Ablation Techniques in Atrial Fibrillation Part I: Anatomy and Stage of Progression

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  • Опубліковано 26 лис 2024

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  • @JosephBello-c1x
    @JosephBello-c1x 12 днів тому +1

    How do you know how many walls of afib you have?

    • @afibeducation
      @afibeducation  10 днів тому +1

      AFib is made up of abnormal cells/sources that form in the walls of the left upper chamber of your heart, the left atrium, and these cells wake up randomly and take over control of your heart electrically away from your normal source of electricity that you are born with that is located in the right upper chamber of your heart. When the AFib cells are in control they make your heart go at faster speeds that can be symptomatic. They also increase the chances of a blood clot forming in your heart that can break loose, go to your brain, and cause a stroke. As one gets older the AFib cells/triggers/sources keep developing, growing, and spreading to more and more walls of the left atrium. The more walls you have AFib cells on, the more AFib cells you have total, the stronger they become, the more they want to wake up, and the longer they stay awake before going back to sleep. When you have them on all 6 walls of that chamber they are strong enough to be awake 100% of the time and that is when your AFib is called "Permanent AFib" because no medication, no ablation no matter how advanced, and even a simple electrical shock (cardioversion) won't get the AFib gone or back to sleep. You will be in AFib 100% from that point forwards, but as long as one stays on their anticoagulation and doesn't have a stroke, you will never directly die from AFib because it is not directly life threatening. However, symptom-wise the best we can do at that point is just use a simple medicine to slow the AFib down to a point where the pt can tolerate the palpitations. When doing an ablation, the overall success rate will depend on how many walls the AFib is on, how progressed it is (the stage), and directly the skill of the operator. How do you know how many walls your Afib has spread to? The amount of time the AFib is waking up correlates with how many walls the AFib is spread to, ie. the stage of progression. When you have AFib on the first 1-2 walls, you are at an early stage of AFib called "Paroxysmal" AFib. This is technically defined as AFib episodes lasting less than 7 days before going back to sleep on their own. If you have AFib on 3-4 walls you are generally at a mid stage that we call "Persistent" AFib where the AFib is generally waking up more than 7 days at a time. If you have AFib cells on 5-6 walls you are at a late stage of AFib called "Longstanding Persistent" AFib and your are in AFib most of the time. How do you know how much your Afib is waking up when you can't always feel every episode? An external Event Monitor that can monitor the heart rhythm for 1-4 weeks is often used to assess what percent of time the pt is spending in AFib to determine the stage of progression. The other thing to note is that staging is based on the time spent in AFib off of an antiarrhythmic medication. AADs (antiarrhythmic medications) are drugs we use to temporarily suppress or keep asleep the AFib cells in order to keep pts in their normal rhythm without doing an ablation. We have 5 drugs of different strength levels that can suppress AFib; the stronger the AAD the more walls worth of AFib it can suppress, but potentially the more powerful the side effects of the drug. From strongest to least strongest: Amiodarone, Dofetilide (Tikosyn), Sotalol, Multaq, Flecainide & Propafenone. These drugs don't get rid of the AFib cells and don't keep them from progressing as one gets older, they just mask them until they can't mask them any longer, so unfortunately they won't work forever. But they can sometimes work for many years. Sometimes they can fool you into thinking you are at an earlier stage than you really are. For example, if you are at a late stage of longstanding persistent AFib on 5-6 walls and without any drugs to suppress it you would normally be in AFib weeks at a time (70-90%) but let's say you are on the second strongest drug Dofetilide (Tikosyn) that is mostly suppressing it but the AFib is becoming strong enough to start to break through the drug but is only breaking through 10% because the drug is still able to keep the other 70-80% of AFib cells asleep. You might think you are at an early "Paroxysmal" stage of AFib when in reality you are at a late stage of AFib and could progress to "permanent" AFib in less than 5 years. This has direct implications when doing an AF ablation. How many AFib cells/sources/triggers one is able to successfully destroy directly correlates with the overall success rate of the procedure. In this case if an electrophysiologist (EP) does just a simple "one wall" ablation which we call "pulmonary vein isolation (PVI)" referring to the fact that AFib cells always start forming on the back wall of the left atrium specifically in the corners of that wall where anatomically the "pulmonary veins," vessels