INR - How low should you go?

ClickerTicker · Aug 18, 2023

Last week I had a stupid accident whilst out hiking - one boot's laces caught in the lace hooks on the other boot - result was spectacular thump onto tarmac with bump to head, painful shoulder, and grazing. A visit to the Emergency Department for a CT scan (potential brain bleed) and shoulder X-Ray followed. Thankfully, both were negative.

The next morning, I checked my INR and it was 2.4. This is below my UK therapeutic range for mechanical mitral valves which is 3.0 to 4. That may well have been beneficial in avoiding a brain bleed.

It got me thinking about how low I should aim to keep my INR. Had my tumble been with an INR of 4 or even above, a brain bleed would be significantly more likely. I gather the US therapeutic range is more like 2.5 to 3.5. I am considering aiming for 2.5 - what do people think?

Superman · Aug 18, 2023

I know mitral and aortic valve ranges are different, with mitral being higher. I’ll defer to people more well read than I as to why that’s the case. I presume it’s due the lower velocity of blood flow through that valve vs the aortic, which leads to the potential for a greater duration of pooling and higher likelihood of throwing off clots as a result.

I’ll also defer to folks with mechanical mitral valves to answer your real question, which I presume to be if it’s safe to go lower or not.

Oh, and glad to read you’re okay!

dick0236 · Aug 19, 2023

Like Superman I have a mechanical valve in the Aortic position and an INR range of 2.5-3.5. As I understand, there are different INR ranges for Mitral as opposed to Aortic valves. My only bad event (TIA) was due to low INR ( probably a little above 1). I have never had any events with an INR a little above 4. I am much more concerned about a clot than a bleed. I like the quote "blood cells are replaceable, brain cells are not".

I know that doctors are much more concerned about bleeds rather than strokes due to clot......but the damage of a stroke is very often perment........I know

! I have fallen more than a few time and had a few nasty cuts that healed nicely with no lasting damage. Personally, I'll take a bleed anytime over a stroke.

I can't see a problem with a target of 2.5......but I personally would be very concerned with dropping much under 2.0 for an extended amount of time. My opinion only and I am not a doctor

.

pellicle · Aug 19, 2023

Hi

ClickerTicker said:
The next morning, I checked my INR and it was 2.4. This is below my UK therapeutic range for mechanical mitral valves which is 3.0 to 4. That may well have been beneficial in avoiding a brain bleed.

its possible, but then again it may have made no difference. Thing is that warfarin and an INR level (even as high as 4 or 5) does not in and of itself cause a bleed. All it does is take one longer to stop.

What causes the bleed is trauma to the tubes (capillaries veins and arteries). If you'd have had any bleed (and it stopped by itself) I would expect they'd say something like "you have a small bleed but its stopped".

So we don't really know.
Also, I'm curious about your INR range, I thought that in the UK that it was INR target = 3 so that would mean 2.5 ~ 3.5

I'd ask about that.

ClickerTicker said:
It got me thinking about how low I should aim to keep my INR. Had my tumble been with an INR of 4 or even above, a brain bleed would be significantly more likely.

I don't think so, but if you had a brain bleed it would need treating and your choice to go to the ER would be even more the right thing to do.

ClickerTicker said:
I gather the US therapeutic range is more like 2.5 to 3.5. I am considering aiming for 2.5 - what do people think?

well that's what it is in Australia too ...

This article seems not to differentiate between valves (Aortic or Mitral)

https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/415179

The optimal intensity of anticoagulation for patients with mechanical heart valve prostheses was an international normalized ratio (INR) of 2.5 to 2.9

I hope that provides a starting point for discussions with your team

Gkeraney · Aug 19, 2023

dick0236 said:
Like Superman I have a mechanical valve in the Aortic position and an INR range of 2.5-3.5. As I understand, there are different INR ranges for Mitral as opposed to Aortic valves. My only bad event (TIA) was due to low INR ( probably a little above 1). I have never had any events with an INR a little above 4. I am much more concerned about a clot than a bleed. I like the quote "blood cells are replaceable, brain cells are not".

I know that doctors are much more concerned about bleeds rather than strokes due to clot......but the damage of a stroke is very often perment........I know! I have fallen more than a few time and had a few nasty cuts that healed nicely with no lasting damage. Personally, I'll take a bleed anytime over a stroke.

I can't see a problem with a target of 2.5......but I personally would be very concerned with dropping much under 2.0 for an extended amount of time. My opinion only and I am not a doctor.

dick, you can have a stroke from either a bleed or a clot. A lack of o2 from a clot, or a hemorrhagic stroke(bleed). This is most of the reason for an inr range, neither too thin or too thick. All the best to you!

