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Atrial Fibrillation Energy Sources and Ablation Ap ...
Atrial Fibrillation Energy Sources and Ablation Ap ...
Atrial Fibrillation Energy Sources and Ablation Approaches – Who Gets What?
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Okay. Good afternoon, everyone. For those who are just coming in, I want to make sure this room is for AFib ablation, just to make sure. Okay, perfect. Thank you for joining us today. We are so happy to have you all here. My name is Christina Kutras, and I oversee the NCDR Registry Products. I'd like to introduce our esteemed panel. I'm so privileged and happy to have them with us today. I'm going to start with Sarah Lash to my right. Sarah is our new EP device implant, AFib ablation, and CVASC registry product manager. CVASC registry is our new outpatient registry for EP and cath PCI procedures. So I'd like to introduce Sarah. She's been with the ACC for three years now. So not brand new to the ACC, but new to this role. So we'd like to welcome her to Quality Summit. She's been an invaluable expert and resource for us at ACC. So we're lucky to have her. And I will move on to Dr. Yousef, who will be presenting for us today. He has done previous presentations for us at Quality Summit and has been a big physician champion in quality. He's an expert in cardiac rhythm management and catheter ablation procedures. And he's here to share some information with us on AFib ablation energy sources. So I'll let him continue any further introductions he would like to do. But thank you so much for being here and welcome, Dr. Yousef. He said you can go left with the mouse if you need to. Just so you know, if you want to. Thank you, Christina. And thank you, everyone, for being here today. All right, great. So we have a lot to talk about and it's going to be an exciting 45 minutes. And I'd love to have you guys jot down questions through the app and we'll have some time towards the end where we can discuss those. We will have a couple of questions. And so here's a QR code and you guys can scan this. And that way you can participate in the questions through the polling. So we're going to be talking about a variety of things today. But first and foremost, what is atrial fibrillation, why it's important and what are the implications? What is the rhythm management and the treatment of atrial fibrillation and the role of catheter ablation as first line therapy for atrial fibrillation? We'll review some clinical data with both radiofrequency and cryo balloon ablation and discuss an emerging technology, which is pulse field ablation and review the clinical trials to date with PFA. And then we'll briefly discuss ablation strategy beyond pulmonary vein isolation in patients with more advanced atrial fibrillation, such as persistent atrial fibrillation. So we'll start with the case. This is a 62 year old woman with persistent atrial fibrillation and hypertension. She was diagnosed with paroxysmal AFib a few months ago, but over the last couple of months, it's become more persistent such that she's in it all the time. She doesn't have any specific triggers. She has a history of hypertension and hypothyroidism, but is otherwise healthy. She had an echocardiogram, which showed a left ventricular ejection fraction of 40 to 45 percent with global hypokinesis and moderate left atrial dilatation with no significant valvular abnormalities. She had a stress test, which was a negative for an ischemic heart disease. And overall, her heart rates are relatively well controlled. Resting heart rates are in the 80s to 100s. But when she performs any bit of activity, her heart rates do increase. She's on metoprolol currently, and she's referred for management of her atrial fibrillation as well as her heart failure. So here are the questions. And so what would you recommend for her? Option one would be catheter ablation. Option two would be antiarrhythmic drug therapy with amiodarone. Option three would be to consider antiarrhythmic drug therapy with dafetilide or tecosin. Option D or four would be increased metoprolol for added heart rate control, followed by reassessment of heart rate with some form of ambulatory monitoring. So you guys will have an opportunity to answer this. Okay. Great. So 44% of our audience would like to pursue rate control efforts at additional rate control. A third of us wants to consider catheter ablation and then the remainder for consideration of medications for antiarrhythmic drugs. And so I'm going to ask you this question again at the end of the talk, and we'll see how these change, if any. So AFib's a major problem, right? It's an epidemic, essentially. There's over 5 million people in the US currently with atrial fibrillation, and another 4.5 million people in Europe. And one in four people likely in this room will develop atrial fibrillation in the course of our lifetime. So it's very, very prevalent, and it continues to rise. And there's a twofold increased risk of mortality associated with AFib. So historically, we've thought of AFib as just a nuisance abnormal heart rhythm, which it is. And it's not life-threatening, but there is compelling data now that clearly shows that there is an impact on longevity of life. And the scope of the problem is not trivial. So it affects over 30 million people worldwide, and annually we're seeing over a million new cases of atrial fibrillation. And largely, this is related to all the increased prevalence and the comorbidities, including coronary disease and hypertension that we see. There's a fivefold increased risk of stroke, over 800,000 cases annually worldwide and 80,000 just in the US. It can lead to heart failure. There's a threefold increased risk of that. There's a twofold increased risk of cognitive decline and premature dementia. And it decreases quality of life and reduces longevity. This is data from a large registry from Minnesota, which looked at patients with atrial fibrillation and compared them with age- and gender-matched controls. And what you see here is basically there's a significant decline in survival in those with atrial fibrillation. And so how is atrial fibrillation triggered? This is a schematic of the left atrium. And what you see here are four pulmonary veins. Most of us have four pulmonary veins. And these pulmonary veins are deemed to have the most amount of triggers for atrial fibrillation. And so these triggers are often the initiating factors for AFib, and they initiate here from the pulmonary veins. And that results in a variety of abnormal, chaotic, irregular electrical activity in the atrium. And there's wavefront collision and a variety of things that we don't even fully understand. But the critical aspect of this schematic is that the source of triggers of atrial fibrillation, majority of them in earlier stages of AFib, arise from these pulmonary veins. And so