Occult Atrial Fibrillation – Diagnosis and Management

thank you thank you dr Malak for putting up weird cases and then we'll be moving on to one of the more routine and common causes so nothing too special there although it's a very important topic so of course we're talking about a cult atrial fibrillation I have one disclosure I'm a Judah cater for cases for the base trial which is a biomarker trial somewhat relevant to the topic and that it's looking at biomarkers to detect the etiology for cryptogenic strokes or strokes as they come in so why do we care so much about occult atrial fibrillation and stroke well atrial fibrillation is extremely common within the United States over 2 million patients in the US have atrial fibrillation and then we kind of come to the rule of thirds we're about one third of all AF patients are yet to be diagnosed with that condition we also have about 800,000 strokes in the US per year with about one-third of those being of an unknown cause so what that basically means is that around 250,000 patients a year will be told they have a stroke but we don't know why that's somewhat disconcerting from the patient's standpoint and then we do know that a EF is very important because it essentially increases the risk of stroke by a multiplicative of 5 so it's a very important cause of stroke so how did we kind of come around to this well focus on cryptogenic stroke and the occult AF well you go back to the wars trial which is warfarin versus aspirin and one of the subgroups they looked at various things and then they looked at the cryptogenic cohort and within this one cohort there was about an 8% reduction in the risk of stroke not statistically significant because this was not really powered to to find this difference but it begged the question what's so special about the cryptogenic cohort why do they respond to anticoagulants more than you than the other conditions so so we want to start to look at how we can identify there's no atrial fibrillation so when a patient comes in a hospital what's one of the first things you do after you've potentially treated them with TPA and other things is you get an EKG and that admission EKG can diagnose up to 7

7% new cases of AF just with that admission EKG in some places or situations where you may not have the opportunity for telemetry perhaps this is a stable patient who's been diagnosed as an outpatient you can actually do serial EKGs and capture another 55% 56 percent of AF cases just by doing EKGs and with the EKG there's a lot of information that you can get from that and this is one of the highest quality exams that you can do from this category because you can see multiple channels you can look at the p-waves you can get very detailed information from those things and those things can actually help you predict whether or not they're gonna go into atrial fibrillation the next thing was well they get admitted and for the most part they're put on telemetry and basically the guidelines suggest that all stroke patients should have at least 24 hours of cardiac monitoring regardless of what type of stroke it is and that by itself will detect another 7% and that during telemetry one of the things that we don't often even notice is you know you're in the room with the patient and you're looking and yeah it's normal sinus rhythm but there goes a P AC there goes a P AC these are relevant we think of P ACS as kind of precursors for paroxysmal atrial fibrillation or or triggers for AF when the PA see perhaps occurs in the atrial vulnerable period so you get more cases that way and then moving forward another option is halter monitor some places don't have inpatient telemetry or EKG monitoring so these patients should get at least 24 to 48 hours of holter monitoring but with halters you can add another significant percentage of AF detection halters are also great because they they can even calculate for you how many PA sees they've they've had and the number of PA sees is very important when you're trying to decide whether or not somebody at high risk or not for atrial fibrillation a couple of studies one that looked at greater than 70 PA C's per hour another one looking at greater than 1500 PA C's and a 24-hour period was significantly associated with high rates of AF in the future so you get a lot of information from that and then NYX is a event recorders external loop recorders and things like that and they got another kind of seven-and-a-half percent or so some of the the newer ones that now they can go on for longer periods of time up to 30 days or so and then I will talk about a couple of other more specific ones going forward so the next one is is M cot or mobile cardiac outpatient telemetry and this one has from these these types of monitors had shown a little bit higher detection rates up to 25 percent or so when used for 21 to 30 days I want to talk about this one a little bit because this is kind of how I got interested in atrial fibrillation and cryptogenic stroke but in 2008 tae-il published 56 patients with cryptogenic stroke and a detection rate of 23% for M cot monitoring of 21 days so that's a really good percentage but that's only 56 patients at a time that I became interested in they say we were doing this routinely on patients and I said why did we do this and it was well because of this one