Here is that word "RARE" again (from the link below).
So this article considers the odds of "0.3–1.3% patient years" of PVT occurring with mechanical valves as rare.
Then it goes on to state that PVT occurring with a bioprosthetic valve is rare when compared to a mechanical valve (that would be rare² for us laymen
).
yes, rare ... my initial intention was to suggest it happened. Unfortunately my choice of words was bad, as discussed. You will see that rare is not NONE.
now, to your interpretation. I feel that you are mixing points up here. The article you cite (which I think I cited or at least read)
You say:
So this article considers the odds of "0.3–1.3% patient years" of PVT occurring with mechanical valves as rare.
no it doesn't the article says:
The incidence of obstructive PVT for mechanical valves varies between 0.3–1.3% patient years
it does not mention this as a reference for rare.
In the paragraph following that paragraph it says:
Thrombosis of a bioprosthetic valve4 is a rare occurrence when compared to mechanical prostheses. Bioprosthetic PVT is usually diagnosed in the early postoperative period, when endothelialisation of the suture zone is not yet complete. Hence, this has led to the recommendation of anticoagulating patients with bioprostheses for the first three months postoperatively, particularly for mitral prostheses.
It make no reference to the above paragraph and so we are left to wonder what the authors regard as 'rare'. So I feel that this article is not discussing late valve degradation.
Further its own citation is for the article "High risk of thromboemboli early after bioprosthetic cardiac valve replacement"
which does not examine end phase of valve life. Which as you go on to say
I have to assume that if one cannot come up with a single article that has specifically studied late stage PVT in bioprosthetic valves, then it must be a rare occurrence.
That's an assumption, and one which I'm inclined to agree with,
after all I never stated this as being common. But there are other reasons, one being research funding and another being research inclination.
My own research for my masters had (by definition) never been done before I did it. So scarcity of research itself does not imply no problem exists.
You did not address my point at post
34
Which was indeed a study of late valve state. I will refer to that again as you asked
Thrombosis and degeneration of Hancock valves: clinical and pathological findings
26 valve specimens were recovered at postmortem examination and 8 at reoperation
hard to get later in valve life than that... I am unable to read more than the summary due to me no longer having good research access to this, however I would ask what this means:
Three patients had late valve thrombosis 12 to 26 months after operation
if not thrombosis from the valve ...
So in brief summary my evidence is not at the irrefutable stage, but it should entreat the enquiring mind to wonder about what happens in late valve life? (you know, answering the question I was asked, not just taking my answer and applying it to anything you like)
Some papers for your to read on late valve thrombosis:
http://www.ncbi.nlm.nih.gov/pubmed/22066356
This paper is from 2011
Bioprosthetic valve thrombosis is an unexpected complication which has no guidelines for its management
Unexpected ... so, is it unexpected because its rare, or simply (previously) rarely diagnosed? I have cited another source which mentioned 3 such diagnoses already.
A 70-year-old female presented 10 days after a stroke, three years after having undergone mitral bioprosthetic valve implantation
so three years and then
A review of the literature shows that late non-obstructive bioprosthetic valve thrombosis, as diagnosed with TEE, is a rare condition that can be successfully treated either by anticoagulant or thrombolytic therapy
which suggests that something is written about it and so inability to find anything on Dr Google does not mean its not there. This also fits nicely with what I said which caused all the trouble. Let me go back to that:
I read that it is not uncommon for them to begin throwing clots in the last few years of their life. So warfarin therapy may be suggested at something like the 7 year mark.
now, if I was to re-word that to:
I read that it possible to begin throwing clots in the last few years of their life. So warfarin therapy may be suggested at some nebulous time which I won't say anything about because I'll get jumped on.
Note that the article suggests successful treatment by anti-coagulation therapy...
There are other articles which I would post links to but I see that none of the protagonists is reading what I say anyway.
http://www.onlinejase.com/article/S0894-7317(09)00578-1/abstract
Bioprosthetic valve thrombosis is considered extremely unlikely, thus usually allowing patients to avoid long-term anticoagulation.
This represents my last post on this matter.
