CACNA1C and atrial fibrillation: Ricardo et al. found that the high expression of miR-21 in cardiomyocytes of patients with AF was negatively correlated with the expression of CACNA1C and the density of I (Ca, L), suggesting that miR-21 may be involved in the downregulation of L-type Ca2+ I (Ca, L) induced by chronic AF, and is the key to the persistence of AF (95).