draining blood from the lungs, insert into the four corners of that back wall. If you ablate or destroy AFib cells/triggers/sources just on that first wall but the patient is actually at a later "late" stage of AFib with cells on 5-6 walls, then obviously you won't get rid of all of the AFib. Which is not to say it can't be a little bit better. Having AFib triggers on one less wall may make it wake up less which is why I think of ablation as "turning the clock" back to an earlier stage of AFib. If you turn the clock all the way back to zero you can have no further AFib if there are no AFib cells left to wake up, but it gets progressively harder and harder to do that the more walls the AFib spreads to. And it is never a permanent cure. Afib cells grow just by aging so they are always forming slowly as one gets older. But the more AFib cells/triggers one gets rid of with the ablation, the longer it will take the Afib cells to grow back to the level that they were. On the other hand, if you are truly at an early stage of AFib (Paroxysmal), you may only have AFib cells on that first 1-2 walls and so a simple ablation targeting just that could be very successful. That's why the success rates for AF ablation decreases the more progressed the AFib stage irregardless of the energy source used. These days it has become fairly straightforwards to ablate that first wall, what we call "pulmonary vein isolation (PVI)." Even an EP straight out of training without a lot of experience can do this successfully and if that is all you have because you are at an early stage of AFib, then it really doesn't matter which doc does your ablation. They will be shooting for an overall 80-90% to "turn your clock back to zero" because you don't have that much to get rid of. But if you have a mid or late stage of AFib, or worse are virtually permanent AFib, then it makes a big difference who is doing the ablation, their skill level, and whether they do complex ablations or not. In these stages less skilled operators and those who don't do complex ablations have success rates dropping to 40-50% whereas some of us who do complex ablations are still targeting 80% overall success. Since AFib starts growing back from whatever level you get it to, if someone has 80% of AFib cells/triggers on 5 walls that is waking up 70-80% of the time and someone does a simple PVI one wall ablation on them and "turns the clock" back to just 4 walls worth, they could still be in AFib 50-60%, but if someone did an advanced, complex ablation and got it to zero or mostly to zero then they could have no AFib or 5-10% or less after the ablation. Just remember, the AFib will start growing and progressing from whatever level one gets it to so if one just ablates a little bit it could progress back to 80% very quickly whereas if one gets rid of most or all of it then it could many years before it progresses back to where it was. In terms of energy sources: Radiofrequency (RF) is the oldest energy source and it cauterizes to destroy cells. It takes the most skill, and potentially can cause the most complications like collateral damage or perforation of the heart wall, but it is the most versatile and in the hands of a skilled operator can reach all six walls of the left atrium for complex ablation lesions sets required to have high success rates for the mid to late stages of AFib. Cryoballoon which freezes is safer and quicker than RF but because of the shape of the balloon catheter it can only effectively reach the pulmonary veins on that first wall, although a few experienced EP's have developed the skill to "drag" it on the roof and back wall to get up to 2-3 walls worth of AFib without breaking out an RF ablation catheter. The newest energy source of Pulsed Field ablation is the safest and quickest. There is zero chance of perforation of the heart walls and minimal chance of collateral damage. However, in its current iteration the catheter is designed to only reach the pulmonary veins on the first wall so it is FDA approved and suited for only early stage AFib or "paroxysmal" AFib. It is a great energy source and definitely the wave of the future. Over years time I expect that the catheter will improve to eventually be able to target other walls and do complex ablations with it, but not yet. Just beware that if you have a more advanced stage of AFib such as mid or late (persistent or longstanding persistent) AFib and an EP performs an AF ablation on you doing just that first wall (PVI ablation) even if they use the newest energy source of Pulsed Field Ablation, while the procedure may go faster and be overall safer than if they did that same amount with RF or Cryoballoon energy sources, the overall success rate in getting rid of your AFib will still be the low 40-50% because they aren't doing enough. They will then often either bring you back for multiple other procedures using an RF catheter to try to ablate on other walls or put you on one of the antiarrhythmic drugs to try to suppress the remaining AF that was leftover which may make it seem like they got it all. And remember, it will progress from whatever level they really got it to, not from zero.

