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The Lead Episode 3: A Discussion of Magnetic Reson ...
The Lead Episode 3
The Lead Episode 3
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Welcome to an episode of the LEAD podcast. I'm here today with Dr. Martin Stiles from the University of Auckland in New Zealand and Dr. Rakesh Gopinathane from the Kansas City Heart Rhythm Institute. We're going to talk today about a paper that was presented as a late-breaking trial at the Heart Rhythm Society and published simultaneously in Heart Rhythm. This is by Dr. Poonasamy and colleagues from Madurai in India. The study is called Magnetic Resonance Imaging Based Dual Lead Cardiac Resynchronization Therapy, a prospective left bundle branching pacing study. Dr. Stiles is going to summarize the study for us. Thanks Martin. Thanks Prash. Yeah, so thank you for the opportunity to have a look at this because I went to the late breakers yesterday and I saw it. I thought he did a fantastic presentation and I guess I learned as much from the methods of this trial than I did about the results because it's an elegantly designed, described way of left bundle how your decision tree might affect how you get the best for your patient. So just to recap, he took patients with non ischemic cardiomyopathy, so excluded those with significant coronary disease, left ventricular ejection fraction less than 35% with left bundle branch block and in fact in the method section is a really good definition of left bundle branch block that I think we could probably all refer to ourselves either for future studies or even just in day-to-day practice. So it was what a single center in Matarai and cleverly they've called it the Matarai study from the acronym and he found 120 patients who were had guideline directed medical therapy for the usual standard time and he did an MRI on all of these patients and quantified the amount of scar in the left ventricle. They said a cutoff of 10% scar so there were two groups in the study. Group one had less than 10% scar burden and group two had a greater than 10% scar burden and I think he admitted himself in the late breakers yesterday this was a fairly arbitrary definition that he talking to his radiologist colleagues decided that this was what they were comfortable in using the 10% mark and I think you know it could be argued it should be 5% it could be more percent there might be areas of scar in the heart that are more important than other areas but this was what they decided and in fact of those 120 patients just 11 patients had a greater than 10% scar burden so it is a minority significant minority so you end up with 109 in group one less than 10% scar and 11 in group two with more than 10% scar and then it gets a little bit complex difficult to describe in a podcast but but basically the group one patients got a pacemaker and the group two patients got a defibrillator most of those patients got a left bundle branch block re-synchronized the LBB pacing re-synchronization most of them but some of them a minority received a left ventricular lead in addition to their their left ventricular left bundle branch pacing lead and so this is where it gets interesting so you know there's this this sort of connectology of this left bundle CRT you know who gets the who gets the the left bundle lead only who gets a left ventricular lead as well so there was a very elegant description of of left bundle branch block capture and I won't go through the details but you can imagine it's the usual sort of thing about you know left ventricular activation time and if you achieved these parameters you've got the left ventricular pacing lead if you did not achieve these parameters they added a left ventricular lead and in fact in the group one that's the group without scar only four of 105 four of 105 got the LV lead whereas in the second group the scar group seven of the eleven got a left ventricular lead so that tells you immediately that if you've got more than 10% burden of scar you're more likely to need a left ventricular lead and the left bundle is not going to do it do you justice so you know that was interesting for me as a as a novice in this area to learn and then and then there's a whole how do you connect the leads and is one or df1 sort of how do you connect it to the device and you have to read that but you know the decision tree I thought was useful for one for left ventricular pacing capture and two whether they needed a CS lead so in fact only 11 out of 120 patients received an LV lead which I guess is testament to the skill of the operator isn't it they managed to get a ventricular pacing leads and the vast majority now if you were in group one you had very little scar and you got resynchronized by whatever means 80% of the patients had normalized the LV function at 12 months and that's incredible I think that's amazing figures even in group two 33% had normalized the LV function and I guess that just grows to show that you can't resynchronize scar or maybe you can but not as much right so but in both groups is interesting to see got progressive improvements in their left ventricular function at 3 6 and 12 months it's better every time so I think that was also really important so I guess that the main things are you know MRI can be really useful to help you decide whether one you need a defibrillator or two whether you're likely to need an LV lead and the outcome data is is also useful it's worse if you have scar and an MRI is able to predict that for you and I think the main take-home that I got is this great results from left bundle branch pacing based resynchronization and I guess that's what I took home for it just those results and also the methods left bundle branch capture how to make sure you you get it and and how to define left bundle itself so I guess that's what I had to say about the study I think that was a great summary and I guess the other thing that I'd add to that is that they they had quite a difference in terms of the composite endpoint that they had as well which was death heart failure hospitalization or sustained VTVF therapies so this was 3.8 percent in the group that received the in group one which received the pacemaker left bundle pacing and it was 36 percent in a group with scar who received the defibrillator in place so so that that was kind of significant so let me hand it over to