Objective To investigate the effect of dapagliflozin on cardiac function and major adverse cardiac events (MACE) in elderly patients with heart failure after acute myocardial infarction. Methods The clinical data of 59 elderly patients with heart failure after acute myocardial infarction, treated in Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology from May 2021 to February 2022, were collected and retrospectively analyzed. The objects were divided into control group (n=29) and dapagliflozin group (n=30) according to whether they took dapagliflozin during routine treatment. The cardiac function indexes [left vetricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter(LVESD)] and the level of N-terminal pro-brain natriuretic peptide (NT-proBNP); as well as clinical total effective rate, Killip grading and MACE occurrence were detected and compared at discharge and within 6 months after discharge. Results At discharge and within 6 months' treatment, the levels of LVEF increased (P<0.05), and of LVEDD, LVESD and NT-proBNP decreased (P<0.05) in the two groups than those before treatment. The level of LVEF in the dapagliflozin group was higher (P<0.05), and the levels of LVEDD, LVESD and NT-proBNP were lower in dapagliflozin group (P<0.05) than those in control group. There was no statistical difference in the clinical total effective rate between the two groups (86.7% vs. 65.5%, P>0.05) at discharge; The clinical total effective rate of dapagliflozin group was 93.3%, which was higher than control group of 62.1% within 6 months' treatment (P<0.05). Before treatment, at discharge and within 6 months' treatment, there was no statistical difference in the Killip classification between the two groups (P≥0.05). The incidence of MACE in dapagliflozin group was lower than that in control group within 6 months' treatment (P<0.05). Conclusion Compared with conventional anti heart failure therapy, combined with dapagliflozin can improve the cardiac function and prognosis, reduce the incidence of MACE of patients with heart failure after acute myocardial infarction.