To further verify that PCSK9 promotes platelet activation in mice after MI and mediates the fibrogenic phenotypic transformation of fibroblasts via TGF‐β, we measured the TGF‐β levels, mean platelet volume (MPV), platelet volume distribution width (PDW), and large platelet ratio (P‐LCR) in the peripheral blood of the four groups of mice; this was done to determine whether PCSK9 gene KO affects peripheral blood platelet activation after MI. The gene discussed is TGFB1; the disease is myocardial infarction.