BRCA1 and cyclic hematopoiesis: MicroRNAs (miRNAs) are a class of non‐coding RNAs of about 22 nucleotides long, and they primarily act as negative regulators of genes by binding to the complementary 3′ untranslated region.6, 7 Previous studies have confirmed that miRNAs play a significant role in the regulation of cell differentiation, proliferation, and apoptosis.8, 9 MiRNAs participate in regulating cardiac function, several of which have been reported as important regulators of CH and HF.10, 11, 12 For example, miR‐22 induces CH,13 miR‐208 protects against CH,14 and miR‐155 regulates CH by targeting BRCA1.15