Right. It gives me pleasure now to introduce, uh, Rick Choi, and Rick, uh, is the director of our, uh, device management program. And, uh, Rick, I still look forward to the day when we see the true advantage of the extracardiac Fontans where there's no arrhythmia. Uh, I don't know if it will ever happen, but I still seem to have a lot of, uh, patients presenting with atrial arrhythmia, which you, you know about. So, uh, um, it would be great to hear, uh, uh, Rick's, um, uh, insights, uh, on, uh, the role of cathode ablation in Fontaine, in our Fontaine patients. Thank you, Grushin, for the opportunity to speak here today. Uh, my admission is that I'm an electrophysiologist and so, uh, sometimes might be inherently dry, but I think this topic is actually interesting. If, if nothing else, because it's controversial and we like controversy. So I'll be talking about the role of catheter ablation in fontan arrhythmia control. And so, kind of two patients that I thought we could think about as the talk goes on and there's a couple of uh polls that I think we can answer as we go through. First patient is a 20-year-old with a non-penetrated extracardiac fontan who recently had their first episode of atrial tachycardia. They were cardioverted without issue, now on Coumadin, and then now 3 months from the first episode of TA. Uh, currently on no anti-arrhythmic medications and kind of the flip side of the same coin as patient 2. 43-year-old with an atrial pulmonary fontan, history of multiple cardioversions for atrial tachycardia, recent increase in symptomatology with 3 to 4 episodes over the last 12 months, had a previous ablation, uh, procedure 4 years ago, is also on Coumadin as well as amiodarone with continued breakthrough, uh, episodes of tachycardia. So I think it shows the diversity of the patients that we're talking about. And if we. Uh, go back through the history, uh, even in the early days of the Fontaine, we knew that, uh, macro reentrant atrial tachycardia was going to be a problem. And if we go back to the data, uh, data from Boston, essentially it was ubiquitous out to 20 years. And so as we have our patients develop tachycardia, we're confronted with a bunch of possibilities. We can cardiovert them, we can ablate them, we can medicate them. We can talk about surgical ablation, pacing, and rate control. But the question is what our real goal is, because if our goal is to keep them tachycardia-free, once patients have their first atrial tachycardia and their first cardioversion, the risk of staying tachycardia-free is, or their, their risk of future tachycardia is quite high, upwards of 80 or 90%. And while the incidence of tachycardia seems to be heavily related to the type of Fontan they have, uh, the risk of recurrent tachycardia, uh, is the same for all Fontan type. And again, if our goal is complete amelioration of atrial tachycardia, I think it's been well documented that atrial, that anti-arrhythmics are not going to get us to a complete suppression of tachycardia. In many studies like this, essentially 100% of patients over some 5 to 6 year period of time are going to have recurrence of tachycardia and anti-arrhythmics alone. And so, I typically think about the decision to ablate or not to ablate as a dichotomous decision. So we either ablate or we don't ablate, but I think in Fontaine's, I think it's more of a circular loop. And so as we have our Fontan patients who develop uh atrial arrhythmias, they seem to enter this loop, and there's a lot of things on this loop we can do to make them better. We can cardiovert them, pace them. Uh, and medicate them. The real question is, is ablation a potential off-ramp, uh, for the circular loop or really just another part of the loop itself? And so if we look, uh, closer at these patients, I think once we have our Fontan patient with arrhythmia, we're then struck, uh, with that we have to make a decision. And so we can ablate them, we can medicate them, we can talk about surgical ablation for some or monitor for recurrence. But really, if we follow out these scenarios, uh, trans catheter ablation is gonna play some role in these patients' life. So it's a bit more of a decision of when, uh, more than it's a decision of, of, uh, if. And I think there are several things that can help us make these decisions initially, as well as throughout their, uh, life. And so, one of the big ones and one that's been changing over time as Doctor Veltman alluded to is Fontan type. And so, I'm an electrophysiologist, so I know there's a lot of different uh types for, for us, there's really 3 types. We have the classic style fontan, the atrial pulmonary fontan, we have the lateral tunnel and the intraattrial conduit, and the extracardiac conduit, uh, fonttan. And even going back to the early Boston data, there was initial hope, uh, that these different, uh, styled fontans would have a significant benefit to the overall incidence of arrhythmia. And this seems to have played out. And things like the lateral tunnel have had significantly less incidence uh of uh atrial arrhythmias. So then the question turned to, is there a difference between the extracardiac conduit and the intracardiac conduit? And that's been a little bit more discrepant with some, uh, showing less um significant difference and some saying that the extracardiac fontan does have a significant improvement. As far as overall incidence of atrial tachycardia, and it becomes important because I think as we change the style of Fontan that we're doing, we're changing the ablation that we're doing, or at least the access to the