normofthenorth
Well-known member
I recently posted the following in a Pre-Surgery thread, and Al C asked me to post it here:
. . . About tissue-valve longevity and other reasons to choose one tissue valve over another. There are some general "high-level" considerations that may not be obvious. E.g., valve "design" is evolving, and newer ones are PROBABLY better than older ones (durability, hemodynamics, maybe ease of implantation). BUT if you're looking for a valve with a proven track record for durability (say 10 or 15 or 20 years), it won't be a new valve!! In the "grey area", you may be happy with an evolutionarily improved version of an old established design, on the assumption that they didn't make it any worse with the latest tweaks.
The established tissue valves I've seen the best durability and hemodynamics studies on, are the Medtronics Hancock II "pig" valve (which I just got) and the Carpentier-Edwards Perimount "cow" valve (which you're probably about to get).
When it comes to hemodynamic performance (not durability), the best and newest study (2007) shows a ~12% advantage to the CEP, at least the new "Magna" version. Whether or not that matters depends on who you ask. It's MUCH more likely to be important if you need a SMALL valve than if you need a BIGGER valve. I got a 27mm AV, and my surgeons have told me that there's no way I'll ever notice the theoretically missing area or the theoretically added pressure-drop. (Of course, they're biased, because they're all committed pig-valve people!) If you want to see the study, it's at ats.ctsnetjournals.org/cgi/content/full/83/6/2054#TBL3 . (My own surgeon's the 4th listed author, but he's not too damned pleased about or impressed with the results, because he lost the bet!)
[edit: I just noticed that the study's measurements were made ONE WEEK post-OP. My own echo-KG-measured hemodynamics 5 days post-op were remarkably poor (1.26cm2 AV area, vs. ~1.7-ish for a normal 27mm Hancock II), and I've been told to wait for a future EKG, because this valve tends to measure "tight" initially and then "relax". I don't know if the CEPM generally shows that pattern, too, but if it doesn't, the difference could be very important to us end-users! --Norm]
As far as DURABILITY, the most thorough and impressive (and hopeful!) study I've seen was just published in The Annals of Thoracic Surgery by another team at Toronto General, including the "boss", Tirone David. The title is "Hancock II Bioprosthesis for Aortic Valve Replacement: The Gold Standard of Bioprosthetic Valves Durability?" Unfortunately, normal people can't get the full text online without springing US$25. I got a full fax copy from my surgeon's office, and I think it's very impressive and helpful, including for a CEP "customer". In addition to presenting the data on their 1100-odd pig-valve recipients, sliced several different ways (the DATA!
), it ends with several pages of "Comment" comparing these TGH results for the Hancock II, with all other published results for long-term durability of other tissue valves, including the CEP. They seem to try to compare apples-to-apples, and point out that most other studies report "freedom from explant" as a key measure of success -- but they shouldn't, because patients who are too frail to have OHS don't get "explants". These TGH authors distinguish between ""freedom from explant" and the more meaningful "Freedom from SVD (Significant Valve Deterioration)", which they wish everybody would report.
The CEP doesn't have any reported 20-year durability yet, because it's a bit newer than the Hancock II (and the CEP Magna is even newer), but they compare the reported results up through 15 years with their own results. The comparison is consistently one-sided, in favor of the Hancock II. E.g.,
Finally, they discuss a recent (2010) study by McClure and colleagues on long-term outcomes of 1000 CEP recipients. ". . . they reported a freedom from reoperation due to SVD at 15 years of 34.7% in patients younger than 65 years and 89.4% in patients aged 65 to 75. The freedom from SVD for the Hancock II at 15 years was 80.7% +/- 2.6% for patients younger than 65 and 99.0% +/- 4.2% for patients aged 65 and older."
The differences seem very striking to me -- e.g., the huge difference between those last two pairs of "freedoms", even though the Hancock numbers are presented as the more conservative "freedom from SVD" rather than the misleadingly optimistic "freedom from explant"!!
These numbers all justify the authors in referring to the Hancock II's longevity as the "gold standard" in the field.
Of course, it's possible that the wonderful surgical and post-op team at the TGH, or Ontario's wonderful no-orphans Obama-eat-your-heart-out health-care system are responsible for these "gold standard" results, and not just a great valve. It's impossible to tease out all those factors -- although they do point out 3 other long-term studies of the Hancock II (from Italy and maybe elsewhere) with very similarly impressive results.
But on the face of it, I think the evidence shows that the CEP Magna has great hemodynamics, significantly better than the Hancock II (and a short track record so far), and that the Hancock II has great durability, significantly better than the CEP and every other tissue valve.
I still occasionally bump into Internet statements (I thought one was on a "sticky" here, though I can't find it now) suggesting that the cow valves last maybe 5 years longer than the pig valves, despite this evidence. If anybody can tell me why either of my conclusions is NOT based on the evidence, please do.
As others have said, there's no "bad" valve, other than the one you've got now. And the valve YOUR surgeon is comfy sticking in YOUR heart is definitely a GOOD valve! But if you like making choices based on evidence, that's how I read the newest and best evidence. And like so many things in this @#$% area, even IT doesn't all point in the same direction!!
