In our study, Western blotting analysis revealed that the expression of the p-PERK-p-eIF2-α-ATF4-CHOP-Caspase 12 axis in the left atrial tissue of patients with atrial fibrillation was significantly increased compared with that in SR patients and that Ang-II treatment significantly increased the expression of the p-PERK-p-eIF2-α-ATF4-CHOP-Caspase 12 axis in rat left atrium tissue and HL-1 cells. This evidence concerns the gene ATF4 and atrial fibrillation.