    • @JosephBello-c1x
      @JosephBello-c1x 9 днів тому

      @@afibeducation Thank you for that thorough explanation. I am 64. I've had afib since my mid 50's occurring every few months. After losing weight and an improved diet my episodes decreased to 1 once or twice per year on 100mg of Flecainide BID. I can feel exactly when I go into afib and I often will revert to sinus spontaneously but I get fatigued and short of breath when it is sustained so by 24 to 48hrs I need to get cardioverted. Would you consider me early stage and a candidate for PF ablation. Cardiologist says either option of continued meds vs ablation. I am gathering by your explanation that intervening with ablation at an early stage may be a better long term solution. I am also concerned about the safety of blood thinners as I get older.

    • @afibeducation
      @afibeducation  9 днів тому +1

      In your specific situation being relatively young at 64 y/o, presumably healthy otherwise, and symptomatic with your AFib, consideration of an AF ablation at some point does make a lot of sense. If your AFib might progress to being on all 6 walls and becoming permanent in maybe ten years, you would only be around 74 y/o and might not want that. However, risk of thrombus and stroke aside, we are just treating symptoms and if having a procedure scares you then treating it every few years with stronger and stronger antiarrhythmic medications like the flecainide to keep it asleep then accepting when it is 100% and permanent after it fails the strongest AAD maybe in ten to fifteen years is the route to go. Remember, the rate of progression of Afib is not linear but exponential. Once you get into your late 60's to 70's the rate of progression of Afib gets faster. If you choose to have an ablation at some point do remember that the AFib is always slowly progressing and it gets progressively harder to get rid of all or most of it with an ablation the more progressed it becomes. So in general the earlier the stage of AFib the higher the success rates of the ablation. Of course the success rates are also directly dependent on the skill of the EP physician doing the procedure and whether or not he/she does complex ablations and how complex. This gets into the concept of doing an anatomical versus functional AF ablation. Many EP's and all surgical AF ablations perform an anatomical ablation meaning they determine ahead of time what they are going to ablate irregardless of how many walls of AF cells are present. So that is why many EP's will do a simple one wall ablation (ie. pulmonary vein ablation-PVI) irregardless of whether the person is at an early stage so that is all they need or a later stage and that isn't enough. Then they will bring the person back if needed over 1-3 additional procedures to do more walls but still usually one at a time. This keeps the procedure time lower and makes them more money. They will utilize energy sources like Cryballoon and now Pulsed Field Ablation that can only do that first wall but do it much quicker and easier but safer than with an RF catheter. Unfortunately if the EP only has the skill to do the first wall with PVI, even if the pt needs a more advanced ablation on more walls, they might do that same first wall area 2-3 times and still not get rid of all the Afib. Surgeons have an excuse because they aren't EP's and don't have catheters sensing the electricity on the heart walls during their procedure to see where the AF is; they are just doing some other open heart procedure like a bypass or valve replacement and it is super easy to do a simple one wall ablation (PVI) externally on the heart while the chest is open. Their attitude is: If it helps great. If not, well they were in there for another reason anyways! But some of us who are experienced and do complex ablations use a functional approach. We do the first wall (PVI) then we methodically do further ablation on the side wall, roof, back wall, floor, other side wall, and front wall as needed until we get rid of all the Afib cells that person has and are often able to "ablate the pt back to their normal rhythm." You can actually see the Afib triggers/sources get less and less during the ablation until it finally stops and the pt converts back to their normal rhythm on their own suggesting we hit all the right areas. And if all of the cells end up dying off from the procedure during the 2-3 month postop period, the pt can be left with either have none or very little Afib. This is why personally after 20 years of doing this, I currently almost never do a third procedure these days and I only do a second 20% of the time because I can usually get all or most of it with the first procedure even at the advanced stages of AFib. This is opposed to the anatomic approach where the doc does whatever amount of walls they had planned at the outset (usually just the first wall) then they externally shock the pt (cardioversion) back to normal rhythm and then see how much Afib wakes back up in the ensuing months to see if it is less. And then they bring the pt back for more procedures. That's why at early stages of AFib (Paroxysmal) the success rates can range from 75-80% with one procedure for those least skilled to 95% for those most skilled with the average success rate still at 80-90% because it is such an early stage with only 1-2 "walls worth" of AFib. At a mid stage of AFib (Persistent) with 3-4 walls-worth of Afib, for the average EP their success rates drop