacing, you can get much greater resynchronization because you can get greater reduction in QRS duration, shortening of LVA activation time or reducing disinferting index and improve hemodynamics. If you can do better than what you're doing just because you've been doing something for a long time, if you can do better than that, why not try that? And that's why conduction system pacing has come along. We learned the limitations. And you've seen these slides multiple times. So the site of conduction block and what type of conduction disease you have is critical and that's what should decide what type of therapy you should do. If you have a proximal conduction disease, I think left bundle branch pacing or his spinal pacing should be perfect in those scenarios. And what better way to utilize the nature's Purkinje activation, the fastest conduction system in the heart to utilize it. So that's why these approaches are better. And you can see when you do whether his spinal or left bundle branch pacing, you're going to have much faster activations. And this has been studied very elegantly by doing intracardiac activation and by hemodynamic measurements and showing that LV septal pacing, these studies were even without left bundle branch capture is better than biventricular pacing and can be much more effective. So obviously we saw that a lot of observational experience, experience centers doing extensive work. His bundle pacing had its limitations, 76% of patient with pure left bundle branch block and non ischemic cardiomyopathy got his bundle pacing. But when you achieve that, in this particular study, 80% of patients were hyper responders. I would like Jackie to show me after these 10,000 patients, multiple randomized studies, one paper showing 50% hyper response rate with biventricular pacing. Even in all the studies that showed you use mainly the left bundle branch block patient, we have not seen a single study that showed that high levels of hyper response. So we can identify a group of patients that have primarily dyssynchrony induced cardiomyopathy. So you correct the problem. It's basically fixing the problem and finding a total solution instead of creating a new problem or new solution or something that could be very simply done. Yes, we've had troubles in terms of achieving high levels of success in these trials. We didn't understand. We didn't know how well to do it and how to choose those patients. So obviously the crossover rates were high on his bundle pacing. And despite the improvement, left bundle branch, his bundle pacing, left bundle branch area pacing came to rescue in those patients where we can't correct enough with his bundle pacing. So we have two solutions, his bundle pacing or left bundle branch pacing. And both can complement each other. And if used well in the type of patient that it's going to benefit, then you're going to get the best results. Yes, we're going to show, demonstrate, Dr. Ellenborn, who's chairing the session, is chairing our largest randomized clinical trial to show us that these benefits can be reproduced. You can reduce death and heart failure hospitalization on top of what you could be achieved with biventricular pacing. So if there is a possibility for that, why not go for that? But by the way, while doing that, you can reduce the incidence of VTVF and reduce the incidence of atrial fibrillation. And why not have a cake and eat it? Jackie, I know if I give it to you, you will do it. And I'm pretty sure the vast majority of patient in your lab undergo conduction system pacing. And you very, very reluctantly do that by V pacing when you randomize them to by V. I've heard you say that, oh, got randomized to by V. And so the echocardiographic response rates are greater with conduction system pacing. So it's the degree of response you get with this conduction system pacing. By V pacing is a phenomenal effective therapy. You can do better than that. That's why we keep trying. And this is a recent randomized trial. Jackie hasn't had a chance to look at it. She hasn't seen it. It's a 200 patient study, three year follow up. And this randomized study showing improved death of heart failure hospitalization compared to well performed by V pacing. 96% success rate in both groups. So there's a lot of meta-analysis showing similar benefits when you combine both together. And on top of that, the first speaker clearly showed as you can correct right bundle branch block with his bundle pacing. And very elegant way of doing it. And similarly, you can do that with this paper has been shown before. So I'm just gonna rush through that. And similarly, we can use his bundle pacing as high threshold. I'll go on to left bundle branch pacing, then you can achieve better results with that. So we have a way of multiple options now and not have to compromise on thresholds or anything like that. But I do concede that CS lead is important. So here's a patient with IVCD, his bundle pacing. I got exact same morphology. If I do left bundle branch pacing in this patient, it's going to be worse than what I have in baseline. I completely agree. It's not the right patient to do his bundle pacing or left bundle pacing alone. But if you combine both together, you may get a better option in those patients. So here's another patient with left bundle branch block. Srivatsan showed us earlier that you