three really nice studies about looking at longer term outcomes. So, fabulous session this morning. So the first speaker I'd like to introduce is Dr Anod, who's going to talk to us about torque transfer occurring during conduction system pacing. Good morning everyone. Thank you Dr Wang, Dr Winard and colleagues. Thank you for coming bright and early on Sunday morning to come and see some of our work. So, my name is Anand Ganesan and I'm an electrophysiologist from Adelaide, Australia. So, the title of my talk is Abrupt Torque Transfer Occurs Frequently During Conduction Systems Pacing Insertion in an Ex-Vivo Model. So, this work deals with some pre-clinical work that we have done on the interface between left bundle area leads and the heart. So, the background to this is of course that conduction systems pacing is a novel technique and it requires additional skills beyond conventional pacemaker implantation. There are some fundamental unresolved mechanical technical questions about the implementation of lead deployment. Question one, and these have been raised by Mark Jastrzebski, is why is there some variability in left bundle branch septal penetration and capture? Question two, is how many lead rotations should optimally be performed? Question three, is there any maximum number of rotations that should be utilised in order to avoid septal perforation? Now, there have been some degree of pre-clinical studies into these kinds of questions. One key paper which I'll highlight is this work by Mark Jastrzebski, which showed in cadaveric hearts and it was a limited study in five hearts where they performed deep septal deployments of Medtronic 3830 leads. And what they showed was that the myocardial lead interface can show quite diverse behaviours. One of the most prominent behaviour in this ex-Vivo model was helix only penetration, which they called defined as endocardial entanglement. The next level was endocardial barrier effect, where you get a partial penetration but really not deep penetration of the lead. The third effect that was described in this study was a drill effect, where you get an initial shallow penetration but then subsequently failure to penetrate further once additional rotations are applied. And finally, what we would like, which is progressive penetration. With each added rotation we get further and deeper penetration into the myocardium. So we actually sought to replicate this model but study the mechanical forces at the lead interface. So the aim of our study was to assess lead tip characteristics at the endocardial interface in a novel pre-clinical model. So our hypothesis is that lead tip rotation and insertion at the endocardial interface does not follow a linear model. So this is a description of our model. So basically what we devised were, we took our ex-Vivo ovine hearts and we used 64 hearts for this study. We tested 1 fixed core lead the Medtronic 3830 and 3 stellet driven leads. And the way the model is established is that we basically mount the lead in its sheath on a jig and we attach a flag at the lead tip and have a high resolution camera taking digitised images of the lead. The flag allows us to monitor the progression of the lead tip rotation while the torque wrench is applied at a consistent speed rotating 90 degrees until 15 revolutions. So approximately 60 images are taken each run and then we digitise the images and measure the outputs of the impact of torque delivered at the base of the lead. So one of the key observations of the JASCREBSI paper, which we were also able to replicate, is this idea of entanglement. And this is something that can occur also clinically. So what is this? What is entanglement and what does it mean? Because it's probably not a term that's commonly used. Endocardial entanglement occurs due to partial screw penetration and helix only penetration. So this is an example video from our study, which we have played at higher speed than deployment. So what you can see is that lead initially, the screw engages, but what you can see is there's build up of torque and you can see a spiralling of the myocardium at the lead myocardium interface. And what we experience on the base of the lead is a build up of torque. And so what we wanted to study was the lead myocardial interface in conduction system spacing in this ex vivo model. So in our in the JASCREBSI study, what they defined was a helix sorry, in our study, I should say, I think this is an error in the slides, my apologies. In our study we actually found a higher rate of entanglement than JASCREBSI's initial study. So we found helix only penetration around 70% of deployments. The drill effect also occurred where we got zero penetration. And we also found similar to JASCREBSI's study, progressive and like consistent penetration occurred actually in the minority of deployments. So we were able to, because of the way we conducted our study, to do some statistical analysis of what was actually going on. So this graph represents what we call a rotation response curve. The x-axis represents the number of rotations in full rotations. And the y-axis shows what we observed as the helix rotation by monitoring the flag. And what you can see is that there are several break points where the slope of the lead response suddenly changes. And we call these, we describe these phenomena using piecewise linear regression. So what we can see is that there are periods which we call reduced torque transfer. So that's where the input rotation to the helix rotation is greater than 1. So you are applying torque to the base of the lead, but it's not actually turning at the tip based on the motion of the flag. So you can see that there's a lot of periods where the lead is not rotating 1 to 1 between the base and the tip. You can also get what we call uncontrolled abrupt torque transfer events. That's where you get a non-linear abrupt release of torque and then the screw penetrates suddenly. So that's, for example, here where you get a jump. And so this allows us to have some insight into the biophysical process or that mechanical