Immunofluorescence study revealed a significant co-localization and juxtaposition of the expression of ROCK2 and the expression of cleaved caspase-3 in the left atrial myocytes both in the MR AF group (Pearson’s coefficient = 0.74 ± 0.03) and the MR sinus group (Pearson’s coefficient = 0.73 ± 0.02) (Fig. 5), indicating the existence of potential interaction between ROCK2 and cleaved caspase-3 and confirmation of caspase-dependent activation of ROCK2 in the left atrial myocytes of MR patients, and this interaction might be involved in the pathogenesis of left atrial myolysis in MR patients. Here, ROCK2 is linked to atrial fibrillation.