This study is a prospective, single-center, randomized controlled clinical trial. Ninety patients with anterior wall ST-segment elevation myocardial infarction (STEMI) who are planned for primary percutaneous coronary intervention (PCI) within 6 hours of symptom onset will be screened. Patients with inclusion criteria and without exclusion criteria will be randomized into three groups in a 1:1:1 ratio: OCT-guided group, 60 MHz HD-IVUS-guided group, and angiography-guided group after signing the informed consent form.

Based on the lesion characteristics detected by imaging in each group, coronary revascularization will be performed for the culprit vessels of myocardial infarction. The TIMI myocardial perfusion frame count (TMPFC) values of the culprit vessels will be recorded immediately after PCI, and secondary prevention medications for myocardial infarction will be administered. Three days after the procedure, a 3.0T cardiac magnetic resonance imaging (MRI) with gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) delayed enhancement (LEG) scan will be conducted to assess the microvascular obstruction (MVO) area.

Patients will be followed in the outpatient clinic visit at 1 month (with a window period of XX days) after discharge, and a repeat cardiac MRI will be performed to determine the presence of MVO and the size of the myocardial infarction.

Inclusion Criteria:

Clinical Inclusion Criteria:

1. Subjects aged ≥18 years;
2. Initial diagnosis of anterior wall ST-segment elevation myocardial infarction, with symptoms occurring within 6 hours, and undergoing primarypercutaneous coronary intervention (PCI);
3. Subjects (or legal representatives) who understand the study requirements and treatment procedures and provide signed informed consent.

Imaging Inclusion Criteria (Visual Estimation):

1. Target lesion is the culprit lesion, located in the native coronary artery, with a visually estimated reference vessel diameter (RVD) between 2.25 mm and 4.0 mm;
2. Culprit segment of the infarct-related artery (IRA) is located between the origin of the left anterior descending (LAD) artery and the emergence of the second diagonal branch (D2);
3. After pre-treatment , the degree of stenosis in the LAD is ≤90%, and TIMI flow is grade 3.

Exclusion Criteria:

Clinical Exclusion Criteria:

1. History of coronary artery bypass grafting (CABG);
2. Known history of myocardial infarction or PCI;
3. Previous thrombolytic therapy before PCI;
4. Severe liver or kidney dysfunction, severe valvular heart disease, chronic obstructive pulmonary disease, etc.;
5. Contraindications to magnetic resonance imaging;
6. Allergy to gadolinium contrast agents and/or accompanying medications for devices or procedures (e.g., any component of drug-eluting stents, all P2Y12 inhibitors, or aspirin);
7. Expected lifespan of the subject less than 12 months;
8. Pregnant or lactating females;
9. Other subjects deemed unsuitable for participation in the study by the investigator.

Imaging Exclusion Criteria (Visual Estimation):

1. Presence of lesions requiring intervention other than the target lesion at baseline surgery;
2. No protected left main coronary artery disease (visual estimate of stenosis >50%);
3. Diffuse severe calcification (>20 mm) or chronic total occlusion in the major coronary vessels (LCX, RCA);
4. Severe coronary artery tortuosity (>45°) or calcification (>270°), or other conditions that may interfere with the use of intravascular imaging.