This study is a multicenter prospective observational clinical study, which will be conducted in 11 hospitals, and approximately 500 subjects will be enrolled. Plaque morphology and stability of non-culprit lesions were assessed by intravascular ultrasound (IVUS) and optical coherence tomography-near-infrared spectroscopy (OCT) after percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS). Plaques were grouped according to high-risk or non-high-risk. Clinical follow-up was conducted after PCI.

Plaque stability is an important criterion for selecting different treatment strategies (interventional and antithrombotic). High-risk plaque characteristics are also considered to be related to the overall incidence of Major Adverse Cardiovascular Events (MACE). Single-modality intravascular imaging has inherent disadvantages in identifying atherosclerotic plaques, while the combination of IVUS, OCT, and NIRS enables multimodal intravascular imaging techniques to complement each other in obtaining plaque information. There is currently a lack of research on the prognostic benefits of multimodal intravascular imaging in assessing atherosclerotic plaques. This study is a multicenter, prospective, observational clinical study that will be conducted at 11 hospitals, enrolling approximately 500 subjects. It will use intravascular ultrasound (IVUS) and optical coherence tomography-near-infrared spectroscopy (OCT) to assess the morphology and stability of non-culprit lesions in patients with acute coronary syndrome (ACS) after percutaneous coronary intervention (PCI), and will follow up at 1 month, 1 year, 2 years, and 5 years post-surgery. The aim is to compare the clinical outcomes between high-risk and non-high-risk patients, as well as between high-risk and non-high-risk plaques defined by multimodal intravascular imaging, and to explore the predictive value of high-risk plaque characteristics shown by multimodal intravascular imaging for adverse cardiovascular events in patients with ACS.

Inclusion Criteria:

• Inclusion criteria for the clinical study:

  1. Aged ≥18 years at enrollment, male or female;
  2. Meets the diagnosis of acute coronary syndrome, including acute myocardial infarction and unstable angina. Acute myocardial infarction includes ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (non-STEMI). STEMI is defined as chest pain lasting at least 30 minutes, arriving at the hospital within 12 hours from the onset of symptoms, changes in the 12-lead ECG (ST-segment elevation >0.1 mV in ≥2 consecutive leads or new left bundle branch block), and elevated cardiac biomarkers (troponin T/I). Non-STEMI is defined as ischemic symptoms without ST-segment elevation on ECG, accompanied by elevated cardiac biomarkers. Unstable angina is defined as chest pain lasting 5-30 minutes at rest, or worsening of exertional angina, and accompanied by one of the following: transient ST-segment depression or elevation; coronary angiography showing luminal narrowing ≥90% or plaque rupture or thrombotic lesions.
  3. Planned to undergo coronary angiography and PCI treatment;
  4. Hemodynamically stable and able to tolerate repeated intracoronary administration of nitroglycerin;
  5. Capable of understanding the requirements of this study, willing to participate in the study, and have signed an informed consent form.

• Imaging inclusion criteria:

  1. Coronary angiography clearly shows that the patient has at least one non-culprit lesion with a visual assessment of diameter stenosis between 40-70%, and the operator believes that interventional treatment intervention is not temporarily necessary;
  2. The site of the non-culprit lesion has not previously had a stent implanted.

Exclusion Criteria:

• Exclusion criteria for the clinical study:

  1. Cardiogenic shock or hemodynamic instability;
  2. History of coronary artery bypass grafting (CABG), or planned CABG;
  3. Severe renal impairment (glomerular filtration rate <30ml/min/1.73m²);
  4. Life expectancy of less than 2 years;
  5. Currently participating in other ongoing investigative device or drug studies that have not yet reached their primary endpoints.

• Imaging exclusion criteria:

The anatomical structure of the non-culprit lesion is not suitable for intravascular imaging catheter imaging (lesions at the left main trunk or right coronary artery ostium, severe calcification, chronic total occlusion, etc.).

Patients with Acute Coronary Syndrome (ACS) who are planned for coronary angiography and interventional treatment. ACS includes acute ST-segment elevation myocardial infarction, acute non-ST-segment elevation myocardial infarction, and unstable angina.