INR

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gerrychuck

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What are the risks. I don’t understand INR . Why would a low INR cause a stroke? I’m trying to learn and really appreciate all of your advice. This is happening so fast and I’m trying to make the right decisions and be as informed as I can be.
The reason for being on warfarin is that clots can build up on mechanical valves, with the potential to break off and cause stroke. If it weren't for that, none of us would be on the stuff! Higher warfarin doses lead to higher INR, which translates into less clotting and lower stroke risk. INR itself is "international normalized ratio" and is an objective comparison of an individual's clotting time compared to "normal"; an INR of 2, for example, means your clotting time is twice the normal time. If INR is too low, the risk of stroke goes up. Likewise, there are risks inherent in INR's that are too high (spontaneous bleeds or dangerously slow clotting with wounds or potentially with concussions/head injury). A couple of the members here have posted links to long-term research that indicates that the risks from too low an INR are significantly greater than those from INR being too high, which is why people here are stressing that there isn't really that much to be gained by a slightly lower INR, but potentially much more risk. Hope that little primer helps!
 

Superman

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The biggest risks with Warfarin are driven by mismanagement. Simple as that. Back when many of us started, there was no home monitoring. We could only go to the lab. Tell a 20 something year old living on his own for the first time with college buddies to get to the lab monthly! I know I went as much as six months between draws back in the day. I’ve been a Warfarin-aholic for 29 years now.

I came through unscathed. Lucky me. With home monitoring, this has been made much easier. Particularly for those who don’t live near a lab. Needle poke and email once a week. Super easy.

So, can you take a medication daily. Every day. Can you manage dosing variations? I alternate 6 and 7 mg daily to stay in range, for example. Can you test regularly? If you can manage all that, Warfarin isn’t an issue.

The reality is that with Warfarin, adverse affects are their lowest between 2 and 4 INR. The bell curve really picks up outside of that range. The standard guideline used to be 2.5 - 3.5, which put your window right smack in the middle of this range with a margin of safety to the high and low end. Meaning, if you are outside the window, you’re likely still safe. Just adjust the dose and get back in there.

Somewhere along the way, people decided that since 1.0 is “normal”, people will feel better if we can get them as close to “normal” as possible, regardless of what the data supports. So the standard went from 2.5-3.5 down to 2-3 (Yay! Mine’s newer and better and closer to normal!). Then came the big push for 1.5-2.0. (Ours is better because it’s closer to “normal”!)

@pellicle has the chart supporting 2-4. Don’t know if he posted it in this thread yet, but it’s all over the forum.
 

DDT77

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pellicle

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@pellicle has the chart supporting 2-4. Don’t know if he posted it in this thread yet, but it’s all over the forum.
I didn't cite it here because the question was about the On-X and I don't think the On-X is included in that study...

from "Optimal level of oral anticoagulant therapy for the prevention of arterial thrombosis in patients with mechanical heart valve prostheses, atrial fibrillation, or myocardial infarction: a prospective study of 4202 patients."




however if like me you think that all the On-X has going for it is a small test done once without subsequent replication elsewhere that I know of (and with quite specific inclusion criteria and weekly testing by probably the best INR monitoring you can pay for) and that it is essentially like the other current bi-leaflet valves (which would be supported also by the GELIA study) then I guess I should post it here (even if it does fester the board like a American Somoan outbreak ;-)
 

pellicle

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My cardiologist said in Europe they only take An aspirin a day with an on X valve and are not required to take warfarin. I believe that’s what he said anyway.
it may have been what he said but the reality is (even if he didn't know it) that you MUST take the Aspirin AND take the Warfarin AND keep your INR strictly above the minimum in that range.

There is no protocol I know of where mechanical valves are exempted from Warfarin (except "stuff this, I'm not taking that drug" failure of patient copliance). As far as I know the attempt to use Dabigatran failed due to incovenient strokes suffered by patients (getting in the way of that pharma plan).

