No significant difference in 15-year survival or stroke rates was found in patients between 50 and 69 years of age who had aortic valve replacement with bioprosthetic valves (made primarily with biological tissue) compared with mechanical valves, according to findings published in the Oct. 1 issue of JAMA. The study results show patients in the bioprosthetic valve group had a greater likelihood of reoperation but a lower likelihood of major bleeding.
According to the study, conducted by researchers at the Icahn School of Medicine at Mount Sinai, New York City, about 50,000 patients have aortic valve replacement surgery each year in the U.S. In elderly patients, bioprosthetic valves pose a low lifetime risk of needing additional surgeries to address structural degeneration and avert many of the complications associated with mechanical valves; bioprosthetic valves are therefore recommended in patients older than 70. Less clear is the best prosthesis type for younger patients because of the higher failure rates of bioprosthetic valves in that age group.
Lead author Joanna Chikwe, MD, associate professor in the department of cardiovascular surgery at Icahn said the new evidence may help patients who want to avoid the complications and lifestyle limitations associated with mechanical valves.
This is one of the largest studies to date on the long-term outcomes of treatment of patients with aortic valve replacement, the studys senior author Natalia Egorova, PhD, MPH, assistant professor in the department of population health science and policy at Icahn, said in a news release. The previous prospective studies have been underpowered to detect differences in long-term survival and major morbidity in the younger age group that we studied.
The studys authors used a statewide patient database to evaluate differences in long-term survival, stroke, reoperation and major bleeding episodes after aortic valve replacement according to the type of valve implanted. The analysis included 4,253 patients aged 50 to 69 years who underwent primary isolated aortic valve replacement using bioprosthetic versus mechanical valves in New York state from 1997 through 2004. Median follow-up time was 10.8 years, with a maximum follow-up of 16.9 years.
Fifteen-year survival was 60.6% in the bioprosthesis group compared with 62.1% in the mechanical prosthesis group. The cumulative incidence of stroke at 15 years was 7.7% for patients who received a bioprosthetic valve, compared with 8.6% for those who received a mechanical prosthetic valve. These differences were not statistically significant, according to the release.
Bioprostheses were associated with a significantly higher rate of aortic valve reoperation than mechanical prostheses: the cumulative incidence of aortic valve reoperation at 15 years was 12.1% in the bioprosthesis group and 6.9% in the mechanical prosthesis group.
Mechanical prostheses were associated with a significantly higher rate of major bleeding at 15 years compared with bioprostheses: 13.0% for the mechanical prosthesis group vs. 6.6 % for the bioprosthesis group.
These outcomes, together with the well-recognized patient dissatisfaction with the prospect of a lifetime of anticoagulation, may partially explain the increasing use of bioprostheses, the studys authors wrote.