In every clinic, we have to spend a long time explaining to patients how much stenting is needed, 50%, 70% or 90%? With the development of the Internet, everyone can look up the appropriate medical knowledge on the Internet, but it is difficult to adapt to the mixed and different information. Thinking about the huge cost of stent, the gray income of medical field, the fear of foreign body put into the body, the anxiety of long-term medication, etc., every coronary heart disease patient wants to find out how much blood vessel narrowing is the standard for stenting, so as not to be confused by the stent installed and have no way to say. In fact, the blood vessels inside the heart are like a big tree, with trunk, stem and maid, called trunk, anterior descending branch, gyrus branch, right crown, diagonal branch, interval branch, etc. The scope of blood supply varies with the thickness of each vessel, and the severity of coronary artery disease is different, so we cannot use the same standard, such as 70%, to determine whether it is time to install stents. The thicker the vessel, the greater the extent of its innervation, and even if the stenosis is less than 70%, stenting may be required; if it is a very distal branch vessel with a very small blood supply area, stenting may not be required even if the stenosis is greater than 90%. The 2012 Chinese Guidelines for Percutaneous Coronary Interventions stipulate what kind of stenosis needs to be stented, and hospitals all over the country are following this standard for treatment. Therefore, if the trunk stenosis exceeds 50%, it should be actively treated. 2, anterior descending branch or other important blood vessel stenosis ≥ 70%, with angina symptoms, drug treatment is ineffective, also need to stent treatment. For example, in patients with heart failure with 2 or 3 vessels with different degrees of stenosis, it may be helpful to improve the cardiac function if the vessels are opened up; if it is confirmed that there is large myocardial ischemia, it is also helpful to open up the stenotic vessels to improve the myocardial ischemia. Therefore, from the above regulations, doctors should install stents according to the guidelines, and cannot install as many as they want. As to how much stenosis is needed to install stents, this question should be left to the cardiologist to decide, because the doctor will take into account the medical history, symptoms, degree of stenosis, heart function and other aspects, and it is more important for patients to find a cardiologist they can trust.