Background <p>Diagnosis and prognostic evaluation of acute myocardial infarction (AMI) are crucial for patients.</p> Objective <p>The clinical significance of serum miR-199a-5p combined with echocardiography in AMI was investigated to provide some reference for clinical treatment.</p> Methods <p>The study subjects were 90 AMI patients and 50 acute chest pain patients (control). All patients were examined by echocardiography and recorded LVEDV, LVESV, and LVEF. RT-qPCR was performed to detect the serum miR-199a-5p level. Pearson analysis was used to analyze the correlation of miR-199a-5p with LVEF and cTnI. The diagnostic value of miR-199a-5p combined with LVEDV, LVESV, and LVEF was assessed by the ROC curve. The occurrence of major adverse cardiovascular events (MACE) was recorded to analyze the prognostic value of miR-199a-5p by the Kaplan-Meier curve and Cox regression.</p> Results <p>Serum miR-199a-5p was elevated in AMI, positively correlated with cTnI and negatively correlated with LVEF. The combination of miR-199a-5p with LVEDV, LVESV, and LVEF enhanced the sensitivity and specificity for the diagnosis of AMI. Patients with high miR-199a-5p expression were more likely to develop MACE. The combination of miR-199a-5p with LVEF improved the prediction of MACE.</p> Conclusions <p>The combination of miR-199a-5p with echocardiography improved the diagnostic efficiency of AMI and provided prognostic information.</p>