study a study of 56 patients that was retrospective well maybe we should look at that little bit more during the time we were looking at it another one came out again relatively small 62 patients but again a really high rate of AF detection so this became a much more important thing in the detection of a cause for Curt regenexx stroke patients so this leads me to the the project that I did during as a fellow when I came up with the idea of doing this which was a little bit of a rehash my supervising staff said I don't do that it's not worth it you know there's nothing so like any good fellow I didn't listen to them and I went ahead and did it anyways it turned out well you know it was more than it was a you know a great study or anything like that it was just good timing I think people were saying yes we need more of this and I got to meet Jose biller who's in picture right there and that was for the you know the mobile cardiac update telemetry we had 156 patients a little over 17% like seventeen and a half percent detection rate for AF and it kind of led me down this path of interest in this topic so here is what the mobile cardiac outpatient telemetry unit looks like so when you tell patients about what they're gonna have to wear and things like that you say you put on this monitor you're gonna look like this you tell their wife they're gonna look like this as soon as you put this monitor on them it's super sorry additionally so just kind of new advancement these these monitors are changing constantly and in this particular M cup monitor is going through some other upgrades as well and there's more of a patch based so it doesn't have all the leads and the the thing hanging around his neck is much smaller so they're they're constantly evolving and so we keep an eye out for those evolution and things like that so based on tie L study my study and bot study and a bunch of other retrospective studies looking at a non-invasive external cardiac monitoring prolonged cardiac monitoring even though there was nothing prospective or randomized into 2014 the American Academy of Neurology followed by the American Heart Association American Stroke Association put out guidelines recommending routine use of prolonged cardiac monitoring up to say approximately 30 days or so in cryptogenic stroke patients to look for occult atrial fibrillation so they identified the importance of this condition but again it was basically expert opinion and on randomized control trials if they had waited a few months there was the these two trials the invade embrace trial and the crystal AF trial these were the first two randomized controlled trials looking at this so what what they considered at the time comparing it to usual or baseline monitoring which was only 24-hour halter monitoring so it wasn't comparing to the other prolonged external monitors but comparing to 24-hour halters so the first one was the embrace trial and the embrace trial was like a belt like external event monitor they detected a little over 16 percent at 30 days versus 32 percent with a 24 hour holder so again very good yield with this device and then the crystal AF trial this is the insertable or implantable cardiac monitor detected about 9 percent at 6 months this increased to about 12 and a half percent at 12 months and then if you were you know able to wait three years to get the results you got up to 30 percent so this was really increasing the yield of detection now there you see there's a little bit of a discrepancy with 16 percent at 30 days and then you know kind of take about a year and a half two years based on the numbers to get to that percentage with the implantable there were some differences between the studies patients were a little bit older and the embrace trial things like that there was another study for the implantable monitors that kind of risk stratified and I'll talk about risk stratification a little bit in a minute but you know taking people who are considered at a little bit higher risk for AF so obviously none not all of these patients have atrial fibrillation that you're looking for so there's got to be some maybe signs or risk factors that put people at higher risk than others and and that's really useful information so in that to study when they looked at high risk patients they were able to get you know to that 30 percent mark and within about six months or so here are some of the other cardiac monitoring options you know there's a lot of things like I mentioned for the EKGs you get a lot of information from that I'll list some of those other benefits to the the things that you can see especially the P wave and the Holter monitors I mentioned the P AC counts and things like that atrial runs all of those things the super ventricular ectopic beats these are all important in determining the risk for atrial fibrillation and whether or not you proceed with further monitoring then there's some newer 14-day compact monitors here's a couple of the examples ones kind of a patch like the other one is just kind of a discrete small with a couple of leads and then there's the loop recorders and event monitors and like I mentioned the MCATs and the insertable cardiac monitors but the keys to success is to have a device that's going to give you quality EKG tracings you know garbage in garbage out you're not going