Objective:To investigate the effect and prognosis of preservation of the subvalvular apparatus on left ventricular functions in mitral valve replacement.Methods:Retrospective analysis was made among 92 patients who underwent mitral valve replacement in The First Affiliated Hospital of Chongqing Medical University from March 2016 to September 2019.Those patients were divided into two groups

among which

48 cases preserved the posterior and subvalvular apparatus of mitral valve（experimental group）

while the other 44 cases underwent traditional mitral valve replacement（control group）.Parameters of left ventricular function of echocardio graphic measurements were compared between experimental group and control group at preoperative

early postoperative period（7 days after surgery） and late postoperative period（3 months

6 months after surgery）

and perioperative conditions

etc.Results:The application time of vasoactive drugs in the experimental group was significantly shorter than that in the control group[（4.25±1.19）days vs.（5.64±1.63）days

P<0.05]

and the incidence of complications in the experimental group（8.34%）was significantly lower than that in the control group（25.00%）（P=0.031）.Six months after the operation

the left atrial diameter（LAD） [（32.64±3.76）mm]

left ventricular end diastolic diameter（LVEDD） [（43.60±3.68） mm] and left ventricular end systolic diameter（LVESD） [（31.81±4.73）mm]were significantly lower in the experimental group than those in the control group.The left ventricular ejection fraction（LVEF）[（64.86±4.23）%] and left ventricular fraction shortening（LVFS） [（36.04±2.90）%]were significantly higher in the experimental group than in the control group（P<0.05）.Conclusion:Miral valve replacement with preservation of subvalvular apparatus is beneficial for renewing cardiac function and a short-term improvement of left ventricular function.