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EP on EP Episode 70: Approaching Ablation for Pers ...
EP on EP Episode 70
EP on EP Episode 70
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Hi, this is Erskine and welcome to another segment of EP on EP. It's a real delight for me to have a good friend and one of the top guns in electrophysiology with me today, Dr. John Kalman, who is a professor of medicine at the University of Melbourne in Australia, and he's director of the heart rhythm department at the Melbourne University Hospital. John, welcome to the show. Thanks very much, Eric, pleasure to be here. We're going to discuss a topic that's near and dear to you, persistent atrial fibrillation. So let me start with a general kind of opening comment and get your views on this. Assuming no other factors, and we'll get into the other factors, what would be your general approach when you go to the lab or what you're planning to do with an ablation for persistent atrial fib? So our general approach would still, as a primary procedure, in the majority of persistent AF patients, be wide-antral isolation. We are, however, participating in a number of trials. We had just completed our own Australian trial that we were doing in conjunction with Pete Kistler, who was actually the PI, and this was a randomized trial, the CAPLA trial of wide-antral versus wide-antral plus posterior left atrial isolation. We have, although the data are mixed on posterior left atrial isolation, some studies showing benefit, others not, smaller studies and some randomized data as well that's a bit mixed, we firmly believe that there are a group of patients that do do well and derive additional benefit from posterior LA isolation. So we've just completed enrollment in a 200-patient trial, and we've got another year of follow-up to go. So let's follow up on that. I didn't realize you were involved in a trial, but my next question for you was going to be, regardless of that trial, and at least factors that affect it for me, but I'd like to get your view on this, are duration of the AFib. For example, it's been a year or two years of AFib versus just, and you can argue, let's not get the definition, let's say nine months versus like a month, and also the size of the left atrium. Are there factors before you go in the lab that you're sort of saying, I think I'm going to do more than just isolate the veins? Yeah, I think those are definitely factors. Duration of AF, particularly when it's been longer than a year, and particularly large left atria, let's say a dimension beyond five centimeters, for example, or very elevated LA volumes, really do make you have the additional conversation with the patient about established success rates. The other factor that I think is important and has been raised in the past is whether this is a patient who's transitioned from parapsysmal to persistent in the natural history of the AF course, or whether they're one of those patients that are persistent from the outset. And I do think they behave differently. And I think that those who transition from parapsysmal actually frequently do quite well with just a limited wide anterole ablation, whereas if they're also persistent from the outset, always require cardioversion to get them back to sinus rhythm. I think that those patients often require additional ablation. And of course, the question then is always, well, what do you do? And as we've discussed on many occasions, at least to date, there's no strong outcome data that anything beyond anterole isolation adds efficacy. Now, we are advocates of the posterior left atrial isolation approach because we've got a collection of patients who have come back with ongoing symptoms, no benefit derived from a wide anterole isolation, veins all still isolated. And then we've isolated the posterior wall and they've then maintained long-term sinus rhythm. And of course, that's a segment that's not necessarily applicable to all patients, but I think that it is something that is beneficial in some. And then the question is, of course, how do you identify those patients? Well, that's what I was going to get at. So it's a little different, right? They come back and the veins are isolated. It's like, okay, now what do I do? And that you've just sort of answered a little bit that if they come back and you've only done the veins, you're going to isolate the posterior atrium. But what about the patient that says, hey, I'd really like you to do whatever it takes to minimize my having a recurrence? Well, I guess you could say, I'll do that to everyone or you'll sub-select a group. And from your experience, if you're going to sub-select, which group would that be? Well, the ones that I would isolate from the, do the wide anterole from the outset would be the type of patient that you've outlined, longer duration, larger atrial size, persistent from the outset, those sorts of features. We also do look, although again, and we're looking at this again in the context of the randomized trial as to whether high frequency activity in the posterior left atrium is a predictor of who might derive benefit from addition of posterior left atrial isolation. Again, the evidence in that regard is really mixed. And so I'm not sure, and perhaps we'll have a little bit more insight when we analyze the data from the trial just completed. So a couple of questions on this isolation. As I read through the literature, some people make a box, some people literally wipe out the left posterior atrium. What are you talking about? I mean, what do you actually do when you say you're going to isolate it? Because I've seen a variety of approaches in the literature. Yeah. I