Some things to consider...
- Comorbidities (when you have other things wrong with you as well as your valve issue) are definitely the biggest predictor. Particularly so if it includes arterial instabilities that lead to aneurysms, or if they have lung or kidney issues. A larger percentage of those who present with valve difficulties this early in life have other, major health issues as well. Those people, sadly, bring the life expectancy down. But not for those who are otherwise healthy.
- A cohort of 35-year-olds with valve issues would be a difficult thing to assemble. There just aren't that many and they're too scattered. Most studies of this type wind up being a very small subject group, often taken from a very narrow overall group (like from only a few or even one hospital or clinical practice). I would be very loathe to take any one study as being definitive of the age group, even if they were sorted as to comorbidities, and I've been looking at valve studies for over a decade.
- If the average lifespan after valve implantation were 16-22 years, that means the study had to run longer than 22 years to find that out. That means that even if the study just came out this year, the study could not have been started any earlier than the mid 1980s at best. More likely, it was begun in the 1970s. That means old technology. Not just the valves, but more critically the surgery itself, treatments for lung and kidney issues, and the echo technology (and MRI and CAT scanning) used to determine expanding aneurysm size. Those items alone account for a much longer life expectancy now for many with comorbidities who died underdiagnosed in earlier years.
- I would also doubt that the data would reasonably specifically demonize mechanical valves, vs. other types of valves. If the cohort were all people with mechanical valves, there is no data that could compare the mechanical valves to anything else, and thus no information as to whether the mechanical valves were part of the lower than expected lifespan.
I will, however, say that even in this unhappy study, people lived 14-22 years longer than they would have averaged had they not had the mechanical valve impanted.
I really, really wouldn't worry about what you read in that study, nor take it as applicable to your individual situation. Although we are far from there yet, things are as different medically between the 1970s and now as computers are different between then and now. From a $200,000 9'x9'x6' cube representing 1 MB of storage to a $39.95 4 GB mini-SD card the size of a standard Frito.
Be well,
Along these lines, I keep thinking that for the most part the group with the higher comorbidity AND other conditions that affect life expectancy, going INTO surgery, would probably be the tissue valve patients, partly because of their age, since they are the older group, chances are more of the people would have the conditions that generally come along as you age, compared to the younger (sometimes decades younger) patients who usually mechanical valves.
(at least until the past few years where more younger people are choosing tissue)
The other reason is for the MOST part the only younger people (I'm talking 20-50s NOT early 60s) who got tissue valves were/ are either young women who wanted to have get pregnant/have children OR people who had other health problems (GI,bleeding disorders, Liver, ect) and were advised coumadin COULD make it more difficult.
SO I would think most of the studies that looked at ALL valve patients, the majority of the people who got mechanical valves were like Bill, (to use his example) and have essentially NO co-morbidity.
Since MOST valve problems are structural problems, many from birth and usually NOT aquired problems caused by living and/or lifestyle choices (poor eating, poor excercise, bad habits, like drugs ect) that can sometimes effect your other body systems, many of the patients are relatively healthy going into surgery so don't tend to have as many comorbidites as say a CABG would.
IF one group would be expected to have lower life expectancy based on comorbidity, it would be people that got tissue valves, so it is interesting that this study shows tissue valve patients have a higher life expectancy. I guess it must be from comorbidities that happen after the person has the surgery as they get older.
I thought it was interesting in the study Bill posted they went back and read 32 older studies, starting with valves replaced in 1975, and only ended up with about 17,000 patients, pretty much 1/2 Tissue and 1/2 mechanical and the tissue patients ended up with only slightly more reops at 5.0% than the mechanical valver patients 3.8 %. That was surprising, but I didn't see if there was a breakdown of how long after the origonal surgery did they need a redo. It could have been the valves patients got in the late 70s, who knows, it was just interesting. The death rate was higher for the tissue valve patients, BUT they were an average of 10 years older at the time of surgery.
That's one of the studies used in
http://circ.ahajournals.org/cgi/content/full/117/2/253?etoc Choice of Prosthetic Heart Valve in Today’s Practice
about the trend going going toward tissue valves for younger patients, and
"A meta-analysis of 32 articles evaluated mortality from 15 mechanical and 23 biological valve series including 17 439 patients and 101 819 patient-years of follow-up. This meta-analysis found no difference in risk-corrected mortality between mechanical and bioprosthetic aortic valves regardless of patient age9 and suggested that the choice between a tissue and mechanical valve should not be based on age alone"
Its good that patients, for the most part, get to talk about valve choice with their surgeons and choose which ever valve they feel best fits their personalities.
It will be interesting to see what the studies show in another decade.
