Does OCT Optimise Results of Stenting on the Left Main Stem

Inclusion Criteria: Patients aged 18 years or over presenting with: * NSTEMI or unstable angina or stable angina or documented silent ischemia AND * De novo angiographic lesion (% diameter stenosis \>=50%) or functionally significant (FFR\<=0.80) lesion of the left main stem (median or distal) with or without lesions of the ostia of the LAD and/or circumflex arteries (= Medina classification 1-0-0, 1-0-1, 1-1-0, 1-1-1) or ostial lesion of the LAD and/or circumflex artery requiring angioplasty with stent implantation that will cover the distal left main stem (=Medina classification 0-0-1, 0-1-0 ou 0-1-1) AND * SYNTAX score ≤ 22 (or \>22 and ≤32 and validated by the Heart Team) * Lesion with reference angiographic diameter \<=5.5mm * Signature of written informed consent form. Exclusion Criteria: Patients with: * ST segment elevation myocardial infarction * Ostial lesion of the left main stem * Technically impossible to perform OCT * Creatinine clearance ≤ 30 ml/min/1.73m² * Left ventricular ejection fraction \<30% * Hypotension or cardiogenic shock * Unstable ventricular arrhythmia * Contraindication to dual antiplatelet therapy for at least 6 (or 12) months (duration depending on the initial clinical presentation). Shorter dual antiplatelet therapy is possible in patients with long-term anticoagulation. * Hypersensitivity or contraindication to any of the antithrombotic therapies used during or after the procedure * Life expectancy \<1 year * Persons under judicial protection * Subjects with no social security coverage * Anticipated non-compliance with the study procedures * Pregnant or lactating women * Subjects within the exclusion period of another clinical trial * Failure to provide written informed consent