still have residual conduction problem here. As you can see with selective his bundle pacing, it's 125, you still have notched QRSs there. There's still some degree of conduction delay. So you may have to do better than just conduction system pacing alone in these patients. And you have patients with mixed conduction disease. His bundle pacing only partially corrects. Pace QRS is even wider. And then we do left bundle branch pacing. And here is the non-selective left bundle branch pacing. This is the case that Jackie was showing us. You don't have any of the criteria for left bundle branch capture if I just look at this alone. But this patient has left bundle branch capture. It's a selective capture here, but a long conduction time. When the ventricle is huge, stretched, these things will happen. But don't underestimate the power of conduction system pacing. So what we did was combine the best of both, or worst of both, whichever way you want to look at it, whether it's half empty or half full. The reason I'm showing this is this is the baseline ECG. This is the final ECG. And this is the baseline echo. Very enlarged, dilated LV, thinned out. This was a 50-year-old woman who had left bundle branch blocked for 10 years and came in with cardiogenic shock, severe MR. This is six months after with a lot CRT. So you have to choose the right therapy for the patient and give the best option for that particular patient. So I do agree that in patient with classic left bundle branch block, given a choice, if you can normalize the QRS, I would rather do conduction system pacing versus coronary sinus lead or biventricular pacing. Have a patient with narrow QRS at baseline. Why do you want to make it worse than what it is at baseline? Patient with right bundle branch block, we don't have an answer yet. We will have an answer by next year. We have almost close to completing a HIS-CRT randomized trial of 120 patients with right bundle branch block, BIV versus conduction system pacing. But what is important is that identify who has true left bundle branch block or true right bundle branch block, or those with mixed conduction disease or IVCD. You may need combined approach. And so that would be the way to go. I'll stop there, thank you. We have some time for questions. If there are any questions from the audience, there's a microphone over there. And you can come up, state your name, and ask a question. So feel free to ask the debaters or any other speakers questions. Can we put the mic on, please? Either that or you're going to come to the front of the... Yeah. See, the thing is that we are very keen to, we are, our group is very keen to do CSP in every patient of Brady as well as CRT, but there is still debate going on in our country, CSP versus traditional BIV. So I just tell them that there is at least no harm of doing CSP along with the hot CRT as compared to traditional CRT. In most of the patients, you get better results with the left bundle pacing. And, you know, the first speaker is right. In some of the patients, the ventricle is so large, you don't know where the septum is and where to go about it. But I think that is because still the hardware is developing and we will have more options in these difficult cases to go to the septum. We'll let all the speakers sort of respond or give their response. So, yeah, that's a very good point. The problem is we don't have the tools for lot CRT just yet. If you're going to have, for example, a biventricular device with an ICD lead, then you're stuck performing lot CRT by capping the IS-1 part of that, the pacing RV defibrillation lead. Now, I think with the newer leads that are going to be coming out where we can put these shock leads within the left bundle branch, although, you know, it might not be there yet, I think that's where we're heading. And eventually, although those are only DF4 for now, which might be a problem in the future if you don't get really good resynchronization, I think that that's probably where we're heading. And I think everybody should be able to do both CSP and coronary sinus lead. Can I ask a question? So then do you concern about the battery usage in that patient? I don't. I want to just ask one question from Dr. Vijayraman that there are many patients where dilated cardiomyopathy, typical left bundle, you just left bundle pacing QRS is less than 110 or 105 milliseconds. So we even don't put the LV lead in those patients. But what do you think is the future chances of a distal conduction system blocks occurring in these patients? Whether the LV lead implantation is a must in all the patients, or we can leave and be happy that most likely it won't be required? Yeah. We'll repeat the question so everyone can hear. Yeah, great question. So I think what the question was, is patients who have left bundle branch block and you put a left bundle branch pacing lead, and we have great results now, what happens in the long term is one of the main questions, all right? So this came up quite a bit when we were doing his bundle pacing. And this was important at that time for us to understand. So we did a lot of follow-ups on patients with his bundle pacing in patients who had HV block. So we learned quite a bit that HV block was intrahisian disease in the vast majority of patients, 95, 96% of the patients, it's intrahisian. And this is more of a