think that's a really good and important question because, you know, people do have the idea that you can do a roof line and an inferior line and isolate the majority of patients. And there's no doubt that there is a segment of the AF population where that is entirely effective. You do two clean lines and you're isolated. But many patients, and I really subscribe to the whole, you know, the role of epicardial fibers and epicardial bundles. And Rod Pung has actually had a lovely case where he demonstrated that endocardially, the posterior LA was isolating and epicardially, isolated and epicardially, the, you know, epicardial bundles was still connected to fibrillating atrial myocardium. I think the septopulmonary bundle can have multiple insertions along its course into the posterior left atrium. And sometimes, you know, you can do a quite focal ablation in the middle of the box that you've created and isolate with that, you know, clearly an epicardial connection. And sometimes you wind up with really quite extensive ablation within the box before you've eliminated the signals and rendered that region in it to high output pacing. And I think the other question when you're doing posterior left atrial isolation, which is a very significant limiting factor that does modify the approach is the esophagus. And, you know, we do monitor temperature in the esophagus. We use the multi-electrode so-called circuit probe. I like it because it seems to conform to the esophagus and gives you an idea of where it is. And, you know, like most people, when we start to see significant dramatic temperature rises, we're really conservative. And, you know, there are a proportion of patients where it almost becomes impossible to isolate the entire posterior LA because of the degree of esophageal heating. And we'll do a monitored, modified, more limited isolation under those circumstances. So I think they're all factors. And I think once you take on, you know, routine posterior left atrial isolation, you rapidly realize that one size does not fit all. So I'm going to say one last thing and get your response to it. But I'll tell you where I get more conservative. If you go back in and the veins are totally isolated, you know, this is what I discussed with my ablation team. I think more harm is done just blading tissue because you think, you know, I don't mean maybe the left atrial is one area, but I always worry about these recurrent flutters and they become a mess. Honestly, many of my patients have been very happy with taking a drug that didn't work before and having zero afib after the initial ablation. I until we know more, I mean, my own personal feeling, John, is don't go in there and wreak havoc if the veins are isolated. If you have a target approach, I'm OK. But just to go in and do some of these like massive ablations, I think may do more harm than good. But I'm curious to get your input on that. No, I'm 100 percent on the same page, Eric. I over the years have become much more like you, as you described. I'm not quite sure how to put it, but let's say enthusiastic to tell patients the benefit they're going to derive from an AF ablation. I think as the procedures got more certain, our RF times are shorter. Our fluorous times are really short. The procedure duration is much shorter and really you can achieve it extremely reliably in a set amount of time with a very low risk and in paroxysmal and let's say early persistent with a very high efficacy. And I agree in those patients, why would you spend months and years on medication that aren't particularly effective? And and so I think that that's definitely the case. But I agree when you get patients with longer lasting, persistent atrial fibrillation and the veins are isolated, maybe the veins in the posterior left atrium are isolated. Then, you know, I say to patients, very frankly, I'm not sure what to do next and that there are advocates of extensive ablation. And I'm worried about as much about the efficacy. I'm worried about the risk of that extensive ablation and the proarrhythmia, as you say, because the flutters can be even more symptomatic and more difficult to control in the fib. And we all know that. And so, yeah, it's a detailed discussion and I tend to become relatively conservative at that point. Well, this has been a wonderful discussion. And for the viewers, you need to know that I'm here in Indianapolis and my good friend John Kalman is in Melbourne, Australia. So he was very kind to start his day with this EP on EP. And John, thank you so much. And thanks for all the information you provided to the listeners. Now, you can go have a good case in the lab. Thanks again, Eric. It was really a pleasure and always a pleasure to chat. Thank you. Bye, John. Bye.
Video Summary
Dr. John Kalman, an expert in electrophysiology, discusses the treatment approach for persistent atrial fibrillation (AF). He mentions that the general approach for primary treatment is wide-antral isolation, but there are ongoing trials investigating the additional benefit of posterior left atrial isolation. Factors such as the duration of AF and the size of the left atrium are considered when deciding the treatment approach. While there is no strong outcome data supporting additional ablation beyond antral isolation, Dr. Kalman believes that posterior left atrial isolation may be beneficial for certain patients. However, he also emphasizes the importance of individualized treatment based on patient characteristics.
Keywords
persistent atrial fibrillation
wide-antral isolation
posterior left atrial isolation
treatment approach
individualized treatment
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