ST-segment bow-back elevation often suggests the presence of pericardial effusion and is less likely to be considered a myocardial infarction. ST segment elevation is commonly associated with pericardial effusion, and the change of ST segment may be related to the effect of pericardial effusion on electrical activity. Cardiac ultrasound should be performed in time to clarify the amount of pericardial effusion and assess the severity of the disease. Patients with myocardial infarction may also have ST-segment elevation, which is characterized by hyperacute T-wave in the early stage, and with the gradual progression of the disease, S-segment and bow-back upward elevation will appear, suggesting that the patient’s coronary arteries have been completely occluded, and myocardial necrosis will occur if the treatment is not timely. Clinically found ST segment elevation patients should pay attention to the specific situation, if necessary, perfect cardiac enzymes cardiac ultrasound examination, clear specific diagnosis, under the guidance of the physician can be treated to avoid delaying the condition.