On-X approved for lower INR Range in the U.S. - Stuck with conservative guidelines

[realkarl]

I am a patient with an On-X aortic valve since 2009, and I have been following the results of the PROACT trial for years. I was very happy to receive a letter from On-X notifying me that they have finally received FDA approval to recommend a lower INR range (1.5 to 2.0 for On-X aortic valves). As per On-X's recommendation, I tried to bring this up with my doctor, but was very disappointed in their conservative reply:

"I am responding on behalf of Dr. Belz.
The American guidelines for management of prosthetic valves has not changed their recommendations to date. I appreciate the information and will review it with my colleagues. For now, we will not plan to change your target INR until more data is avaiable.
Sincerely,
Tina Ghia, MD"

So it looks like I will never be able to run a lower INR range. I have doubts the American guidelines (ACC) will ever change.

I am an active bicyclist, and even though I am careful, once in a while an accident can happen. I also have always had trouble with nosebleeds, despite cauterization, so for me a lower INR range would have been useful, although not critical. I have been doing fine for almost 6 years.

EDIT: Two days after this post, when Dr Ghia had conferred with colleagues, with additional materials provided, and possibly influenced by On-X, I was informed I would be allowed a lower recommended INR range. See post #6 below for details.

 

[CATDOG]

I read something somewhere that suggested that it is just "mid-year" for the annual (?) review process. I'm not sure when the next new guidelines will be published, nor whether they will have had enough lead-time to address the issue beforehand.
I suspect that when they've had enough time to review everything, the agency will address the issue one way or the other in their subsequently published recommendations.
I think the doctors are mindful of the current published agency recommendations, and also their local review boards which monitor/tally how well they follow the published recommendations. Perhaps there is hope still down-the-road for the non-high-risk aortic On-X valvers.

 

[Gail in Ca]

I was told with my latest carbomedic aortic valve (09), that I could try to keep my INR at 2.0, and that going down to 1.8 would be okay. I found, however, that it's somewhat difficult to keep the INR from going to 1.6 if I didn't do any adjusting when it was at 1.8. So, my range is more like 2-2.5, which works very well. I'm rarely out of range, testing weekly. I have never found that having a lower INR makes my nose bleeds less. I think the docs are worried about clots, and it's very hard for them to change what's been done for years (range of 2-3). It was my surgeon that told me I could let my INR go down to 1.8, not my cardio.

 

[dick0236]

After almost 48 years on warfarin I have never had an issue of bleeding(externally or internally) with INRs around 3, but I had a significant stroke when my INR fell to near normal(INR approaching 1.0). There used to be a saying around here that....."blood cells are easier to replace than brain cells". In my case the brain cells never replaced and I am very hesitant about low INR. A few years ago I stumbled across a chart that correlated "INR values" and "clotting time in seconds":
INR.......... seconds
1.0(normal)..... 12
1.5..... 17
2.0..... 21
3.0.... 30
4.0.... 38
5.0.... 48
10.... 82

We all know that it is not safe, with todays science, for mechanical valves to be at normal INR levels and a 1.5 gives only a 5 second safety margin. At 3.0 the clotting time is about 2-1/2 times normal and gives me a much more comfortable feeling.......and my increased "cuts and bruises" clotting time is almost imperceptible. I am all for a long lasting valve that requires NO warfarin but until that is achieved I kinda think shooting for a 1.5 INR valve is "using a sledge hammer to kill a flea"...........but that is only my opinion LOL.

 

[pellicle]

Hi

to further (and agree with) Dicks point

... I kinda think shooting for a 1.5 INR valve is "using a sledge hammer to kill a flea"...........but that is only my opinion LOL.

I feel that this guideline is 9 parts marketing and 1 part practical. I don't mind this however as if this gets rid of some of the "FEAR" people have of warfarin then well and good.

As Gail observes above, its very hard to attempt to tread the line of 1.5 in real life. On paper it looks like a number, the reality is that the number is a measurement of a complex system. Anyone who has been measuring their INR and doing their own dosing (because we tend to have longer histories of the numbers recorded than those who go to clinics) will tell you: your INR wiggles around from time to time.

As I've said before; to me this new number is a benefit for the peace of mind that it brings when targeting an INR of 2.5 ... it means that if your INR drops to 1.5 then you have confidence that you don't need to reach for the heparin (Lovenox is a trade name) to be confident of avoiding a stroke.

