Coronary artery stenosis is clinically classified into four levels: 1.Grade Ⅰ: the degree of coronary artery stenosis is <25%, which is relatively mild coronary artery stenosis and can be treated with medication; 2.Grade Ⅱ: the degree of coronary artery stenosis is 26%-50%, which is relatively mild coronary artery stenosis and can be treated with medication; 3.Grade Ⅲ: the degree of coronary artery stenosis is 51%-70%, which is moderate coronary artery stenosis and some patients Some patients need drug treatment together with coronary stent implantation and coronary artery bypass grafting; 4.Grade IV: the degree of coronary artery stenosis is above 70%, which is severe coronary artery stenosis and needs drug treatment together with coronary artery stent implantation and coronary artery bypass grafting.