The term qtc prolongation means the prolongation of the time it takes for the heart to go from depolarization to repolarization, and is an abnormal electrocardiographic condition. The term qtc prolongation is usually found on the description of the results of an electrocardiogram (ECG) and is related to the physiological process of depolarization and repolarization of the heart. The range of the QTC interval in a normal electrocardiographic situation is 0.32-0.44 seconds, and exceeding the upper limit of the normal range is called qtc prolongation. The prolongation of qtc generally represents the prolongation of the time needed for the heart to go from depolarization to repolarization, the heart is in an abnormal state, and the electrocardiographic activity is abnormal. The causes may be related to genetic diseases, drugs, myocarditis, heart failure, etc., and there is a certain potential risk, which can be manifested as tip-twisting ventricular tachycardia, which is a kind of arrhythmia, and in serious cases, sudden death may also occur.