. . . About tissue-valve longevity and other reasons to choose one tissue valve over another. There are some general "high-level" considerations that may not be obvious. E.g., valve "design" is evolving, and newer ones are PROBABLY better than older ones (durability, hemodynamics, maybe ease of implantation). BUT if you're looking for a valve with a proven track record for durability (say 10 or 15 or 20 years), it won't be a new valve!! In the "grey area", you may be happy with an evolutionarily improved version of an old established design, on the assumption that they didn't make it any worse with the latest tweaks.
The established tissue valves I've seen the best durability and hemodynamics studies on, are the Medtronics Hancock II "pig" valve (which I just got) and the Carpentier-Edwards Perimount "cow" valve (which you're probably about to get).
When it comes to hemodynamic performance (not durability), the best and newest study (2007) shows a ~12% advantage to the CEP, at least the new "Magna" version. Whether or not that matters depends on who you ask. It's MUCH more likely to be important if you need a SMALL valve than if you need a BIGGER valve. I got a 27mm AV, and my surgeons have told me that there's no way I'll ever notice the theoretically missing area or the theoretically added pressure-drop. (Of course, they're biased, because they're all committed pig-valve people!) If you want to see the study, it's at ats.ctsnetjournals.org/cgi/content/full/83/6/2054#TBL3 . (My own surgeon's the 4th listed author, but he's not too damned pleased about or impressed with the results, because he lost the bet!)
[edit: I just noticed that the study's measurements were made ONE WEEK post-OP. My own echo-KG-measured hemodynamics 5 days post-op were remarkably poor (1.26cm2 AV area, vs. ~1.7-ish for a normal 27mm Hancock II), and I've been told to wait for a future EKG, because this valve tends to measure "tight" initially and then "relax". I don't know if the CEPM generally shows that pattern, too, but if it doesn't, the difference could be very important to us end-users! --Norm]
As far as DURABILITY, the most thorough and impressive (and hopeful!) study I've seen was just published in The Annals of Thoracic Surgery by another team at Toronto General, including the "boss", Tirone David. The title is "Hancock II Bioprosthesis for Aortic Valve Replacement: The Gold Standard of Bioprosthetic Valves Durability?" Unfortunately, normal people can't get the full text online without springing US$25. I got a full fax copy from my surgeon's office, and I think it's very impressive and helpful, including for a CEP "customer". In addition to presenting the data on their 1100-odd pig-valve recipients, sliced several different ways (the DATA!
), it ends with several pages of "Comment" comparing these TGH results for the Hancock II, with all other published results for long-term durability of other tissue valves, including the CEP. They seem to try to compare apples-to-apples, and point out that most other studies report "freedom from explant" as a key measure of success -- but they shouldn't, because patients who are too frail to have OHS don't get "explants". These TGH authors distinguish between ""freedom from explant" and the more meaningful "Freedom from SVD (Significant Valve Deterioration)", which they wish everybody would report.The CEP doesn't have any reported 20-year durability yet, because it's a bit newer than the Hancock II (and the CEP Magna is even newer), but they compare the reported results up through 15 years with their own results. The comparison is consistently one-sided, in favor of the Hancock II. E.g.,
Referring to a CEP study by Aupart and colleagues, they conclude "the Hancock II again comes [out] ahead on durability, particularly in patients aged younger than 70 years."
Finally, they discuss a recent (2010) study by McClure and colleagues on long-term outcomes of 1000 CEP recipients. ". . . they reported a freedom from reoperation due to SVD at 15 years of 34.7% in patients younger than 65 years and 89.4% in patients aged 65 to 75. The freedom from SVD for the Hancock II at 15 years was 80.7% +/- 2.6% for patients younger than 65 and 99.0% +/- 4.2% for patients aged 65 and older."
The differences seem very striking to me -- e.g., the huge difference between those last two pairs of "freedoms", even though the Hancock numbers are presented as the more conservative "freedom from SVD" rather than the misleadingly optimistic "freedom from explant"!!
These numbers all justify the authors in referring to the Hancock II's longevity as the "gold standard" in the field.
Of course, it's possible that the wonderful surgical and post-op team at the TGH, or Ontario's wonderful no-orphans Obama-eat-your-heart-out health-care system are responsible for these "gold standard" results, and not just a great valve. It's impossible to tease out all those factors -- although they do point out 3 other long-term studies of the Hancock II (from Italy and maybe elsewhere) with very similarly impressive results.
But on the face of it, I think the evidence shows that the CEP Magna has great hemodynamics, significantly better than the Hancock II (and a short track record so far), and that the Hancock II has great durability, significantly better than the CEP and every other tissue valve.
I still occasionally bump into Internet statements (I thought one was on a "sticky" here, though I can't find it now) suggesting that the cow valves last maybe 5 years longer than the pig valves, despite this evidence. If anybody can tell me why either of my conclusions is NOT based on the evidence, please do.
As others have said, there's no "bad" valve, other than the one you've got now. And the valve YOUR surgeon is comfy sticking in YOUR heart is definitely a GOOD valve! But if you like making choices based on evidence, that's how I read the newest and best evidence. And like so many things in this @#$% area, even IT doesn't all point in the same direction!!
