mech vs. bio statistics

[Randy & Robyn]

http://www.diva-portal.org/diva/getDocument?urn_nbn_se_uu_diva-5929-2__fulltext.pdf

The above link has some statistics that seem to contradict what I have heard to date concerning risks associated with mechanical versus biological valves. I hope I am not starting another firefight by posting this. I just found it interesting.

Specifically, on page 45, it states that embolism rates are lower for a mechanical valve than a biological regardless of age. I would have assumed this was due to the fact that more older people receive tissue valves and the rate of non-valve-related embolic events increases with age but this study denies that. If that is not the case, doesn't that tip the scales in favor of mechanicals concerning overall risk when you include resurgery?

Another very interesting statistic, also on page 45, states that the incidence of bleeding events in younger patients was equal among mechanical and biological valve recipients. This also contradicts what I previously thought was true. Does this even make sense?

The paper also correlates a higher bleeding risk with greater age which does make sense.

But if this were all true as well as the generalization that mechanical valves last roughly 30 years on average, wouldn't it be a viable plan to go with a mechanical at my age of 36 and, if it fails as projected, go with a tissue valve in my 60s that would then last the remainder of my life and at the age when anticoagulation complications are the highest? Kind of the opposite logic many people are using.

Is this a legitimate study and are my conclusions logical? Perhaps I am just, once again, reading more into a bunch of numbers than I should be.

Randy

 

[Karlynn]

Randy,
I had my St. Jude installed at 32 years of age. I've had it 14 years now with no incidents of clots or bleeding (knocking wood so hard, I'm bleeding. ) However, if it needs to be replaced sometime, depending on my age, I may go tissue if they're pretty sure it would last long than the rest of my body.

No matter what, my St. Jude has served it purpose for me in my "youth" and would do it again.

 

[Phyllis]

Randy, not sure about the validity of the link but your plan to go mechanical now and tissue in your 60's if needed, makes very good sense. I wish you well and know that you will make the decision that is right for you and then it is time to "never look back" and find peace with your choice.

 

[PapaHappyStar]

Cant see whats wrong with your conclusion, mechanical instead of a non-viable tissue valve right now would make sense to me too, if I were in your position.

Although that study sounds good -- dont know if it has been commented on by real experts, in a globally accessible peer review, looks like they're attempting to answer too many partially independent questions in a single thesis.

Its plausible that there are more thrombosis events in people with tissue valves since the deterioratation is faster than mechanical valves and there is often no anticoagulation, I would like to see events "binned" by time after valvereplacement to see if there is a relationship between the age of a mechanical valve and thrombosis related events ( from this graph on pg. 47 though it looks like that may be flat... ):

If there is deterioration in the surface of mechanical valves with age then the INR should be adjusted according to how old the valve is.

 

[Nancy]

I think PappHappyStar nailed it. Mechanicals always have anticoagulation, and thus less clotting episodes, if the anticoagulation is handled correctly, and that is a big "IF". If the person doing the monitoring doesn't know what they are doing, then blood clots can happen even with anticoagulation.

There are too many variables in the mix here, and I'm not at all sure they are all considered for this study. It would have to be a highly scientific and controlled study to be completely accurate.

 

[Randy & Robyn]

I think PappHappyStar nailed it. Mechanicals always have anticoagulation, and thus less clotting episodes, if the anticoagulation is handled correctly, and that is a big "IF". If the person doing the monitoring doesn't know what they are doing, then blood clots can happen even with anticoagulation.

Now I have a question that might be best answered by Al. Published valve thromboembolism rates must take into account people who are not properly anticoagulated, either through negligence or the incompetence of so-called medical professionals. Assuming that someone has a well-functioning modern bileaflet mechanical valve and their inr is in the median part of their range, is there still a chance of thromboembolism or would it be negligible?

 

[Ross]

Negligible. You have to consider that many people are walking blindly to their care providers which more often then not, have no clue what they're doing or the patient is so old, that they cannot responsibly take care of their dosing and own management.

