At the same time, miR-21-3p can be enriched in exosomes derived from MFBs, and its action on CMs can lead to the downregulation of the expression of L-type calcium channel Cav1.2, a marker of ionic remodeling associated with atrial fibrillation in CMs, which may be a key substance in increasing the susceptibility to atrial fibrillation in the process of atrial fibrosis (Li et al., 2020). Here, CACNA1C is linked to atrial fibrillation.