Last Updated: 2010-07-14 10:50:26 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Nearly a third of kidney transplant patients who have new heart valves implanted will die within a year afterward, a new study shows.
Survival was somewhat better with tissue valves than with mechanical prostheses. Given the warfarin requirements with mechanical valves, "I believe that our findings would lead most clinicians to favor tissue valves," senior author Dr. Charles A. Herzog told Reuters Health by e-mail. "No clinician would choose to have a patient on warfarin if there were an equivalent 'non-inferior' alternative."
The study also showed that the risk of endocarditis was approximately 5% per year, "which is not trivial," Dr. Herzog said. "I think it should increase our level of attention to infectious risk and perhaps raise the issue of whether these patients deserve more aggressive endocarditis prophylaxis."
In the June 29th Circulation, Dr. Herzog, from the United States Renal Data System in Minneapolis, Minnesota, and colleagues report on 1355 kidney transplant recipients who received new aortic valves (66%), mitral valves (25%) or both (9%) between 1991 and 2004. Thirty-eight percent had coronary artery bypass grafts created at the same time.
Half the patients were between 45 and 64 years old, 28% were 65 to 74, 17% were younger than 45, and the remaining few were 75 or older.
Most patients (72%) received nontissue valves, although the use of bioprosthetic valves tripled over the study period (from 13% in 1991 to 38% in 2000-2004).
The mean length of follow-up was 34 months (median, 24 months).
The estimated all-cause survival for the entire cohort was 75.3% at 6 months, 70.8% at 1 year, 60.1% at 2 years, 52.8% at 3 years, 38.4% at 5 years, and 16.0% at 10 years, with no significant difference in unadjusted survival between patients who received tissue valves and those who received nontissue valves.
In the Cox proportional-hazards model, however, mortality was 17% lower for kidney patients who received tissue valves compared with those who received nontissue valves.
In-hospital death rates were 14% overall (11.4% for patients receiving tissue valves, 15.0% for patients receiving nontissue valves, P=0.09).
The most powerful independent predictors of all-cause mortality included age over 75 years, age 65-74 years, combined aortic and mitral valve replacement, and end-stage renal disease due to diabetes mellitus.
The research team estimated the rate of hospitalization for endocarditis with tissue vs nontissue valves, respectively, at 5.0 vs 5.2 per 100 patient-years, and the rate of gastrointestinal hemorrhage at 4.4 vs 5.2 per 100 patient-years. These differences were not statistically significant.
"As a group of patients receiving chronic immunosuppression, and who have heightened cardiovascular risk, they qualify for aggressive treatment of hypertension, dyslipidemia, etc. -- i.e., similar to other high-risk populations," Dr. Herzog said. "All renal transplant recipients require special attention with regard to prevention and treatment of infection, and this is especially true in renal transplant patients with prosthetic heart valves."
"I think that our data will help better inform renal transplant patients (and their physicians) regarding operative risk and long-term morbidity and mortality with heart valve replacement surgery, as scant data were previously available on this topic," he said.
SOURCE: http://link.reuters.com/qej57m
Circulation 2010;121:2733-2739.
Copyright © Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