Mrviking9! · Aug 19, 2023

Glad to hear that you’re ok after your scare. I am about to go in for my 3rd AVR. First two were tissue, last one was the Abbot trifecta GT. Yeah that one , unfortunately it’s failing early. My surgeon has recommended the ONYX valve I’m 62 so theoretically this would be my last SAVR procedure. I know what your thinking and your right I should have gone with mechanical valve at 47 but I didn’t and here we are my new surgeon who I absolutely love told me that with ONYX my INR can go as low as 1.5 would anybody out there care to comment, please and thank you. I am new to this site and I’m amazed at all the wonderful and kind people that I’ve come across already

dick0236 · Aug 19, 2023

Mrviking9! said:
....... my new surgeon who I absolutely love told me that with ONYX my INR can go as low as 1.5 would anybody out there care to comment, please and thank you. I am new to this site and I’m amazed at all the wonderful and kind people that I’ve come across already

The 1.5 INR is part of the marketing of the Onyx valve. More and more physicians suggest an INR above 2.0 for that valve. Personally, I am very concerned about numbers under 2.0........and I really can't see any advantage of "walking too close to the edge of the cliff". My personal opinion and I'm not a doctor.

pellicle · Aug 19, 2023

Welcome aboard the good ship cardiac abusive old bastards

Mrviking9! said:
who I absolutely love told me that with ONYX my INR can go as low as 1.5 would anybody out there care to comment, please and thank you. I am new to this site and I’m amazed at all the wonderful and kind people that I’ve come across already

Ok, well pardon me if I effectively cover areas which are already well known to you but I'd start with this post from a while back:

https://www.valvereplacement.org/threads/newbie-needs-advice.889156/post-925506
which gives an introduction to the mech valve types then looks at the differences between St Jude (the market leader who doesn't do marketing) and On-X (a relatively new valve on the market who appeals to people with a fear of being on warfarin). Hint, no reason to be afraid.

This post gives data on how the marketing of specifications does not actually meet up with real world performance on actual measurements

https://www.valvereplacement.org/threads/aortic-valve-choices.887840/post-902334
As one would expect from finding "well one claim was false" that one may expect there to be more than one (old truism of mine: where there is one there's two, but where there's two there's more). This is indeed the case that there is little evidence to support the veracity of the lower INR protocol. I comment on that here:

https://www.valvereplacement.org/threads/new-here-getting-ross-procedure.888757/page-3#post-921066
and here:

https://www.valvereplacement.org/threads/inr.889214/#post-926383
I recommend you read the cited articles in those too.

Lastly I'd say don't fck around with lower INR or any belief that you are "immune" to strokes because of the protection claims of the On-X valve, because such things can end badly for you

https://www.valvereplacement.org/th...-compliance-with-an-on-x-aortic-valve.888128/
As a first part of "informing ones self" the review of academic and professional literature is important (we call that a literature review). Its best done with a guided search with pointed research questions, but to do that justice takes 3 or 6 months (if you want to do it properly and rigorously). The alternative is this:
http://cjeastwd.blogspot.com/2021/07/done-my-research.html
Anyway, sorry about the amount of reading, but I hope I've set you on the path towards informing your informed decision in helping you understand how to review literature.

Best Wishes

LondonAndy · Aug 19, 2023

ClickerTicker said:
Last week I had a stupid accident whilst out hiking - one boot's laces caught in the lace hooks on the other boot - result was spectacular thump onto tarmac with bump to head, painful shoulder, and grazing. A visit to the Emergency Department for a CT scan (potential brain bleed) and shoulder X-Ray followed. Thankfully, both were negative.

The next morning, I checked my INR and it was 2.4. This is below my UK therapeutic range for mechanical mitral valves which is 3.0 to 4. That may well have been beneficial in avoiding a brain bleed.

It got me thinking about how low I should aim to keep my INR. Had my tumble been with an INR of 4 or even above, a brain bleed would be significantly more likely. I gather the US therapeutic range is more like 2.5 to 3.5. I am considering aiming for 2.5 - what do people think?

I'm glad you are OK, and can't directly help with the "how low should I go" question, but as ever @pellicle makes some strong arguments as to why your INR level may well not have been a factor. However, my concern is that 2.4 is significantly below your therapeutic range - how often do you test? If it is not weekly then you are at risk of things like colds/flu causing a significant drop (I find this even before I get the symptoms) and if you're aiming low you have no margin for error.