substrate. And so, in the early days of Fontan ablation, we were talking about putting our catheter into the heart and really attacking substrates where our catheter naturally uh entered the atrial chamber. And as we change our fontan type, our catheter is now not entering. Uh, the atrial chamber, at least as far as an access point. And so now we have to figure a way out of the conduit, uh, back into the, uh, atrial chamber, either through a conduit within the heart or from outside the heart, uh, back into the heart. So it's set up this really interesting paradigm that with these differing. Fontan styles we've made the, we've had a significant benefit in terms of frequency of tachycardia, but I think we've been making our ablations more difficult procedures. And so, uh, even in these lateral or extracardiac fontans, some brave souls have shown us that we can find our way back into the atrium with relative safety. Overall, the Fontan ablation carries some inherent risk. And so this was a nice study again out of Boston where they looked at about 90 patients. Over half of them required some sort of trans baffle procedure, and the risk of complications was relatively high. So if moderate or severe complications, about 10%, and this was actually similar in the non-trans baffle puncture group. Except for the fact if we look at the complications in those that didn't require a trans baffle procedure, it was really driven by a kidney injury, which is probably not highly driven by whether or not they needed a trans baffle procedure, but in those with a trans baffle procedure, they had the. complications the catastrophic death and the major shunts and cyanosis. So I don't think this has been definitively proved, but I think it's not a, uh, particularly low risk procedure. And so there's been several strategies that we've all used to try to make this easier. This was a patient who had a lot of tachycardia, uh, prior to the Fontan and had an ablation. Uh, and at the Fontaine, we asked our surgeon if they could leave a little marker where the, um, uh, lateral tunnel in the fontan was approximated, uh, worried that if we have to go back in, this would give us kind of a landing, uh, area. And the other thing that we've used, uh, are these 3D models. We've used them both for planning of surgical ablation in the operating room, but also to kind of understand the anatomy, uh, and, and where we might have to do a trans baffle, uh, puncture. I think tachycardia type is important and probably not something we think about uh as far as uh ablation. I think as an electrophysiologist, if you say Fontan and tachycardia, I'm gonna tell you it's macro-oriented, and I'm probably gonna be right. But if we look at the type of ablations that we're doing, at least as far as targeting substrates during ablation. There's a multitude of different mechanisms. And so again, this was a study on 52 patients, and the first thing that we saw was that there was actually 80 different arrhythmia mechanisms identified. So, um, the majority of these patients had more than one mechanism. And if we look at the type of ablations they had, yes, macroorientent was the most common type, but was less than half of the ablations with focal atrial tachycardia being important. But as we've started to see as well, ABNRT is a big player in these patients. And not always the easiest ablation uh in a single ventricle patient. And then there was kind of a larger group that was kind of undefined in this study, if you really look at it, uh, was mostly atrial fibrillation. And I think, uh, luckily for the most part, atrial fibrillation uh as an isolated phenomenon is relatively rare, but I think this uh type scenario is more common. So, we'll often put a patient on telemetry and over time we'll see these, uh, periods of time that look overtly fibrillatory. Uh, but if you follow them forward, there's times where it looks much more regular, uh, and kind of the decision is, is this, uh, strictly a fib or is this potentially macro reentrant. And at least for this patient, when we put catheters in the atrium, we can see here on the map catheter that the atrial activation was pretty regular, consistent with a focal or uh macro reentering atrial tachycardia, while at the same time in another area of the atrium, there was highly fractionated signals consistent with atrial fibrillation. And then at other times we would see things like this where again there was regularity to part of the atrium and more fibrillatory in other parts, though even in these other parts there seemed to be a dominant signal, and at least in this patient when we mapped out the dominant signal and did the macroranri ablation, the atrial fibrillation was also cured. And I think this has been shown by other groups. This was a patient where they took more of an atrial fibrillation approach where they went after cafe spots and as they put some lesions in these different areas, there was more and more regularity and then ended with a macro ran and ablation and was successful in terminating both types of tachycardia. So frequency of tachycardia plays a big role. I think there's a big difference between having two episodes over 5 to 10 years and having 2 episodes over a year, and that's probably gonna drive both uh physicians and patients to take a different look at the risks and benefits of ablation. I think one thing we don't have a great handle on is what, what is the actual risk to patients of atrial tachycardia or SVT in general? What's the rate of the tachycardia? What's the rate of ventricular response, but some very smart people