precipitously to 40-50% just doing it anatomically versus 70-80% for those who are skilled enough to do a functional approach. For late stage AFib (longstanding persistent) with 5-6 walls worth of Afib, the success rates drop to 20-40% for the average EP doing an anatomical approach to 60-70% for a skilled functional approach.Most EP's do an anatomic approach involving many procedures because it is easier skill-wise and makes more money since unfortunately we are paid by health insurances for doing a procedure, not for a specific result. When you have all 6 walls worth of AFib, are spending 100% of the time in AFib, and are considered "virtually" permanent but are within the first three years of that, the success rates are 10% doing it anatomically. And this is not getting rid of the AFib completely but just making the AFib not be there 100%. In these situations by doing a very complex, advanced ablation lesion set on all 6 walls (I essentially do an endocardial MAZE lesion set that mimics the surgical Cox MAZE 3 procedure but from the inside) I've been able to essentially pull the pt back from being permanent about 50% of the time, but in truth I personally consider that to be no better odds than flipping a coin and I can't make any promises at that stage. When one is 100% in AFib and has been like that for more than 3 years their AFib is truly permanent and no ablation no matter how complex will make it less or gone. At that point we just slow it down with a rate controlling med and the pt just lives with it symptom-wise. But Afib is never life threatening as long as one stays on anticoagulation and doesn't have a stroke. That's why no matter the skill of the operator, overall success rates are better the earlier the AFib stage of progression. In your specific case you are breaking through our weakest antiarrhythmic drug flecainide but having episodes lasting 2-3 days requiring cardioversion back to normal rhythm. The question is how long your AFib would stay awake before going back to sleep on its own if you weren't cardioverted after 1-2 days. If it is 7 days or longer you have mid-stage persistent AF and if less than that then still early-stage paroxysmal AF. Since you are symptomatic you never let it go longer than that before converting it. This means your AFib could be still early stage (1-2 walls worth) but might be mid stage (3-4 walls worth). If you undergo ablation at this stage and all they do is Pulsed Field Ablation to anatomically electrically isolate the first wall pulmonary veins (PVI), your success rate with one procedure could be as high as 80-90%, but would drop to 40-50% and likely require more than once procedure (with the other procedures using RF catheter ablation to reach the other walls) if you are in fact persistent AF stage. If you find an EP who does more complex ablations and does a functional approach either doing both PFA and RF ablation if needed at the same time or RF ablation for the entire case, then your success rates with one procedure might still be up to 80%. Obviously if you just tolerate your symptoms for now and wait until you progress to more advanced stages of AF or fail stronger antiarrhythmic drugs than flecainide, your overall success rate with ablation will decrease and vary depending directly on the skill of the operator doing the ablation. And lastly, even doing a successful ablation that completely gets rid of all your AFib (whether that be with one procedure or many) still doesn't guarantee you can get off the blood thinner long term. One's risk for thrombus and stroke with AFib has nothing directly to do with symptoms because the risk of clots forming in the chamber of the heart where AFib cells form, the left atrium) occurs any time AFib cells wake up and take over control of the heart whether the patient feels the AFib or not. One's risk of clots forming and breaking loose, leaving the heart, and going to the brain to cause a stroke is determined by one's CHA2DS2VASc score. Every point on this scoring system increases your risk by about 1 to 1.5%. With a risk score of 2% or greater, standard of practice guidelines recommend that anticoagulation be used. Since the ablation is never a permanent cure and the AFib can grow back on other walls that were not ablated (but they start growing from whatever point one gets the pt to with the ablation, eg. if one ablates an 80% worth of AF to 60%, it will start growing from 60% whereas if one ablates that same pt to 0% it will start growing from 0%), we know the AFib will eventually return but not always at the original level right away. It might come back slowly and if the person doesn't feel their AFib they could present with a stroke. This is why anticoagulation is continued irregardless of the success of the ablation if your longterm risk is 2% or greater. I don't know your medical history, but once you hit age 65 y/o that gives you a point (so 1% risk), and if you have a diagnosis of high blood pressure, diabetes, any previous heart blockages, a weakened heart, or previous stroke or TIA even if these conditions are treated, your overall risk will definitely be over 2% long term and you would not be able to safely stop the blood thinner even if you were free of AFib for years. This is why we do AF ablations for symptoms, not to get someone off a blood thinner. I hope this helps!

    • @JosephBello-c1x
      @JosephBello-c1x 9 днів тому +1

      @@afibeducation It has helped greatly. Your response is much appreciated.Joe