these pulmonary veins have become a robust area for a therapeutic target. And when we put on our catheters in these pulmonary veins, we can see there's very high frequency irregular electrical activity occurring in these pulmonary veins that initiates the atrial fibrillation. And if we step back a little bit and look at the anatomy of the left atrium, this is a posterior view, meaning you're looking at the heart from behind. And what you see here is basically a variety of muscular bundles that encapsulate not just the pulmonary veins, but the entire posterior left atrial wall. And it's these muscular bundles and the ostium of the pulmonary veins that are considered to have the most triggers of atrial fibrillation in earlier stages of atrial fibrillation. But AFib is very complicated, and we only know the surface of it. And what you see here on the right is a variety of other mechanisms beyond just triggers in the pulmonary veins that can drive and sustain AFib. And so shown up here are autonomic ganglia, plexi, which are located in a variety of locations in the left atrium that are deemed to potentially drive atrial fibrillation. And then there are small and large reentrant circuits that can initiate and sustain AFib. There's also this blue structure here, which is the coronary sinus and the ligament of Marshall. And this is encapsulated with smooth muscle that is also thought to have triggers of AFib. And then there are extra pulmonary vein triggers that can drive AFib. This can be in the right side of the heart, in the superior vena cava, or in the posterior left atrium. And so the conglomerate of all this, you can see, is a variety of things that are going on. And we currently don't have all the tools to recognize which one of these biological mechanisms is at play that drives AFib. And this is why AFib is a very complicated arrhythmia. And currently, we don't, unfortunately, have a cure for AFib, despite all the advancements we've made in catheter ablation therapy. And AFib really begets AFib. And what that means is that there's a variety of risk factors that perpetuate AFib. And this includes high blood pressure, diabetes, obesity, sleep apnea, aging, alcohol. And initially, it starts with an electrical problem isolated in the pulmonary veins. There are triggers that can drive paroxysmal AFib, which is self-terminating AFib. And eventually, it progresses, and it becomes persistent atrial fibrillation, which means that the AFib is continuous for at least seven days or longer, and often requires some form of intervention, either a cardioversion or chemical cardioversion with medications or electrical cardioversion, and ultimately can be restored to sinus rhythm. But if we do nothing about it and let atrial fibrillation be, then it becomes permanent AFib, or it can become permanent AFib. And permanent AFib is basically a strategy of treatment whereby all rhythm control efforts have failed, and there are no longer efforts that will be considered for rhythm control, and we accept permanent rate control efforts, essentially. And so this is what beginning AFib is, such that the paroxysmal AFib, as it progresses, it transitions from an electrical problem to a structural problem, whereby the atrium becomes larger, there's increased fibrosis that then drives more atrial fibrillation, and it's just a vicious cycle. So it's critically important that we try to target AFib and any therapeutic interventions in the paroxysmal stage or in the early persistent phase before we allow for this to develop into a structural problem and an atrial cardiomyopathy. When we think about AFib, there's four pillars of management. So we think about risk factor management, which is critically important, anticoagulation for stroke prevention, rate control medications, such as metoprolol or diltiazem, and then rhythm control. And our focus today is, of course, going to be on rhythm management. This study came out about four or five years ago now, in 2020, and it really has changed the way we think about AFib. So historically, any therapeutic intervention or rhythm management was reserved for people who were very symptomatic from AFib. But this study looked at about 2,800 patients, and they randomized them. So it took 2,800 patients with AFib, and they randomized them to an early rhythm control. About half of them were enrolled in that group, and the other half was usual care. And what rhythm control meant is that they can undergo a variety of therapeutic options, including antiarrhythmic drugs or catheter ablation. About 20% of them had an ablation, and the rest of them were on a variety of different antiarrhythmic drugs, as opposed to usual care, which majority of them, 95% of them had just rate control efforts, and very few received any rhythm control. And what this showed over the course of many, many years, seven to eight years, that really after the first year, the curve starts separating, such that there was a dramatic improvement in the group that received rhythm control early on, with early onset AFib. All these patients were patients who had developed AFib within the first year. And so there was a significant reduction in not just AFib burden, but cardiovascular death, stroke, and hospitalization for heart failure or heart attack. And so this really changed the way we think about AFib. And when they looked at the data, regardless of symptoms, so if you were asymptomatic or symptomatic, there was still significant benefit for rhythm management, as opposed to routine care. So this really supports a systemic and early initiation of rhythm control therapy, even in asymptomatic patients. And so historically, we used to think that perhaps a conservative approach with antiarrhythmic drug therapy should be considered before ablation, and that's what the guidelines recommended for certain selected patients. And that's evolving, and our recent set of guidelines that were updated about a year ago has changed this even further, and we'll discuss that. So when we think about rhythm management, antiarrhythmic drugs have issues. Foremost, they have limited efficacy. So anything to the left of this line shows that there's no improvement. And so when we look at antiarrhythmic drug therapy studies compared to placebo, there's really no significant benefit of antiarrhythmic drug over the long haul. And over the course of time, only 30 percent of patients maintain sinus rhythm with antiarrhythmic drugs. So they have very limited efficacy, and they're poorly tolerated. So anything to the right of this line shows withdrawal of antiarrhythmic drug therapy due to adverse effects. And essentially, across the board with most antiarrhythmic drugs, their tolerability is limited and withdrawal rates are very high. And there's potential toxicity. So amiodarone is associated with a three-fold higher risk of adverse side effects compared to placebo, and Sotolol is