Objective: To compare outcomes after aortic valve replacement (AVR) according to valve type specifically in older patients since valve-related risks are age-dependent; two randomised trials comparing mechanical and bioprosthetic valves found better outcomes with mechanical valves, but the samples were small and the patients were considerably younger than most who undergo AVR.
Design: Cohort study.
Setting: 1199 US hospitals.
Patients: Patients 65 years and older undergoing AVR during 1991-2003 (n = 307 054) identified through Medicare claims data.
Main outcome measures: Relative hazard ratios associated with bioprosthetic valves of (1) death (n = 131,719); (2) readmission for haemorrhage (n = 31,186), stroke (n = 25,051) or embolism (n = 5870); (3) reoperation (n = 4216); and (4) death or reoperation (reoperation free survival) in Cox regression analyses adjusting for demographic and clinical factors and hospital-level effects.
Results: Overall, 36% of AVR patients received bioprosthetic valves. Bioprosthetic valve recipients were older (77 vs 75 years, p<0.001) and generally had higher comorbidity. Bioprosthetic valve recipients had a slightly lower adjusted hazard ratios of death (HR = 0.97; 95% CI 0.95 to 0.98); readmission for haemorrhage, stroke or embolism (HR = 0.90, 95% CI 0.88 to 0.92); and death or reoperation (HR = 0.97, 95% CI 0.96 to 0.98), but a higher hazard ratio of reoperation (HR = 1.25, 95% CI 1.16 to 1.35). However, overall mortality and complication rates were more than 20 and 10 times higher, respectively, than the overall reoperation rate.
Conclusions: In older patients undergoing AVR, bioprosthetic valve recipients had slightly lower risks of death and complications, but a higher risk of reoperation. Given the low reoperation rate, these data suggest that bioprosthetic valves may be preferred in older patients.