Might want to post this to Al in the Anticoag forum since he doesn't usually roam about like the rest of us do.

 

[PapaHappyStar]

Now I have a question that might be best answered by Al. Published valve thromboembolism rates must take into account people who are not properly anticoagulated, either through negligence or the incompetence of so-called medical professionals. Assuming that someone has a well-functioning modern bileaflet mechanical valve and their inr is in the median part of their range, is there still a chance of thromboembolism or would it be negligible?

Thats probably something that biases some of these studies -- guess patients must visit the clinic to test and so they are being regularly followed i.e. they are not in the category of people lost to follow-up by default. These are the ones who get good anti-coagulation follow-up and advice.

I went and re-read these two threads:

http://valvereplacement.com/forums/showthread.php?t=9951
http://valvereplacement.com/forums/showthread.php?t=10001

I would like to have the citation to:
a) The animal study for the On-X
b) The South African study -- they must have really invested a lot of effort into tracking more than 500 people over an extended period, wonder who financed this...
c) A study with age binned TE events after VR with a mechanical valve -- plenty of statistics available for this and I wouldnt think funding would be much of an issue either

 

[Superbob]

Don't know about the study, but as one who got a tissue in my 60s, I think your game plan sounds logical to me: a mechanical in the 30's, and then if replacement were necessary as a sixtysomething, a tissue. That's just my opinion, though -- not meant to be firefight material.

 

[Karlynn]

Don't know about the study, but as one who got a tissue in my 60s, I think your game plan sounds logical to me: a mechanical in the 30's, and then if replacement were necessary as a sixtysomething, a tissue. That's just my opinion, though -- not meant to be firefight material.

I don't think you'll get much of a fire-fight on this opinion. I think it's the "young-uns" that join and think repeat valve surgeries throughout their (hopefully) long life is going to be easier and less of a threat to their life and lifestyle than warfarin, that makes it a touchy subject. And I think the touchiness comes from all the erroneous information we hear about warfarin. Unfortunately (and sadly, this in itself could be a good argument for tissue valves at any age) a significant portion of the medical community is the one spreading this erroneous information.

 

[Kate]

As one of the "young-uns" mentioned, I feel the need to respond. Like everyone else forced to make this difficult decision, I spent a great deal of time reading the available literature and thinking about what would be best for my life. For me, that was a biological valve with repeat surgeries, but I have never claimed that was the right course for everyone or that it was without risks.

Although most of the people on this list make a real effort to provide a balanced view of the mechanical vs biological debate, I am uncomfortable with statements claiming that the health risks associated with Coumadin are imaginary. I'm glad that most people don't seem to have a problem, but the reality is that some people do and all you have to do is look through past threads to see this is the case. Perhaps it is human nature that mechanical valvers see us biological valvers as the trouble makers and vice versa, but I really would like to encourage us all, as much as possible, to be moderate in our statements - about risks and about other people's choices. Thanks, Kate

 

[tobagotwo]

It is a college thesis, rather than a deliberate study of a particular aspect of events. It wanders back and forth through several, disparate themes, giving the strong impression that the writer never actually settled on one. This comes across as unfocussed and self-contradictory to me: it looks like a means to an educational end, more than an important, unifying document.

The studies vary from 2004 to 1978, which represents an incredible breadth of clinical practice and valve technology, much of which is irrelevent for current practical purposes. The problem with using data from so long a time span is that you blur the consequences of treatment variations over distinct time periods between innovations in both hardware and understanding.

On page 45 it does say the bleeding episodes were equivalent in "younger patients," despite valve type. On page 46, in the summaries, the mechanical bleeding rate is 50% higher in all three depictions, and doesn't display that finding (which must be from a different, undisclosed ager group). I would suggest you locate and peruse that original study, rather than her interpretation of it.

A note about bleeding events: with self-testing, and more educated patients, INRs can be better managed. Several studies have come to that conclusion already. I believe there's a strong likelihood that the bleeding event rate for warfarin users will drop significantly over the next decade, simply due to better control.

