Stupid question... Re mech valves

[markp66]

I was speaking to one of my avr friends the other day about mechanical/ tissue valves.

He is 32 and has a tissue valve. All is going well 2 years post surgery. He said that if this went within the next 5 years he would still opt for a tissue valve as the risk of a reop and even a 3rd reop would still be less than being on warfarin for the rest of his life. As some of you know my tissue valve has lasted only 4 years and already needs replacing. I mentioned that I'm keen to go with the on x mech valve mainly because of the great feedback/ research I've done and I really don't fancy another op within the next 20-30 years!

His point was this-
There is roughly a 1-2% chance of having a stroke or major bleed every year. He said that over 30 years this would mean that you have a 60% chance of this happening compared to relatively low reop risks for replacing tissue valves.

This is stupid thinking right?! I'm pretty confident the stats don't really work like this.....???? Surely if you go 20-30 years without a problem occurring you are in the same position as someone who has just had a mech valve implanted. In some ways it could be argued that if your body has coped without problems for such a long time as long as the INR is consistent then it is unlikely you will run into problems later down the line...

Any feedback would be great. Sorry for sounding stupid but he got me thinking! (not good when I'm already stressed about everything!)

Ps. Just off to see the surgeon re my future op...

 

[lance]

I'm not sure I agree with everything you have posted but I'm far from being an expert.
Hopefully you have mentioned your concerns to your surgeon especially about re-ops of any kind--tissue or mechanical. When a heart valve needs replacing you're better off replacing it (whichever you choose tissue or mechanical) than you will be with a failing natural valve. Valve replacement is major surgery and each one harder on the body than the previous one. Speaking from experience surgeons are not the best resource on anti-coagulation either. Some cardiologists probably are.
Most, not all, doctors are more concerned about their ACT patients bleeding over stroking. Speaking for myself I don't want to survive a major debilitating stroke. Finding a qualified, knowledgeable person to manage INR is a must. Too many "professionals" don't understand warfarin philosophy. Being anti-coagulated means being educated about warfarin.
Have you read the "stickies" at the top of the pages? There is a wealth of info there.
The only stupid question is the one not asked so be glad you've asked.
Proper warfarin management is the key to successful mechanical valves. If there is a test to determine whether or not your system will accept ACT than I'd take it.
Some valve recipients whether tissue or mechanical develop AFib and all require warfarin therapy
Otherw will be along to help.
Sandra

 

[dick0236]

.....His point was this-
There is roughly a 1-2% chance of having a stroke or major bleed every year. He said that over 30 years this would mean that you have a 60% chance of this happening compared to relatively low reop risks for replacing tissue valves.
...

Wrong:confused2:. There may be a 1% or 2% risk of stroke or bleed per year, but it is not a cumulative risk. The risk will remain 1% or 2% each year, although it may increase some as a person becomes elderly:tongue2:. If you search the threads, you will find this discussion on a number of previous threads.

Your friend is saying that if you don't have an "event" in the first year, your have a 4% chance in the second year...6% in third year....8% in fourth year...etc. This is simply not accurate according to the laws of statistics. The risk is 2% in the first, second, third....tenth, or twentieth year. If what your friend said was true, my risk today would be 88%:eek2:....I'd better not play golf this morning:rolleyes2:.

BTW:redface2:, I had a stroke only seven years post surgery, so my risk that year was 100% and was due to my own stupidity and/or lack of knowledge about using warfarin. The drug DID NOT "jump up and bite me"....and I found out, the hard way, that warfarin MUST be taken as prescribed. My 37 years since the "event" have been "unevenful"....simply by following two simple rules. Take the pill as prescribed and test routinely.....works for me:angel:.

 

[ElectLive]

His point was this-
There is roughly a 1-2% chance of having a stroke or major bleed every year. He said that over 30 years this would mean that you have a 60% chance of this happening compared to relatively low reop risks for replacing tissue valves.

This is stupid thinking right?! I'm pretty confident the stats don't really work like this.....???? Surely if you go 20-30 years without a problem occurring you are in the same position as someone who has just had a mech valve implanted. In some ways it could be argued that if your body has coped without problems for such a long time as long as the INR is consistent then it is unlikely you will run into problems later down the line...

Any feedback would be great. Sorry for sounding stupid but he got me thinking! (not good when I'm already stressed about everything!)

