microRNAs (miRNAs) are small regulatory RNAs implicated in various cardiac disorders. In this review, the role of miRNAs is discussed in relation to acute myocardial infarction and chronic heart failure. In both settings, miRNAs are altered, contributing to injury and adverse remodeling. Notably, miRNA profiles differ between acute ischemic injury and progressive heart failure. Owing to miRNA variabilities between disease stages and delivery difficulties, translation of animal studies to the clinic remains challenging. The identification of distinct miRNA signatures could lead to the development of miRNA therapies tailored to different disease stages. Here, we summarize the current understanding of miRNAs in acute and chronic cardiac diseases, identify knowledge gaps and discuss progress in developing miRNA-based treatment strategies.