Dr. Nicholas Olson discusses clinical outcomes and expectations for patients who undergo ablation for atrial fibrillation.
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All right, so, we're gonna move on to dr Olson, who's uh one of our partners at scripts public and the private party party basket Institute and he's going to talk to us um does a lot of complex ablation and is also an expert of device related therapy. Does a lot of micro cases combined note ablation, but it's going to talk to us today about what to expect after an atrial fibrillation ablation. Perfect. Thanks for the warm introduction. Doug um my disclosures. So, a fib the most common arrhythmia in an aging population. And the statistics are actually quite staggering. If you take a look, patients over 60 up to one in 25 we'll have a fib diagnosis and once you get beyond 80 maybe up to one in 10 patients will have a fib. There was a nice systemic review of worldwide population studies that estimated a worldwide af prevalence of 33 million people in 2010. So, obviously a huge problem. And on top of that we know a fib is associated with a lot of bad outcomes right. Historically, stroke, systemic embolism has been closely linked to atrial fibrillation, but there are a number of other clinical outcomes that have been associated with a fib that we'd like to avoid heart failure, dementia, myocardial infarction and even death. Those type of outcomes have been clearly linked to the to a fib as well, so that breeds the age old question. What should we do about a fib? Should we suppress a fib? No, I think sometimes the answer that question is pretty clear from a symptom standpoint if you have symptoms despite adequate rate control or intolerable side effects to the rate control medications. I think rhythm controlled by whatever means is a good option. Sometimes we have challenges in achieving rate control, prepare dismal patients where they go fast when they're in a fib and slow when there are normal rhythm and those patients are rhythm control strategy or trying to suppress the A. Fib can be warranted as well. But what about those other clinical outcomes stroke? Heart failure, preventing death seems like they're associated with a fib. And for successful in that endeavor to suppress it. We should be able to tackle those endpoints. But that's the answer to that question is still in flux prior to the development of catheter of ablation. That question has been extensively studied. And one of the large trials that we always historically compared to is the affirm trial. A number of other trials with similar results. Looking at large population 4000 patients, Uh they had aged over 65 or younger with a cardiovascular mortality risk factor. We want to have a high burden of disease or high event rate in this patient population in order. So it benefits from our outcome from our efforts to suppress a fit compared randomized to rate or rhythm control strategy. The primary endpoint, look, we're looking at clinical outcomes here mortality, secondary endpoint composite of death stroke, encephalopathy, bleeding, and cardiac arrest. A little bit more details about the study. Uh, first of all, Rhythm control was achieved in 62%. Only the patient population where we try to suppress. There was some cross over in both directions, which is not surprising considering the potency of these medications and the uh, and they're not necessarily high success rates at times. One thing to note though is these patients in this trial were were put on pretty heavy medicines, a lot of flack and I a lot of soda and by the end of the trial, 63% were on amiodarone. So the investigators really went through exhaustive means to try their best to suppress this A fib Not surprisingly, there was a lot of discontinuation of medications, both in rate, but more so in rhythm control. You can see here, well over 30 of patients had some type of drug discontinuation, whether it was from one to another or transitioning to rate control strategy because of side effects. So a lot of drug discontinuation. And what did it show? Unfortunately, despite all of this effort, all of this effort, we did not show us to significantly a statistically significant improvement in clinical outcomes with our rhythm control over rate control. In fact, there was a trend for improved mortality. Remember this is this is a mortality in point, it was actually a slight trend towards improvement with rate control over rhythm control. If you look at the secondary endpoint also no significant difference between the two. So, conclusions from that and this is how we practice before revelation. Rhythm control with medicines is hard to achieve 62 success rate with our rhythm control strategy and lots of side effects, as mentioned with rhythm control medications. Rhythm control with animal anti arrhythmic therapy unfortunately did not reduce hard clinical endpoints, morbidity, mortality and stroke. And therefore, how do we practice most circumstances patients with asymptomatic a. Fib when they are raped control do not benefit from rhythm control strategy. That was hard to believe, right? Nobody wanted to believe that we spent all this effort. We trained all these years to suppress a fib. How could we not be affecting these clinical outcomes? So, of course that this trial came with a lot of critiques. Right patients were too old, average age over 70, lots of sick patients, 25 mortality. Maybe they didn't have enough time to benefit from the successful rhythm control strategy and address those clinical outcomes. Most of these patients were actually a symptom asymptomatic from there, a fit patients that were heavily symptomatic didn't want to be enrolled in the trial in the first place. There was a lot of heavy medicine use, especially amiodarone, which could have mass the positive effect due to medication toxicity. And lastly trial didn't look at quality of life and heart failure outcomes and actually an ablation. Another critique is later down the line. Ablation has a better success rate than our rhythm control medication. So perhaps what the advent of ablation maybe those hard clinical endpoints can actually be affected by by implementation. So that leads us to ablation. But what exactly is this black box patients go down. They have this thing called an eighth of ablation. But what exactly are what exactly are we doing down in the E. P. Lab? You know? There's a lot of uh there's some disagreement still on the underlying mechanism of atrial fibrillation but there is some general