To me if you aim to sit on 1.8 two things happen:
1) you will fail and be under 1.5 and worry
2) you will lose the peace of mind that dropping down to 1.5 isn't a problem and you can just add a teeny smidge of warfarin to your daily intake.

In truth we have (as yet) no idea how this 1.5 target was reached and what long term effects it has on the valve operation ... heck I don't even know if they did anything more than test for signs of clotting in the blood.

So take 1.5 as peace of mind not a target. There is a wealth of independent studies showing that being between 2 and 3 is safe. Err on the side of prudence.

 

[realkarl]

I never expected anything else than what was commented above, and I do agree with most of what was said, except the trivialization of bleeding events. There are significant advantages to lowering the risk of bleeding. I am not talking about "cuts and bruises", but potential brain hemorrhage or internal bleeding. As a daily bicyclist (7000km distance / 80000m elevation gain last year) , accidents unfortunately can happen. Twice since surgery I have bumped my head (inside a helmet) hard enough I felt I needed a check-up. Neither was my fault, but fortunately, no serious issues either time. With an INR around 2 I was still black and blue for a month+ afterwards. Second, I easily have nosebleeds - despite having been cauterized several times - one time in urgent care the doctor had severe problems stopping it, because it bled so much he could not cauterize. INR was 2.5 or so. I have rarely been more scared, blood streaming, not dripping, out of my nose for hours. Third, when my INR is above 2.5 I get post exercise migraines almost every day. With home testing I keep my INR to be in the 2 - 2.5 range and closer to 2 most of the time.

Then to the good news. Yesterday, an On-X representative called me, after I had sent them a brief message about the initial reaction from the doctor to my request. The representative was going to ask my surgeon, Dr Mark Hill @ Virginia Mason in Seattle, who I remain so incredibly grateful to for a successful procedure allowing me to continue bicycling, to call my cardiologist and explain in detail how the lower range is safe for On-X aortic valves in low risk patients. This was one of the reasons Dr Hill and I chose this valve in 2009. I am not sure if this ever happened, but I also faxed the doctor in charge of anti-coagulation the materials I had received from On-X, as she was going to confer with her colleagues about the issue.

Then already today, surprisingly, she wrote me back saying that after discussing with her colleagues, they all agreed I could have my recommended INR range reduced after all.

Now in practical terms what this means was partially mentioned above. I will not be trying desperately to stay between 1.5 and 2. I will most likely stay around 2 as before, but not worry too much if it dips a little below, making it easier to avoid going above 2.5, my "migraine threshold". So in fact not too many changes, just more peace of mind with a greater practical range (1.5 to 2.5) instead of 2 to 2.5, and less risk of accidentally being closer to or above 3, if I should have a severe nosebleed or another bike accident (hopefully, I'll avoid both).

Thanks for all your replies.

 

[Noyolk]

I met with my Cardiac Surgeon last week and asked his advice on the ON-x results. He agreed that it is a marketing strategy, but he recommends the valve as he sees it as a better valve in the ultrasounds. I am assuming he means the smoother flow and less pressure drop. I presented my home monitoring results and discussed the high risk activities that I enjoy(dirt motorcycle trail and track riding, Skiing and snowboarding), and since I have a history of stable INR, he thought I would be a great candidate. We agreed on 1.5 to 2.5 and my only concern was my home meter accuracy. Today that was slightly alleviated as a lab draw and my meter were tested within minutes of each other and had the same result. I know that it is only one data point, so I have put in my calendar to retest with lab in 6 months. I buy 12 months of home test strips at a time so the first and middle of the batch will be tested against the lab.

I have not lowered my 5mg warfarin dose, nor changed my eating habits, but my primary care DR. will not be upset(and change my dose) anymore when I call in the results at a 1.7. So for me personally, that is what I gained, as I have tried to keep my target at 2.

 

[Bonbet]

Wow, Noyolk, you are in Portland and had your surgery at Good Sam?? I am in Eugene and planning to have mine a† Mayo. But, I am curious about your Good Sam impressions, if you don't mind sharing. I do need a quasi-local backup in case of complications post-op. Bonbet

 

[Noyolk]

Bonbet, Check your pm's.

 

[Bonbet]

Thanks Noyolk, for the message. I haven't figured out how to reply via "pm's" yet. Bonbet