process by which that's occurring. So these are some of the summary statistical results. So the first point to make is the key outputs that we measured were what we call the mean response slope, the mean number of reduced torque transfer events and the number of uncontrolled abrupt torque transfer events. So the slope is lowest and we have the reduced torque transfer with the Medtronic 3830. So that tends to be the lowest, because obviously it lacks a stilette. So it's easy for failure to penetrate and it has to be something that is taken into consideration. You get fewer uncontrolled events with the Medtronic device, but all the stilette driven devices are fairly similar in terms of their response slope, the number of reduced torque transfer events and the number of uncontrolled abrupt torque transfer events. So in conclusion, reduced torque transfer events are common during lead insertion. We think that this is an area which requires more study about the deployment of the lead in left bundle area pacing. Uncontrolled abrupt torque transfer events represent a sudden release of torque at the helix and potentially is something to consider during lead deployment. And I think more study needs to be done into these technical issues around lead placement during conduction system pacing and optimisation of the technology, I think will also improve some of these issues over time. Thank you. Thank you. Thank you. That's a fabulous study. Really, really interesting. I think we've got time for a few questions. So I'll start, because I've got loads. Clinically, when we experience what we think is entanglement, often we'll stop and go to a different position. How often did you see in your study where you got the entanglement experience and then the lead then progressed? It looks from the data like that was the normal situation. Entanglement, it's the majority of the case in the ex vivo model. Entanglement is higher than when you do it in a patient, because obviously it's an ex vivo heart, so it doesn't have the exact elastic properties of, even though they're fairly fresh hearts, but it doesn't have the elastic properties of true myocardial tissue. I think you can get some progression after the initial release, so I think after entanglement. So you can keep trying, and we tended to keep trying, because what we wanted to do was have a fixed protocol. We were going to apply a set number of rotations and then just see what happens. So that's the way we did it in this study, rather than like what you might do clinically, which is to take it out and then put it again. So what we did was we decided to have a fixed protocol, so we would apply the same number of rotations every time and just measure what happened at the lead myocardial interface. But it's really interesting that actually quite often you were then able to move it. Yeah, you can keep going. And do you think those times when there was the accelerated torque transfer, was that to do with entanglement and then release? Yes, we think so. Really nice. Pugal. Very nice work. Just a couple of thoughts and questions. So some of the things we have learned over the years is changing techniques. So early on, we would do very slow rotations and trying to penetrate and stop at each step and then do what happens. So most of us, current technique is really rapid rotation. Yes. So have you seen a change in entanglement effect when you do slowly versus rapidly? That's a great question. So the way this model, this is our first attempt at developing a preclinical model in this area. So I think in this model, we used a slow, steady rotation and so that we could monitor the mechanical output. So it doesn't replicate this particular model the way we've done it, like rapid rotations, which is what is done clinically. But what our intention is with the development of the second generation model, so future studies, is to do a few things. We're developing tools to measure the buildup of torque in the lead and allowing us to also take high resolution video images, because this was done mainly with static images in this first generation study. And then what we are intending to do is measure torque buildup and also to do the deployment at a faster rate and measure the impact on rate. Can I have another question? So one of the challenges currently is that lack of adequate tools to have very close contact in enlarged atria and enlarged ventricle. Often you have to deploy the lead a little bit far away with the sheath not opposing the septum. So if we can also look at studies to see if your sheath is far away, if you have to rely just on the lead alone to penetrate, is there different effects? When the sheath is very close, obviously it's much more effective. No, we haven't studied that yet, but we should include that. That would be easy for us to do. We haven't done it yet, but I think it's a great question. Professor Huang's raised one really interesting point as well. Another thing we want you to study, this is an outstanding model, is the way the lead interacts with the ventricle. So whether it's entirely perpendicular or not and whether that increases the... Yes, that's right. So in this model we only used an orthogonal angulation and we haven't tested the effect of angle, but I think obviously in the real world you don't get to choose an orthogonal angle every single time. And I think it's an excellent question and something that's worth future investigation for sure. Thanks very much. Thank you. Please stay, because there may be some more questions at the end. Okay, the next speaker is Pablo from Italy. His topic here is... I'm from Spain. Sorry, from Spain. His topic is the result of the physiological pacing registry and international multisensory prospective provisional study of conduction system pacing. Please. How can I go to my... Hello, everybody. Good morning. Okay, this is my presentation. So, first of all, I would like to thank Abbott and Lee Quanticoff, also Puglia, for support and valuable support in helping me to develop this study. Also, I would like to thank all the elders who have