ECM metabolic imbalance is involved in various cardiovascular diseases such as myocardial infarction, heart failure and AF.68, 69, 70 Moreover, miR‐30c overexpression decreased the ECM‐regulated gene expression levels of Col I and Col3α1 in CFs, whereas MiR‐30c inhibition promoted these processes. The gene discussed is COL3A1; the disease is heart failure.