Fever after cardiac surgery is usually caused by several factors as follows: First, post-surgical comorbidities and complications can occur after cardiac surgery, such as factors such as infection. In the case of infection, bacteria, viruses or other pathogenic microorganisms can cause fever in the body. Secondly, non-infectious factors can also lead to fever after heart surgery, such as inflammatory exudate and sterile necrotic tissue material in the heart. In myocardial infarction, the patient’s body temperature regulating point is raised in the body due to the absorption of myocardial necrotic tissue, which can cause fever. The absorption of myocardial necrotic tissue after myocardial infarction will cause a fever with a body temperature of about 38°C, which usually occurs within 24-48 hours.