Thromboembolism rates are and will generally be higher in biological valves, as there is (was) usually no ACT provided at all. It will be interesting to see how the current, common use of aspirin therapy will affect those numbers. That's not in those studies yet.

Also, the thromboembolism rate was described as valve-related for the biological valves. I believe it was the rate of strokes found in the group. I strongly doubt that the original study described the rate as having been actually valve-related. A more realistic comparison would place that tissue valve group against a similarly aged control group that is also not taking ACT, to see if there is a risk that is truly related to having the valve, excluding directly surgery-related incidents. Other studies have not found biological valves to be a significant increase to stroke risk over time.

The valves in the studies, especially the older ones, were mixed in terms of mechanical types and brands as well as biological types and brands. Ex: A tiliting disc valve has shown to have had good results in the mitral position, but is less effective in the aortic position. That mix of early models is going to affect the outcomes for both types.

The mortality figures given overall are dismal. But I see a number of the studies are from overseas, which allows for wider care and follow-up variables. And while the other causes of demise are discussed and percentages given, they're still left in many of the figures quoted. They also do not correspond to the mainstream VR mortality figures seen in most current, US studies.

The biological valves from the 20- and 30-year-old studies are barely related to the valves that are produced now. Many of the mechanicals from that era, other than the St Jude, were also experimental. (The St. Jude was also basically experimental at the time, but it was a successful experiment.)

There are some interesting tidbits in this college theme paper, but I would pick them out gingerly, with a good pair of tongs. I would not personally equate this with a quality "study of other studies" as performed by a professional. It just doesn't strike me that this is a document I would hang my hat on.

I strongly urge you to look through a variety of other sources - including some of the more current sources that were used as fodder for this paper. In your situation, at your age, having had one surgery already, I can see very good arguments for you getting a mechanical valve at this point. I would lean that way myself, in your individual situation. But those arguments stand on their own, and don't require a derivative paper like this one to prop them up.

Best wishes,

 

[geebee]

I didn't see any reference to people being troublemakers, only that valve selection is a touchy subject, which is a statement impossible to dispute.

I wonder if there is a study out there that compares the dangers of long-term coumadin use with the dangers of reoperations. If there has been one mentioned, perhaps this thread might be a good place to post it again.

Perhaps it is unfortunate that there are so many of us that have had multiple surgeries and survived. I think it might give creedence to the thinking that multiple surgeries are a breeze and without risk. However, we recently lost a member to the dangers of multiple surgeries. I don't think we have lost anyone recently to coumadin dangers.

And no, I am not saying coumadin has no risks. Even those with properly managed INR levels can have problems. However, as someone with experience with both coumadin and multiple surgeries, I would take coumadin any day over another surgery which, I have already been told, would probably be my demise. I could have switched to a tissue valve during my second or third surgery but I chose the path I believed would prevent future surgery because each one was progressively harder.

Yes, it is up to each of us to make our choice and for all of us to respect those choices. I just think it is really important for us to read these posts at face value and not to read between the lines and think things are being said that are not. That is really what constitutes respect of other's statements.

 

[Karlynn]

As one of the "young-uns" mentioned, I feel the need to respond. Like everyone else forced to make this difficult decision, I spent a great deal of time reading the available literature and thinking about what would be best for my life. For me, that was a biological valve with repeat surgeries, but I have never claimed that was the right course for everyone or that it was without risks.

Although most of the people on this list make a real effort to provide a balanced view of the mechanical vs biological debate, I am uncomfortable with statements claiming that the health risks associated with Coumadin are imaginary. I'm glad that most people don't seem to have a problem, but the reality is that some people do and all you have to do is look through past threads to see this is the case. Perhaps it is human nature that mechanical valvers see us biological valvers as the trouble makers and vice versa, but I really would like to encourage us all, as much as possible, to be moderate in our statements - about risks and about other people's choices. Thanks, Kate

