Objective to evaluate the effect of Shexiang Baoxin Pill on myocardial ischemia in patients with coronary microvascular dysfunction (non obstructive coronary heart disease) through a randomized, double-blind, placebo-controlled clinical multicenter study.At the same time, the effects of exercise tolerance and quality of life were also observed.

Inclusion Criteria:

1. Patients aged 18-80, male or female;
2. Selective coronary angiography or coronary CTA showed that the diameter of coronary artery ≥ 2.5mm, the degree of stenosis < 50%, without myocardial bridge;
3. They were able to perform treadmill exercise, and the treadmill test (EET) was positive;
4. Angina pectoris was found;
5. Patients are willing to follow up and sign informed consent; All the above criteria should be met.

Exclusion Criteria:

1. Coronary heart disease complicated with hypertrophic cardiomyopathy;
2. There was a history of AMI, PCI and CABG, and myocardial bridge was found by angiography or CTA;
3. Patients with severe medical diseases (liver, kidney, hematopoietic system and other serious primary diseases, etc.);
4. Mental disorders and mental diseases;
5. Patients with pulmonary failure and NYHA heart function grade III-IV, unable to carry out exercise test;
6. Contraindications of Shexiang Baoxin Pill: forbidden for pregnant women;
7. Those who have known history of allergy to Shexiang Baoxin Pills;
8. Recently, the patient has taken Shexiang Baoxin Pill and other anti ischemic traditional Chinese medicine regularly, or it contains borneol, toad venom and other ingredients in Shexiang Baoxin Pill;
9. Combined with frequent ventricular premature beats, ventricular tachycardia, atrial fibrillation, sinoatrial block, atrioventricular pathway block, left bundle branch block and right bundle branch block, which may affect the judgment of exercise ECG results;
10. Researchers think that there are other factors that are not suitable to participate in the trial; If one of the exclusion criteria is met, it can be excluded.