Mechanical versus bioprosthetic valve for aortic valve replacement: systematic review and meta-analysis of reconstructed individual participant data

Objectives: The aim of this study was to compare biological versus mechanical aortic valve replacement.

Methods: We searched MEDLINE, Scopus and Cochrane Library databases for randomized clinical trials and propensity score-matched studies published by 14 October 2021 according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. Individual patient data on overall survival were extracted. One- and two-stage survival analyses and random-effects meta-analyses were conducted.

Results: A total of 25 studies were identified, incorporating 8721 bioprosthetic and 8962 mechanical valves. In the one-stage meta-analysis, mechanical valves cumulatively demonstrated decreased hazard for mortality [hazard ratio (HR): 0.79, 95% confidence interval (CI): 0.74-0.84, P < 0.0001]. Overall survival was similar between the compared arms for patients <50 years old (HR: 0.88, 95% CI: 0.71-1.1, P = 0.216), increased in the mechanical valve arm for patients 50-70 years old (HR: 0.76, 95% CI: 0.70-0.83, P < 0.0001) and increased in the bioprosthetic arm for patients >70 years old (HR: 1.35, 95% CI: 1.17-1.57, P < 0.0001). Meta-regression analysis revealed that the survival in the 50-70 year-old group was not influenced by the publication year of the individual studies. No statistically significant difference was observed regarding in-hospital mortality, postoperative strokes and postoperative reoperation. All-cause mortality was found decreased in the mechanical group, cardiac mortality was comparable between the 2 groups, major bleeding rates were increased in the mechanical valve group and reoperation rates were increased in the bioprosthetic valve group.

Conclusions: Survival rates seem to not be influenced by the type of prosthesis in patients <50 years old. The survival advantage in favour of mechanical valves is observed in patients 50-70 years old, while in patients >70 years old bioprosthetic valves offer better survival outcomes.