four-fold higher risk. And when we look at—there was a trial that really put the hamper on rhythm management a number of years ago. This is a historical trial called the AFFIRM trial, which looked at rate versus rhythm and basically showed no difference. But when they looked under the hood, what they saw is that patients who actually were in sinus rhythm, there was a dramatic improvement in mortality. However, it was offset by the use of antiarrhythmic drug therapy. So if it took antiarrhythmic drug therapy to get into sinus rhythm, over half of these people died because of toxicity associated with antiarrhythmic drug therapy. So any benefit of sinus rhythm was negated by the use of antiarrhythmic drugs, and hence it was a wash of a trial. And over the years, we now have very compelling data from many, many studies that show that ablation is far more effective than antiarrhythmic drugs at preventing not just recurrence of AFib, but also improving quality of life. And this has been consistently shown in numerous clinical trials. And when we look at large meta-analysis of over 27,000 patients over a three-and-a-half-year follow-up, there was a 37% reduction in mortality across the board in numerous clinical trials. And same thing for rate of heart failure hospitalization. So there's a significant reduction with ablation versus medications for heart failure hospitalizations. And so our recent set of guidelines were updated just last year. The prior versions were from 2017. And we now have a class one indication, which means that there's strong evidence that supports use of catheter ablation for symptomatic paroxysmal AFib patient, and ablation is given as a first-line therapy over antiarrhythmic drugs. And it also has a class one indication for patients who either don't desire to be on medications or have not tolerated antiarrhythmic drugs. And perhaps more importantly, there's now a class two indication, which essentially says that it's very reasonable to consider catheter ablation as first-line therapy for patients with persistent atrial fibrillation. So not just paroxysmal, but even slightly more advanced stages of atrial fibrillation, where we know outcomes are not as good, but they're still very effective and better than medical therapy. And so perhaps ablation may be better if performed earlier and first. There's a variety of energy sources that are used. Historically, radiofrequency ablation, which uses thermal-based energy and heat energy to destruct the cardiac tissue, is used, and it's still the most dominant source of energy used across the world. But that's slowly evolving. And then we have cryo-balloon therapy, and this came out probably about a decade ago. And this uses a balloon-based technology, which uses very, very cold temperatures to freeze the tissue, but essentially coming to the same goal, which is to destroy abnormal electrical tissue outside of the pulmonary veins that harbor a lot of the triggers for AFib. And more recently, in the last couple of years, there's been a new excitement in our field as it relates to a new non-thermal way of delivering ablative therapy, and that's with pulse-field ablation. And we're going to talk a little bit more in detail about that. So when we look at studies related to cryo-balloon therapy, across the board, numerous studies have shown cryo-balloon therapy to be more effective than medications at reducing rate of atrial fibrillation. And not just rate of atrial fibrillation, but there's a significant improvement in reduction in healthcare utilization. AFib accounts for almost a billion dollars of healthcare costs, and more than half of that is in acute care. So there's significant reductions in hospitalizations as well as healthcare dollars that are being spent with ablation as opposed to medications. One of the issues with our scientific dogma is that when we look at therapeutic efficacy of these technologies, a lot of them are based on historical standards that have been set. And essentially, efficacy is judged on a dichotomous event, whether or not you had recurring atrial fibrillation of 30 seconds or more in the monitoring period after the intervention. And so 30 seconds of AFib is not a lot of AFib, and perhaps a more meaningful endpoint is not necessarily whether you have a binary recurrence of 30 seconds or longer, but what the overall change in burden of AFib is after ablation. And so this is a really nice diagram which shows patients who had atrial fibrillation ablation and had implantable loop recorders pre-ablation, and what that showed post-ablation. So this is basically the number of hours in a day that patients were in atrial fibrillation. You can see the majority of these were upwards of 12 to 20 hours. And then they had the intervention, and you can see there's a marked reduction. We don't quite see it here, but there's a little blip of an AFib that occurred here. This would be considered failure of ablation according to typical clinical efficacy standards for primary endpoints for clinical trials, but you can see there's a marked reduction in AFib burden. And across the board in multiple studies, you see a significant upwards of 98 to 99% reduction in burden of paroxysmal AFib post-catheter ablation. And so cryo-balloon has been shown to not only reduce AFib recurrence, but improve quality of life, reduce dollars spent, reduce hospitalization, and the adverse event rates were similar to medications. And even when we look at persistent atrial fibrillation, the safety rate is very, very good at 0.6%. But one of the issues with persistent AFib is that the recurrence rate is very high. So 55% of patients were free of arrhythmia at the 12-month mark. And so as many as 40% to 50% of patients have recurrent atrial fibrillation with persistent AFib if we use just as a dichotomous outcome of recurrence. But nonetheless, there was increased quality of life and reduction in symptoms associated with cryo-ablation. So there's a big debate, right, a number of years ago, is cryo better, is heat better? And so the fire and ice trial was performed comparing the two therapies, heat versus cold, and they took about 770 patients, about split roughly in half, and randomized them to either cold or hot forms of energy. And essentially what we learned is that there's no difference between the two therapies. So both cryo-ablation and radiofrequency ablation offer the same efficacy for paroxysmal atrial fibrillation. And this has been shown to be true in numerous other studies since then. But one of the challenges with thermal ablation is that there are collateral structures when we utilize this energy inside the heart. And more specifically, there's the esophagus that sits right behind the posterior left atrium. There is a phrenic nerve that innervates our diaphragm that runs alongside the right pulmonary veins. There are coronary vessels. And so thermal-based ablation