There are many friends who have asked: “I have myocardial ischemia, how do you think to treat it?” “How do you have myocardial ischemia?” It turns out that a doctor said to them, “Your ECG has T-wave inversion, which indicates myocardial ischemia.” This understanding is actually incomplete. T-wave inversions seen clinically are not always a manifestation of cardiovascular abnormalities; many non-cardiovascular etiologies can also cause them. The electrocardiogram is a record of the electrical excitation that occurs during the heartbeat, which relies on the conduction system inherent to the heart’s anatomy and physiology. Each time the heart beats, the ECG records a complete cardiac cycle waveform. Ventricular systole is completed by ventricular diastole producing a T wave. Therefore, various reasons affecting the diastolic function of the ventricle may cause changes in the T wave. 1. Myocardial ischemia: This is, of course, the cause that most people can think of. It is usually believed that at least one large coronary artery with luminal stenosis of more than 50% will trigger symptoms of transient myocardial ischemia (oxygen) when myocardial oxygen consumption increases to a certain level with overexertion. The ischemic electrocardiogram may have S-T segment reduction and T-wave inversion at the time of ischemia tracing, but the ischemic S-T segment and T-wave changes disappear with the relief of ischemic symptoms. There is no protracted T-wave inversion in the quiet state. Unless myocardial infarction has occurred, T-wave inversion may remain for several months or longer after the acute phase. 2, ventricular hypertrophy: long-term hypertension, hypertrophic cardiomyopathy, congenital heart malformations, and various causes of heart valve disease can cause ventricular hypertrophy and dilation. The T-wave inversions caused by the above-mentioned causes are more persistent and do not change much, and as the degree of ventricular hypertrophy increases, the T-wave inversions may also gradually become deeper. 3, myocarditis: various causes of myocarditis after recovery may remain persistent T-wave flat, bi-directional or inverted. 4, pericardial disorders: various causes of pericarditis or pericardial effusion can appear T-wave flat or inverted. 5, arrhythmia: such as complete bundle branch conduction block or non-sinus conduction ectopic rhythm can appear T wave changes, paroxysmal tachycardia or atrial fibrillation can appear after the conversion of electro-tension adjustment of T wave inversion. 6.After cardiac surgery: T-wave inversion can be seen in the pacing rhythm after ventricular pacemaker implantation and the electrocardiogram after coronary artery bypass grafting. 7.Electrolyte disorders in the body: severe vomiting and diarrhea caused by digestive system diseases, chronic wasting diseases leading to hyperemesis, excessive fluid loss due to diuresis, hypokalemia and hypocalcemia can cause T-wave flattening or inversion. 8, drugs: such as digitalis, anti-arrhythmic drugs can also lead to T-wave inversion. 9, other diseases: hypothyroidism, pulmonary embolism or chronic lung disease, intracranial hemorrhage, etc. can be seen in the T wave flat, bidirectional or inverted.