The coronary angiography-derived index of microcirculatory resistance (caIMR) can be used to provide a binary assessment whether patients（with stable angina, unstable angina, suspected myocardial ischemia, or coronary artery stenosis of less than 50%, and without cardiomyopathy or obstructive epicardial coronary artery disease） have microcirculatory dysfunction, using a cutoff value of 25.

This study aims to evaluate the binary classification performance of caIMR in two specific groups of patients: (1) those with caIMR values between 20 and 30, and (2) those with diffuse disease. We will do this by looking at differences in their Seattle Angina Questionnaire (SAQ) scores and their health outcomes over a three-year period.

The coronary angiography-derived index of microcirculatory resistance (caIMR) is a novel, non-invasive, imaging-based functional index for diagnosing coronary microvascular disease, which has been clinically validated for market release. It can be used to provide a binary assessment of whether patients with stable angina, unstable angina, suspected myocardial ischemia, or coronary artery stenosis of less than 50% (without cardiomyopathy or obstructive epicardial coronary artery disease) have microcirculatory dysfunction, using a cutoff value of 25.

This trial is a prospective, multicenter, observational real-world study. We will regularly collect clinical diagnostic data (including angiographic images) patients who undergo caIMR measurement using the Coronary Artery Functional Measurement System and single-use pressure sensors as part of their routine medical care. After verifying the inclusion and exclusion criteria, patients who meet the inclusion criteria and do not meet the exclusion criteria will be enrolled in this trial.

The primary objective of this trial is to evaluate the binary classification performance of caIMR by comparing patients' Seattle Angina Questionnaire (SAQ) scores before the procedure and at six months post-procedure in two specific groups of patients: :

1. Assessing the binary classification performance of caIMR in patients with values between 20 and 30.
2. Assessing the binary classification performance of caIMR in patients with diffuse disease.

The secondary objective is to validate the prognostic value of caIMR in these two groups of patients based on the occurrence of major adverse cardiovascular events (MACE) over a three-year period.

Inclusion Criteria:

1. Age between 18 and 80 years, regardless of gender;
2. Diagnosed with stable angina, unstable angina, or suspected myocardial ischemia;
3. targeted vessel stenosis < 50% and caIMR values between 20 and 30; or

(3) Targeted vessel stenosis < 50%, but with lesion length > 20 mm and caFFR > 0.8, representing diffuse disease.

Exclusion Criteria:

1. Previously undergone percutaneous coronary intervention (PCI);
2. History of heart failure or myocardial infarction;
3. Acute myocardial infarction;
4. Primary or secondary cardiomyopathy;
5. Primary or secondary severe valvular heart disease;
6. Severe systemic infections;
7. Malignant cachectic diseases and an estimated survival of less than one year;
8. Patients who are currently participating in other clinical trials involving drugs or devices and have not yet reached the primary endpoint of those trials;
9. Patients whom the investigator deems to have other conditions that make them unsuitable for participation in the clinical trial.

This study will enroll patients with stable angina, unstable angina, suspected myocardial ischemia, or coronary artery stenosis of less than 50%, who do not have cardiomyopathy or obstructive epicardial coronary artery disease. Specifically, we will focus on two groups: (1) patients with caIMR values between 20 and 30, and (2) patients with diffuse disease.