Whether sinus tachycardia and st-segment changes are serious or not depends on the situation, and can be seen in normal people as well as in some patients with diseases. 1. Sinus tachycardia can be seen in healthy people when smoking, drinking tea or coffee, drinking alcohol, physical activity and emotional excitement. Certain pathological conditions, such as fever, hyperthyroidism, anemia, shock, myocardial ischemia, congestive heart failure, and the application of adrenaline, atropine and other drugs can also cause sinus tachycardia, and need to be treated accordingly. 2.st segment changes can be seen in physiological or pathological sinus tachycardia, but also in coronary artery disease, cardiomyopathy, myocarditis, valvular disease, pericarditis, cerebrovascular accidents, electrolyte disorders, such as low or high potassium, the influence of drugs (digitalis, quinidine, etc.) and autonomic dysregulation. If sinus tachycardia and st-segment changes occur, it is necessary to go to the hospital to find the cause of the disease for treatment, so as not to delay the condition.