Data extraction and analysis
All data were collected independently by two investigators (WMH and QL) from eligible studies using a standardised form. The following information was extracted: (1) study identification, including author name and publication year; (2) country where the study was conducted; (3) study subjects, number of participants and male to female ratio; (4) settings of trial arms; (5) Main indicators: complications, blood transfusion rate, 30-day mortality; mitral regurgitation and paravalvular leakage; secondary indicators: operation time, mechanical ventilation time, chest drainage, physiological score, psychological score, recovery time, hospitalization Total cost. (The ”complication” here refers to postoperative wound infection, pneumonia, liver and kidney insufficiency, myocardial infarction, postoperative atrial fibrillation, stroke, secondary thoracotomy, etc., ”Physiological score or Psychological score” is a score determined according to the quality of life questionnaire (SF-12/SF-36) provided in the literature. The higher the score, the better the effect.)