MicroRNAs as Biomarkers in Hypertrophic Cardiomyopathy: Current State of the Art

Background: Hypertrophic Cardiomyopathy (HCM) is the most common inherited Cardiomyopathy. The hallmark of HCM is myocardial fibrosis that contributes to heart failure, arrhythmias and sudden cardiac death. Objective: Currently, there are no reliable serum biomarkers for the detection of myocardial fibrosis, while cardiac magnetic resonance (CMR) is an imaging technique to detect myocardial fibrosis. MicroRNAs (miRNAs) have been increasingly suggested as biomarkers in cardiovascular diseases. However, in HCM there is as yet no identified and verified specific circulating miRNA signature. Methods: We conducted a review of the literature to identify the studies that indicate the possible roles of miRNAs in HCM. Results: From studies in transgenic mice with HCM, miR-1, -133 may identify HCM in the early asymptomatic phase. Human miR-29a could be used as a circulating biomarker for detection of both myocardial hypertrophy and fibrosis in HCM, while it could also have a possible additional role in discrimination of hypertrophic obstructive cardiomyopathy from non-obstructive HCM. Additionally, miR-29a-3p is associated with diffuse myocardial fibrosis in HCM, while miR-1-3p could discriminate end-stage HCM from dilated cardiomyopathy and left ventricle dilation. Another role of miRNAs could also be the contribution in the differential diagnosis between HCM and phenocopies. Moreover, miRNA- targeted therapy (miR-133 mimics) is promising in inhibiting cardiac hypertrophy, but this is still in the early stages. Conclusion: A more reliable and specific signature of miRNAs is expected with forthcoming studies in samples from HCM patients and correlation of miRNAs with CMR and serum markers of fibrosis may implicate novel diagnostic and therapeutic pathways.