Inclusion Criteria:  Age of at least 18 years. Diagnosis of acute coronary syndrome. Single intermediate lesion in an intervention-naïve major coronary segment (diameter ≥2.5 mm) determining a 40-70% diameter stenosis at quantitative coronary angiography analysis with no other significant stenosis (>70%) in the same vessel. Patient informed of the nature of the study, agreeing to it, and providing written informed consent as approved by the Ethics Committee of the respective clinical study site. Life expectancy >3 years.  Exclusion criteria:  Female with childbearing potential or lactating. Acute or chronic renal dysfunction (defined as creatinine greater than 2.0 mg/dl). Advanced heart failure (NYHA III-IV) Stroke within the previous 6 months or spontaneous intracranial hemorrhage at any time. Severe valvular disease or valvular disease likely to require surgery or percutaneous valve replacement during the trial. Coronary anatomy preventing complete imaging of the segment of interest (including at least 5 mm at both stenosis edges). Diffusely diseased coronary artery segment or presence of ≥1 significant untreated non-culprit lesions (preventing correct adverse event attribution) in the coronary arteries. Prior myocardial infarction or coronary artery bypass graft [CABG] or PCI revascularization in the target coronary vessel. Coronary anatomy unsuitable for PCI. Comorbidities that might interfere with completion of the study procedures. Planned major surgery necessitating interruption of dual antiplatelet. Participating in another investigational drug or device trial that has not completed the primary endpoint or would interfere with the endpoints of this study.