Coronary angiography is performed by puncturing a very thin catheter through the femoral artery at the root of the thigh or the radial artery at the wrist and sending it along the vessel to the opening of the coronary artery, injecting contrast into the coronary artery and recording the process like a movie to determine whether there is a narrowing or blockage of the coronary artery. In general, coronary angiography should be performed in all patients with possible coronary artery disease to confirm the diagnosis and treatment. This is because coronary angiography is the current “gold standard” for coronary artery disease diagnosis. It can clarify the presence of coronary artery stenosis, the location, degree and extent of stenosis, etc., and can guide the measures to be taken for further treatment accordingly. Patients who communicate with me by phone are advised to upload their imaging reports to the website in advance so that I can take a look at them. For details on how to upload, please refer to “How to upload images”. For those who have clear symptoms of angina pectoris, meaning that they have chest tightness before physical activity or emotional excitement, which can be relieved after resting for a few minutes, it is better for these patients to have coronary angiography to determine whether the patient has coronary artery disease and to be able to clarify the degree of stenosis and to provide a basis for the next treatment. If the stenosis is very severe, more than 70%, it is more difficult to control by medication, and it is necessary to place a stent to hold up the lesion like an umbrella, so as to restore the coronary blood flow.