has been shown to potentially cause harm to these structures. And there's a risk of developing pulmonary vein stenosis over a longer period. And so this has resulted in a lot of excitement around a newer technology, which is called pulse-field ablation, to essentially deliver non-thermal-based energy to destroy the cardiac tissue. And the way this works, pulse-field ablation, is basically using very high-frequency, rapid electrical currents to deliver inside the heart in very, very short bursts. And what it does is that it creates electroporation, which is creating pores in the cellular membrane of the cardiac cell, of the cardiac myocyte. And essentially, that results in a variety of biological changes resulting in cell death. So it's using rapid electrical fields delivered very, very quickly to destroy the tissue without using any heat or cold. And the biggest benefit, other than that it's non-thermal, is that it has tissue selectivity. And we're going to talk a little bit about that. But you can see here, this is a schematic of radiofrequency ablation. You can see that the esophagus sits right behind it. The phrenic nerve runs in the thorax alongside the pulmonary veins. And so there is real risk of injury to these collateral structures. And these are catastrophic complications, at least with respect to the esophagus. The mortality rate is over 90% if one develops an atriosophageal fistula. And unfortunately, this is a delayed complication that presents itself a month later and often gets missed, because patients present with air emboli to the brain and sepsis from multiple bacteria from the oral flora, and they're very, very ill. And cryoballoon, particularly, is known to have issues with injuring the phrenic nerve. Most of these are transient, but there are well-reported outcomes of permanent paralysis of the phrenic nerve. And so can pulse field ablation provide selective ablation such that we don't have injury to these collateral structures? And so far, the answer is yes, possibly. And the reason is that there's tissue selectivity with pulse field ablation. So as opposed to radiofrequency or cryoballation, which delivers energy basically in a discontinuity in a discontinuous fashion, and you get indiscriminate lesions, pulse field ablation, think of it as like a blast zone. And so once the electrical fields are dispersed, you have a homogenous area that gets ablated. And the threshold of injury to the cells is very specific for the type of cells in our body. So for instance, the cardiac myocyte has a tissue selectivity of 400, whereas other cells have a much higher selectivity to injury based on the amount of energy that's delivered. And so can we deliver the right amount of energy with this non-thermal energy source and destroy only cardiac tissue, but not have any implications on esophageal smooth muscle tissue or vascular tissue or nerve tissue? That's the ultimate question. And you can see here, this is a catheter in the pulmonary vein. The sharp electrogram here are electrical activity inside the pulmonary vein prior to ablation. And then these rapid pulses of ablation is delivered with PFA, or pulse field ablation, and you can see that these sharp electrical signals no longer exist, and they're abated immediately. This takes about two seconds, and we typically deliver about eight cycles of these per pulmonary vein. So in less than 30 seconds, you can completely ablate one pulmonary vein. And there's been a number of studies looking at animal models of what happens when you deliver this kind of energy source. So when we look at animal models after RF ablation, or radiofrequency ablation, what you see here is that there is very heterogeneous fibrosis that occurs over time. You can see there's all this white, it's very irregular, it's not homogenous, and you can see there's hemorrhage inside the blood vessels, which get necrosed. As opposed to pulse field ablation, there's a very homogenous area of fibrosis that develops, and the tissue architecture is largely preserved, particularly adjacent tissue structures. So here's a blood vessel inside the heart wall, and you can see that it's completely patent, as opposed to completely hemorrhaged after radiofrequency ablation. There's also fat tissue here that's not effaced, and here we don't even see it. So the impact of the source of energy is quite significant, in animal models that we've learned. But the effects of PFA are very parameter dependent, and there's a number of new technologies with PFA, a number of catheters, a number of companies that are running into this space, because they think this is the next holy grail of a fib ablation, but each therapy has a variety of dose prescriptions that can be prescribed, and it's very dependent on the catheter. It depends on the electrogeometry of the catheter, what the spacing is, how much electrical energy you deliver, over what time duration. So there's a variety of parameters that are used to deliver PFA, and so one PFA catheter does not mean that it's gonna have the same efficacy with another PFA catheter, as opposed to with radiofrequency ablation, if you use one competitor and the other, it's the amount of wattage we're delivering is the same out of those catheters. This is a schematic showing, basically, where this field is going. Currently in the US, we have two catheters approved for PFA, this is the Boston Scientific's Ferropulse catheter, and this is Medtronic's Pulse Select catheter. Europe has a couple of more that have been approved, and there's a number more that are in the pipeline. And so this is a very exciting time for us in the field of EP, and we'll see how this progresses. But you can see the slope of this innovation. The first PFA case was done in 2021, and by 2023, over 10,000 patients treated, and prior to the start of this year, when we first received FDA approval in the US, there were over 40,000 patients that have been ablated with PFA worldwide, and that number is even higher today, ever since FDA approval in the US. This is a little schematic, let's see if it plays, on how pulse field ablation works. So this is a catheter, this is a pentaspline catheter, it has five splines with electrodes. It's inserted over the wire into each pulmonary vein, and the electrical impulses are delivered. And you can see that these are all the adjacent structures. There's the esophagus right here, there's nerves like the phrenic nerve, there are blood vessels, which are all spared with pulse field ablation. And you can see the blast radius from the high-frequency electrical field delivery, where contact is good and necessary, but unlike radiofrequency energy or cryoablation, where you need really adequate contact, this really needs close proximity to the tissue to result in adequate ablation. I wanna go over a couple of key trials that have been performed with PFA. This is the ADVENT trial, which