Patients with myocardial ischemia will have certain changes on the electrocardiogram, which is the main diagnostic basis for diagnosing the presence of myocardial ischemia in most clinical settings. The test is relatively inexpensive and easy to perform. T-wave hypotrophy refers to the amplitude of the T-wave in the R-wave dominated leads is less than 1/10 of the R-wave in the same lead, while symmetric inversion of the T-wave is clinically significant and indicates the presence of myocardial ischemia, which may be caused by coronary artery disease. In case of asymmetric inversion, myocardial damage due to hypertension is considered a possibility. In addition, the ECG manifestations of myocardial ischemia include horizontal downward shift of ST segment or downward oblique shift. Horizontal downward shift of ST segment is more clinically significant and represents a more serious degree of myocardial ischemia in patients. If the ST-segment is elevated, it may be considered to be a variant of angina pectoris or acute myocardial infarction, both of which represent the presence of myocardial ischemia.