The ECG manifestations of stable angina are mostly in the normal range during the remission phase. During an angina attack, ST-segment depression with T-wave inversion may occur. During the exercise stress test, the ECG changes are mainly in the form of horizontal or downward sloping ST-segment depression greater than or equal to 0.1mv for 2 minutes. During exercise, patients may experience transient ventricular tachycardia and changes in blood pressure. In a 24-hour ambulatory ECG, the ST-segment change is greater than or equal to 0.1mv and lasts more than 1 minute, and the interval between episodes is also greater than 1 minute. The ambulatory ECG provides a complete record of ST-T changes and the presence of various arrhythmias, the presence of these arrhythmias and the changes in the S T segment corresponding to the time of the angina attack.