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

Background: Hypertrophic Cardiomyopathy (HCM) is the most common in-herited 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 myocar-dial fibrosis, while cardiac magnetic resonance (CMR) is an imaging technique to detect myocardial fibrosis. MicroRNAs (miRNAs) have been increasingly suggested as bio-markers 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 cardiomyopa-thy from non-obstructive HCM. Additionally, miR-29a-3p is associated with diffuse myo-cardial 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, miR-NA-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 forth-coming studies in samples from HCM patients and correlation of miRNAs with CMR and serum markers of fibrosis may implicate novel diagnostic and therapeutic pathways.