transverse conduction disease, not a longitudinal disease. But there are patients who have longitudinal disease, as the examples we showed. Patients have septal scar, cardiomyopathy, they have additional conduction disease there. So those patients, at least at the time of implant, we understand them, and that's where combining conduction system pacing with coronary sinus pacing is important. But coming back to your main question, in left bundle branch block, I consider them similar to intrahisian HV block. They are all intrahisian disease. We can say it's left-sided his, right-sided his, or proximal left bundle. Vast majority of patients, I would again say 95 plus percent of those true left bundle branch blocks are proximal. In those patients, disease doesn't progress. Those who have septal scar, cardiomyopathy, those patients, we have to be careful. And if you're using only one as a primary CRT therapy, I think it may be a mistake, which is where combining them both with the newer leads may give us more options in that scenario that we don't get into that situation. So that's where those patients viewed. In all patients, yeah. So why not use lot CRT or hot CRT in all patients? Yeah. Hot CRT will be challenging connections, but lot CRT is probably doable for all patients. So the current scenario, based on what we have right now, lot CRT is not possible, which means you have to add four leads because of the ICD, DF1, or because they are not designed for left bundle branch pacing at this point. We just have one trial just, we showed early defibrillation, and we have to add four leads. We showed early defibrillation efficacy data on that. We don't know how effective it is in the left bundle branch area location. Since we didn't have that, I can't answer that question, but it is a possibility because you're right. Why not combine both in these patients? And that may be the better way. Or we may have to find out who we need to use that. We need to do three leads in all patients. Maybe two leads is enough for the vast majority, and choose those patients that will need three leads. So less leads is better in the overall scenario. So we have to become very prescriptive, patient specific, disease specific, in terms of trying to use what might be the best. We need to learn more to get there. Can I make a comment? Please, yeah. Yeah, I think in left bundle branch block, the axis shift will tell you whether there is a distal conduction system disease. If you have a left axis deviation, like left anterior fascicular block, there is a distal left anterior fascicular block if your axis is shifting to the left. If you're extreme right axis with left bundle, then you're going to have right ventricular dysfunction. I think there may be some evidence you should have normal axis with left bundle, because it should not fundamentally shift the axis if it is pure left bundle branch block. I think that's been studied quite a bit. I think Dr. Wellens wrote a lot of articles on left axis deviation in the process of left bundle branch block. I think my question for Puga would be that if I start with the CSP and the QRS completely narrows, is there a need for me to go for the CS lead or just leave the patient alone and see? I don't. You can't make it better than what you have in nature. So if you have a narrow QRS, although impulse dynamics may say things differently, because you can pace a narrow QRS and still get some benefits. So I don't know if CS lead would do anything extra. We haven't studied in those patients. So Jacqueline mentioned that we had about 18% of patients had a CS lead in that study. I think about 12% of those patients that CS leads were not used. They were a backup lead. So only 6% of them got CRT. So we don't generally use them. Not only that, not only if you have multiple leads, you have greater drain on the battery, but we don't know epicardial pacing is not physiologic in patients, especially in patients who have relatively normal conduction. So you can see somebody with heart block, but they may have a narrow, relatively narrow QRS. So putting a CS lead makes no physiologic sense in those patients, especially if your his bundle or proximal left bundle normalizes their QRS or near normalizes their QRS. Can I make one point? Since Jacqueline mentioned that quite a bit by showing a lot of her worst case scenarios, but that's important because it's important to know that have you achieved maximum electrical resynchronization? If you don't have maximum electrical resynchronization as conduction stem pacing, you have to put a CS lead. And that's probably the most important lesson I would do because that's what I do. If I don't have left bundle capture and if I don't have full synchrony, I want to see a CS lead because I don't know if this is going to be any good. So why give up a good therapy that we already have? Questions? How about for the patient who comes with a narrow QRS complex, rapid AFib, tachycardia mediated cardiopathy, but the EF isn't bad enough to warrant a CRT device. So let's say their ejection fraction is 45%. The frustrating thing right now with CMS and the United States is we cannot put an LV lead in. So what I've been doing is putting just a left bundle branch lead in and doing the AV node ablation from above. But what are you guys doing? Are you putting a second lead in? I was using a