When a patient undergoes an electrocardiogram that suggests ST-segment fishhook-like changes, the most common cause is electrocardiogram changes caused by the use of digitalis drugs or after the use of digitalis drugs such as digoxin, which reach a certain amount of drug concentration in the body. If, after using digoxin and other digitalis drugs, ECG fishhook-like changes occur, accompanied by nausea, vomiting, dizziness, hallucinations, blurred vision, yellow-green or double vision, hallucinations and other clinical manifestations and symptoms, it is considered to be caused by digitalis drug poisoning. It is necessary to stop the drug immediately and seek medical attention for symptomatic treatment. If the patient does not use digitalis, and there are fishhook-like changes in the ECG, actively improve the examination to exclude whether it is caused by other diseases such as coronary heart disease, and give treatment and review the ECG.