looked at patients with paroxysmal atrial fibrillation about 300 of them, and randomized them to PFA versus thermal energy source, either cryo or RF, which is the gold standard. And essentially, over the course of a year, what we saw is that the arrhythmia-free survival rate was no different between the two modalities. And it is very safe. The safety endpoint was 2.1% with PFA and 1.5% with RF and cryo. Overall, there was no differences in the safety endpoints. And one of the things that we have learned from this is that these are very, very efficient procedures because these impulses can be delivered very, very quickly. And so the procedure times are considerably shorter with pulse field ablation. And when we look at registry data, a lot of this comes from Europe. This looked at over 17,000 patients that have received the ferropulse pulse field ablation therapy, and what we see is that the risk of adverse events are very, very low at 1%. And the energy-specific adverse event rates are extremely low. So there's been, to date, zero atrial esophageal fistulas that have been reported with over 50,000 patients that have been ablated with this therapy. No pulmonary vein stenosis, no phrenic nerve palsies. There have been some reports of coronary spasms if this is performed in the cavo-tricuspid isthmus, like for typical atrial flutter, the circumflex artery runs in that area, and there are some reports of coronary spasm. But that can be mitigated with use of nitroglycerin or other coronary vasodilators. And overall, the risk of adverse event rates are very low, with vascular access-related adverse events being the highest as it is for any catheter-based ablation therapy. And there's a learning curve to this, and that's what we learned with this, that the initial cohort were 1,500 patients. Shown in dark blue are an additional 7,800 sites that were added to this registry, and that continued to expand. And what we see is that across the board, there's been a consistent decline in the adverse event rate as the experience increased. And across multiple registries now, the risk of any major complications is extremely low, between one and 1.9%. So there is a new clinical trial that's undergoing for evaluating the same therapy in patients with persistent atrial fibrillation. The advent trial was in patients with paroxysmal AFib. The next trial is the PULSE-DF trial, and this is Medtronic's catheter. And you can see that the catheter morphology is very different, as opposed to having splines. This is a circular-based design. And they looked at about 300 patients. This was not a randomized study, so they didn't compare it with traditional thermal-based therapies. They just included patients with paroxysmal and persistent atrial fibrillation who had failed a prior antiarrhythmic drugs, and everyone underwent pulmonary vein isolation with this therapy. And what we learned is that there was a 66% rate of freedom for paroxysmal atrial fibrillation, and much lower for persistent atrial fibrillation at 55%. And this continues to be a problem, right? So here we are employing a therapy, but yet almost half the patients have recurrent atrial fibrillation. And so we haven't figured this out, and PFA is unlikely going to figure this out. Although there is some notion that PFA potentially offers transmural injury across the entire cardiac myocyte, and potentially there is greater benefit of ablating in other areas where we typically have difficulty with ablation with radiofrequency energy, particularly in the posterior wall because the esophagus sits in such close proximity. And so if we look at freedom from atrial arrhythmias, both with paroxysmal and persistent, there was about 30 to 40% risk of recurrence, but this is consistent with data from radiofrequency ablation and cryoblown ablation. And the safety event rate was very, very low at 0.7%. Basically one person had cardiac tamponade. There's an additional catheter that is currently not FDA approved, but there's been a number of studies that have been performed with this. And this is an interesting design of this catheter. This is also made by Medtronic. This is called the Sphere 9. And essentially this catheter allows for both pulse field ablation and radiofrequency ablation. And so the idea is that if you need to do linear ablation, not just a single shot procedure of just isolating pulmonary veins, then this potentially offers that. And so this is a trial where they performed radiofrequency and pulse field ablation using this catheter and pulse field ablation across the board. And you can see the lesion delivery here. In the anterior wall, they used radiofrequency ablation. In the posterior wall, they used pulse field ablation. And they compared this with traditional radiofrequency ablation. And what they saw is that essentially there's no difference between the two therapies. And shown here are the different doses. So as I mentioned earlier, all these catheters, all these different technologies have different waveforms and different amount of energy that can be delivered. And so we don't know what that right answer is for this particular catheter. So part of this clinical development of these new tools is to figure out what is the right energy prescription to achieve the most durable outcome. And so they had iterative improvement in the different energy sources as they went along with the trial. And if you break this up between paroxysmal or persistent, whether PFA was used in both anterior and posterior or it was split between radiofrequency and PFA, the bottom line is there were no differences between the two different imaging, or two different ablative therapies. And there's a similar trial that was performed in persistent AFib and that showed similar findings with a very low adverse event rate. And so what we've come to learn is that PFA is very effective. It's as effective as our current therapies. It's potentially safer. It's certainly quicker. What the right answer is, we don't know. And the verdict is still out. And there's increasing data that's being accumulated in the space. And so this is a study where they looked specifically at cryo-balloon and comparing it with PFA. And so they took 400 patients, 200 that underwent cryo-balloon therapy and 200 that underwent pulse field ablation. And the message is the same. PFA resulted in no phrenic nerve injury. Phrenic nerve injury is an issue with cryo-balloon therapy. There were three phrenic nerve palsies in the cryo-balloon arm, but the overall complication rates were really no different. And when we looked at the outcomes between the two therapies, they were no different in both paroxysmal and persistent AFib. And here's another study looking at pulse field compared to cryo-balloon and radiofrequency. And overall, the safety event rate is low amongst all three groups. The procedural efficiency is much improved with PFA. And