second lead in the coronary sinus and getting very nice narrow QRS complexes. Then we had some patients that weren't getting paid or we weren't getting paid. And I guess that's number one. Number two, I send most of these patients home the same day. So I like to put a second lead in and I've put in some, I've kind of gone to putting the second lead in the RV outflow tract, which is frustrating. So I just wanted to get your comments on that. Well, yes, you're correct. If you put a lead in the coronary sinus for a patient as a normal EF who has rapid AFib, you're not going to get paid for that. So those patients are just ideal, perfect patients to get a conduction system lead, particularly that bundle, because the AV junction ablation is so easy when the lead is slightly more distal. And there's a lot of data that those patients do spectacularly well, as well as are better than people who get by the pacemakers. So that's the easy solution to that. So the second question was, how comfortable are you with pacing thresholds with left bundle pacing, making someone pacemaker dependent, sending them home six hours or four hours later? Want to answer that? You've done a lot of that. Yeah, I think it's a judgment call. In Canada, at least, we're paid for each procedure separately. So if we do it both at the same time, you won't get paid. But that's not the point. The point more is that if these patients are from far away or it's difficult to get back in, I'll do it the same day if I'm comfortable with the lead. If I'm not comfortable with the lead, I just wait. And that's fine. Similar to when you do the pacemaker for the complete heart block, right? So I sometimes send the patient the same day. Like you said, if you feel comfortable with your left bundle pacing, have a good threshold, wait, suture slower, and make sure that you feel comfortable, look at the x-ray. I think it's good. But if the patient is far away, like eight hours away, of course, I'm going to admit the patient. Yeah, we send almost all our patients home the same day. We've never had a problem. We had one problem with his bundle pacing, but never with left bundle pacing. Never say never. But in the very vast majority of patients, I think it's safe to send them home the same day. Ken, can I ask you for a clarification since you may have all the answers? So one of the questions was that EF is 45%. That's a block HF patient. That you can put a CS lead in. Correct. CMS should cover it. So that's class 2A indication in the United States. But if they come in with AFib and their EF is 50% to 55%, then you're going to put a lead in. If it's less than 50%, you should be able to do. Secondly, I'll answer the other question slightly differently because I do it slightly differently. I do his bundle pacing for all my AV node ablation patients, and the current guideline, both ERA and CPP guidelines from HRS, allows you with a class 2A indication, put a backup lead. And I do left bundle as my backup lead. And I get the best of both worlds. So she has a his and a left bundle. And the EF is low, you get a by AV device, and it's OK. Sorry. Next question. Thanks. Marga Pujol. Very nice talk, Dr. Bode, regarding right bundle range block. I only want to make a small comment. You have said that maybe he's on the pacing. Can you speak closer so we can hear? Sorry. Very nice talk, Dr. Bode. I only want to make a small comment. You have said that his bundle pacing and left bundle range pacing, maybe both can be suitable for his bundle, for right bundle range block. We have done a small study with Dr. Lembogen and Phoenix, and we have seen that in patients with right bundle range block, the block is very distal. It's the contrary, that left bundle range block, that the block is very proximal. Then if you have very distal block with right bundle, it will be more suitable to do maybe left bundle range pacing. And I think that one of the papers of Dr. Villay-Amaran have shown this because it's the Herring-Odo's paper, 2022. They showed that half of the patients, they have tried his bundle pacing, but they moved to left bundle range pacing because they failed. Then maybe for right bundle range block, if the block is very distal, then we need to do left bundle range pacing. Thank you so much. Thank you. Any comments? Yeah, so in our original series, we were also, Dr. Lembogen and I, we published together our experience on right bundle branch block. So the 78% of those patients, we were able to correct the right bundle branch block from proximal his bundle pacing. In about 22%, we couldn't. But they were narrower because we have RV pre-excitation from non-selective his bundle pacing. And the idea was that by pacing the his bundle and you have left-sided activation is not affected. It's maintained normal synchrony. By repacing, we'll create some new dis-synchrony. So, but RV fusion without correction of right bundle branch block. So what's the exact number of patients who have proximal or distal block? That's the study that I think you're doing right now, Rod Tong and your group. So hopefully that'll shed more light. It also depends on the type of patients we are studying. It's patients who are coming for VT ablation or patients coming for CRT, what's underlying pathology. So a lot of those things may make a difference on where the block will be. It's a small study. We have 