Early mortality after aortic valve replacement with mechanical prosthetic vs bioprosthetic valves among Medicare beneficiaries: a population-based cohort study.

Abstract

Early mortality for patients who undergo aortic valve replacement (AVR) may differ between mechanical and biological prosthetic (hereinafter referred to as bioprosthetic) valves. Clinical trials may have difficulty addressing this issue owing to limited sample sizes and low mortality rates. To compare early mortality after AVR between the recipients of mechanical and bioprosthetic aortic valves. A retrospective analysis of patients 65 years or older in the Medicare databases who underwent AVR from July 1, 2006, through December 31, 2011. In the mixed-effects models adjusting for physician and hospital random effects, we estimated odds ratios (OR) of early mortality to compare mechanical vs bioprosthetic valves. Mechanical or bioprostheticaortic valve replacement. Early mortality was measured as death on the date of surgery, death within 1 to 30 or 31 to 365 days after the date of surgery, death within 30 days after the date of hospital discharge, and operative mortality (death within 30 days after surgery or at discharge, whichever is longer). Of the 66 453 Medicare beneficiaries who met inclusion criteria, 19 190 (28.88%) received a mechanical valve and 47 263 (71.12%) received a bioprosthetic valve. The risk for death on the date of surgery was 60% higher for recipients of mechanical valves than recipients of bioprosthetic valves (OR, 1.61 [95% CI, 1.27-2.04; P < .001]; risk ratio [RR], 1.60). The risk difference decreased to 16% during the 30 days after the date of surgery (OR, 1.18 [95% CI, 1.09-1.28; P < .001]; RR, 1.16). We found no differences within 31 to 365 days after the date of surgery and within the 30 days after discharge. The risk for operative mortality was 19% higher for recipients of mechanical compared with bioprosthetic valves (OR, 1.21 [95% CI, 1.13-1.30; P < .001]; RR, 1.19). The number needed to treat with mechanical valves to observe 1 additional death on the surgery date was 290; to observe 1 additional death within 30 days of surgery, 121. Consistent findings were observed in subgroup analyses of patients who underwent concurrent AVR and coronary artery bypass graft, but not in the subgroup undergoing isolated AVR. In this cohort analysis of Medicare beneficiaries, use of mechanical aortic valves was associated with a higher risk for death on the date of surgery and within the 30 days after surgery compared with bioprosthetic aortic valves among patients who underwent concurrent AVR and coronary artery bypass graft but not isolated AVR.