to get a good diagnosis if you can't see the tracings you want to have the device should have quality automated AF detection algorithms so now they've gotten much better at detecting atrial fibrillation but there's still differences between different devices and you want to make sure that they have gone through some sort of vetting and things like that to make sure that they can actually detect reliably since these are asymptomatic episodes so and then you need to know that they're going to be able to monitor for a long enough duration so what we've seen is from our study and the other studies is that seven days 14 days 21 days 30 days you're it's kind of a linear line where you're continuing to get AF episodes throughout that that time period so you really need to do at least 21 30 days or so and then perhaps at that point risk stratify and decide whether or not further monitoring is warranted so this is kind of getting back to the refining our search and using all the information that we thus ambient information that we tend to ignore we don't take all this stuff into consideration obviously age is a big factor so as people get older the risk of AF goes up and up and up the PA CS I mentioned on the EKG you know if in our study if somebody had a PA C on their baseline EKG they had a 60% chance of having AF detected on monitoring for 21 days and that's just cuz you know if if they're having enough PA C is to have them randomly on your EKG they're probably having so many that they're gonna end up having afib because they're at that higher risk the Holter monitors are really nice as I mentioned because you get a lot of information on those then the P wave morphology so you can see left a Trull dilatation based off the P wave there are other things like P wave inversion in the terminal force in the v1 lead so if you're good with EKGs cardiologists other you know internist or whoever may be good at looking at these things you can use these and they will predict whether or not they're at high risk for afib there's a the P wave max duration and the P dispersion value of greater than 40 milliseconds these are all risk factors for for AF that most people don't know about or think about another big one and we're doing with the residence a review we were able to utilize the electronic health record system and pull data from 8,500 patients looking at their left atrial size from normal mild moderate and severe and you see very straight correlations with the size of the left atrial dilation to the likelihood that they have AF and those with severe left atrial dilatation have about a 50% chance that they've already been diagnosed with atrial fibrillation so what about the other 50% so if you look at patients that have a dilated left atria of any size a little over a third of them have been diagnosed with afib but what about the other two-thirds we know that they're probably at very high risk so you know these should be people that we look at and I have gone against the guidelines you know looking for atrial fibrillation and somebody who has a lacuna infarct that's not what we're supposed to do but I'm sitting there I'm seeing PA CS and I see that on the echo they got a moderately dilated left atria I know they probably have done it a few times and sure enough when we find HF fibrillation so we could even move start to move away from just looking at cryptogenic stroke patients and move this to even primary diagnosis primary prevention for people who are at high risk based on echos and EKGs and things like that and that's one of my interest is going forward there's other things that you can find out at EEE this is things like left atrial appendage smoke emptying velocity the morphology all these things that increase the risk or change that and other things are the biomarkers like the n-terminal Pro BNP that's a big biomarker for treatment aspirin 20% warfarin reduces by 60% it's a kind of a miracle drug so what is this miracle drug well it's a pesticide for rats and mice and Oracle prescribing practices are bismal and the adherence is you know even worse so it's kind of a nightmare drug because of all of its issues and yes it's rat poison that comes up repeatedly and we have patients who say I won't take that rat poison literally coming after day I won't take that rat poison so you have alternatives these dough acts that we've heard about they're great they have a lot of options different doses and things they have some limitations but they have a lot of benefits as well and you still get people that say well no I don't care about the cumin and I don't care about the darks no no no no thank you well how do we convince them well you take studies the average trial picks a band versus aspirin and you know this showed reduce reduction and stroke no major bleeding increase RI CH and then she comes back at you and she's still there looking at you so I but before or never again so what alternatives do you have left atrial appendage occlusion 90% of thrombi occur in the left atrial appendage you can and our cardiologists will tell you they basically shove this thing in there block it off and prevent strokes and then there's the layer at procedure which they may mention as well but just wanted to throw that in there hold on thank you [Applause]

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