Atrial fibrillation (AF) is the most common arrhythmia, which leads to reduced cardiac output and promotes the occurrence of heart failure, and abnormal hemodynamic changes in the left atrium induce thrombosis, which seriously reduces the quality of life, and even leads to death. For patients who need cardiac surgery combined with the Cox-Maze IV (CMIV) surgical ablation, oral amiodarone postoperatively for three consecutive months was recommended as the preferred treatment option. However, the study found there were still 15%-35% of patients at risk of AF recurrence. Dapagliflozin, a sodium-glucose cotransporter 2 inhibitor, has been widely used for the treatment of type 2 diabetes mellitus and heart failure. Nonetheless, it remains unknown whether dapagliflozin can improve the recurrence of AF and reduces adverse cardiovascular events for patients who need CMIV ablation, and whether it can be routinely used for AF patients without diabetes or heart failure. Therefore, this study aims to explore the effect of postoperative oral dapagliflozin on the recurrence of AF after CMIV.