in this particular study, there was actually a greater recurrence of atrial fibrillation in the radiofrequency group as opposed to cryo-balloon shown in the blue and PFA shown in the yellow. So these are not randomized studies, so it's not clear. It's possible that there's some selection bias, right? The people undergoing radiofrequency ablation, there's some thought that they need more ablation, not just a single shot pulmonary vein isolation, which is what current PFA is being used for mostly and is FDA approved for. And so the question is, which one of these current two catheters is better? And we don't know the answer to that, but we do have some data from these trials in terms of the number of patients requiring repeat ablation. So between PFA and thermal-based ablation, PFA had a 4.5% rate of repeat ablation. And if we compare that to reconnected veins, so the number of veins that are reconnected when we go back in, that's pretty similar between the two groups. The efficacy of pulmonary vein isolation in persistent AFib remains a huge challenge, right? In paroxysmal AFib, we do really, really well, and especially if we do it early and if we perform them in patients without significant comorbidities. But contemporary analysis have shown success of pulmonary vein isolation in persistent AFib to be really poor in the order of 40 to 55% for a very invasive procedure. And so the natural tendency is, well, let's just ablate more because that's what a lot of surgical literature suggested. If you do more, perhaps you get better outcomes. But many pulmonary vein isolation plus strategies, plus meaning do more, either isolate the posterior wall, go after abnormal fractionated atrial electrograms, they've been shown to be ineffective. One of the more common, more strategies is to isolate the back wall of the heart because of this continuous nature with the pulmonary veins and there's a similar embryologic remnant. But one of the biggest issues is the proximity of the esophagus. And so there are some observational data that suggests increased risk of atrial esophageal fistula with isolating the back wall. PVI alone has a lower efficacy in persistent AFib. There's some embryologic development, as I noted, with the back wall of the heart, which is the same as the pulmonary veins. And there's some data that suggests that there are triggers of AFib that come from the back wall of the heart. And the posterior wall was part of the surgical Cox-Mays procedure. And so perhaps there is some role in ablating that. And there's some inherent stress on the back wall of the heart. And there's some relationship to remodeling of AFib to the observed fibrosis that's seen in the back wall of the heart. So it seems pretty easy. And you can connect the left and right pulmonary veins, a roofline and a floor line, and we can isolate it. The problem is that many of them have epicardial connections and it's difficult to electrically isolate it. And many of them reconnect. And as such, our recent guidelines give it a 2B recommendation to do more ablation beyond pulmonary vein isolation. And 2B essentially means that the data is uncertain and we don't know if there's any benefit. And this is shown in, this is actually just a study just published recently, a couple of years ago, which looked at persistent AFib patients, 340 of them who underwent PVI, pulmonary vein isolation, with posture wall isolation or PVI alone. And you can see this is how we isolate the back wall. This is pulmonary vein isolation by itself and a roofline and a floor line can isolate the back wall. But the rate of recurrence was the same. So really the posture wall offered no significant benefit. There's been some data on surgical ablation. So let's have the surgeons ablate the posture wall epicardially, and then we'll go in endocardially subsequently and do a catheter ablation. And that's shown potentially some promise in improvement. And that's called the convergent procedure, but it's very invasive. Patients don't like it. It's, and the risk of complications is not trivial. There's some data on, can we inject ethanol in the vein of Marshall, which innervates certain areas in the atrium that may have triggers of AFib. And there's, so there's some data on potential benefit of that, but it's also difficult to do. And not everyone has a vein of Marshall. And our own data looking at data from the AFib ablation registry in patients with heart failure and without heart failure shows that many patients continue to get a variety of additional ablation, upwards of 22 to 30% beyond pulmonary vein isolation. And this is from a contemporary analysis of real world data. And you can see that these are a variety of lesion sets for persistent AFib, and most of them have shown no promise. So this is the definition of insanity, but we continue to isolate the posterior wall. And I'll be the first to admit, I'm Omer and I do it occasionally, we'll ablate the posterior wall, because the reality is that, you know, when patients come back and the veins are isolated, we don't know what to do. And this is where the field needs to move. But unfortunately, our understanding of AFib remains very limited. And the definition of persistent AFib is also very heterogeneous, right? Is this someone who's been in a week of AFib that's persistent AFib, or have they been in two years of AFib? It's a very different substrate that we're dealing with. So what we can do is deal with what we know, and that is target the substrate for AFib, right? Can we halt the process if we can address the underlying ingredients that got us here to begin with? And that's risk factor management. We know this works. Unfortunately, it's difficult, it's boring, it's not exciting, it doesn't bring in money, but it works. And at least in Australia, it works. So this is a phenomenal study from Australia where they took people who were coming in for AFib ablation, and they randomized them to routine care where their doc told them, hey, you should lose some weight, address your diabetes, hypertension, and another group which enrolled in a very intensive program where they focused on weight management and blood pressure control and diabetes and treatment of sleep apnea. You can see everyone got an ablation. And as early as a couple months, the curves are significantly varied in terms of freedom from AFib, right? So this is the group which underwent intensive lifestyle modification. This is the usual care group. And so this clearly works, and we probably need greater emphasis on this. And so the way forward, what is it? I don't know, but it seems reasonable to abandon strategies that don't work. We have to focus on risk factor management through a multidisciplinary team because it's difficult for someone to come in just to see an EP after they've failed all sorts of therapies, and for us to say, hey, go lose some weight and then come back and