The electrocardiographic manifestations of anterior wall myocardial ischemia: the following four manifestations appear in anterior wall leads V1-V4: ST-segment arch-back elevation or ST-segment downward shift, T-wave depression or inversion, u-wave, and pseudonormalization, among which ST-segment arch-back elevation can be seen in variant angina; ST-segment downward shift is divided into upward sloping downward shift, flat downward shift, and downward shift, the latter two being more significant in ischemia. Pseudonormalization refers to an inverted T wave of the ECG when there are no symptoms; when myocardial ischemia occurs, the T wave is upright and the ECG appears to be normal. The above-mentioned ECG changes in myocardial ischemia last very briefly, and the ECG returns to its usual appearance upon termination of ischemia. Chest pain plus dynamic changes in the ECG consistent with chest pain suggest myocardial ischemia. However, in special cases, such as multiple coronary lesions, even if myocardial ischemia is present, the ECG does not show abnormal changes because of vector offset. Therefore, in myocardial ischemia, most ECGs can show the above changes, but the above ECG changes are not necessarily caused by myocardial ischemia.