Rakesh now to perhaps talk to us about anything else you wanted to add in the potential limitations of the study I think it's a fantastic study I think they clearly show sort of feasibility of left bundle pacing in this population and the way they use the MRI was great I mean in terms of limitations obviously it's an observational study with relatively you know short-term follow-up one year and the I would say the one of the major limitations is the less number of patients in the LGE arm or the those who had scar and and Emma even among that so that's clearly a very high risk population if you look at the scar burden in that particular group or 11 patients like there are like five of them had like almost 40 some percent scar and other had almost a 50 percent so these are like really sort of burned out ventricles in that and so I think that sort of contributes to the outcomes that you are seeing in that case and and as Martin was pointing out the another interesting aspect is the relative lack of impact if it L left bundle pacing in the patient group with scar basically and they almost majority of the meter and LV lead to get that and so you know I think the other thing is that they don't really get into specifics of we don't know was there any medical therapy differences between these two arms and it just says that they were given three months of medical therapy and then randomized so that part and then I think it'll be interesting to see scar distribution in some in these patients and as Martin was pointing out earlier like you know that may change how you look at things and outcomes in that but overall I mean this is a you know with longer-term follow-up we would also want to know what happens to these left bundle leads over the years because they are using the left bundle leads to sense basically for CRT in especially in the even if they put the implant an ICD they're using the septal LBB lead to for sensing so that's interesting to understand but I think overall despite the limitations it's a great hypothesis you know which really need to be tested in a population and it could be a sort of in a practice changing concept here. I mean there's really a few practice changing concepts here isn't it the concept of looking for scar using an MRI as Martin has pointed out no scar with left bundle you may actually get away without needing a different blader at all and that's key number two is the possibility of putting in a left bundle pacing lead consistently in in this single center series I mean I think that was quite amazing and then the contrary to that also is if you have scar you probably are going to end up putting a left ventricular lead okay so let me now ask you ask you both an opinion you know clinical implications of this paper we understand that we need to undertake further randomized studies to evaluate this and there's clearly a signal so you have a population relatively young 58 55 and 58 who have a guideline indication for a defibrillator and a CRTD device how comfortable would you be to to implicate this into your clinical practice now I mean again we would definitely need a randomized study I really like to see more data on the high risk group and one thing I know how conceptually I think that there is a group of left bundle patients who can be quote-unquote benign left bundle and then there is a group that are associated with substantial scarring and and there are some subtle signs in here the left bundle patient the group two patients had wider QRS they had lower ejection fraction so they there were signs they had bigger LVs so they there were signs that they actually were more sicker but I think with you know if it can be confirmed in larger randomized studies and this could be this could be a practice changer. Martin any any changes to your clinical practice out of this well yeah I think firstly just to reiterate that if you've got sort of simple left bundle branch cut him off I can call it that then then you probably don't need a defibrillator and it depends whether you're European American which guidelines you read you don't know how much encouragement you get in that direction I've been more nervous on the younger people because they have less competing causes of mortality so I've tended to favor defibrillators and perhaps the younger people but maybe I don't need to the other thing I'm thinking is that if I've got someone with significant scar on the MRI why would I bother pepper potting their septum for you know trying to infutilely get left bundle branch capture I just go straight to an LV lead perhaps yeah yeah and I guess that the other take home for me is perhaps we'd give them a bit longer to look at what guideline directed medical therapy would do if you didn't have scar formation here that's a great point I think you know they the three months is enough for now I mean especially with the you know armamentarium of drugs that you have and I think you know and also interesting to see the subgroup of people with this so-called high-risk left bundle group like you know are there gradations on the risk in there and and it's why would left bundle lead don't work there is it due to septal scar alone or is there another feature or they you know that prevents it right thank you both for joining me at this episode of the lead this was a very informative paper and we look forward to the next episode thank you you
Video Summary
In a recent study called "Magnetic Resonance Imaging Based Dual Lead Cardiac Resynchronization Therapy," researchers explored the use of left bundle branch pacing in patients with non-ischemic cardiomyopathy. The study found that patients with less than 10% scar burden in the left ventricle had significant improvements in left ventricular function when treated with left bundle branch pacing alone. However, patients with more than 10% scar burden required the addition of a left ventricular lead for optimal results. The study also highlighted the potential usefulness of MRI in determining the need for a defibrillator and the overall outcome of the treatment. Further randomized studies are needed to confirm these findings and potentially change clinical practice.
Keywords
Magnetic Resonance Imaging Based Dual Lead Cardiac Resynchronization Therapy
left bundle branch pacing
non-ischemic cardiomyopathy
scar burden
left ventricular lead
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