The results showed that the increase in the expressions of cleaved caspase-3 and PARP had been shown a statistical significance (P < 0.05) after AF cells were stimulated by 100 μmol/L H2O2 for 1 h and the highest level was achieved at 4 h (P < 0.01) (Fig. 3a), indicating that H2O2 could obviously induce the apoptosis of AF cells in a time-dependent manner. Here, CASP3 is linked to atrial fibrillation.