G
Guest
I think that I posted something similar to this about a year ago but one of my students brought this up again yesterday, so I'll post it again.
There was a study done in Canada where they looked at records of valve replacement people between 1970 and 2002. This included 3,576 valve surgeries accounting for 20,096 patient years. The study is big enought to be able to draw strong conclusions.
About 20% of the people had a stroke within 15 years after valve replacement. The biggest risk factors were smoking, mitral valves, aortic tilting disc valves, and waiting until the left ventricle was greatly enlarged before mitral surgery. My guess is that the rate for people who are getting valves today and in the near future is much smaller. My reasons are that fewer people smoke than in 1970, tilting disc valves havent been used in years, and we know so much more about heart function that we no longer wait until the left ventricle is enlarged.
Back at the start of the study it was unknown how long, if at all, warfarin was needed. So many people did not get it. Even when they did get it, there was very little known about how to manage it.
In my clinic I know that we have 1 case of minor bleeding about every 1.5 patient-years. Major bleeding about once in 33 patient-years. Clotting occurs about once in every 100 patient-years.
My guess is that if this study were done 10 years from now on valves implanted from here on out, the stroke rate would be about 10%. Still fairly high but to put it in perspective, it is about the heart attack rate for diabetics.
In the past week I have reviewed the possible replacements for warfarin and there is nothing that is being tested for mechanical valves that will be available before 2010.
Hope this helps clarify the issues involved
There was a study done in Canada where they looked at records of valve replacement people between 1970 and 2002. This included 3,576 valve surgeries accounting for 20,096 patient years. The study is big enought to be able to draw strong conclusions.
About 20% of the people had a stroke within 15 years after valve replacement. The biggest risk factors were smoking, mitral valves, aortic tilting disc valves, and waiting until the left ventricle was greatly enlarged before mitral surgery. My guess is that the rate for people who are getting valves today and in the near future is much smaller. My reasons are that fewer people smoke than in 1970, tilting disc valves havent been used in years, and we know so much more about heart function that we no longer wait until the left ventricle is enlarged.
Back at the start of the study it was unknown how long, if at all, warfarin was needed. So many people did not get it. Even when they did get it, there was very little known about how to manage it.
In my clinic I know that we have 1 case of minor bleeding about every 1.5 patient-years. Major bleeding about once in 33 patient-years. Clotting occurs about once in every 100 patient-years.
My guess is that if this study were done 10 years from now on valves implanted from here on out, the stroke rate would be about 10%. Still fairly high but to put it in perspective, it is about the heart attack rate for diabetics.
In the past week I have reviewed the possible replacements for warfarin and there is nothing that is being tested for mechanical valves that will be available before 2010.
Hope this helps clarify the issues involved
