If you have suffered from heart attack in the past and have tearing pain under the heart, you need to have electrocardiogram and cardiac enzymes examination to determine whether there is myocardial infarction again. 1. Electrocardiogram: The electrocardiogram is used to evaluate whether there is a myocardial infarction or not, and if there is ST-segment elevation, it is also needed to evaluate the lesions in the relevant leads, to determine whether there is myocardial necrosis and whether there are changes in the Q-wave. In case of non-ST-segment elevation, T-wave inversion, ST-segment downshift and severe chest pain, the presence of myocardial infarction should be evaluated. 2. Cardiac enzyme examination: cardiac enzyme examination, including troponin, myoglobin, creatine kinase test, the earliest elevation is often myoglobin, and troponin’s sensitivity and specificity are relatively high. For the diagnosis of myocardial infarction, the diagnosis is usually made on the basis of the patient’s clinical symptoms electrocardiography and cardiac enzymes. It is also necessary to assess the location of the pain, the time of assessment, the radiation of pain, etc. It is recommended to consult the emergency department in a timely manner.