Video Opinion: AFib doesn't cause strokes - Thoughts?

If you're interested please watch this video through.

York Cardiology - Why I Don't Believe that AFib Causes Stroke

For those that have watched it, I'm curious what your thoughts are. Dr Gupta seems to make alot of sense. The studies he references are interesting too!

In a nutshell he is saying.... "The risk of stroke is based on the comorbidities that often accompany AFib. Not on the presence or absence of AFib."



Edited 1 time(s). Last edit at 02/14/2020 09:03PM by cirenepurzalot.

Sorry if I seem brusque, but that is bunk. AF raises stroke risk. So do other things, for sure, but stagnating blood flow in your atria is not a thing to be ignored.

Thanks. I wonder why afib isn’t included in the calculation of the chadsvasc score? Seems like it should be a factor due to the LAA.

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cirenepurzalot
Thanks. I wonder why afib isn’t included in the calculation of the chadsvasc score? Seems like it should be a factor due to the LAA.

Afib wasn't included in the original CHADS score because the CHADS score assumes you have afib. Having afib is built into the score, so it really just doesn't apply to people who don't have afib.

You have a good point about the LAA, but LAA isolation is still so rare that it's just viewed as an exception to CHADS. Anyone coming away from an ablation with an isolated LAA is dealing with a top tier EP who will know you need specific instructions on how to deal with it and going by your CHADS score isn't the way.

I seem to recall that Hans (founder and previous moderator of this site) said that AF did not increase stroke risk. But that was a while ago.

Gill

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wolfpack
Sorry if I seem brusque, but that is bunk. AF raises stroke risk. So do other things, for sure, but stagnating blood flow in your atria is not a thing to be ignored.

Yeah. It's what is commonly said. And it makes sense, for the reason you mentioned.
OTOH, I reckon I like Dr Gupta's vids (at least those I watched). Usually interesting and informative. Despite I don't understand why he said that about afib and clotting, I think it may be worth investigating. But I'm no scientist...so I can't argue.

Thanks everyone for your opinions! I appreciate it. The various studies he mentioned is nonetheless very interesting. Especially the one having to do with "younger" people having afib and the stroke risks. These sounded like pretty large and significant studies. But, should still be considered in full context.

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Gill
I seem to recall that Hans (founder and previous moderator of this site) said that AF did not increase stroke risk. But that was a while ago.

I doubt he said that, or at least not so broadly. If he said it I would expect he was more specific and nuanced, because stating that afib doesn't increase stroke risk is flatly false and Hans wasn't prone to flatly false statements.

The data is unmistakable and freely available to anyone who cares to actually look at it. I honestly can't believe anyone would even raise the question. I get what Gupta is saying, but really, he's making a big point out of small things and presenting a misleading picture.



Edited 1 time(s). Last edit at 02/16/2020 07:26PM by Carey.

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Carey

The data is unmistakable and freely available to anyone who cares to actually look at it. I honestly can't believe anyone would even raise the question. Don't waste your time listening to this Gupta character.

Please provide a reference which shows that stroke risk is increased and by how much with AF in the absence of comorbidities as measured by low CHADS.

Note that a study is cited which shows that stroke risk is similarly increased in the presence of comorbidities as measured by high CHADS regardless of AF.

Also it doesn't matter that CHADS was initially used only in the AF population. That does not invalidate in any way its use in other populations (like just mentioned).

Gupta makes several good points, all largely correct it seems. What exactly does he say that is wrong? It is true he doesn't address cardiofversions without anticoagulants or ablations with LAA isolation or perhaps some other special cases, but those are seperate issues.

I am certain that Hans used to say that. George - can you help here? I’ve tried searching but had no success.

Gill

I would say, Hans knows a lot of stuff that Carey doesn't.

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Gill
I am certain that Hans used to say that. George - can you help here? I’ve tried searching but had no success.

Gill

Hi Gill, don't have time to look it up. I do have Hans' 3rd edition of his stroke book & will take a look when I have time.

Here is my understanding. While in afib, the velocity through the LAA can materially drop. This provides an opportunity for blood to coagulate more readily. All of the metrics in the CHA2DS2-VASc score are associations that indicate there are constituents in the blood making clotting more probable. If you combine the two, the clotting/stroke risk is very materially increased. In the case of an afibber without comorbidities (i.e. CHA2DS2-VASc score = 0), or the younger people, who don't have the comorbidities in the study mentioned by Dr. Gupta, clotting/stroke risk is not materially increased even though there is lower LAA velocity. So, if you have comorbidities, your stroke risk is increased. If you have comorbidities and afib it is increased even more.