collaborated in reporting patients. I would like also to do a special mention to my colleague, Teresa Muladera, for supporting collecting accurately the data of more than 180 patient image centers. So, this is the result of a physiological patient registry, and it is international, multi-centered, and prospective. And, as everybody knows, right ventricular apical pacing provokes ventricular dyssynchrony, and this can have deleterious effect in the long term, and also in the short term. In fact, we admit it in our days, the system or truly cardiac-induced pacing-induced cardiomyopathy. So, conducive system pacing, including both his bundle pacing since more than 20 years ago, more recently described by Dr. Juan, the left bundle branch at a pacing that has been proposed as an alternative to conventional pacing to avoid this cardiomyopathy, this pacing-induced cardiomyopathy. Despite its effectiveness has been very well proved, still many technical and clinical challenges persist, including some difficulties in delivering the lead in the desired position, also ensuring accurate capture confirmation, especially in the left bundle branch area, and also some concerns about maintaining a stable pacing threshold over time. So, this is a pacing registry, international, multi-centered, prospective of patient receiving conduction system pacing in order to characterize and plan a follow-up result in the long term. It is important to know that the registry was planned initially to enroll only patients who had his bundle pacings. Starting from October 2020, patients with left bundle branch area pacing were also enrolled and new centers joined to our study. So, finally, the registry was carried out across 44 sites located in 16 countries worldwide. The patients were included when they need to be implanted either a pacemaker, a defibrillator, or a CRT device. The only requirement was that the generator should be a voltage generator, but any commercially available pacing lead or delivery system was permitted and the implant was performed according to the personal routine care in every center. Patients should have at least 18 years of age, willing and able to comply, obviously, with the prescribed follow-up tests, and, of course, all the patients provided writing, prior to the registry. These are the key exclusion criteria, a history of the cuspid bulb, previous chronic physiological pacing lead implant, life expectancy less than a month, and they were excluded also if the patient were participating in a study with an active treatment at the time of enrollment. This is the study flow and disposition. Initially, 870 patients were enrolled, 768 were successful, and 667 patients completed the six months of follow-up. In the meantime, some patients missed because of death or because of missing visits. Between 2018 and 2031, there was a gradual rise in his bundle implant, as you can see in the figure, and in the fourth quarter of 2020, also was permitted left bundle branch area pacing, and they also increased over time. Related to the result, patients included had an average of QRS duration of about 120 milliseconds. The average elation fraction was normal, but a number of pacing about, I can't remember, I think 56 patients had elation fraction less than 50%. The predominant QRS morphology was normal, but also pacing with left bundle branch block, right bundle branch block, and other conductive diseases were included. Most of the patients had no cardiomyopathy, 70% of the patients had no cardiomyopathy, and the primary indication was pacemaker. And what about the implant success rate? Well, the fact is that the result depends on the criteria that we use to define what was success. Taking into account the site reported by the physician involved in the implant, the success rate of his bundle pacing was 88%, and left bundle branch area pacing was 95%. But as you know, the criteria for his bundle capture are very clear, but in the case of left bundle branch area pacing, we are still debating which are the best criteria to define success. That is why we decided to send a sample of the ECG to our expert in order to decide what was accepted or not. When we took into account this criteria, the implant success was very similar between his bundle branch and left bundle branch area pacing. However, when we took into account the pacing parameters, the result were favorable for left bundle branch area pacing, 79% and 95%. And what the result taking into account the previous experience of the implanter. In this case, when the implanter have done more than 10 cases previously, the result were very similar, 90% and 95% in cases of left bundle branch. However, with less than 10 cases, there was a favorable result for left bundle branch area pacing. Related to the procedure duration, fluoroscopy duration, and pacing parameters, you can see in this table that were very reasonable for a standard clinical practice. Fluoroscopy duration, 12 minutes, similar for common plastic. However, when we have a look to capture dress hole and to the pulse width, you see that also acceptable in both cases are a little bit better in the case of left bundle branch area pacing. In both cases, the PACE-QRS at 6 months was narrow, and in the case of ejection fragile, there was an average improvement of 6 points in those patients that previously had less than 50%. When we compare the result between these two electrodes, the 3830 electrode from Mectronic that was the most used during the registry, and the 2088, the result were very similar between them in terms of capture, impedance, and stability in the long term. Very similar result between the two electrodes. The main concern with the conduction system and pacing are the complication. What about complication? In fact, the complication were only a few, and most of them were not related in fact with the position of the electrodes, such as bleeding, only exit block, and perhaps lead migration, but the rest of the complication are not related at all with the position of the electrode. So in conclusion, overall conduction system