Myocardial infarction refers to ischemic necrosis of the myocardium. On the basis of coronary artery lesions, blood flow in the coronary arteries is drastically reduced or interrupted, causing severe and persistent acute ischemia in the corresponding myocardium, which eventually leads to ischemic necrosis of the myocardium. Patients with acute myocardial infarction often have a series of characteristic clinical evolution such as severe and persistent retrosternal pain, fever, elevated white blood cell count, elevated serum cardiac enzymes and electrocardiogram reflecting acute myocardial injury, ischemia and necrosis, and may have arrhythmia, shock or heart failure, which is a serious type of coronary heart disease. The hazards of myocardial infarction: 1, heart rupture: about 3% to 13% of fatal cases, often occurring within 1 to 2 weeks after myocardial infarction, preferably in the lower 1/3 of the anterior wall of the left ventricle. 2. Ventricular wall tumor: about 10-38% of infarction cases. It can occur in the early stage of infarction or in the healing phase when the infarct foci have been fibrotic. The infarcted myocardium or scar tissue under intraventricular pressure, limited outward expansion and formation of ventricular wall tumor. Ventricular wall tumors can be followed by appendage thrombosis, arrhythmia and cardiac insufficiency. 3. Epicardial thrombus formation: Mostly seen in the left ventricle. Thrombus formation is induced by rough endothelium in the infarct area, ventricular wall tumor and atrial fibrillation. The thrombus can be mechanized, but it may also be dislodged by cardiac diastole to cause embolism in the arterial system. 4, acute pericarditis: permeability infarction, often after myocardial infarction occurs plasmacytic or plasmacytic fibrinous pericarditis. It accounts for about 15% of myocardial infarcts and often occurs 2 to 4 days after MI. 5. Arrhythmia: accounts for about 75% to 95% of myocardial infarction. Myocardial infarction involves the conduction system and causes conduction disturbances, some of which can lead to emergency cardiac arrest and sudden death. The loss of myocardial contractility in the infarcted area causes left heart, right heart or total heart failure, which is a more common cause of patient death, accounting for about 60% of myocardial infarction. 6, cardiogenic shock: about 10% to 20% of myocardial infarction. When the area of myocardial infarction > 40%, the contractility of the myocardium is extremely weakened and the cardiac output is significantly reduced, which can cause cardiogenic shock and lead to the death of the patient. The danger of myocardial infarction is very serious, if not treated in time may lead to a variety of complications, pericarditis, pleurisy or pneumonia, etc., will make patients suffer from the trauma of the disease, so only timely treatment can reduce the possibility of these dangers. Therefore, it is very important to provide timely treatment for myocardial infarction. How to perform home first aid? 1.Family members call for help and dial 120 in time and open the door to facilitate rescue by emergency personnel. 2.Control emotions and reduce activities. Patients should immediately rest in bed and take the initiative to restrain their nervousness. 3.Oxygen inhalation. If conditions are available, oxygen is a better choice. In order to ensure the best treatment time for the patient, family members need to pay more attention to the preparation of materials and measures to prevent sudden myocardial infarction: 1, the relevant medical records, medical insurance cards (book) and previous cardiac data are put together and placed in a convenient place to access, while other family members should be informed of the storage location, in case of an attack can be quickly accessed. It is a good idea to have a contact card for immediate family members in the medical record book so that emergency personnel can contact family members. It is also advisable to write down allergy history and major medications in the medical record book, and prepare blood pressure monitor and oxygen intake facilities such as oxygen cylinders or oxygen machines in the family if available. 2, prepare some drugs, patients with frequent angina attacks can prepare some nitroglycerin and so on. It can relieve the symptoms when angina attacks, such as myocardial infarction attacks, can help identify. 3, early onset to contact emergency personnel as soon as possible. Patients should usually inform their immediate family of their heart condition so that family members are not able to inform the doctor of the situation in an emergency. Or keep a logbook to write down the daily medications, blood pressure and blood sugar values, etc., and put them together with the medical records. Remember, myocardial infarction is a critical illness that patients cannot manage on their own and has a high mortality rate, so the best plan is to seek medical attention as soon as possible and not to miss the best time.