This is not at all a stupid question, in fact, it's probably one of the most important questions to understand. It is easily misunderstood, by patients and even some doctors. I am not a math professor, but feel pretty confident about my understanding of this issue, so here goes:

Stroke and hemorrhage risks are constant risks over time (until old age anyway) and are quoted as a percentage risk per year. This means that every year you have that identical risk per year. Theoretically, you could have that constant risk factor for 100 years, and even at a 1% risk, you still might not have a bad event.

On the other hand, a cumulative risk is a risk that gets higher each year. Tissue valve deterioration is a cumulative risk. It’s more and more likely to fail the longer you have it, and it will in fact fail after a certain point.

Now, here’s where some confusion often enters in: Even though the stroke/hemorrhage risk is constant, and not cumulative, you are at an overall higher risk long term, than short. While the risk factor stays the same, you are exposed to it more and more each year, so you are in fact being put more at risk overall.

This wasn’t easy for me to understand either until I considered something more tangible, much higher risk. Suppose you flip a coin, and you have a stroke every time it turns up heads. Would you rather flip the coin once or five times? It’s the same 50-50 odds every time, but 2 tosses later, the odds of having turned up at least 1 heads is 75%, and at 5 tosses, the odds of at least 1 heads is actually around 97%. Just because it will never hit 100% risk doesn’t mean it’s not risky.

Now, as I said, I am not a math professor. So see this thread for further info and some of the math behind it, look specifically for the posts of Bradley White: http://www.valvereplacement.org/forums/showthread.php?19796-I-m-only-24!/page2

So, that's a general math discussion, do we just plug in 1% or 2% and see where the numbers land? Not so fast.

I questioned my surgeon on typically seen mechanical valve stroke and hemorrhage risk numbers like your friend has used, after I’d seen a few studies indicating that mechanical valves were actually no worse than tissue valves. All studies have bias, I admitted, so I asked him what does he trust and why?

His most trusted source was the FDA’s Object Performance Criteria (OPC) that any new valve must meet in order to be approved for use in patients, based on historical data of all previously approved valves. Here’s a link: http://ats.ctsnetjournals.org/cgi/reprint/82/3/776 that includes the OPCs. They do clearly show a difference in risk factors for mechanical and tissue, as you'll note, though, tissue valves have risks too.

Now, stepping back even further, even if the OPCs are fairly objective historical data, how relevant is history anyway? What about advances such as home testing, that improves risks, right? I'll even point out that On-X has a marketing brochure on their website (http://www.onxlti.com/heart-valves/.../clinical-comparison-of-fda-approval-studies/ ) showing that they are actually better than tissue valves in some of these areas. Now, I don’t necessarily believe On-X, I think they’re measuring fewer, younger, and lower risk patients, but who knows for sure. At the end of the day, numbers and data only go so far. Individual patient risk factors can often be more important.

In my opinion, it's a chase that just never ends. If you look around enough, from medical studies to the current advice of top flight surgeons, a comparison of assumed additional risk over time of stroke and hemorrhage with a mechanical valve, versus the re-op risks of a tissue valve, yields just about even odds. Even for those with a more "easy" decision - a 20 year old or an 80 year old, there's still no guarantees.

 

[ElectLive]

If what your friend said was true, my risk today would be 88%:eek2:....I'd better not play golf this morning:rolleyes2:.

Funny.

You are an inspiration for all of us.

 

[neil]

well both are better than the one you got ,but its the age old question tissue or mech, theres pluses and negatives in each, i choose tissue and am at ease with another op down the line, most of us with tissue dont need anti goags but you do get the odd one who will,re ops esp the 2nd are no more risk than the first, warfarin is the 2nd most common drug after insulin implicated in emergancy room visits accourding to one site 43,000 cases a year,thats not a risk id like to take, but there again plenty on here do well on it,

 

[rubywhistle]

so its 1-2% a year .....over your life ... and the more you are exposed the more the risk... yep this is tricky

 

[hook]

Keep in mind those stroke and bleeding statistics include people that do not take the drug correctly. I would like to see stroke stats for people who were in range at the time.

Think of this; every time you get OHS, you risk permanent afib as a result. Afib means you will be on coumadin anyway.

It sounds like your friend is more interested in you sharing his descision rather than help you make yours. Listen to your medical team, and do your own reading.

 

[texasmike]

I agree with hook. Also, my doc at Mayo pointed out that any statistic regarding warfarin prior to the development and use of home testing (in his opinion, any statistic using data prior to 2002-2003) was corrupt and basically useless. So, as in anything, be very careful what statistic you are using!
Good luck!