in plant success rate was 90%, very similar between both position. Pacing threshold defined success was better in the case of left bundle branch area pacing, but although pacing parameter seems better in this position, in left bundle position, the clinical impact in longevity and functioning of device still need to be determined, and is the opinion of the committee and also my personal opinion, but probably new leads specifically designed for not left bundle, but mainly for his bundle area pacing could improve our results. The implant success rate was influenced by the level of prior experience, but only with 10 cases, with 10 cases the results were very similar. The electrical performance between 2088 and 7030 leads were comparable, and what is more important, the incident of serious adverse effects associated with conduction system pacing was very, very low in this large prospective registry. Thank you very much. This is a very interesting study to compare his bundle pacing and the left bundle pacing. We know his bundle pacing had many advantages, for example, less track hazard while regurgitation. What do you think between the track hazard and regurgitation? We didn't evaluate the regurgitation in this registry, but in my personal experience in my lab, we have not had problem with regurgitation in the case of his bundle pacing. We have done a study comparing the results when the lead is over the bulb or below the bulb, and the results are very similar with no specific problem with tricuspid regurgitation. Okay, and we know left bundle area pacing had many advantages, for example, with simultaneously capture of local myocardia and high amplitude, so left bundle pacing has more safety than his bundle pacing for patients who is pacing dependent. What do you think of it? I don't know. I think it's a question we have to resolve in the future, because in my lab, we don't study specifically this in this registry, but in our personal experience in my center, we have no data. Thank you very much. I think we'll have to move on. What's unique about this series is that it's prospective data, so it gives us really valuable information about what is happening in practice, truly prospective, so really interesting. In the interest of time, we're going to move on, so Dr. Diaz from Las Vegas is going to talk to us about left bundle area pacing in patients with severely reduced left ventricular ejection fraction. First of all, I would like to start by thanking the organizing committee for having me here, for inviting me here. And on behalf of all the co-authors, I would like to present to you our results of our study comparing biventricular pacing versus left bundle branch area pacing or clinical outcomes in patients with very low left ventricular ejection fraction, which we define for this study as a left ventricular ejection fraction less than or equal to 20%. My name is Juan Carlos Diaz. I'm an electrophysiologist at Clinica Las Vegas in Medellin, Colombia. This is the group of authors, and these are my disclosures. Importantly, I have received speaker and proctoring honoraria from Medtronic for this kind of procedures. The rest of the authors have no conflict of interest. So as we all know, cardiac resynchronization therapy has been associated with significant improvements in both clinical outcomes, including reduction in heart failure, hospitalization, and all-cause mortality. However, it has several drawbacks mainly related to how we approach the patient and how we are able to implant a left ventricular lead due to varying venous anatomy, varying anatomy of the phrenic nerve, and lead dislodgement and related complications during follow-up. Left bundle branch area pacing has been established as a suitable alternative in patients who require cardiac resynchronization therapy. And although most clinical trials have demonstrated the impact of cardiac resynchronization therapy in patients with a left ventricular ejection fraction generally over 20%, there has been few representation of patients with less than 20% in clinical trials and registries. And to date, left bundle branch area pacing has not been compared specifically in this population. So our objective is to determine the outcomes of left bundle branch area pacing in patients with very low left ventricular ejection fraction. And as I had told you before, it has been defined for this study as a left ventricular ejection fraction of less than or equal to 20%. This is a multi-center perspective registry with several participating centers in Colombia and in the U.S. And we included consecutive adult patients referred for cardiac resynchronization therapy using either LBUP or VIVE pacing between January 2020 and August 2022. These patients are all included as first-line therapies, which means that for patients undergoing LBUP, we offer patients LBUP as a first-line therapy, not as a bailout therapy or as an alternative therapy. And the same goes for biventricular pacing, that the individual choice on which pacing strategy was chosen for each individual patient was based after thorough discussion with the patient on the risks, benefits of each of these procedures and whether or not the patients accepted or not left bundle branch area pacing. The inclusion criteria were patients with persistent heart failure-related symptoms despite optimal guideline-directed medical therapy for at least three to six months, a left ventricular ejection fraction of less than 35%, and left bundle branch block according to Strauss criteria. We excluded patients with previous attempts at cardiac resynchronization therapy, and obviously patients with mechanical tricuspid valves were excluded from this analysis. The study procedures are pretty standard for biventricular pacing. The dedicated tools and techniques were chosen by each participating physician. We aimed always to place the lead in the lateral vein, anterolateral vein, lateral or posterolateral vein. In all cases, the anterior interventricular vein or the mid-cardiac vein were avoided, as they had been demonstrated to increase mortality. All