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Background/Aims: Recent studies have shown that circulating microRNAs (miRNAs) are emerging as promising biomarkers for cardiovascular diseases. This study aimed to determine whether miR-19b-3p, miR-134-5p and miR-186-5p can be used as novel indicators for acute myocardial infarction (AMI). Methods: To investigate the kinetic expression of the three selected miRNAs, we enrolled 18 patients with AMI and 20 matched controls. Plasma samples were collected from each participant, and total RNA was extracted. Quantitative real-time PCR and ELISA assays were used to investigate the expression of circulating miRNAs and cardiac troponin I (cTnI), respectively. Plasma samples from another age- and gender-matched cohort were collected to investigate the impact of medications for AMI on the expression of the selected miRNAs. Results: Levels of plasma miR-19b-3p, miR-134-5p and miR-186-5p were significantly increased in early stage of AMI. Plasma miR-19b-3p and miR-134-5p levels reached peak expression immediately after admission (T0), whereas miR-186-5p achieved peak expression at 4 h after T0. All of these times were earlier than the peak for cTnI (8 h after T0). In addition, all three miRNAs were positively correlated with cTnI. Receiver Operating Characteristic (ROC) analysis indicated that each single miRNA showed considerable diagnostic efficiency for predicting AMI. Furthermore, combining all three miRNAs in a panel increased the efficiency of distinguishing between patients with AMI and controls. Moreover, we found that heparin and medications for AMI did not impact the expression of these circulating miRNAs. Conclusion: Circulating miR-19b-3p, miR-134-5p and miR-186-5p could be considered promising novel diagnostic biomarkers for the early phase of AMI.