Mechanical vs. Biologic Prostheses for Aortic and Mitral Valve Replacement

Biologic prostheses are increasingly being used, despite the eventual structural valve deterioration, to avoid the risks of continued anticoagulation after mechanical prostheses. In a retrospective cohort study based on claims data, investigators compared the long-term benefits and risks of these two prosthetic types for aortic and mitral valve replacement (AVR and MVR, respectively) at 142 non-federal California hospitals between 1996 and 2013.

The study population included 9942 AVR and 15,503 MVR patients. The use of biologic prostheses increased from 12% to 52% for AVR and from 17% to 54% for MVR during the study period. Median follow-ups were about 5 and 8 years for biologic and mechanical prostheses, respectively.

In adjusted analyses, 30-day mortality for AVR was similar for biologic and mechanical prostheses, but long-term (i.e., 15-year) mortality was higher with biologic prostheses in patients aged 45 to 54 (31% vs. 26% with mechanical prostheses; hazard ratio, 1.23). The relative mortality benefit with mechanical prostheses persisted to age 53.

For MVR, 30-day mortality rates were similar for biologic and mechanical prostheses, except in the youngest cohort (ages 40–49) where biologic prostheses were associated with higher mortality (6% vs. 2%). Long-term mortality was also higher with biologic prostheses up to about age 68, with the most marked difference in those aged 40 to 49 (HR, 1.88).

In general, biologic valves were associated with lower risks for both stroke and bleeding, particularly in younger patients. However, reoperations were more frequent with biologic valves and were associated with high perioperative mortality rates of 7% for AVR and 14% for MVR.