patients received quadripolar leads for this kind of procedure, but there was no indication on any kind of lead specifically or on any vendor. For the LBEP technique, we used a nine-partition technique described by Dr. Wang's group some years ago, and we used specifically for this study in all patients the Medtronic SelexiCure 3830 lead with a fixed curve sheath, a C315 sheath. Our primary approach was to achieve capture of the left bundle branch. In every case, this was our primary target, and we defined it according to currently accepted criteria. If we could not produce left bundle branch capture after several attempts, then we aimed at leaving the lead at the left ventricular septum and accepted that as a favorable outcome. In all cases, all devices were programmed to achieve the shortest cure restoration. In the case of BiB pacing, we chose first the electrode, the most basically located electrode that did not have phrenic nerve stimulation and had a reasonable threshold. And then in all cases, we tried to achieve fused rhythms and adjust the AV intervals and the interventricular intervals to try to achieve the shortest cure restoration. In patients undergoing LBEP, we first tried unipolar pacing and evaluated the cure as morphology with unipolar pacing. Then we tried bipolar pacing to see if we could achieve anal capture of the RV septum. And then we tried different AV intervals to achieve the shortest cure restoration, again, aiming to achieve a fused rhythm. All these patients had lead bundle branch block, and as such, we did not aim to look for the left bundle branch potential during lead placement. The primary outcome was a composite of all-cause mortality and heart failure-related hospitalization, comparing the BiB pacing group versus the LBEP pacing group. The secondary outcomes were the individual components of the primary outcome, procedural characteristics including procedural and fluoroscopy time, improvement in the functional classes established by the NYHA functional class scale, and improvement in left ventricular ejection fraction. And finally, paced cure restoration between both study groups. For the paced cure restoration, we measure it from the onset of the QRS to the final deflection of the QRS. Although we are aware the current guidelines recommend that we should measure the QRS duration and left bundle branch error pacing from the stimulus to the end of the QRS duration, we believe that because there is a latency expected because you're spacing the conduction system pacing, it would not be fair for the lead bundle branch error pacing groups. An additional sub-analysis was performed to evaluate the impact of very low left ventricular ejection fraction on LBEP procedural characteristics and clinical outcomes, which means that in patients with undergoing LBEP, we compared those groups who had less than 20% with those who had 21% to 35% and evaluate all these procedural characteristics and clinical outcomes. These are our results. There were a total of 126 patients included, 58 in the LBEP group and 68 in the VIV pacing group. There was a significantly higher use of ACE inhibitors or ARB blockers in the biventricular pacing group with no other differences in baseline characteristics. Importantly, although there is no significant difference, statistically significant difference in the left ventricular ejection fraction at the beginning of the study, patients in the VIV pacing had a slightly higher, albeit not significant, left ventricular ejection fraction, which should be taken into consideration when we see some of our results. Procedural curious duration was around 160 milliseconds, was the median duration. There was no significant difference in the primary outcome. Here, LBEP is shown as a red line and biventricular pacing as a blue line. The primary outcome of heart failure hospitalization or cause mortality, it was not significantly different between both pacing strategies, as neither were the individual components of this primary outcome. However, procedural success, which was defined as achieving placement of an LV lead or achieving left bundle branch capture was significantly lower in the patients undergoing LBUP, but procedural time and fluoroscopy time were significantly reduced in these patients. Remember that although we defined that these patients had failed, we did leave them with a left ventricular septal pacing lead. That is, we achieved LBUP in them, but we did not achieve left bundle branch capture as defined by the currently accepted criteria. The post-procedural left ventricular ejection fraction had no significant difference between groups. However, the change in left ventricular ejection fraction was significantly different between groups with a marked increase compared to biventricular pacing in those patients undergoing left bundle branch error pacing. Moreover, the post-procedural cure restoration was significantly shorter in patients undergoing left bundle branch error pacing, as well as a significant improvement in the functional class as asserted by the NYHA functional class. As I told you before, we performed a sub-analysis comparing LBUP outcomes depending on how the baseline left ventricular ejection fraction, patients with a very low left ventricular ejection fraction were younger, had a higher use of digoxin, and as expected, had a lower median left ventricular ejection fraction than patients having a left ventricular ejection fraction between 20 and 35 percent. There were no differences in other baseline characteristics. And in this subgroup and in this sub-analysis, we found that in patients undergoing LBUP with a left ventricular ejection fraction of less than 20 percent, there was a marked increase in the primary outcome and the risk of the primary outcome, as well as a significant increase in heart failure hospitalizations without any significant differences in all-cause mortality. When we have evaluated procedural characteristics, there was no significant difference in procedural success, although there is a slight numerical difference. It is not