Many patients with acute myocardial infarction develop the disease after returning home from work or while sleeping. Therefore, as a family member of a heart patient, it is necessary to understand the manifestations of myocardial infarction and the precursors of the onset of myocardial infarction in order to provide timely initial first aid. The performance of acute myocardial infarction has the following aspects: 1, precordial pain often occurs in quiet or sleep, pain is difficult to prevent, long duration, oral nitroglycerin tablets still does not work, while cold sweat, restlessness, a sense of fear of dying. 15% to 30% of patients, pain may not be in the chest, some in the upper abdomen, some in the neck, and some in the back, often making a wrong judgment. In contrast, acute myocardial infarction in diabetic patients, but often no pain symptoms, the beginning of the performance of shock or acute heart failure. 2, blood pressure or shock some patients with acute myocardial infarction when the onset of blood pressure dropped, shock, the patient is often pale, wet and cold skin, weak and fast pulse, urine volume decreased, confusion, serious coma. 3. Heart rhythm disturbance occurs in 75% to 95% of patients with acute myocardial infarction within 1 to 2 weeks of the onset of the disease. Ventricular rhythm disturbances are common, especially premature ventricular beats, and can lead to ventricular fibrillation. 4. Heart failure is mainly left heart failure, often within the first few days of onset. 5, nausea, vomiting and epigastric pain. 6, fever appears 1 to 3 days after the onset of the disease, with a temperature of 38℃ to 38.5℃, sometimes 39℃. 20% to 80% of patients have aura symptoms before myocardial infarction, manifested as an increase in angina pectoris. Its attack is heavier and lasts longer than before, and the time is fixed, and nitroglycerin cannot make it slow angle. Angina is also accompanied by symptoms such as nausea, vomiting, sweating, arrhythmia, or large fluctuations in blood pressure. For patients with acute myocardial infarction, even if only suspected, should follow the steps of initial first aid and treatment; 1, lying flat on the ground, even if they fall on the ground, do not “kindly” have to move to bed. 2. Immediately observe the patient’s carotid or femoral artery (on the medial side of the wall at the base of the thigh) for pulsations. In case of cardiac arrest, take the following measures immediately: ① give the patient nitroglycerin tablets or sniff isoamyl nitrite; ② try to call an emergency physician; ③ if it is difficult or impossible to call an emergency physician, try to transfer the patient to a hospital after quiet rest, when there is no obvious shock and the pulse rate and rhythm are normal. Don’t do unnecessary moving on the way; ④ If you have conditions (such as always have oxygen bags at home), you should give oxygen first.