see me. That doesn't work. So it requires really a multidisciplinary team between our nutritionists and pulmonary docs who manage sleep apnea to really address this. Is PFA the holy grail for transmural lesions to allow for more effective durability and long-term efficacy? We don't know the answer to this yet, but there's a lot of exciting data that early intervention is important. And if there's, you know, one slide I want you to take away from this is this, is that this is a schematic of what happens, right? So we start off as paroxysmal AFib where it's a trigger-based problem. There are triggers, isolated triggers, largely isolated in the pulmonary veins, but with time, this becomes a substrate problem. This becomes a tissue problem where the atrium becomes large and remodeled and scar tissue develops, and that's where it becomes persistent AFib, and if it goes unchecked, we really have no options. And so the earlier we can target it, the better our outcomes. And there's a lot of data on this. So this is just showing diagnosis to ablation in quartiles, and what we see here is that basically the arrhythmia-free survival is markedly lower the more we wait to ablate these patients. And this is a really nice recent study that looked at a similar thing, but they basically, what they saw is that the first three years of having AFib is where it matters. So if you can ablate them early, you can change the slope of this. This is nonlinear, and there's a steep rise in terms of recurrence rate. After three years, no matter what you do, it's basically too late. And so early intervention's important, and this is really remarkable. I mean, this is looking at patients, a bunch of studies. In orange is shown is patients who underwent ablation. Blue are medications. So if you left them with medications, over the course of 15 years, patients go from paroxysmal to persistent to permanent AFib because medications don't work. If you can halt the process, you essentially let them remain in paroxysmal self-limiting episodes. So even though recurrence rates may be high as a binary outcome, clearly burden of AFib dramatically changes with earlier therapy. So back to our original case, I'm gonna let you guys answer that same question. So it was a 62-year-old woman who had developed cardiomyopathy, had AFib over the last three to six months, and the options were ablation, medications with amioticocin, or rate control therapy. All right, wonderful. Yeah, that's what I would do. And we didn't talk about heart failure, but ablation's very effective, and particularly when it is a cause of the cardiomyopathy, which it likely was in this case. And so the next question is, let's see. Which ablation strategy would you employ? Pulmonary vein isolation alone with radiofrequency energy, pulmonary vein isolation with cryo-balloon therapy, number three, pulmonary vein isolation with PFA. So all of these, we achieve PFA with a variety of different energy sources, or do we do pulmonary vein isolation plus additional ablation with radiofrequency energy or with pulse field ablation? So I'll let you guys answer that. Yeah. And so there's no right answer for this, right? But I think PVI is probably what we all should be doing, is first-line ablation, regardless of how persistent the AFib is, because we have compelling data that suggests that we don't really know what else to do that is very, very effective. And I think that next year, we'll update you whether these actually happen in real life, these numbers, right? Currently, RF still has the largest market share, but this is a very rapidly evolving field, and my guess is that in the next couple of years, PFA will likely become the dominant source of energy source for pulmonary vein isolation. And so I think restoring the sinus rhythm of life is very important. The energy source currently is less important. Efficacy is pretty equal currently with PFA radiofrequency or cryo. PFA may be safer for rare complications, but that are very significant. Ablation as first-line treatment is better than antiarrhythmic drugs. And the really key thing is to get to patients early. The diagnosis to ablation matters, and it delays progression of AFib and structural remodeling. And we don't quite know what to do with persistent AFib beyond a PBI, and perhaps we need to rethink our classification of AFib. And risk factor modification is extremely important, and it's complex, and it's the bedrock of what we should be doing, but we don't do enough of. So here's the ABCDEF for an AFib-free survival, which is cessation of alcohol and tobacco, blood pressure goals that are adequately controlled, CPAP therapy for sleep apnea, diabetes management for adequate glycemic control, exercising, and then weight loss efforts. But this is complex, and it really needs to be individualized. We go through a variety of these stages in each individual patient, and every patient is different. So it really requires a team. So thank you. Sorry we ran a little over, but I'd be happy to take any questions. Thank you. We have a number of questions that have come in from the audience throughout the talk. Thanks, everybody, for those. We'll try to get through as many as we can in the next five or six minutes. The first one is, what are your thoughts on concomitant procedures for an AFib ablation and LAAO placement? Yeah, so that's a relatively new thing that has developed, and largely because CMS has recently, in the last, I think, six to nine months, has approved billing and reimbursement for hospitals for concomitant left atrial appendage closure with either a Watchman or an amulet device with an AFib ablation done in the same setting. So yes, now hospitals will get reimbursed, and so it's possible to do it. The question ultimately is, who are these patients? The patients that are being referred for appendage closure are typically patients who should not or cannot be on long-term anticoagulation. And it's a different substrate than the younger, less comorbid substrate we're thinking about, AFib ablation. Not that they can't be the same, but generally it tends to be a different substrate. Also, for AFib ablation, they need to be able to at least tolerate anticoagulation for at least three months. So patients who've had a prohibitive intracranial bleed who can't be on blood thinners at all for any short duration, they're not even an ablation candidate. So I think that it's a niche. It's probably a small number of patients that might be candidates that need both appendage closure because they're not good long-term candidates, but can tolerate perhaps short-term anticoagulation such that they would benefit from appendage closure and rhythm management. But most patients, the reality is, can tolerate anticoagulation, and there are a lot more AFib patients that can tolerate anticoagulation than those that cannot. Next question. Do you attempt cardioversion