statistically significant. But patients with a very low left ventricular ejection fraction had longer procedural times, probably related to the dilated cavities they have, and longer fluoroscopy times than patients who have a left ventricular ejection fraction between 20 and 35 percent. There was no difference in the PACE-CURAS duration between both groups, and there was no difference in the change in left ventricular ejection fraction between both groups. This study has limitations, as any observational study is inherently prone to bias. And even though we performed this as a prospectively enrolled patient, it is impossible to eliminate all confounders. One of the main confounders is that although most operators had a lot of experience and many years of experience with biventricular pacing, this was our first experience with LBAP. And although it has been shown that patients do have good clinical outcomes and good initial results with LBAP, even from the first cases, that is a significant limitation. The other limitation is that we have a small sample size, around 60 patients in each group, and as such, many difference in hospitalizations could have not been detected by our study. So in conclusion, in patients with left ventricular ejection fraction of less than 20 percent, LBAP is not associated with a significant difference in the composite outcome of heart failure-related hospitalization and all-cause mortality compared to biventricular pacing. However, LBAP resulted in shorter procedure on fluoroscopy time, shorter PACE-CURAS duration, and significant improvements in left ventricular ejection fraction and functional class of these patients. In patients undergoing LBAP for heart failure and cardiac resynchronization therapy, the presence of a pre-procedural left ventricular ejection fraction of less than 20 percent is associated with longer procedure and fluoroscopy times. However, the improvement in left ventricular ejection fraction and the PACE-CURAS duration are no different. Thank you. I think we've got time for one or two very short questions. So very interesting. About 30 percent of patients, you didn't get left bundle capture. You had LB septal capture. Did you notice any difference in the EF improvement in those? We have not performed that analysis because the number of patients is very small, but we think that is something very important that, for example, Dr. Wang, Dr. Vijay Raman, who have very large registries, we are planning on doing this. Maybe we could get together and work on this, is trying to define what are the outcomes and whether or not we should be aiming at left bundle branch specifically pacing, or should we just leave it if you get a good left ventricular septal capture. But for the moment, we're aiming at the left bundle branch. We didn't have enough power to. I think it's nice that you stuck with the conduction system approach rather than crossing over, which is easier. It's quite novel. Yeah. Thank you. Nice study. But we saw this analysis regarding the left bundle pacing patients less than 20 percent, but we didn't see what was happening with the biventricular pacing between the patients less than 20 percent and more than 20 percent. Have you done this analysis? No, we didn't do that analysis in less than 20 percent. We have done this analysis for another, but we didn't present it here. Specifically, patients have more highly hospitalizations, which is expected, but the procedural success rate does not vary a lot. It would be interesting, you know, to compare also these two categories. Thank you. Any other questions? He's come. He has come. Next speaker is Zhu Haojie. His topic is long-term clinical outcome of left bundle branch pacing versus biventricular pacing for heart failure treatment. Real-world experience, please. Okay. Looks like he's not coming. So that gives us a little bit more time for some questions. I've been very strict with time. Anyone got further questions in terms of? No, I think the important point raised about left bundle branch capture. So we kind of accept left ventricular septal pacing in bradycardia patients, and we struggle with the concept of how hard should we try, especially when biventricular pacing is such an effective therapy. So one of the challenges with left bundle branch area pacing is that confirmation of left bundle branch capture, when it's absent, doesn't mean there's no capture. That's the challenge, all right? Sometimes you can confirm it, but may still have left bundle branch capture. So the criteria for the high specificity criteria, sensitivity is lacking. So we have to come up with what is the minimum acceptable standard, especially when you do for CRT indications. So once we agree upon, then analyzing these results will be quite helpful, because otherwise we don't want to discard patients with LV septal pacing who may still have reasonable outcomes. I think this is really interesting, isn't it? Because it's the concept of stimulating the LV septum and then sort of delayed activation and sort of latency before we then, but then we do get LV activation. So the lateral wall is still activated physiologically. And our big challenge at the moment is how to detect latency of conduction system activation versus true LV septal capture. And the criteria we have at the moment are not ideal for doing that. And perhaps we need to look at some sort of indirect or more direct pattern of activation to confirm that. But that's the crux of the question at the moment. The big question is when is it good enough and in which patients. I have a question that pertains to Dr. Anand, the clinician's lecture on the interactions between the tissue and the lead and the screw. You know, there's been a fair amount of studies done in the past on interactions between the needle, the needle puncture of tissues. And when you do transeptal punctures. So one of the things that happens is when you first apply forward pressure in the absence of radio frequency energy, you know, there is tissue displacement or boundary displacement. And then all of a sudden when you