Long-Term Safety and Effectiveness of Mechanical Versus Biologic Aortic Valve Prostheses in Older Patients: Results From the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery National Database

Study Questions:

How do long-term outcomes of mortality and valve-related morbidity compare between patients 65-80 years old who underwent tissue versus mechanical aortic valve replacement (AVR)?


The Society of Thoracic Surgery (STS) database was used to identify a cohort of Medicare-linked fee-for-service patients between 65 and 80 years of age who underwent elective or urgent tissue (n = 24,410) or mechanical (n = 14,789) AVR during 1991 through 1999; patients undergoing re-do AVR or a concomitant procedure other than coronary artery bypass grafting were excluded from the analysis. Follow-up information was derived from Medicare inpatient analytic claims through 2007. Mean follow-up was 12.6 years; range was 8-17 years. Outcomes were compared using propensity methods.


Among Medicare-linked AVR patients (mean age 73 years), reoperation (4.0%) and endocarditis (1.9%) both were uncommon through 12 years. However, the risk for other adverse outcomes was high, including death (66.5%), stroke (14.1%), and bleeding (17.9%). Compared to patients undergoing mechanical AVR, patients after bioprosthetic AVRs had a similar adjusted risk for death (hazard ratio [HR], 1.04; 95% confidence interval [CI], 1.01-1.07), higher risks for reoperation (HR, 2.55; 95% CI, 2.14-3.03) and endocarditis (HR, 1.60; 95% CI, 1.31-1.94), and lower risks for stroke (HR, 0.87; 95% CI, 0.82-0.93) and bleeding (HR, 0.66; 95% CI, 0.62-0.70). Although results generally were consistent among patient subgroups, the absolute risk of reoperation at 12 years was high (10.5%) after tissue AVR among patients 65-69 years.


Long-term mortality rates were similar after tissue and mechanical AVR. Bioprostheses were associated with a higher long-term risk of reoperation and endocarditis, but a lower risk of stroke and hemorrhage. Risks vary as a function of patient age and comorbidities.


Prospective randomized trials comparing tissue and mechanical valves are so dated that prostheses and patients both have substantially changed. Although this study is limited by reliance on propensity matching between dissimilar groups (with inherent risks of failure to control for all differences between groups) and use of inpatient insurance claims to define events, the study is important, owing to the large cohort and length of follow-up. Differences in mortality associated with tissue versus mechanical AVR seen in various small studies were not observed in this study. As predicted, younger patients who underwent tissue AVR were at high risk of reoperation. However, the different profiles of risks associated with tissue and mechanical valves, with no difference in mortality, support using informed patient preference as a strong factor in valve choices among patients undergoing AVR.

Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Cardiac Surgery and Arrhythmias

Keywords: Heart Valve Prosthesis, Stroke, Endocarditis, Reoperation, Thoracic Surgery, Medicare, Coronary Artery Bypass, Cardiac Surgical Procedures, United States

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