Background: Several microRNAs (miRNA) have been associated with hypertrophic cardiomyopathy (HCM), but studies differ regarding methods employed. In an attempt to understand their role in the disease, we performed a systematic review of studies assessing miRNAs and their association with HCM.
Methods: The literature search was based on The Medical Subject Headings (MeSH) terms "Hypertrophic Cardiomyopathy" and "MicroRNA" combined with other synonyms on Embase, Medline and LILACS databases in April 2020. The selected studies and data extraction were independently evaluated. Only human reports with a clear definition of HCM diagnosis were included.
Results: The search found 68 studies, 13 fulfilled the selection criteria, with a total of 329 patients. Eighty-seven miRNA were differentially expressed in HCM patients, being mir-21, mir-29a and mir-133 the most reported. The miRNA were mainly up-regulated, where mir-29a was up-regulated in 6 studies, followed by mir-133 in 4 and mir-21 in 3. The other miRNAs were mainly up-regulated. Blood samples were evaluated in the majority of patients (86%), but a greater number of miRNAs (79%) were assessed in myocardium. Six studies evaluating the phenotype correlation demonstrated that several miRNAs, mainly mir-1-3p, mir-19b, mir-21, mir-29a, mir-155, and mir-221, were related to either hypertrophy or fibrosis. Mir-29a showed a more consistent phenotypic correlation.
Conclusion: Eighty-seven miRNAs were differentially expressed in HCM patients, the majority in up-regulation. Mir-21, mir-29a and mir-133 were the most reported. Correlation with left ventricular hypertrophy and fibrosis was evaluated in six studies for several miRNAs, nevertheless, mir-29a showed more consistent findings and seems to be a promising biomarker.
Keywords: Cardiomyopathy; Epigenetic; Hypertrophic cardiomyopathy; Left ventricular hypertrophy; Myocardium fibrosis; microRNAs.
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