1.Suspected coronary artery disease For patients suspected of having coronary artery disease, if they have chest discomfort and the diagnosis cannot be made clearly by electrocardiogram and exercise test, coronary angiography should be performed to clarify whether they have coronary artery disease or not. 2.Patients with known coronary artery disease For those who have been diagnosed with coronary artery disease, if myocardial infarction occurs without symptoms, as well as if there is still mild angina with medication, or if angina occurs repeatedly with severe arrhythmias and decreased blood pressure, etc., and unstable angina still occurs early after myocardial infarction, coronary angiography should also be performed to facilitate further treatment. Patients who have had an acute myocardial infarction should be decided by the doctor on a case-by-case basis whether to perform the interventional procedure immediately or after a few days. 3.Patients with recurrence after hematologic reconstruction Those patients who have undergone coronary balloon dilation or stent implantation or bypass surgery, and have atypical chest discomfort again, some even painless myocardial ischemia due to postoperative restenosis, vascular bridge reocclusion and atherosclerosis progression, should undergo review of coronary angiography. 4.Heart valve disease Aortic stenosis can also cause angina pectoris, which is difficult to distinguish from angina pectoris caused by atherosclerosis of coronary arteries, and coronary angiography should be performed. In addition, patients with valve replacement surgery, if they are older than 40 years old, should be routinely done.