have, then you have needle puncture. And when you have a needle puncture, there's a sudden release of energy. How much do you think that is relevant here? Do you have significant tissue displacement before the screw punctures, penetrates the myocardium? I think the answer to that is the tissue displacement with a lead seems to be once that very first puncture of the part, that distal part of the screw enters the myocardium. Then you get that endocardial entanglement occurring, right? So in the absence of like full penetration. I don't know if that answers the question. So do you think there is significant displacement of the septum happening before the screw, you know? In other words, when you look at the fossil of Alice, when you puncture, you know, there's a significant displacement of the fossil. Does that happen in the septum of the right, you know, right ventricular septum? In this model, we haven't monitored that aspect. We monitored as our kind of output as the lead depth. So we carefully measured like what depth of lead was achieved. So I didn't present that data, but we've got that data, but we didn't measure what you're asking, which is a quite good question, which is, is there any prior to lead penetration, is there any mechanical displacement of the ventricular septum? Because when there is mechanical displacement before the puncture occurs, there is pent up energy. Yes, yes, absolutely. Absolutely. So, yeah, I think that the forces around the lead myocardial interaction, I think there's a lot of opportunity for further research in this area. If I may, I was speaking earlier with Dr. Anand. One of the things that you see in many review articles is that with stylet-driven leads, you can push against the lead against the interventricular septum. But I do believe, and in my experience, that is not a good thing, and maybe that's something you should add to your model, because when you push against the septum, you're increasing force normal and mathematically you're increasing friction, and that could increase the risk of producing entanglement within the myocardium. So maybe that's something you could add to your model, how much push you give to the lead. It's very interesting, because actually you saw less sort of jumping forward of the lead with the 3830 rather than the stylet-driven lead, which is a little bit unexpected. I have to say, if I was going to predict what I would have thought it would have been the other way around, so maybe this is the explanation, you actually can displace a little bit more and actually produce much, much more friction. Hi. This would be a question for the entire panel. Given that this left bundle branch area pacing is a new technique and hasn't been around for as long as the standard apical placement of pacing leads, and that these leads were not really designed to be lodged within the septum with a hinge point, I guess the question is, what do you think the long-term durability of the leads that we're placing now will be? And at some point will we start seeing a lot of lead fractures? I mean, there have been some reports of early lead fractures. The other corollary, just another complication question, is long-term tricuspid regurgitation. There do seem to be a number of studies coming out suggesting that more basal placement leads to more TR. So, two questions regarding long-term complications. So, that's a great, great question. Obviously, the companies have been doing testing, and there's certainly, I know, Medtronic, the 3830 have done vigorous testing, and the direct-driven leads, the companies have looked into that. And because, as you say, they weren't originally designed for being in that deep septal position. The findings from their bench testing have been encouraging, but of course, what we want to know is subclinical data. Professor Huang's probably got the most experience. So, have you seen many lead fractures in your patients, and what's the sort of longest follow-up you've got? No definite lead fracture found in our center. We have finished more than 2,500 cases with left-of-the-bundle branch placing. But one patient with a very high threshold, I suspect, maybe lead fracture. But we cannot find exact evidence. Well, we, in my center, we have been doing his bundle branch patients since more than 20 years ago with standard leads, and our main problem was how to fix the lead in the past, not now, in the his bundle area. But in those patients with more than even 20 years of follow-up, we have not had any specific problem with lead fracture in this area. We have problem with threshold, with very old techniques, with rudimentary techniques. But since we are using the technique described by Francesco, our experience with his bundle area related to problem with leads is not important. I guess time will tell, and this is why it's important for these studies to be published. The other big question is... And when we started biventricular pacing, we did not know the long-term outcomes of these leads, and then, again, we did it. I understand there's a risk of a hinge you're doing there. But one of the beauties of left-bundle branch air pacing, when everybody starts worrying about what will happen in the future, is that when you have patients, for example, in this study, less than 20%, most people would just be worried about what would happen the next year with that patient. Now we're worrying what would happen in 10 years. So I think that patients improve significantly. You will see a couple of studies later. And I think it's... As we develop more evidence, I think we will be starting to use this more, even though we do not know what will happen in 10 years. Right, but it's not just heart failure patients that are getting left-bundle pacing leads. It's patients with sinus node dysfunction and normal ejection fraction. So, you know, it's certainly a long-term question, as is extraction of these leads down the line, if anybody's had any experience with that. So for me, the question, the biggest outstanding question is the extractability with leads when they've been in for 10 