prior to ablation? So it depends. If they've been in persistent AFib for a while, I like to halt that process as quickly as possible. So if I'm seeing someone who's been in AFib for several months or they have no idea, they've been in it for a long time, I do like to send them for a cardioversion because we generally can't do an ablation a week from the time we see them. So it's nice to do a cardioversion, get them out of AFib. And it also tells us a little bit about the substrate. If they have immediate recurrence of AFib, it tells us that they're probably a more advanced substrate that we're dealing with. Is it better to ablate persistent AF in sinus rhythm post-cardioversion with and without AFib? That's another good question. It really also, again, depends on how advanced we think their AFib is. So my goal generally is we know that ablation is not perfect. I've shown you that. If someone with persistent AFib is coming and they have a large atrium, they've had some remodeling, their atrium is enlarged, we know that it's going to be a bit difficult. And we'd like for them to reverse remodel, shrink them. So we'd like to try to help maintain sinus rhythm for as long as possible to allow for that reverse remodeling, which then hopefully will help maintain normal rhythm. So I will sometimes put patients on antiarrhythmic drugs for the first three months as I'm planning an ablation. I'll put them on antiarrhythmic drugs, cardiovert them, help maintain sinus rhythm, do an ablation, keep them on the meds for three months. And by then, hopefully their atrium has shrunk a bit and they've had an ablation. So it's basically a double whammy, right? We don't do that in every persistent AFib, but in people who I think are, you think are more advanced substrates based on their atrial size, their comorbidities, their prior cardioversion history, that's something that I think should be considered. So in one of the studies you showed, it's asking if a burden was evaluated post ablation at six months. I believe this came in right when you first introduced RFA. But it goes on to ask, what's the typical timeframe used to determine ablation efficacy, one year or longer? So a lot of trials are done one year trial. So that's where our data comes from. And we know that over time, risk of recurrence increases. But I think two years, there's data that suggests that the outcomes are pretty similar at two years. So that's what I typically tell patients that the efficacy rate for paroxysmal AFib is upwards of 80% at two years. The rate of recurrence risk increases over time. But I think more importantly, as I showed you, is the burden of AFib. And so they may have a recurrence. But if someone has an ablation and two years later, or even a year later, they have one isolated recurrent event, does that mean that they failed ablation? I would argue no. And so I think the dichotomous variable of 30-second recurrent rate of AFib is just probably not a good clinically meaningful measure. But that's what we use, because that's how all our clinical trials are designed. But that is changing. There's now implantable loop recorders that are being placed to really judge the burden of AFib, which is much more clinically relevant. Great. I actually want to sneak in one of my own questions here. Given that the AFib ablation registry will be introducing the option to report follow-up data beginning in the next quarter, what would you advise the team considering whether or not to report that to NCDR? Yeah, so actually we just went through a whole update with the AFib ablation registry. And that's really exciting, because I think the version 1.0, which is currently in place, it's not quite clear in terms of energy sources what additional ablations were performed. And so I think the new version is going to be very helpful. And it's going to have very distinct energy sources, radiofrequency, cryo. It's going to have pulse field ablation. It's going to have additional ablations that were performed, such as a roof line or a floor line. And so I think it will be much more contemporary to our current clinical practice. And so it's exciting. And I would encourage you all who will participate in that to really provide that data, because that's the data we use to inform decisions. We're looking at an analysis on how patients do with heart failure. And we have 50,000 patients from this registry. And it really provides a lot more relevant real-world data than some of the data from clinical trials, which are highly selected patients in experienced high-volume centers and not reflective of what a real-world cohort looks like. Great. Last question. Considering lifestyle management, does your team include certified health coaches? Yeah. So we don't, but I think that's an excellent idea. And that's one of my goals of getting ready to start an AFIP program. And it's one of my goals to have a nutritionist or a health coach, someone who really focuses on lifestyle changes. Because as we know, lifestyle changes are easier said than done. And it really requires more than a 30-minute visit with a physician. It requires dedicated support. And it's really important, as I've shown you. Excellent. Thank you all for the questions. Thanks for coming to Quality Summit. And join me in thanking Dr. Yusuf. Thank you.
Video Summary
In this detailed presentation, Dr. Yusuf addressed atrial fibrillation (AFib) management, emphasizing advances in ablation techniques as a primary therapy. Dr. Yusuf discussed the significance of early rhythm control for AFib, highlighting the limitations of antiarrhythmic drugs in terms of efficacy and side effects. The primary focus was on different forms of catheter-based ablation, particularly contrasting traditional thermal methods, like radiofrequency and cryo-balloon ablation, with newer non-thermal techniques such as pulse field ablation (PFA). PFA, noted for its tissue-selective and efficient ablation, potentially reduces collateral damage to adjacent structures like the esophagus and nerves, offering a promising alternative. The presentation highlighted the critical importance of early intervention in the AFib lifecycle to prevent structural heart changes, and discussed risk factor management as a cornerstone of treatment strategy. Dr. Yusuf emphasized how clinical guidelines are evolving to support the use of ablation earlier in the treatment process and discussed new clinical trials and technological innovations driving advancements in AFib treatment. The talk concluded with insights into potential improvements in lifestyle management involving multidisciplinary collaboration for better patient outcomes.
Keywords
atrial fibrillation
ablation techniques
early rhythm control
antiarrhythmic drugs
catheter-based ablation
pulse field ablation
early intervention
risk factor management
clinical guidelines
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