In this study, the proportion of Th17 cells was positively correlated with IL-17, IL-6, and MMP9, indicating that the increase of Th17 cells in the peripheral blood of AF patients can induce the production of inflammatory cytokines IL-17, IL-6, and MMP9, which in turn affects AF, and also indicating that Th17 cells can be used as one of the risk factors for AF. Here, MMP9 is linked to atrial fibrillation.