70% necrosis of myocardium belongs to large myocardial infarction, its prognosis is very poor, the mortality rate can be as high as 70%~100%, the specific time that can be survived varies from person to person, and it is not possible to make a generalization. Myocardial infarction refers to the necrosis of myocardial cells due to blockage of coronary arteries and insufficient blood supply. The main causes of myocardial infarction include coronary atherosclerosis, diabetes, overweight and obesity, and emotional stress. Clinical symptoms of myocardial infarction can be manifested as sudden onset of chest tightness in the precordial region, crushing pain, lasting more than 30 minutes, and the patient may experience a sense of near death. The length of survival of patients after myocardial infarction has a great relationship with the area of infarction, when the area of myocardial necrosis foci is more than 40%, the scope of myocardial necrosis is too large, and the function of the heart is severely impaired, and cardiogenic shock can occur. Therefore, when 70% infarct foci are present in the myocardium, the survival period of the patient is very short and death may occur soon. When the symptoms of myocardial infarction appear, it is recommended to go to the regular hospital for timely treatment.