Sudden death and myocardial infarction differ mainly in definition, etiology, clinical manifestations and treatment. 1. Definition: Sudden death refers to death caused by heart disease within a short period of time, usually within 24 hours; myocardial infarction refers to necrosis of myocardial cells caused by coronary ischemia. 2. Etiology: Sudden death can be caused by myocardial infarction, severe arrhythmia and so on, which is called sudden cardiac death, and it can also be caused by respiratory diseases, cerebrovascular diseases and so on; myocardial infarction is mostly caused by coronary atherosclerosis, and hypertension, diabetes and so on, which are also risk factors. 3. Clinical manifestations: Sudden death is characterized by cardiac arrest, loss of consciousness, respiratory arrest, and even death; myocardial infarction is characterized by crushing pain in the anterior chest area, which can be radiated to the left upper limb, toothache, etc., and is often accompanied by chest tightness, dizziness and other symptoms. 4. Treatment: Sudden death requires resuscitation, chest compressions, respiratory support and electric defibrillation to save life; myocardial infarction requires the use of urokinase, aspirin and other drugs for thrombolysis, anticoagulation and other treatments. Sudden death and myocardial infarction are both more serious, should promptly call for help 120, and CPR, oral nitroglycerin and other emergency measures to buy treatment time.