33 patients. It's recentric with Virginia, the study, and 33 patients. And more than half of the patients, the block is very distal. The median distance of the one-to-one his to the block is median three centimeters. Then it's very distal, the block. And it's very difficult. Maybe fusion plays a role there. Thanks. Good morning, everyone. Thank you very much for sharing with us. I come from Brazil. My name is João Paulo Pucci. And if you permit, I would like to spice up a little bit the discussion. In Brazil, we are used to implant pacemakers in patients with Chagas disease. So we are very used to big hearts and difficult right ventricle anatomy. So in a few cases in our center, in these patients, the left bundle branch area, it's kind of frustrating because you can even worse the right bundle branch block. And in a few patients, we have implanted a second lead searching for the largest electrical delay in the right ventricle or even a more distal right bundle, even the more distal right bundle branch. And the results, the electrocardiographic results and clinical results were pretty incredible. And that's my question for you all. Have you ever thought about trying to correct the electromechanical dysfunction related to the right bundle branch block in these patients? So I don't have much experience in Chagas disease. So I think as we start applying conduction system pacing to a lot of wider group of patients, because we always learn to be selective early on, the infiltrative disease is a challenge. Conduction system pacing can be answer for every patient. So you have to fine tune and find ways to do something better for those patients. Your approach is very good. But my concern is that as we learn even for left bundle branch block, IVCD, electrical therapy may not be the answer. Electrical problems may be secondary to the underlying disease process. And we are trying to maybe do some cosmetic surgery for those patients. We may not change the process. So it may work for some patients that has purely bundle branch block induced dyssynchrony. And are we dyssynchrony so hard to quantitate and qualitate? It becomes a challenge. And I have no experience. Yeah, nor do I. But there has been, in the pediatric cardiac EP literature, some attempt to do that before conduction system pacing with by V pacing, but by V pacing with multi-site pacing in the right ventricle. Particularly in pediatric congenital disease, corrected, surgically corrected, where there's surgical damage to the right bundle. Obviously, that damage is probably can be anywhere along the right bundle. And often, they can correct it RV endocardially by pacing, the QRS narrows, and often the function gets better. But none of it's randomized. It's all in the pediatric EP. It's, you know, five cases here, 10 cases there. Yeah, I mean, our own unpublished observation about 10 cases, whenever the R prime duration and right bundle is greater than 110 milliseconds, we find that the left bundle actually may increase. In fact, we may get that R peak duration into R peak duration 45 and 50. We were feeling great. We got the left bundle. Then we're causing a new problem with the right. I think there are two sites where right bundle predominantly has problems. One is where it emanates out of the membranous septum. And the other is moderate aband. I think I would put we have in our eight cases, so we're not published. But we put it in the RV, this moderate aband. The second lead, the QRS shrinks quite a bit. Where the QRS synchronically leads to RV mechanical improvement. I don't know the TAPC and other things. We've looked at it, but it's not substantial for us to publish. I think at this point, I would consider these are the two sites of two pickle right bundle branch block. Okay. You have the last question. I was just going to add to the previous conversation. So Jeff from Yale. The pediatric congenital data on RV resynchronization is tiny little bits and pieces in various things. But if you really sort of think hard about it, I think the physiology holds, right? So you have to decide, are you resynchronizing the RV because the RV is failing, right? If you have Tetralogy of Fallot and the RV ejection fraction is 10% and the clinical symptomatology is RV failure, perhaps there is value to resynchronizing the RV, right? And there are other patients. There are perhaps patients with pulmonary hypertension where RV failure really is the primary disease. But if your clinical presentation is LV failure, then I think you have to be clear about what you're trying to accomplish, right? If there's LV dyssynchrony mixed in and the ECG is just not sophisticated enough to capture the degree of dyssynchrony, well, then yeah, maybe we have to map them. Maybe we need the cardio insight vest to figure them out various things, but don't try to resynchronize the RV to make the LV better, right? We resynchronize the RV perhaps to make the RV better. Thanks, Jeff. That was great. I want to thank all our speakers and our audience. I hope you enjoyed the meeting. We'll see you next year in Chicago.

heart rhythm innovations

cardiac resynchronization therapy

physiologic pacing

right bundle branch block

RBBB

his-bundle pacing

left bundle branch pacing

biventricular coordination

electrical synchrony

heart failure

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