Rosebud54, I think you've got the basic info to make your choice. The stats on overall life expectancy, or (what the statisticians call "freedom from") nasty events resulting from either choice, are about an even "saw-off" at 56 years old, according to my reading of the studies. There's no perfect choice, but both choices are better than keeping what you've got until it fails!
Down one path is a valve that should last forever, but might well be audible and definitely needs Coumadin/Warfarin forever. That combo of mech valve and Coumadin/Warfarin (aka ACT or INR) carries extra risks along with the nuisance, even if you find it easy to keep your INR stable in the "goldilocks" or "just right" range where it's supposed to be. That range is a compromise between controlling two new risks -- the risk that your new mech valve will "throw a clot" that will go to your brain and cause a stroke (higher INR generally lowers that risk) AND the risk that you will suffer some kind of "bleeding event", especially in the brain, that lasts longer and does more damage because your elevated INR keeps your blood from clotting as quickly as it normally would. (Higher INR generally increases that risk.)
There's no doubt that having a well-managed INR is much better and lower-risk than having one that's badly managed. There's also no doubt that many patients -- especially those who measure and manage their INR themselves, with a home testing unit -- are very good at maintaining their INR within their target therapeutic ranges, with minor nuisance and disruptions when they need dental work or other surgery.
But I think there's also little doubt that even a perfectly-managed INR, and a mech valve, adds both of the aforementioned risks in some measure. A steadily perfect INR provides the best tradeoff between the two hazards, but it doesn't eliminate either of them. E.g., one recent study found that people who'd had "head trauma" (mostly old people who'd fallen and hit their heads) had several TIMES higher risk of coma and cerebral hemorrhage if they had an INR higher than TWO (2) than if they didn't. TWO is a very low INR, and EVERYBODY's therapeutic target range is higher than that. (Mind you, it's possible that MANY of the patients in the study with INR>2 actually had INR much higher than that; I didn't see the numbers on that.)
So that's the bad news for the mechanical valves. The bad news for the tissue valves is much simpler and more obvious: they don't last forever, and yours probably won't last as long as you do, so it will have to be replaced. The replacement is obviously undesirable in a bunch of ways that don't have to be explained, though the actual risks that it will kill you or severely injure you are actively under study and under debate. These "re-op" risks have been improving markedly in the past few decades, and many people are very hopeful that we recent tissue-valvers will eventually be able to have replacement "core valves" slipped inside our failing tissue valves through a catheter inserted in our groin, just like an angiogram or a stent implacement is done today. Maybe, hard to be sure.
Even if the risks of a nasty outcome from ACT turn out to be 1%-2% per year forever, and the risks of a nasty outcome from a re-op (done at a good cardiac center that KNOWS about re-ops) are only 1%-2% per re-op, lots of people would choose the mech + ACT because the idea of going through OHS again is so awful in their minds (in their hearts?) that an increase in statistical risk is a bargain in return for a good shot at never having to have OHS again.
So far, the total life expectancy numbers for a 56-year-old do NOT look asymmetrical, they look pretty even, with the clot-or-bleed death risks roughly balancing out the valve-failure or re-op death risks. So if the MAGNITUDE of the risks of dying early are about the same either way, then the choice is mostly between the KINDS of risks (Are you really determined never to have another OHS? Are you really determined to avoid having a stroke, no matter what?) and the difference in lifestyle and "nuisance" (Are you good or bad at taking pills and getting your blood tested and avoiding big "binges" in diet; Do you jump off roofs or cliffs for fun, and would your life be ruined if you had to stop?)
With those kinds of choices, you're the expert! Again, NEITHER choice is perfect, but EITHER choice is way better than NO choice.
There are some other interesting parts of the choice -- like reasons to believe that one particular valve "model" will perform better than the others (mostly either a tissue valve lasting longer, or a mech valve being quieter or being less likely to "throw" a clot) -- and there are also reasons to think that the situation will change soon in ways that influence the choice. But basically, that's the tradeoff. Lots of people here have already made that choice one way or the other, and most of us are happy with the tradeoff we chose.
A few people here had miserable experiences on ACT, at least one of whom was only doing ACT temporarily, so she's very happy she didn't choose ACT forever. Others have chosen tissue valves that have failed prematurely. Some of them went mechanical the second time, and some went tissue again. In making a choice, it's probably useful to remember that neither choice comes with any guarantee -- though the risks and downsides and nuisances are probably more reliable than the wonderful parts, since Murphy was an optimist!
Young folks and old folks face asymmetrical life-expectancy stats (young mech folks live longer than tissue, and old tissue folks live longer than mech), but I think 56 is up on the "plateau" where the newest and best studies show no difference, or at least no statistically-significant difference, in total risks or LE.
If you're an info junkie, or enjoy reading studies or abstracts of studies, there's lots more posted and linked here, but that's the gist of it, at least as I see it.