Kate,
I'm sorry if you misconstrued my post. I thought I was moderated. Maybe I wasn't clear enough, but it is my feeling that there is still much irresponsible information being disseminated by some in the medical community that, in my opinion, gives the use of Coumadin an over-weighted and unwarranted position of being much riskier than repeat surgeries. You have to admit that most of our new members who post here and say they are looking at a mechanical valve choice (and even a tissue valve choice) state that they are very fearful of having to take warfarin. Why is that? I don't think we see nearly as many new members post that a tissue valve was recommended but they are very fearful of having to have repeat surgeries. Why does warfarin use have much scarier information associated with it than repeat surgeries? Part of the reason is that the art of surgery has been around longer and is much more accepted as a common occurrence by the general public. Which I think gives surgery a seemingly lower risk factor in general.

I did not say that the argument starts because "young-uns" make irresponsible decisions. I was inferring that it starts because the posts remind us just how much warfarin is misunderstood by the very people who are entrusted to save our lives - the medical community. I even went as far as to say that it is this high level of misinformation accepted by our medical professionals that may very well be a good reason to choose a tissue valve. Why would we choose a course of treatment that our own doctor has little idea how to manage? I am not nearly as disturbed by a 28 year old choosing a tissue valve, as I am by a doctor who flatly rejects the idea of a mechanical valve for anyone under 40. It's not the people who join here and read all the information they can that worries me. I respect their choice, regardless of what it is. It's those that don't join and make a choice based on a physician's own uneducated biases that concern me.

One of my first concerns when someone posts that they are getting a mechanical is "Gosh, I hope their doctor knows how to manage warfarin." And I think that's really sad. I also think that we tend to look at the risk of resurgeries as -do you live or do you die. We haven't (that I recall) had a discussion on what shape the heart will be in after repeat surgeries. Will scar tissue impede an optimal redo? Will it weaken the heart? We don't talk a lot about quality of life after repeat surgeries, just if there will be life. This is not to say that the individual doesn't consider this, we just haven't discussed it here - and maybe we should.

 

[Randy & Robyn]

I will give you some insight into my current mindset. When I went into surgery five weeks ago the goal was a repair that would last a lifetime. My backup plan was a tissue valve and I was perfectly willing to accept the risks of a second surgery in ten or fifteen years.

Unfortunately my repair failed and another surgery is now staring me right in the face and I am once again scared to death. My recovery from my first surgery went flawlessly. I am five weeks out and feel great. This, however, gives me little consolation as I am well aware of the scar tissue that now resides around my heart, possibly even adhering it to the sternum itself that once again has to be separated.

From other posts, I am aware that some repeat surgeries go smoother than the first one. However, most do not. Time under anesthesia is increased, time on the pump is increased; both of which wreak more havoc with your system. Plus there is a small but significant risk of damage incurred by separating the scar tissue.

These are the things running through my mind right now and I can only hope that after this next ordeal I never have to deal with this anxiety again. The thought of taking an active role in my own health through self-managed coumadin therapy appeals to me greatly compared to the terror of having that mask put over my face and not knowing if I will ever wake up again.

This is just my own thinking right now which has changed dramatically since my first surgery.

Randy

 

[PapaHappyStar]

Now I have a question that might be best answered by Al. Published valve thromboembolism rates must take into account people who are not properly anticoagulated, either through negligence or the incompetence of so-called medical professionals. Assuming that someone has a well-functioning modern bileaflet mechanical valve and their inr is in the median part of their range, is there still a chance of thromboembolism or would it be negligible?

Al did address this question in a thread he started here not long ago:

http://valvereplacement.com/forums/showthread.php?t=13478

[SNIP...]

In my clinic I know that we have 1 case of minor bleeding about every 1.5 patient-years. Major bleeding about once in 33 patient-years. Clotting occurs about once in every 100 patient-years.

My guess is that if this study were done 10 years from now on valves implanted from here on out, the stroke rate would be about 10%. Still fairly high but to put it in perspective, it is about the heart attack rate for diabetics.

In the past week I have reviewed the possible replacements for warfarin and there is nothing that is being tested for mechanical valves that will be available before 2010.

