Intravascular Ultrasound-derived Assessment of Hemodynamically Negative Lesions in NSTEACS Patients

Clinical Inclusion Criteria: 1. Moderate to high risk NSTEACS requiring invasive strategy based on current guidelines and local clinical practice. 2. Patient agrees and is able to follow all protocol procedures. Clinical Exclusion Criteria: 1. STEMI or SCAD. 2. Hemodynamic instability (e.g. cardiogenic shock, refractory ventricular arrhythmias, acute and severe conduction system disease and left ventricular ejection fraction ≤30%). 3. Contraindication for FFR, PCI, IVUS and OMT (e.g. severe allergy to antiplatelet drug or contrast, significant bleed within the past 6 months, bleeding diathesis and serum creatinine ≥2.5 mg/dl). 4. PCI within 6 months or any prior CABG. 5. Anticipated life expectancy \<3 year. 6. Pregnancy 7. Unwilling or unable to provide informed consent Imaging Inclusion Criteria 1. Patients must have at least \> 1 de novo lesion in a native coronary segment with a visually estimated diameter stenosis of between 40 and 90 %. 2. Successful FFR-guided PCI performed in all major epicardial coronary arteries (including their branches): PCI for all lesions a) with 40%-90% diameter stenosis and FFR\<0.8 and b) with ≥90% diameter stenosis. 3. The FFR-negative lesions must be available for assessment of IVUS. Imaging Exclusion Criteria: 1. Target lesion reference diameter \<2.0 mm. 2. Anatomic conditions precluding FFR and IVUS (e.g. marked calcification or tortuosity, chronic total occlusion or thrombus). 3. After successful FFR-guided PCI, no FNL is left. 4. Any remaining lesion with diameter stenosis ≥90% or FFR\<0.8 after PCI. 5. Left main coronary artery lesion. 6. CABG planned by the investigators according to extent and severity of coronary artery disease.