years from the deep septal position. And that's... I'm not so worried about the fracture. I'm quite convinced by the extensive soft bench. But the extractability is something that we don't know. And that's something that's potentially very relevant for our young patients. And we've got to have this trade-off. I'm convinced that we'll see fewer events due to pacing-induced cardiomyopathy. So on that side, we'll have a trade-off. The other thing is challenges in the few patients with extracting it. It could be that we have to think about different extraction tools. Any other questions? I think... Yep, one more. So what scares me the most when I do these procedures is when you inject dye sometimes and you see the vasculature in the septum lighting up. You know, the interventrical septum is a very, very vascular structure. I mean, there have been complications of a fistula between the septal perforator artery and the RV, septal hematomas, and, you know, LED spasm from tickling the septal perforator artery. Like the comments of the experienced operators in this room. That's what scares me the most. Yes, this is a very important issue for us. In the center, we know we should avoid how to damage the right bundle branch block. The right bundle branch and also another severe complexion is septal perforation. So in the center, no potential. Then we start screwing the lid because in the right ventricle, if the potential is recorded, I suspect this is the right bundle. And how to reduce septal perforation, we should continue monitor for local myocardial current of injury. That's very important. And we screw the lid deep, about seven millimeter deeper, then we should slowly turn patient lid. That's very important. Yes, so I'll try to answer some other questions based on our experience. So the concerns raised are quite valid. Long-term durability of this lid is a concern. With critical follow-up of all of these patients, it's our responsibility to follow this and report it. So one of the interesting things is a study that's recently published in Heart Rhythm. It's shown multiple 400 million cycles of repetitive testing to see what is the impact on the hinge point, what kind of interactions. And so far that lid has withstood the test and seems to be reliable. Other vendors are also working on similar testing to make sure the tip to ring, the face of those lids are stable. These are the questions raised by many of the investigators and continue to be answered. So we have to continue to request those studies to be done and follow up with those results and make amendments to what we do. In terms of lid extractability, at least our early experience suggests surprisingly, we are putting together a series of patients, but at least our early experience from three to five years of these lids, they come out a lot easier than expected. So I don't want to imply that it's going to be that easy 10 years from now. But even at two, three years, the lid coming out of the septum is not been challenging. Other lid to lid interaction, those issues remain, but at the septum it seems to come out easier. So we need to follow that more carefully. Thanks, Pugal. And going on to your question about the septal hematomas and coronary artery fistulas, yes, they were reported. If you look at the MELOS experience, the European experience, 2,500 patients, they were reported in the small percentage of patients. But actually the clinical outcomes of that seem to be good. I mean, it didn't seem to result in long-term problems. But I agree, this is something that we need to be mindful of. One final question. Thank you. So in that vein, recognizing that the basal septum has larger septal perforators, and that when you're very basal in positioning, you're more likely to impinge on the septal leaflet of the tricuspid valve, maybe we should be targeting a more mid-septal position a little bit further away from the base of the heart, although the current recommendations are to be more basal if possible. So I wonder if there's a tradeoff. Certainly your LV activation time is going to look better the further down the septum you are, because you're closer to the free wall of the apex, but your QRS complex is likely to be broader. The more basal you are, the narrower the QRS, but the longer the LVAT. So I think the LVAT can be misleading in terms of success. And to avoid these serious complications, maybe we should be not as basal, a thought for more experienced operators. That's a great question. I think we don't know. I mean, physiologically we think more proximal in the conduction system is better. But for complication purposes it might be less, it might be easier to implant further down the septum. I think one of the important things to raise, but we just had a large hematoma, I mean, out of 2,000 cases. There's a poster later today. So just the look of that hematoma is so scary. The entire septum is like ballooned up, obliterating RV. But thankfully the patient did well conservatively without doing anything. But I think avoiding higher septum or lower septum in the basal region is quite important because the large perforator arteries are in the proximal LAD or the posterior descending artery. So if you go quite posterior, many operators like to go to posterior because it's easier and penetration is better. But then you can encounter these large perforators, and that can lead to hematomas. Thankfully the numbers are small in all of our large experiences. Well, I'm still trying to stay closer to the proximal conduction system, so I don't know yet. But your thoughts are correct in that mid-septum may be safer, lesser large perforators there. So, yeah, still got some really interesting data. Still lots of outstanding questions. So lots more work to do. Thanks, everyone, for joining us. I thought it was a great session. Thanks to the speakers. Really great talks.

conduction system pacing

torque transfer

lead deployment

endocardial entanglement

left bundle branch pacing

biventricular pacing

heart failure treatment

procedure time

fluoroscopy time

clinical outcomes