consent uh that a fib events are composed of two components. Right? So this is the left atrium. A fib is an arrhythmia, predominantly the left atrium. This is from the back of the patient. Looking forward, we see two left sided pulmonary veins and to right sided pulmonary veins bringing blood back to the left atrium and the left atrial appendage out here on the front again. What causes a fib predominantly to events? Right. We have bursts of politics which predominantly come from the pulmonary veins. So these bursts of starting the pulmonary veins, they exit the pommery Vans and they create little reentry circuits occurring within the left atrium early in the natural history of a fib these paroxysmal patients when they first start developing a fib usually these uh These these circuits are in the annual regions of the of the of the left atrium and therefore by pulmonary vein isolation ablation around these veins were able to achieve eradication of these pcs as well as getting rid of the reentry circuits Right after a from ablation, early recurrences in the 1st 2-3 months we call that a blanking period. We don't really count that against the ablation. The inflammation is going down. There's 40 of the time we see early recurrences with formally vein isolation doesn't mean it's not necessarily going to work success rates uh improving with time and better technology. This is the latest studies looking at pulmonary vein isolation using our contact force catholic about 80 to 85% success rate. And that's clinically what we see in our clinical practice as we move towards more persistent atrial fibrillation. Uh These mechanisms expand to include P. A. C. Origins outside of the pulmonary veins as well as reentry circuits outside as well. Consequently, our ablation strategy oftentimes includes ablation outside of the pulmonary veins. To better tackle those regions, we do ablation targeting these little reentry circuits. If they can be identified by very technologies or additional lines, as a surgeon would do an amazed procedure. What's the problem with that? Well, when we do more ablation, we can create gaps and a little reentry circuit or electrical impulse can sneak through the area that we a bladed and that results in the infamous atypical flutter that happens after our tribulations, which can be very challenging to rate control and oftentimes requires additional ablation. As you can see here, a typical flutter waves. Additionally, heavy ablation, the left atrium can decrease the compliance, increases the stiffness of that left atrium which functions as a reservoir for the filling the left ventricle. With that stiffness increase. Oftentimes with physical activity, we can see increases in pulmonary capillary wedge pressure and pulmonary hypertension really adding to significant exertion, All dystonia. We call that stiff luck, atrial syndrome. Success rates of more persistent a. Fib ablation techniques. Unfortunately, the success rates are dipped quite a bit from paroxysmal to persistent A. Fib. Here is one largely quoted trial, a little bit disappointing success rates in this trial but typically we say between 60-70 success rate with a single ablation procedure for our person save. So now with the advent of ablation, let's re examine those clinical outcomes. They're big trial. The cabana trial published just recently, 2019 took a similar approach to the affirm trial and randomized patients that had aged over 65 or younger with risk factors to ablation strategy or med's strategy. You could do multiple abrasions, you could do meds in the ablation in the ablation group. The med group was either rhythm or rate control medicines. But we wanted to see if we could tackle some of those hard clinical outcomes. Death stroke, bleeding, cardiac arrest. We also included heart failure and hospitalizations and mortality is a secondary endpoint and quality of life as well. What do we find? Unfortunately, the similar result, at least in the initial incident or the primary endpoint on the initial analysis. Drug therapy, catheter ablation did not achieve a significantly difference between the two therapies. Although this time catheter ablation did trend below drug therapy. Now, if you look at the secondary endpoint mortality and heart failure, hospitalizations, We did achieve a significant or a statistically significant difference because there was much more events. And even though there was relatively only about an eight or so absolute reduction between drug therapy and catheter ablation that did reach statistical significance. Now, a lot of patients, 28 went from rate control or from med therapy to ablation strategy. Not surprising because if they had symptoms and they wanted to address that oftentimes, they had to go over to ablation strategy. But when that was completed, when we took that into account and looked at a protocol analysis, I wanted the patient actually get, you can see the catholic ablation started trending even further below drug therapy, not quite just statistical significance, but getting there Now, this is where it starts getting interesting. If you look at subgroup analysis, there are certain patient populations, young patients less than 65 and heart failure patients that particularly did well with a catheter ablation strategy. In fact, just in february of 2021 a post hoc analysis of the cabana trial looked at 780 patients with heart failure predominantly 80% E. F. Preserved, but some with drought with lower ejection fractions. We could see that both the primary and point and mortality or statistically improved with catheter ablation over medical therapy. So, and the heart failure population, perhaps these patients are doing better and better with a more aggressive strategy. Now looking at quality of life, there was a significant difference between the two favoring catheter ablation, pretty much at all. Uh follow up intervals, looking at quality of life indicators. So in conclusion, despite notable decrease in recurrent a fib frontline ablation did not decrease the primary endpoint. It did improve quality of life compared to medical therapy. It reduced heart failure events and particularly in patients with a history of heart failure may have even had some more significant impacts on hard clinical outcomes, including mortality. Is there any other data to help support this? Yes, there's actually another trial that was recently got. A lot of press is the Castle A. F trial. And what happened in that trial, as we looked at its much smaller 180 patients. But these