Hope this helps clarify the issues involved

So he thinks that the TE event rate for the new generation mechanicals is around 10% in ten years. If you have other risk factors reduced ( getting an aortic valve for one is associated with less risk, age, smoking, possessing a Y chromosome etc. here is a post on risk factors http://www.valvereplacement.com/forums/showpost.php?p=94207&postcount=17 ) you would better off than the average.

 

[Kate]

One of the unfortunate things about communicating in writing is how difficult it is to figure out the tone with which someone is "speaking". I certainly didn't intend for my post to sound as starchy as it did (although I do have to admit to writing it after having a fight with my SO, something I probably won't do again ) and I clearly misunderstood the message Karlynn was trying to get across. If I had taken the time to think about it, I would have realized that it was very out of character for Karlynn to be speaking critically of others, as that is the exact opposite of what her posts are usually like. Mea culpa!

As far as the coumadin vs. resurgery issue goes, I really do believe there is no right answer. The statistics my surgeon gave me were a 1 - 2% annual risk of severe bleeding on coumadin vs 4% mortality risk for my second surgery and 8% mortality for my third (hopefully that will get me to 75). That, combined with quality of life issues and the extremely limited medical services in my small town, tipped me in the direction of biological, but I can really see someone going the other way. It just isn't clear cut. Perhaps it would be easier if it were.

Randy, I'm so sorry for what you are going through. When I read your first post about your valve repair not working out, I was only 8 weeks post-op and couldn't even imagine contemplating another surgery so soon. I think it is remarkable you can remain positive in the face of such disappointment and, for what it's worth, it sounds like you're making a good decision. I have great faith that this next operation will be the permanent fix you are looking for. Take care, Kate

 

[Karlynn]

Kate,
Mary and I can fill you in on where we purchased our crystal balls. They help immensly in making choices. But they must be handled with great care and responsibility.

I think you have a point that also hasn't been discussed here - how does geography and ones location to large medical facilities impact their choice. It would seem wise to make the choice that reflects your community's medical capabilities. No one wants to hear a doctor say to them "Wow, this is cool! You're my first!"

 

[Randy & Robyn]

Thanks for the rundown on the stats, Bob and Burair. I was suspicious of this paper. I think I will go into this thinking like Ross stated. Keep your coumadin levels where they are supposed to be and odds are overwhelmingly in your favor that there will be no problems.

Kate, I abhor being depressed so I figure I will just enjoy the holiday season and then roll the dice one more time. I will admit the first words out of my mouth to my wife after finding out about my repair failing were that I would never have another surgery and would just live as long as I could. Needless to say, she smacked the sense back into me real quick.

And Karlynn, if I based my decision on the competence of the local medical establishment I definitely would not be going mechanical. My infectious diseases doctor expressed how much he despises coumadin as have all the nurses I talked to while in the hospital. When I told my pharmacist I might be going on coumadin, he gave me a look like it was a death sentence. I guess my next step should be to start searching for an anticoagulation expert in my area who actually knows what they are doing. Any suggestions?

 

[Karlynn]

And Karlynn, if I based my decision on the competence of the local medical establishment I definitely would not be going mechanical. My infectious diseases doctor expressed how much he despises coumadin as have all the nurses I talked to while in the hospital. When I told my pharmacist I might be going on coumadin, he gave me a look like it was a death sentence. I guess my next step should be to start searching for an anticoagulation expert in my area who actually knows what they are doing. Any suggestions?

Sounds like you've run across the people I'm speaking of. I give you a lot of credit for going beyond their biases.

I know that Al has posted a link to a site where you can look for anticoagulation clinics by area. When I get the time, I'll try to hunt that down. I would also suggest looking into home testing. It used to be that you'd have to be on Coumadin for a year prior to being released to home test, now some hospitals and doctors are sending people home from the hospital with the okay to home test. I know that Raytel (and maybe QAS) has a program where you home test and call in your results to them and they speak to your doctor, or a specialist, about any dosage adjustment. So it's quite possible that you may not need a clinic in your immediate area.