ClickerTicker · Aug 19, 2023

The UK guidance for target INR levels seems more complex than a straightforward value for e.g. an MVR. It depends on the "thrombogenicity" (potential to generate clots) of the valve itself, together with "patient risk factors" such as "mitral, tricuspid, or pulmonary position; previous arterial thromboembolism; atrial fibrillation; left atrium diameter >50 mm; mitral stenosis of any degree; left ventricular ejection fraction <35%; left atrial dense spontaneous echo contrast".

So, it varies between 2.5 and 3.5. In my case I certainly tick the Mitral box, the AF box (left bundle branch block) and am fairly close to the LVEF <35% - in fact at my last check-up we were debating a CRT pacemaker, but it was decided I'm not that far gone.

Hence the target of 3.5 and my range of 3.0 to 4.0. I test weekly, taking particular care if I'm on holiday and my diet is significantly different - although it normally goes up rather than down as I eat more greens when at home.

pellicle · Aug 19, 2023

ClickerTicker said:
The UK guidance for target INR levels seems more complex than a straightforward value for e.g. an MVR.

same everywhere as I understand it, but its usually a good place to start. People seem to prefer simple (less wordy answers). However as you observe the devil is in the details. This table is from an older standard of INR guidelines from the Journal of Cardio Thoracic Surgeons

the fine print is also worth reading.

David Robbins · Aug 19, 2023

ClickerTicker said:
Last week I had a stupid accident whilst out hiking - one boot's laces caught in the lace hooks on the other boot - result was spectacular thump onto tarmac with bump to head, painful shoulder, and grazing. A visit to the Emergency Department for a CT scan (potential brain bleed) and shoulder X-Ray followed. Thankfully, both were negative.

The next morning, I checked my INR and it was 2.4. This is below my UK therapeutic range for mechanical mitral valves which is 3.0 to 4. That may well have been beneficial in avoiding a brain bleed.

It got me thinking about how low I should aim to keep my INR. Had my tumble been with an INR of 4 or even above, a brain bleed would be significantly more likely. I gather the US therapeutic range is more like 2.5 to 3.5. I am considering aiming for 2.5 - what do people think?

Having a mechanical valve, my range is 2.5-3.5. I test at home so I like to keep closer to 3.5 to avoid blood clots. But, I had brain surgery, too and too high an INR could cause a brain bleed. If it’s 3.6, the doc will advise a lowered dosage, but I review my diet and I know it’s diet related, I may not adjust, just eat less greens. My doc gave me 2.5mg tablets and a dosage chart which gives a more subtle dosage change when INR is out of range.

Mrviking9! · Aug 19, 2023

pellicle said:
Welcome aboard the good ship cardiac abusive old bastards

Ok, well pardon me if I effectively cover areas which are already well known to you but I'd start with this post from a while back:

https://www.valvereplacement.org/threads/newbie-needs-advice.889156/post-925506
which gives an introduction to the mech valve types then looks at the differences between St Jude (the market leader who doesn't do marketing) and On-X (a relatively new valve on the market who appeals to people with a fear of being on warfarin). Hint, no reason to be afraid.

This post gives data on how the marketing of specifications does not actually meet up with real world performance on actual measurements

https://www.valvereplacement.org/threads/aortic-valve-choices.887840/post-902334
As one would expect from finding "well one claim was false" that one may expect there to be more than one (old truism of mine: where there is one there's two, but where there's two there's more). This is indeed the case that there is little evidence to support the veracity of the lower INR protocol. I comment on that here:

https://www.valvereplacement.org/threads/new-here-getting-ross-procedure.888757/page-3#post-921066
and here:

https://www.valvereplacement.org/threads/inr.889214/#post-926383
I recommend you read the cited articles in those too.

Lastly I'd say don't fck around with lower INR or any belief that you are "immune" to strokes because of the protection claims of the On-X valve, because such things can end badly for you

https://www.valvereplacement.org/th...-compliance-with-an-on-x-aortic-valve.888128/
As a first part of "informing ones self" the review of academic and professional literature is important (we call that a literature review). Its best done with a guided search with pointed research questions, but to do that justice takes 3 or 6 months (if you want to do it properly and rigorously). The alternative is this:
http://cjeastwd.blogspot.com/2021/07/done-my-research.html
Anyway, sorry about the amount of reading, but I hope I've set you on the path towards informing your informed decision in helping you understand how to review literature.

