Mechanical or Biological Prosthesis for Aortic Valve Replacement in Patients Aged 45 to 74 Years

The selection of valve prostheses for patients undergoing surgical aortic valve replacement (SAVR) remains controversial. In this study, the authors compared the long-term outcomes of patients undergoing aortic valve replacement with biological or mechanical aortic valve prostheses. 

The authors evaluated late results among 5,762 patients aged 45-74 years who underwent biological or mechanical aortic valve replacement with or without concomitant coronary artery bypass from 1989 to 2019 at four medical centers. The Cox proportional hazards model was used to compare late survival; the age-dependent effect of prosthesis type on long-term survival was evaluated by an interaction term between age and prosthesis type. Incidences of stroke, major bleeding, and reoperation on the aortic valve following the index procedure were compared between prosthesis groups. 

Overall, 61 percent (n=3,508) of patients received a bioprosthesis. The 30-day mortality rate was 1.7 percent (n=58) in the bioprosthesis group and 1.5 percent (n=34) in the mechanical group (P=0.75). During a mean follow-up of 9.0 years, the adjusted risk of mortality was higher in the bioprosthesis group (HR=1.30, P<0.001). The long-term survival benefit associated with mechanical prosthesis persisted until 70 years of age. Bioprosthesis (vs mechanical prosthesis) was associated with a similar risk of stroke (P=0.20), lower risk of major bleeding (P<0.001), and higher risk of reoperation (P<0.001). 

Compared to bioprostheses, mechanical aortic valves are associated with a lower adjusted risk of long-term mortality in patients aged 70 years or younger. Patients <70 years old undergoing SAVR should be informed of the potential survival benefit of mechanical valve substitutes.