Essentially this boils down to a marketing solution where no problem exists. SImply put despite over 50 years and millions of prescriptions and hundreds of studies we find:
  • no repeatable reliable evidence that Warfarin has any ongoing side effects (except to induce ageing by the prevention of early death)
  • keeping INR in the theraputic range of 2~3 for Aortic and 2.5~3.5 for Mitral valvers and remaining in that range for over 90% of the time reduces your thrombosis risk to around that of the age related general population
  • the introduction of Point of Care testing enables people to conveniently test at home and increases their time in therapeutic range. (and challenges the profitability of easy INR tests for labs)
  • changing from a vein draw to a finger prick test reduces the damage to that vein over time (remember, you're on it for life)
I recommend you listen to this presentation segment, it is not in any way On-X specific.

Best Wishes
 
Last edited:

jlcsn2015

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Sep 21, 2015
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Toronto
Thanks everyone for all the great advice. I thought with the on X valve that your INR would be more in 1.5 to 2.0 range. It seems that all of you are more in the 2 to 3 range. Why all the literature and ad campaigns touting a lower INR if nobody is in those ranges??
Well, is a good peace if mind to know that in the event of your INR going below 2 you are safe, mine at the begining went on for 1.5 to 1.9 for weeks, and all went fine. Now after 4 years, i just keep it above 2, so IF it goes down in one of travels to other countries/places, i know for a fact that at 1.6 it works fine, BUT, yes, i do try to keep it at 2.2, and if it goes to 2.5 if fine, and if it goes to 1.6 is fine too, that is how it works " for me", we all have different realms of thought
 

Protimenow

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Okay.

In a rather large nutshell, this is the thing about INR and heart valves.

Prosthetic heart valves (Medtronic, On-X, St. Jude's, etc.) have surfaces inside them where blood can connect. At the surfaces where the large vessels connect to the valves (they're sewn together), clots can form. Even with On-X valves, which reportedly don't have as big a problem with clots forming, clots can still form.

The problem with the clots that form is that they can break off, and go into the bloodstream. These clots floating through the bloodstream could end up in the brain, clogging blood supply and potentially causing a stroke, or can end up doing damage in the lung (pulmonary embolism). Peole with prosthetic valves take an anticoagulant (warfarin) that prevents the clots from forming.

INR - International Normalized Ratio is a ratio between the length of time that it takes the blood to clot, divided by a value for the particular chemical (reagent) that promotes the clotting. An INR of 1.0 is approximately the value for normal, un-anticoagulated blood. An INR of 2.0 is an indication that blood takes twice as long to clot as blood with an INR of 1.0. And so on - the higher the INR, the longer it takes for blood to clot.

From personal experience, and the reported experience of hundreds - if not thousands - on this forum, having an INR between 2.5 and 3.5 (for example), is no big deal. It doesn't change your life. It's not the nightmare that some marketers would want you to believe. It's not like taking 'rat poison' - and being instantly fatal if you take a bit too much. It isn't really that big a deal.

Unlike the way it was twenty or more years ago, there are now meters that you can own, and do self-testing.

I have a St. Jude valve. I got it in 1991. If I had an On-X today, I'd prefer not to take the risk of maintaining a low INR, or just taking aspirin (on the possibly rare likelihood that this low INR wouldn't increase my risk of a clot form, or throwing a clot) and would STILL want to maintain an INR of 2.5 - 3.5.

To me, it's not worth the risk to have a low INR to support the On-X marketing machine and possibly risk major, life-changing results. IF and WHEN there's proof in long term, independent, retrospective studies that demonstrate little or no risk for ON-X users to keep INR's around 1.5 (or just taking an aspirin a day), I may be more comfortable with a low INR. But keeping a slightly higher INR will reduce or eliminate that risk, so even if such a study existed, I may not shoot for a lower target INR.