Best Wishes

Thank you for all that info I will try to soak up as much as I can. Yeah I kind of thought an INR of 1.5 was fairytale talk. Thanks again much appreciated

pellicle · Aug 19, 2023

David Robbins said:
but I review my diet and I know it’s diet related, I may not adjust, just eat less greens

its less diet related than you may think. I suggest you read this

https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC4998867/

In conclusion, the available evidence does not support current advice to modify dietary habits when starting therapy with VKAs. Restriction of dietary vitamin K intake does not seem to be a valid strategy to improve anticoagulation quality with VKAs. It would be, perhaps, more relevant to maintain stable dietary habit, thus avoiding wide changes in the intake of vitamin K. Based on this, until controlled prospective studies provide firm evidence that dietary vitamin K intake interferes with anticoagulation by VKAs, the putative interaction between food and VKAs should be eliminated from international guidelines

Indeed one could argue that this stupid restriction is what has led to conclusions that bone density is effected by warfarin when in all probability it was the "well meaning actions" of people who didn't know enough and reduced an essential dietary component (that's what it means to be a vitamin) from the diet of elderly people.

I instead suggest that you carefully conduct some experiments over month or so of duration (and more than once each) of

a month of high vitamin K
a month of low vitamin K
eat how you feel like

then compare the data and run a regression analysis. Yes, I've done that. No I couldn't see in the analysis (nor in the graphs) any significant correlations that bore thinking about.

ClickerTicker · Aug 20, 2023

pellicle said:
same everywhere as I understand it, but its usually a good place to start. People seem to prefer simple (less wordy answers). However as you observe the devil is in the details. This table is from an older standard of INR guidelines from the Journal of Cardio Thoracic Surgeons
View attachment 889523
the fine print is also worth reading.

The table I was quoting from is from the UK's "NICE" - National Institute for Health and Care Excellence" document on warfarin anticoagulation. It's pretty much the same as yours but doesn't specifically mention valve types - so thanks! Nice to know my Carbomedics valve is low risk (no pun intended).
CKS is only available in the UK

Slightly off topic, but on reviewing the CT scan done for my fall they also discovered I've an enlarged pituitary gland. I now need an MRI scan. Now that's a whole new can of worms as each valve has its own limit on how powerful an MRI scan should be. The MRI booking folks wanted exact details of my valve - luckily, I do have them recorded. Not everyone may have this info to hand, and you never know when you're going to need an MRI. Maybe they should tattoo implant details somewhere inconspicuous but standard, like under the armpit (that was meant as a joke, but doesn't sound such a bad idea on reflection).

pellicle · Aug 20, 2023

ClickerTicker said:
like under the armpit (that was meant as a joke, but doesn't sound such a bad idea on reflection).

or on the scrotum?

just going with the joke ;-)

pellicle · Aug 20, 2023

pellicle said:
just going with the joke ;-)

hopefully reoperation isn't too frequent with a mech valve, wouldn't want a long medical history in that regard...

LondonAndy · Aug 20, 2023

ClickerTicker said:
... Maybe they should tattoo implant details somewhere inconspicuous but standard, like under the armpit (that was meant as a joke, but doesn't sound such a bad idea on reflection).

Not being a fan of tattoos, I have a MedicAlert bracelet instead. They are a global organisation who offer a variety of wearable products that have key information about your medical conditions engraved on the back of a metal disc but also a 24 hour helpline for paramedics to call for further details. You can give them as much information and documents as you wish, including next of kin info.

dick0236 · Aug 20, 2023

LondonAndy said:
Not being a fan of tattoos, I have a MedicAlert bracelet instead. They are a global organisation who offer a variety of wearable products that have key information about your medical conditions engraved on the back of a metal disc but also a 24 hour helpline for paramedics to call for further details. You can give them as much information and documents as you wish, including next of kin info.

I think having available information is a good idea. For decades, I have had an "anti-coagulant" tag on my key fob. I recently added a "DNR" bracelet to alert any emergency caregivers of my desires.

ClickerTicker · Aug 21, 2023

LondonAndy said:
Not being a fan of tattoos, I have a MedicAlert bracelet instead. They are a global organisation who offer a variety of wearable products that have key information about your medical conditions engraved on the back of a metal disc but also a 24 hour helpline for paramedics to call for further details. You can give them as much information and documents as you wish, including next of kin info.

I agree - the tattoo thing was meant as a joke, there are many reasons both current and historical that make having personal info tattooed on the body a tacky idea. I've worn a Medicalert bracelet since about 2003.

INR - How low should you go?

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