Source



Edited 1 time(s). Last edit at 02/15/2020 07:22PM by GeorgeN.

I saw this video a few months ago and I did post about it. If AF causes a stroke, many of us should have had one when we have episodes of AF I believe Dr. Gupta when he says that we have to have other issues that contribute to having a stroke. My half brother had a stroke a few years ago, he never had any episodes of AF, my mother was in permanent AF for about 8 years and she never had a stroke. I know of a couple of people that had strokes and never had AF. I have had episodes of AF for almost 20 years, I always did convert on my own, until now, I never had a stroke and I wasn't on any blood thinners during that time. I went into persistent AF in Nov. of last year so I did go on a blood thinner. I don't know what will happen to me in the present and future, but I can tell you what has happened in the last 20 years, so I would say there is some merit to what Dr. Gupta says.

Liz

Thanks for sharing! I value all of your opinions. I find Dr Gupta to be pretty interesting. He almost always quotes actual studies.

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GeorgeN

Here is my understanding. While in afib, the velocity through the LAA can materially drop. This provides an opportunity for blood to coagulate more readily. All of the metrics in the CHA2DS2-VASc score are associations that indicate there are constituents in the blood making clotting more probable. If you combine the two, the clotting/stroke risk is very materially increased. In the case of an afibber without comorbidities (i.e. CHA2DS2-VASc score = 0), or the younger people, who don't have the comorbidities in the study mentioned by Dr. Gupta, clotting/stroke risk is not materially increased even though there is lower LAA velocity. So, if you have comorbidities, your stroke risk is increased. If you have comorbidities and afib it is increased even more.

There does not appear to be any study which shows that in the general AF population there are changes to the LAA velocity which significantly increases the risk of stroke beyond that of the comorbidities themselves. Also, the table you provide doesn't affirm or refute anything since it only provides annualized risk in the AF population, without any comparisons to those without AF. It does not show relative risk (relative to the normal population), if that is what you are suggesting.

To refute the studies cited by Gupta, one needs to provide other studies which compare those with and without AF, and show that for example

(i) stroke risk is significantly increased in the AF population in the absence of comorbidities as measured by low CHADS (independent association)

(ii) stroke risk is significantly increased in the AF population in the presence of comorbidities as measured by high CHADS (additive association)

In effect, what Gupta is doing in this video is explaining the evidence for the use of CHADS for stroke prediction as determined by the AHA/ASA. Things may change when studies enable risk stratification based on how people exhibit AF. The only thing I can find that weakens Gupta's argument somewhat is his assertion that the lack of correlation between AF timing and stroke incidence is evidence of an overall lack of association of AF and stroke. It turns out that there is some recent evidence that AF cumulative burden (but not timing) is associated with stroke. I don't remember the outpoints of the study, but I recall being surprised at just how much burden was required. But Gupta didn't know about this preliminary work in 2016, and his views are generally accepted, or at least I think they are until someone can demonstrate otherwise..



Edited 1 time(s). Last edit at 02/15/2020 04:57PM by safib.

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colindo
I would say, Hans knows a lot of stuff that Carey doesn't.

And I would say the opposite is also true, especially if we're comparing things Hans said over a decade ago with the information available to him at the time. I hear "Hans said...." quite often on this forum as if it's a citation of gospel fact. It's not. Hans is a sharp engineer, and good at research, but he's not a medical authority. I'm not a medical authority either, but at least my knowledge is more up-to-date than what he had when he wrote here years ago.

I note that no one has produced this alleged statement. I have a strong suspicion that if he said it, it wasn't the blanket statement it's being made out to be. Knowing Hans, it would be much more nuanced than flatly declaring that afib doesn't cause strokes.

I'm taking my wife out to dinner shortly so I don't have time to go dig up the research, but I will tomorrow.

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Gill
I am certain that Hans used to say that. George - can you help here? I’ve tried searching but had no success.

After a brief review of Hans' (399 page) comprehensive book Thrombosis and Stroke Prevention 3rd. Edition: The Afibber's Guide to Stroke Prevention, I would say it is much more complicated. For example LAA velocity declines with age, even without afib. It also declines with age during afib. It also appears to decline with comorbidities. The 3rd edition was published in April 2018. Hans does an excellent job. Those of you who've read his other books know this. I would recommend reading his book (Kindle version $7.99 US). It is extremely well referenced so you can read the references if you want to do so.

