Mechanical versus Biological Mitral Valve Replacement: 25 Years of Experience in Over 2,000 Patients

Objectives: Heart valve disease is frequently treated by valve replacement with either mechanical or biological prosthesis. Despite limited evidence, the use of biological prosthesis is increasingly favored, and accordingly, the age limit for biological prosthesis is decreased in current guidelines. However, it has been shown recently that the use of biological prosthesis in mitral position is associated with higher mortality rates even in higher age cohorts. Therefore, the aim of the present study was to analyze the impact of the type of the prosthesis on mortality hazard in patients undergoing isolated primary mitral valve surgery.

Methods: A retrospective analysis of prospectively collected data of patients who underwent primary isolated mitral valve replacement between January 1993 and December 2017 was undertaken. Data sources included the prospective institutional database, social registry, general practitioner data, and follow-up questionnaire. Descriptive statistics, Kaplan–Meier, Mantel–Cox, Breslow, and Tarone–Ware analysis was performed by using the SPSS statistic software.

Results: A total of 2,012 patients were included in the study (1,212 mechanical vs. 740 biological prosthesis). Baseline patient characteristics did not differ between the groups. Overall cumulative survival was significantly higher in patients with mechanical prosthesis (mean survival: 139 ± 4 vs. 102 ± 5 months, 10 years survival: 55 vs. 33%, p < 0.0001). Subgroup analysis according to age decades revealed significantly higher survival among patients received mechanical prosthesis up to 60 years (≤ 39 years p = 0.047, 40–49 years p < 0.0001, and 50–59 years p = 0.001). In the cohort of 60 to 69 years, overall survival did not differ significantly; however, in survivors beyond 8 years, mechanical prosthesis was associated with significantly improved survival (p = 0.014). While between 70 and 79 years, survival curves were nearly identical, above 80 years patients had a better survival with biological prosthesis (p = 0.014).

Conclusion: The present data demonstrate a clear survival benefit of mechanical prosthesis in wide range of patients after mitral valve replacement. Our findings also emphasize that the current trend toward biological prosthesis in younger patients cannot be justified. Especially in the grey zone (60–70 years), or even beyond, the choice of prosthesis should be based on life expectancy and individual factors of the patients.

No conflict of interest has been declared by the author(s).