Abstract:Objective To analyze the efficacy of sacubitril/valsartan in the treatment of patients with heart failure after myocardial infarction and the relationship between microRNA-155 (miR-155) level and left ventricular ejection fraction (LVEF).Methods A total of 80 patients with heart failure with reduced ejection fraction after myocardial infarction admitted to our hospital from January 2019 to December 2020 were enrolled. They were randomly divided into experimental group and control group, with 40 cases in each group. The control group was given diuretics and other basic treatment, while the experimental group was additionally treated with sacubitril/valsartan. The differences of left ventricular end-diastolic volume index (LVEDVI), left ventricular end-systolic volume index (LVESVI), LVEF and miR-155 level before and after treatment in the two groups were measured, and the relationship between miR-155 level and LVEF was analyzed.Results Compared with the control group, the differences of LVEDV and LVESV before and after the treatment were higher (P < 0.05), while those of LVEF and 6‐min walk distance before and after the treatment were lower in the experimental group (P < 0.05). The difference of miR-155 level before and after the treatment in the experimental group was higher than that in the control group (P < 0.05). Besides, the relative expression level of miR-155 negatively correlated with LVEF (r = -0.447, P < 0.05).Conclusions After the treatment with sacubitril/valsartan, heart failure patients with reduced ejection fraction after myocardial infarction exhibited improved cardiac function and decreased miR-155 level, and LVEF was negatively correlated with miR-155 level.