Mechanical versus bioprosthetic valves in patients on dialysis

The aim of this study is to evaluate the outcomes of bioprosthetic versus mechanical valves in patients on dialysis.

All patients who underwent aortic (AVR) or mitral valve replacement (MVR) at a single institution from 2011-2017 were reviewed. Primary stratification was bioprosthetic versus mechanical valves. The primary outcome was all-cause mortality. Secondary outcomes included hospital readmission, valve reoperation rates and bleeding events. Kaplan-Meier curves were generated and Cox proportional hazards regression models were used for risk-adjustment.

During the study period, 3,969 patients underwent AVR or MVR, of which 97 (2.4%) were on dialysis. In dialysis patients, unadjusted 30-day mortality was comparable between bioprosthetic (12.7%) versus mechanical (5.9%) valves (P=0.31). However, the bioprosthetic group had higher rates of 1-year (40.3% versus 15.2%; P=0.03) and 5-year mortality (67.9% versus 60.7%; P=0.02). Most patients were readmitted within 5 years with no differences between the groups (bioprosthetic 80.3% versus mechanical 100%; P=0.57). There were no valve reoperations in either group at 5 years. The 5-year readmission rate was higher in the mechanical cohort (10.5% versus 53.8%; P=0.05). Risk-adjusted analysis confirmed these findings, where mechanical valves were independently associated with reduced mortality at 1-year and 5-years.

Despite the limited life expectancy of patients on dialysis, mechanical valves have an intermediate term mortality benefit compared to bioprosthetic valves. This comes at the expense of a higher rate of readmission for bleeding. Although valve choice should consider multiple factors, these data suggest that mechanical valve usage in dialysis patients is reasonable.