Intracoronary stent implantation is to solve the lack of blood supply due to severe stenosis of coronary arteries. The indications are as follows: 1. Severe stenosis, i.e. stenosis more than 75%; 2. Stable condition but stenosis more than 90%; 3. Patient’s blood vessel has plaque breakage and acute infarction or thrombosis. Whether the stenosis can be diagnosed by coronary angiography, intravascular ultrasound, optical imaging, pressure guidewire, etc., and whether it is suitable for stent implantation should be clarified by examination in a tertiary hospital.