feel that it's a risk factor for sudden death. This was from Ed Walsh's paper on sudden death and different congenital heart disease lesions, and for Fontan's, he felt that atrial tachycardia was a risk. And while I'm not sure we've definitively shown that. Uh, a direct link, I think what we can say in, in, in several studies is that, uh, fontans with arrhythmias do worse than fontans without arrhythmias if we talk about things like freedom from overall death or transplant. And uh I'm sorry, it covers it over, but the, these also have been put in risk stratification models and arrhythmia seems to be a big predictor of outcome. The question that we don't inherently know is if we ablate these substrates, will we change their overall risk? And then I think there's harder things like patient preference, physician preference, and center of philosophy, which are really probably driven by most of the questions we asked above. But the real question I think we need to ask and go over with our patients is, is what's the real goal of Fontan ablation. And what are the real outcomes of Fontan patients with atrial arrhythmias who undergo ablation. And so we don't have a lot of large studies. This was a nice study out of Mayo. 260 patients. The vast majority of them were on atrial, uh, or I guess half of the patients were on atrial anti-arrhythmics alone. About 25% underwent catheter ablation and 25% underwent surgical ablation. And again we see that if we look at the group as a whole, almost all the patients ended up having recurrence of atrial tachycardia regardless of their strategy. Though if we really break it down, this was highly driven by the fact that they had a high prevalence of patients on atrial arrhythmias alone, as we have seen previously. And there was a significant improvement in the patients that had a catheter ablation, though not like our other type ablations where we quote 95, 97%, probably more in the range of 40 to 50%. And so I think other groups have kind of realized this and started to look at outcomes slightly differently. So this group looked at it in terms of clinical arrhythmia severity scores, so things like are they on a medication, do they have a recurrence, and how often. And what they showed is in patients with Fontan who didn't have an ablation, they tended to have less or lower arrhythmia scores and not surprisingly didn't change over time. But those patients who had ablation had higher scores to start off with and had significant improvement following ablation, not to zero, but a significant reduction in burden. And in patients who had no reoccurrence, it was a very significant change, but even in patients who had recurrence of tachycardia, while not as robust, there was still some improvement in the overall burden. Maybe for some patients, the way to look at this is not a complete suppression of any recurrence, but a tailoring of the overall burden. And so not really. Designed to talk much about the fontan conversion and arrhythmia surgery, though we know for certain patients it can be quite helpful and I think very different in different hands. I think our experience is probably somewhat more of this variety where fontan conversion is probably somewhere around the 50 to 60% mark and probably not all that different than catheter ablation alone. So at least from my standpoint, the way I typically treat patients is once we have a Fontan patient with an arrhythmia, my preference is usually to try to give them one episode and then to monitor them going forward, either off or on medications, so that can certainly be based on physician preference and patient preference. And then once they have their recurrent atrial arrhythmia, the question becomes, do they circle back around and do we do another cardioversion and monitor, or do we do a cardioversion and now go forward towards trans catheter ablation. And then this may not even be kind of the end of the therapy, and as they have recurrences, do they need future uh cardioversions, uh, ablations, or even talk about surgical ablation. So, in conclusion, I think my main points are, uh, Fontan patients with SVT are likely to have recurrence of SVT. Anti-arrhythmic medications are certainly reasonable, but unlikely to keep patients completely tachycardia-free. A new onset atrial tachycardia or increased tachycardia burden is often an early indicator of other issues. Cathheter ablation plays a major role in the management of SVT in Fontan patients, and I think it is reasonable either as first or second line management, though we need to clearly define our goals with our patients. The role of catheter ablation is going to vary based on center and preference and maybe most importantly, I think the role of catheter ablation is in evolution is going to continue to change significantly over the next decades based on our changing fontan anatomy. So I had the poll questions and can answer uh any other questions that we have. Thanks. Thanks, Rick. Any comments from the panel? Maybe I can ask a question, shoulder, I mean the the AVRT um issue is relatively small, but should er should Jim be doing. Some sort of line of block in all of his front arm patients. A line of block meaning like tricuspid isthmus or what lines of blocks would you be proposing simple, small block. Well, you know, I got to say, at, at the time of most of these procedures, we're rarely, if ever, blessed with that type of macro entrant. They tend to be in the younger patients, I think we've seen they're more scar related to the atriotomy and things like that. And in the Older patients, they're just