Mechanical or Biologic Prostheses for Aortic-Valve and Mitral-Valve Replacement

Background

In patients undergoing aortic-valve or mitral-valve replacement, either a mechanical or biologic prosthesis is used. Biologic prostheses have been increasingly favored despite limited evidence supporting this practice.

Methods

We compared long-term mortality and rates of reoperation, stroke, and bleeding between inverse-probability-weighted cohorts of patients who underwent primary aortic-valve replacement or mitral-valve replacement with a mechanical or biologic prosthesis in California in the period from 1996 through 2013. Patients were stratified into different age groups on the basis of valve position (aortic vs. mitral valve).

Results

From 1996 through 2013, the use of biologic prostheses increased substantially for aortic-valve and mitral-valve replacement, from 11.5% to 51.6% for aortic-valve replacement and from 16.8% to 53.7% for mitral-valve replacement. Among patients who underwent aortic-valve replacement, receipt of a biologic prosthesis was associated with significantly higher 15-year mortality than receipt of a mechanical prosthesis among patients 45 to 54 years of age (30.6% vs. 26.4% at 15 years; hazard ratio, 1.23; 95% confidence interval [CI], 1.02 to 1.48; P=0.03) but not among patients 55 to 64 years of age. Among patients who underwent mitral-valve replacement, receipt of a biologic prosthesis was associated with significantly higher mortality than receipt of a mechanical prosthesis among patients 40 to 49 years of age (44.1% vs. 27.1%; hazard ratio, 1.88; 95% CI, 1.35 to 2.63; P<0.001) and among those 50 to 69 years of age (50.0% vs. 45.3%; hazard ratio, 1.16; 95% CI, 1.04 to 1.30; P=0.01). The incidence of reoperation was significantly higher among recipients of a biologic prosthesis than among recipients of a mechanical prosthesis. Patients who received mechanical valves had a higher cumulative incidence of bleeding and, in some age groups, stroke than did recipients of a biologic prosthesis.

Conclusions

The long-term mortality benefit that was associated with a mechanical prosthesis, as compared with a biologic prosthesis, persisted until 70 years of age among patients undergoing mitral-valve replacement and until 55 years of age among those undergoing aortic-valve replacement. (Funded by the National Institutes of Health and the Agency for Healthcare Research and Quality.)

Supported by the National Institutes of Health, National Center for Advancing Translational Science, Clinical and Translational Science Awards (NIH TL1 TR000084, to Dr. Goldstone; NIH KL2 TR000083, to Dr. Chiu; and NIH UL1 TR001085, to the Stanford Center for Clinical Translational Education and Research) and by a grant (KHS022192A, to Dr. Baiocchi) from the Agency for Healthcare Research and Quality.

Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.

Drs. Goldstone and Chiu contributed equally to this article.

Source Information

From the Departments of Cardiothoracic Surgery (A.B.G., P.C., B.L., W.L.P., M.P.F., Y.J.W.) and Health Research and Policy (A.B.G., P.C.) and the Stanford Prevention Research Center, Department of Medicine (M.B.), School of Medicine, Stanford University, Stanford, CA.

Address reprint requests to Dr. Woo at the Department of Cardiothoracic Surgery, Stanford University, Falk Bldg., CV-235, 300 Pasteur Dr., Stanford, CA 94305-5407, or at joswoo@stanford.edu.