MMP9 and atrial fibrillation: Th17 cells and their related cytokines (IL-17, IL-6, MMP9) in the peripheral blood of AF patients were negatively correlated with LVEF (r = − 0.462, − 0.457, − 0.313, − 0.375, all P < 0.05), while Tim-3 + cell ratio and their related cytokines (Tim-3, Gal-9) were positively correlated with LVEF (r = 0.428, 0.416, 3.724, all P < 0.05).