patients had low, yes, 35% are left clinical heart failure. They all had a defibrillator. And again, we're looking at hard endpoints hospitalization, worsening heart failure. And what did it show? Primary endpoint death or hospitalization for heart failure improved with ablation over medical therapy. Pretty pretty significant, absolute reduction. Now, it's interesting if you break down that endpoint into mortality and heart failure, you see that the heart failure outcomes started separating early on but not until more delayed analysis. Time points did we see um sorry, the separation of the curve in terms of mortality. Another trial papa chf looked at a much smaller group 82 patients, but I thought this was really interesting because they did a fib ablation. These patients all had by v defibrillators and they're a V nodes were a bladed. So they had very definitive rate control strategy and they looked at heart failure score, ejection fraction, clinical outcomes. Now I will say that the success rates with ablation in this category were a little bit unexpectedly high considering the heart failure diagnosis nonetheless, what do they see significant improvement in ejection fraction at six months compared to CRT A V node ablation As well as clinical outcome, six minute walk test and Minnesota living with heart failure questionnaire. We can see there was a significant improvement with ablation therapy over medical therapy. So that being said. What did the guidelines say? Remember back after the affirm trial we practiced along these lines, persistent symptoms are associated with A. F. Made the most compelling indication for rhythm control, although some other factors may include difficulties achieving rate control. Younger patient age, tachycardia mediated cardiomyopathy. Uh First episode of a fr precipitated by an acute illness or even patient preference. Flash Forward to the update in 2019. And what do we see? We see the addition of a new recommendation that says A. F. Catheter ablation may be reasonable and selected patients with symptomatic af and heart failure with reduced LV. E. F. To potentially lower mortality and reduce hospitalizations. Um I do have a quick case at the end with one minute. I'll breeze through this real quickly. This is a patient of mine. I might go over here. Doug don't cut me off, 75 year old. I thought it was a really informative case known her for years 75 worsening heart failure, not ischemic cardiomyopathy. E. F. 32% had some P. A. F. A big left bundle branch block. So we took her in. We did a nice CRT. I thought it was a nice result, nice separation of the LV lead and the RV lead. Um Really nice electrical result as well. Clinically she did really well. You can see nice narrowing in the QRS. Not quite as good as those his bundle pacing occupations but as best as we could E. F. Remained stable in the mid thirties. But she felt great, much improved. Then she got admitted twice for two months for acute heart failure. Exacerbation after diaries. Is new york heart association class three. And if you look at our device interrogation, what do you see? Looks like she progressed to persistent a fib. She's 100% mode switch right now. So we transitioned about Oprah lol, soda lol. We cardioverter her, not surprisingly, with her heart failure diagnosis. She went back into a fib and we had to take her uh in for ablation required pretty heavy ablation after taking a look at her atrium. The amount of fibrosis and she did great. She stayed in normal rhythm and no heart failure admissions for a year. But unfortunately referred back from a primary cardiologist for worsening dismay on exertion. And as you can see here she's an atypical flutter. So we brought her back in. Um this is the map you can see there's extensive fibrosis here. This is the left atrium, red is bad. That means low voltages and fibrosis, the electrical impulses, these little dots going around and you can see it's pretty organized but it goes up to the scar region, it breaks through it and comes out. This is an atypical flutter, cauterized right here and ultimately broke the tachycardia and this was just really recent. So I'm looking forward to see how she's going to do. She hasn't had any heart failure exacerbation since the holidays, christmas time and uh hopefully she stays that way. Thank you. Yeah. Thank you. That was a great case. Can you talk just a little bit while we're getting set up for john's talk about how you choose when you evaluate a patient with heart failure in a fib how do you choose a fib ablation versus a. V. Note ablation and baby or some other therapy. Mm Even ablation of micro for example. Yeah. Well I mean I think you know what I've learned, what I kind of interpret these studies as is I still think you know really symptoms are the way to address a fib. But I'm starting to view heart failure, exacerbations and hospitalizations as a symptom of a fib. You know so someone who has, you know if they have a fib history of heart failure a low E. F. And they go into a fib and they noticed on device interrogation but they don't see much change in their clinical outcomes or their clinical symptoms pathology. They're not increasing their frequency of hospitalizations. They're not complaining about shortness of breath. We don't see a lot of clinical change and I'm not going to be really you know not every ef You know you have below 35 with a fiB needs to be addressed with ablation or what should I say, aggressive rhythm control. But in those patients who do have heart failure, I think we just need to be cognizant and really take a look at, hey, when they go into a fib, does their heart failure get worse? And if the answer to that is yes, I think we need to be a little bit more aggressive in that patient population historically, before these trials came out. You know, I think they got a device that sublet there may be no, let's keep them well rate control. Then they should do fine. And I just don't know if that's really the right answer in those patients. I think we need to be a little bit more aggressive and the patients that really take a turn for the worst with heart failure. Yeah, I agree. I think in general it's pushed the needle more towards a fetish ablation. heart failure patients. But I'm still very careful. You know about the patient with high pulmonary pressures that don't come down with viruses. I have very reluctant to go create a bunch of extra scarring because of another thing that you mentioned there, that stiff left atrial syndrome. So thank you, nick.
