Sudden onset of chest tightness should first exclude the possibility of coronary heart disease and angina pectoris, and other diseases including pneumothorax, aortic coarctation, pulmonary embolism, and chest pain caused by lobar pneumonia. For patients with sudden onset of chest tightness, they should go to the hospital for cardiology or emergency medicine chest pain center. They can first do the ECG when the chest tightness is present and the ECG after the chest tightness disappears, and compare the two ECGs for any dynamic ST-T evolution. If there is, chest tightness caused by myocardial ischemia is highly suspected. If not, the patient can further undergo blood sampling for myocardial markers to determine whether there is any myocardial cell injury, cardiac ultrasound to determine whether there are any structural changes in the heart, and coronary CT to determine whether there is any significant stenosis of the coronary arteries on the surface of the heart and the precise localization of the stenosis site. If the patient has done the above tests to exclude coronary artery disease, he or she should continue to consider other diseases and can undergo chest CT as well as aortic CT and pulmonary artery CT for excluding lobar pneumonia, pneumothorax, aortic coarctation, pulmonary embolism, etc.