Clinical Study on the Correlation Between IMR（Index of Microcirculation Resistance） and FFR（Fractional Flow Reserve）

Inclusion Criteria:(1) Age: 18-75 years old, unlimited for men and women; (2) Quantitative coronary angiography (QCA) showed that there was a critical lesion in the proximal or middle segment of the coronary artery (diameter stenosis rate was 50% - 70%), and the diameter of the artery was more than 2.5mm; (3) Agree to participate in the study and sign informed consent \- Exclusion Criteria:(1) Patients with acute myocardial infarction within one month; (2) Patients with congenital heart disease, severe valve disease, dilated cardiomyopathy, pulmonary heart disease and hypertrophic cardiomyopathy; (3) With severe heart failure (NYHA cardiac function grade ≥ grade III or left ventricular ejection fraction \< 35%); (4) Patients with less than 1 year of stent implantation or with coronary artery bypass grafting; (5) Patients with left main lesion, severe distorted calcification, open lesion, bifurcated lesion or complete occlusion; (6) Patients with severe hepatorenal insufficiency; (7) Contraindications to adenosine, aspirin and clopidogrel; (8) Patients with advanced tumor or life expectancy less than 1 year; (9) Patients with severe asthma or uncontrolled asthma; (10) Women in pregnancy. \-