Assessment of an Early De-Escalation to a Low-potency Single Antiplatelet Therapy Guided by Genetics Versus a Systematic High-Potency Single Antiplatelet Therapy to Neutralize Bleeding Complications in Patients With High Bleeding Risk Beyond One Month After an Acute Coronary Syndrome

Inclusion Criteria: * Being 18-year-old or older * Admission for type 1 acute myocardial infarction (STEMI or NSTEMI) * Bedside genetic testing for clopidogrel resistance that can be performed during hospital stay for ACS (oral swab kit with result within 1 hour) * Treated with aspirin and ticagrelor, or aspirin and prasugrel at the screening phase and at the randomization visit. * High bleeding risk as defined below (criteria adapted from the Consensus Document From the Academic Research Consortium for High Bleeding Risk) (at least one criterion) : * Age ≥75 years old. * Baseline haemoglobin \<11 g/dl (or anaemia requiring transfusion during the 4 weeks prior to randomization). * Chronic Kidney Disease with estimated glomerular filtration rate ≤ 30 ml/min. * Thrombocytopenia with platelet count \< 100 x 109 / L * Chronic bleeding diatheses: inherited or acquired conditions known to be associated with increased bleeding risk such as platelet dysfunction, von Willebrand disease (prevalence of 1%-2% in the general population), inherited or acquired clotting factor deficiencies (including factors VII, VIII \[hemophilia A\], IX \[hemophilia B\], and XI), or acquired antibodies to clotting factors, among others. * Cirrhosis with portal hypertension. * PCI after major traumatism or surgery. * Any documented stroke in the last 12 months. * Hospital admission for bleeding or transfusion within last 6 months. * Nonskin cancer diagnosed or treated ≤3 years. * Planned daily nonsteroidal anti-inflammatory drugs (other than aspirin) or steroids for ≥30 days after PCI. * patient affiliated to a social security system * signed informed consent form * Women of childbearing capacity with effective contraception for the duration of the research OR man, OR woman not of childbearing capacity Exclusion Criteria: * Currently participating in any interventional investigational device or drug trial * Any prior documented intracerebral bleed * Contra-indication, known allergy or expected interactions with clopidogrel. Baseline treatment (at screening) should not include an antiplatelet therapy for which a contra-indication, known allergy or expected interactions is known (example history of stroke and use of prasugrel, or concomitant use of ticagrelor and ritonavir) * Patients on concomitant treatment with an anticoagulant agent (Vitamin-K antagonists or novel oral anticoagulants such as rivaroxaban, dabigatran or apixaban) * Planned surgery within 12 coming months * Patient under guardianship or curatorship * Pregnancy or breastfeeding * Inability to sign the informed consent form