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Long-term Outcomes of Aortic Valve Replacement in Adults <=40 Years Old: An Analysis of 1478 patients in 136 Hospitals in the State of California
William L Patrick, Andrew B Goldstone, Peter Chiu, *Michael J Paulsen, Bharathi Lingla, Michael Baiocchi, *Y Joseph Woo
Stanford University, Stanford, CA


Background:
Young adults constitute a minority of patients undergoing aortic valve replacement (AVR). The theoretical advantages to placing mechanical valves instead of bioprosthetic valves in younger patients have yet to be demonstrated by a robust multicenter analysis of surgical outcomes in this population. The purpose of this study was to analyze the largest cohort of adults <= 40 years old to understand how the choice of either a mechanical or bioprosthetic valve affects long-term surgical outcomes in clinical practice.
Methods: We obtained records of 1,478 adult patients <= 40 years old who underwent isolated AVR with either mechanical (1,062) or bioprosthetic (416) valves at 136 hospitals in the State of California between 1996 and 2013. Inverse probability weighting was used to compare long-term survival and rates of reoperation, stroke, bleeding, and endocarditis between these two cohorts. Weighted Cox proportional hazards regression with a robust variance estimator was used to compare survival; competing risk analyses were used to compare rates of longitudinal secondary endpoints. Standard errors were calculated from 500 bootstrap replicates.
Results: The total number of AVRs declined over the study period while the proportion of bioprosthetic valves implanted significantly increased (17% in 1996, 28% in 2013, P<0.001) (Figure A). Overall operative mortality was 1.3% (N=19); there was no significant difference in operative mortality when compared between prosthesis types (P=0.13). Bioprosthetic valves significantly reduced long-term survival compared with that of mechanical valves (HR 1.5, 95% CI 1.1-2.1) (Figure B). The cumulative incidence of bleeding was significantly higher among recipients of mechanical valves (HR 2.4, 95% CI 1.7-3.6) while that of stroke and endocarditis were equivalent between prosthesis types. Receipt of a biological prosthesis significantly increased the risk of reoperation during follow-up (HR 3.2, 95% CI 2.2-4.6); an inflection point in the incidence of reoperation was present at 6 years (Figure C). The operative mortality rate after redo AVR was 7.4% (N=11/149).
Conclusions: In young adults <= 40 years old undergoing AVR, mechanical valves significantly improved long-term survival and reduced the risk of reoperation compared with that of bioprosthetic valves. In a cohort of patients receiving newer generation bioprostheses, the risk of reoperation in young adults rises early and is substantial.
Figures:
Figure A: Number of bioprosthetic and mechanical valves implanted per year between 1996 and 2013.
Figure B: Long-term survival after AVR with either mechanical or bioprosthetic valve.
Figure C: Rate of reoperation after AVR with either mechanical or bioprosthetic valve.


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