It is difficult to determine a time standard for how long a forty year old patient with coronary artery disease can live, and it is related to the clinical type of coronary artery disease as well as the early and late period of the lesion. Coronary artery disease generally refers to coronary atherosclerotic heart disease, and there is usually no precise time for the life expectancy of a patient whose coronary artery disease is detected in his or her forties. The quality of survival and life expectancy of such patients is closely related to their poor lifestyle habits, the duration and effectiveness of treatment, and the presence of other complications. If a patient has coronary artery disease in his or her forties, but still has a high-fat diet and does not follow a regular schedule of rest, and does not use any medication to control it, he or she is very susceptible to myocardial infarction and is likely to lose his or her life in a matter of hours or weeks. Therefore, how long a patient will live should be decided completely according to the actual situation of the patient. It is recommended that patients follow the doctor’s advice to actively treat, can prolong the survival time.