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What should the target INR be?

A new study set out to discover what is the optimal level of oral anticoagulation in order to minimize both bleeding and thrombosis, in patients with mechanical heart valves, atrial fibrillation, or myocardial infarction.

The researchers wanted to find that level which reduces the rate of both bleeding and thrombosis to help improve the safety of oral anticoagulant treatment.

Note: This article is a review of a study and is not intended to offer medical advice. Your target INR should be advised by your doctor or INR clinic.

The target INR study

Researchers assessed 4202 patients visiting the Leiden Anticoagulation Clinic, Netherlands with mechanical heart valve prostheses, atrial fibrillation, or myocardial infarction over a 4 year period.

There were 3,226 hospital admissions throughout the study, with 306 due to major thromboembolism or hemorrhage event. They found the lowest event rate for the following:

  • People with mechanical heart valves was for INR range 2.5-2.9.
  • People with atrial fibrillation was for INR range 3.0-3.4.
  • People treated with warfarin after MI was for INR range of 3.5-3.9.

Generally the lowest event rates were very similar for INR ranges. The one exception was that the INR range 2.0-2.4 for mechanical heart valves was linked with a much higher event rate.


The study offers reassurance that current INR target ranges are associated with a minimal level of both bleeding and thrombosis.

The researchers wrote in conclusion, “Our study suggests target INRs of 3.0 for patients with mechanical heart valve prostheses and atrial fibrillation and 3.5 after myocardial infarction as a starting point in future clinical trials.”

The study was published in The Archives of Internal Medicine.

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One Response to “A safe target INR range”

  1. John Boy says:

    I am sometimes in disagreement with where I go for my inr testing.I have had this done for 17 years now,so I am no rookie,I know what happens when my coumadin is decreased as well as increased,as of late in 16 checks I have been in range 10 times and out 6 times,when I was out,I had a 2.4,2.3,2.1,2.2,3.7,3.7 my target range is 2.5 to 3.5 as you can see some of the readings wasn;t out that much,and some was.My bitch is when its only out by I call it two points,it could have been something I ate or drank,now the last two check ups it was the 3.7 and my medication wasn’t decreased,I just feel I am being screwed around with when I have to come back in a two week span,and I don’t always get the same person,if I got the same person I think they’d get use to how I react to a medication change,the person that did it the last time at the 3.7 level said eat some vitamin k products and we’ll see what they does,I am surprised she did’t have me take one pill less then reduce by 1/2 pill every week,right now I am takeing 7.5 mgs 6 days a week,and 5 mgs 1 day a week,I just figure it should have been changes to 5 mgs to days a week and 7.5 mgs 5 days a week,this has been done in the past when I have been on the high side.or even take 1 and a 1/2 pill 5 days a week,one day take 1 and a 1/4 pill one day,then 5 mgs the other 2 days.

bottom KellieMyHS

About Kellie

Kellie is 37 years old and together with her brother Steve makes up the My Health Software team.

She helps on the websites and gathering news for the programs. Kellie worked in the medical industry prior to having her two children (8 and 6) and has a strong interest in self awareness and management of health conditions.


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