I hope this gives you more information than you need.
 

vitdoc

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Basically clots can form around valves made of non biological material. They can do at least two things. One is to break off go downstream and lodge in a blood vessel somewhere and stop the local blood flow. If in the brain a stroke. The other issue is that the valve may become immobilized by a clot forming in the orifice. Neither is very good. So years ago when the first valves were made patients were placed on Warfarin to reduce the ability to clot. Studies have shown a marked reduction in stokes and other complications of potential clotting using Warfarin. The ON-X valve has been touted by the company to require a lower degree of anti coagulation. INR is a way of quantitating the clotting mechanism. The longer it takes to clot the higher the INR. The studies by the ON-X company showing that lower INR levels are OK were rather limited and if one looked closely at them they did show a higher stroke rate than higher INR levels. Just not that much. The fear of very high INR levels is that there is a significantly higher bleeding risk. But these have to be fairly high before they become very worrisome. So one balances the risk of stroke vs bleeding. Aiming for a low (1.5) INR might lead to a 1.2 INR -> possible stroke. Aiming for an INR of say 2.5 might lead to a 3.5 which is usually not a big deal and can be adjusted. Also the ON-X company did their testing with aspirin. So this is important to continue. With the higher INR levels ASA is not required. As I mentioned in a previous post physicians don't always have the time to read the fine details of studies. The ON-X studies were weak and probably many cardio vascular surgeons may hear about them from the reps from the ON-X company. The valve seems fine and probably is a strong competitor to the St. Jude but I was not convinced by there low INR claims. Just to further complicate these issues was the surprising discovery that the newer classes of anticoagulants did not work as well as Warfarin in reducing stroke. They are not recommended for mechanical valves. Primarily for Atrial Fibrillation. I personally have had around three or four fortunately transient retinal artery occlusions even on Warfarin. So this is a real issue.
 

Protimenow

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Superman: If your dose alternates between 6 mg one day and 7 mg the next, why don't you just take 6.5? (Yeah - I think I know the answer - it's harder to get a dose of 6.5 than it is to get 6 or 7 - but the answer may be as easy as taking one 4 mg and one 2.5 mg pill per day).

Taking the same dose every day will give you test results that are more representative of your actual INR -- if you alternate from day to day, your results will be higher on one day than on the day before it.

----

Years ago, I had a TIA. I was testing my INR with a bad meter every week or so. The InRatio meter was giving me a 2.6, consistently, but at the hospital, my INR was 1.7. At that point, I began searching for the most accurate meter (or the one that I was willing to trust my life to). I used regular lab blood draws as a control.

The InRatio has since been discontinued by the manufacturer - for obvious reasons.
 

Superman

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Grand Rapids, MI, USA
Superman: If your dose alternates between 6 mg one day and 7 mg the next, why don't you just take 6.5? (Yeah - I think I know the answer - it's harder to get a dose of 6.5 than it is to get 6 or 7 - but the answer may be as easy as taking one 4 mg and one 2.5 mg pill per day).
Using 1 mg as my second pill allows me to adjust the number of days I need to take 7 mg quite easily. Sometimes I need just one more or less mg per week. Very easy to do with 5’s and 1’s on hand.
 

tom in MO

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MO USA
Thanks everyone for all the great advice. I thought with the on X valve that your INR would be more in 1.5 to 2.0 range. It seems that all of you are more in the 2 to 3 range. Why all the literature and ad campaigns touting a lower INR if nobody is in those ranges??
I have a St. Jude valve. The range recommended is 2-2.5. That's what I keep it at by testing every 2-3 weeks. I take warfarin and aspirin as directed. The range comes from two personal cardiologist and at least 3 others within the practice's Coumadin Clinic. Since I occasionally get a bleeding hemorrhoid I have a good reason to not keep my INR higher than needed. I also can get nose bleeds In addition, I had a surgery where my recovery time was longer due to extra bleeding caused by my higher than normal INR.

I believe the path to total body health is helped by taking only the drugs you have to and at the minimum dose needed for the desired therapeutic effect. I don't believe there is any need to keep my INR higher "just in case." If I am worried about my INR, say due to poor diet while traveling, I test more often and adjust my dose accordingly.
 
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