For Patients With Myocardial Infarction and Multiple Vessel: Testing if Ultrasound (UFR) Can Guide All Needed Treatment in One Procedure, Avoiding a Return Hospital Visit for a Second Operation.

Prior treatment

• Prior history of Coronary Artery Bypass Grafting (CABG) surgery.The target NCV has received prior PCI (e.g., existing stent) or surgical revascularization.
• Standard contraindications to CMR examination (e.g., claustrophobia, non-MRI-compatible metallic implants/pacemakers).
• Currently participating in another interventional (drug or device) clinical study.

Other illness

• Known severe allergy to iodinated contrast media or gadolinium-based contrast agents (used for CMR).
• Female participants who are pregnant, breastfeeding, or planning pregnancy within the 1-year study period.Unprotected left main coronary artery disease (stenosis \<50%) requiring intervention.
• Known presence of a severe non-cardiac comorbidity with an expected lifespan of \< 12 months (e.g., advanced malignancy).
• Known severe hematological disease (e.g., severe anemia, active bleeding, thrombocytopenia \< 70 x 10⁹/L) rendering the participant unsuitable for multiple invasive procedures.
• Inability to provide informed consent or comply with the complex longitudinal follow-up protocol due to psychiatric, cognitive, or other reasons.
• Any other condition which, in the investigator's opinion, makes the participant unsuitable for enrollment (e.g., severe valvular heart disease, cardiomyopathy).

Lab values

• Severe renal insufficiency (eGFR \< 30 ml/min/1.73m²) or currently undergoing chronic dialysis.

Other

• Presence of cardiogenic shock on presentation, or persistent hemodynamic instability despite successful PCI of the culprit vessel.
• The target NCV is a Chronic Total Occlusion (CTO).

• Age \>18 years, any sex.
• The participant is able to understand the study procedures and provides voluntary written informed consent.
• Diagnosed with Acute Coronary Syndrome (ACS) and meets the criteria for one of the two pre-specified cohorts:
• STEMI Cohort: Symptom onset \< 12 hours with ECG findings of ST-segment elevation myocardial infarction.
• High-Risk NSTEMI Cohort: Meets at least one of the following: GRACE score \> 140, dynamic ECG changes (ST-T), or significant Troponin elevation.
• Has undergone successful emergency PCI of the Culprit Vessel (CV), with post-PCI TIMI flow Grade 3.
• Coronary angiography confirms Multi-vessel Disease (MVD), defined as: at least one Non-Culprit Vessel (NCV) with a moderate stenosis (visual diameter stenosis 50-90%).
• The target NCV (50-90% stenosis) is deemed by the investigator to be anatomically suitable for IVUS and pressure-wire assessment.
• The participant agrees and is confirmed to be willing and able to strictly adhere to the protocol and complete all required invasive procedures, CMR scans, and follow-ups at the four timepoints (T0, T-CMR, T1, T2).