The manuscript: “Comparison of Biological and Mechanical Prostheses for Heart Valve Surgery: Systematic Review of Randomized Controlled Trials” addresses a controversial issue. The authors conducted a meta-analysis of randomized trials involving long-term follow-up of patients requiring cardiac valve replacement revealing similar mortality among patients who underwent implantation of biological prostheses and those who underwent implantation of mechanical prosthesis. There were no significant differences in the risk of thromboembolism and endocarditis. However, the risk of bleeding was approximately one-third lower among patients treated with biological prostheses than those treated with mechanical prostheses. In contrast, the need for reoperation among patients treated with bioprostheses was at least three times greater than that of patients treated with mechanical prostheses.

The authors selected “randomized” trials to avoid evaluation bias. The trial is interesting, as it seeks to be faithful to randomized evaluations, which are very unusual in the literature on valve diseases, especially at the time when the trials were conducted.

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