related to stretching I think it's a prophylactic measure, I guess the only I guess if you did an isthmus ablation, it would be fairly low risk. I mean, I guess the AV node could potentially be at risk depending on the morphology of the ventricle. If you create an incomplete lesion, then you've probably increased their risk. So I would say no. I mean, I think even if you go back to the surgical data from Chicago, the isthmus ablation only. The strategy was much worse than these more aggressive strategies. The problem is with the more aggressive strategies you bring science no dysfunction well into the equation and things like this. So it would be interesting to look at. You'd have to really go forward in time, you know, 20 years to get to answer to the question, which is always hard to do scientifically. Is the, is the patient in the modern era undergoing an extra cardiac conduit Fontana at the same risk? As an atrial pulmonic fontan long term for any arrhythmias, and are they going to be the same arrhythmias? I think they're going to be different. I think they're going to be the same but present at a different stage. And so again with these older patients, you know, we go in and seriously 2/3 sometimes of the atrial tube. Issues essentially scar with no electrical activity and so I think yeah we're going to cut down on the surgical scarring at the time. So that's why we haven't had the incidents early. My concern would be late. They're still at the same risk of overall stretch and fibrosis and things like this. So those, I don't, I don't really understand why they'd be completely. Uh, free from that style unless there's some sort of true hemodynamic benefit out to 20 or 30 years. So yes and no. The Mayo Clinic was largely atrial pulmonary, yeah, yes, all of our data is largely predominant, so it may be very different. Absolutely, absolutely. That's why I think this discussion. It is an evolution and probably should be talked about completely differently. I mean, you should probably have a talk, you know, if, if that's, that's what we're discussing on the atrial pulmonary versus the lateral tunnel versus the intracardi, you know, they're, they're all very, very different patients with very, very different procedures. I mean, we can go from the tunnel back into the heart, but it, you know, gives us pause, and you have to do a lot of preparatory work to do that safely, so. Can I ask you a favor? Can you throw up that case because they, they want to see the case that? Oh, the case that, oh, there's questions with no case, right? So the first, uh, was the 20 year old with the extra cardiac fontan had one episode of tachycardia. Um, currently I'm not on any anti-arrhythmic medications. As, as a true electrophysiologist, I wrote the questions far too long. So, uh, number 1 is, would you ablate them? Number 2 is, would you just monitor them, uh, without anti-arrhythmic medication? And 3, would you monitor them without ablation on an anti-arrhythmic, uh, medication? Or 4 would be other. Great. And then Uh, what's the answer? Oh yeah, well, for me, the answer is that I would wait for their second episode. I think if that episode is 3 years down the road, but we, you have to talk with them. What's your goal? If you, if your goal is to be completely off Coumadin, I don't even know if that's a strategy once you've had your atrial arrhythmia, but if you have to be off Coumadin, the only way to probably do that safely with risk is to, to go ahead with catheter ablation. That's the only advantage I really see. Um, though I think groups have been very aggressive about first-time, they're much better, they're easier procedures, right? If you get them early, you probably have one or two circuits where if you wait 5 or 6 years, you're taking on these, uh, more complex 5 or 6 circuit cases and these other things, so. So the answers are coming in, but after the break we'll probably have more. So far, 57% say recommend starting anti-arrhythmic medication without ablation. 20, uh, it keeps changing. 37.5% recommend monitoring without ablation or anti-arrhythmic medication, and 12% recommend catheter ablation as a first line strategy. I would say that's exactly probably what we do. I mean, maybe 1 out of 10 go right for ablation and the rest are either on or off medications depending on, depending on a multitude of factors. So I gotta say we have not seen a lot of young patients with atrial arrhythmias, and we've been doing lateral tunnels or extrac cardiac for a long time primarily. So I think it's really gonna be an advantage. All of our patients are patient too with, you know, multiple, you know, ablation attempts and, and kind of further down the line. OK, well, um, I, uh, First of all, I want to apologize to the viewing audience. Apparently about an hour ago our global server, I don't know where it's located, but apparently there was a 2 minute outage, so we apologize, and that I blame the Russians. Uh, so that, that obviously none of that will affect the recording. We, we obviously encourage all of you to go back and watch the recording, uh, afterwards, anything that you might have missed. So I apologize for that. But the good news is we have all the numbers here, so we didn't have any attrition. Uh, so, we're gonna alter the schedule a little bit and take a break now. Uh, and we'll probably, is it still gonna be a 10-minute break? Do you want a 10-minute break? We'll do a 10-minute break. And then I think when we come back, uh, Doctor Tweddle is gonna be, uh, giving his talk. So, uh, we'll take a 10-minute break. We'll see you in 10. Thanks.