For those who don't know, Hans is a Professional Engineer, educated with a Master's degree in Chemical Engineering. His later career was abstracting for the publication Chemical Abstracts. This carries over into his writing style in this and his other books. Much of the book is abstracted from studies.

Disclaimer. Hans sent me a review copy.



Edited 1 time(s). Last edit at 02/15/2020 07:23PM by GeorgeN.

Let’s be careful not to misinterpret what CHADS means. It’s evaluating the risk/benefit of anticoagulation in an AF patient. Low CHADS score doesn’t mean you aren’t at an elevated stroke risk due to AF. It just means that the risk of bleeding on an anticoagulant is greater.

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Gill
I am certain that Hans used to say that. George - can you help here? I’ve tried searching but had no success.

The first two chapters of Hans' book are available for free to read if you pull up the Kindle version and "Look Inside."

Here is the last paragraph of Hans' summary at the end of Chapter 2, again, I suggest reading the whole book or at least the free chapters (and reading the references for yourself).

I have to say, I am impressed with the level of knowledge in these forums. Many of you seem to know more than my cardiologist!

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cirenepurzalot
I have to say, I am impressed with the level of knowledge in these forums. Many of you seem to know more than my cardiologist!

I'm impressed too, that's why I like this forum. I'm french speaking, and there's nothing as informative to find in my language.
I'd like to thank the previous posters for their comments. They help me understanding what's said in this kind of videos, and don't misinterpreting it only from what I hear (I've to re-listen most of the times).

I think this video deserves a closer look for clarifying what Gupta is reporting based on several studies. I dont believe he is concluding that Afib doesnt increase stroke risk because he does state that those with Afib are at a 5 times higher risk of stroke. He does bring up some good points that may ruffle some feathers of mainstream and alternative thinkers. A warning, to believe that simply because Afib is not present, our stroke risk is lessened, and simply because Afib is present, stroke risk must be accompanied by another co-morbidity to be higher. Because he does state that Afib is not a direct cause, but those with Afib are at a higher risk, doesnt necessarily change our protocols for prevention. The big objection may come when those with Permanent AF claim to refuse blood thinners because either way their stroke risk is no different than the Paroxysmal Patient.

I think Hans did cite at least 1 study that showed that Blood Flow through the Atria was preserved during AFIB, if you had a good pumping strength (Ejection Fraction), and your rate was well controlled. The mechanism being that if the Ventricles are pumping strong, that they physically push up against the Atria during each stroke, and create blood flow that way. This would explain all of those people who have gone untreated with relatively Asymptomatic AFIB with an un-elevated HR who never had issues with Clots forming in the Atria during AFIB.

Another related issue is regarding post AFIB Atrial Stunning. Many strokes happen after NSR is restored, but while the Atria is still not contracting. In a healthy patient that can challenge the Heart by elevating the HR through exercise, the Atria tend to resume functioning rapidly post AFIB episode vs a patient who has comorbidities and is not active will have a longer recovery time until proper Atrial contractibility is resumed. (the LAA contracts with the rest of the Atria).



Edited 1 time(s). Last edit at 02/16/2020 06:59PM by The Anti-Fib.

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The Anti-Fib
The mechanism being that if the Ventricles are pumping strong, that they physically push up against the Atria during each stroke

Does anyone have any idea how low ventricular filling pressures would affect this? I ask because I am in a patient cohort who has this problem.

Important to keep in mind the association between blood viscosity and clearance velocity.

Long ago, there were numerous post on what that means. We were talking back then about the benefits of using the enzyme Nattokinase to help keep blood from adverse clotting - especially during AF event. The studies then were on Hemorheology and references were made to the studies being done at that time.

We investigated what causes elevated blood viscosity... such as inflammation as just one example... and the notation from the hemorheology people was simple... thick, sticky blood increases the risk of stroke and MI ....
Example: Churn cream, you get butter. Churn blood, you get a clot. If you don't have good clearance velocity out of the heart, then there is more risk of forming a clot (as it churns ) and elevated risk of stroke.

Check the links listed in this archived post on this topic...
Several reports related to clot risk.

[www.afibbers.org]

Jackie