Eligibility criteria
Studies that meet the following inclusion criteria were included: (1) the design of the study was a clinical retrospective cohort study about MR; (2) The experimental group and the control group received different surgical treatments; and (3) at least four of the data indicators for the perioperative period. Exclusion criteria were as follows: (1) irrelevant studies and duplicate literature; (2) unavailable data in the literature;(3) letters, reviews, case reports. (4) The type of disease involves other major diseases that may affect the efficacy of the operation.