Objective To investigate the expression of serum microRNA-29b(miR-29b),microRNA-199a(miR-199a),and microRNA-19a-3p(miR-19a-3p)in patients with acute cerebral infarction(ACI)and their relationship with disease severity and prognosis.Methods(1)Rats were randomly divided into a control group(Control group)and a model group(Model group),with 6 rats in each group.ACI was induced in the model group using the modified Longa suture method;the expression levels of miR-29b,miR-199a,miR-19a-3p in rat serum and brain tissue were detected and analyzed.(2)A total of 106 ACI patients diagnosed at Tangshan People's Hospital from June 2023 to June 2024 were enrolled as the study group,and 108 healthy individuals who underwent physical check-ups at the same hospital during the same period were chosen as the control group.According to the NIHSS evaluation results,the study group patients were assigned into mild(42 cases),moderate(34 cases),and severe(30 cases)groups.Based on the mRS evaluation results,the patients were assigned into good prognosis(68 cases)and poor prognosis(38 cases)groups.Real-time fluorescence quantitative PCR was applied to measure the expression levels of serum miR-29b,miR-199a,and miR-19a-3p.Pearson correlation analyzed the correlation between serum miR-29b,miR-199a,miR-19a-3p levels and NIHSS score and mRS score in ACI patients.The risk factors for poor prognosis in ACI patients were analyzed using multivariate logistic regression.ROC curves were used to analyze the predictive value of serum miR-29b,miR-199a,miR-19a-3p levels and NHISS scores in poor prognosis of ACI patients.Results(1)Compared with the Control group,the levels of miR-199a and miR-19a-3p in the serum and brain tissue of the Model group rats were significantly increased,while the level of miR-29b was significantly decreased(P<0.05);(2)Compared with the control group,as the severity of ACI patients gradually increased,the levels of serum miR-199a and miR-19a-3p unusually increased in the mild,moderate,and severe groups,while the level of miR-29b was significantly decreased(P<0.05).The NHISS score,miR-199a and miR-19a-3p levels in the poor prognosis group were significantly higher than those in the good prognosis group,while miR-29b was significantly lower than that in the good prognosis group(P<0.05).The levels of serum miR-199a and miR-19a-3p were positively correlated with NIHSS score;the level of miR-29b was negatively correlated with NIHSS score(P<0.05).Elevated serum miR-199a and miR-19a-3p levels and increased NHISS score were independent risk factors for poor prognosis in ACI patients,and elevated serum miR-29b levels were protective factors for poor prognosis in ACI patients(P<0.05).The combined prediction of poor prognosis in ACI patients using serum miR-29b,miR-199a,miR-19a-3p levels and NHISS scores yielded an ACI of 0.988,which was superior to individual predictions(Z=2.878,3.551,3.300,3.452,P<0.05).Conclusion The serum expression levels of miR-199a and miR-19a-3p were significantly up-regulated,while miR-29b levels significantly down-regulated,which were related to the disease severity and prognosis.The the combination of the three miRNAs had certain value in predicting the poor prognosis of patients.MiR-29b,miR-199a,and miR-19a-3p can be used as important predictors to evaluate the progression and prognosis of ACI patients.