Currently, for the diagnosis of acute myocardial infarction, there is no absolute biomarker that has the maximum possible specificity and sensitivity. Circulating microRNAs, which not only regulate key functions in a healthy heart, but are also important in the mechanisms of cardiovascular diseases such as myocardial hypertrophy, fibrosis, and apoptosis, have great potential as new early biomarkers for managing patients with acute coronary syndrome. This literature review summarizes the current understanding of the role of microRNAs in the development of atherosclerotic plaques at all stages of atherogenesis, the diagnostic value of small molecules as a biomarker of myocardial infarction and the differential diagnosis of this pathological condition with unstable stenacordia. Despite the great interest in the problem and a significant number of scientific papers, further research is needed. The perspective in the study of microRNAs significantly expands the range of diagnostic capabilities of this method.