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 duringhospital stay for ACS (oral swab kit with result within 1 hour)

• Treated with aspirin and ticagrelor, or aspirin and prasugrel at the screening phaseand at the randomization visit.

• High bleeding risk as defined by the Consensus Document From the Academic ResearchConsortium for High Bleeding Risk (at least one criterion) :

• Age ≥75 years old.

• Baseline haemoglobin <11 g/dl (or anaemia requiring transfusion during the 4weeks 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 beassociated with increased bleeding risk such as platelet dysfunction, vonWillebrand disease (prevalence of 1%-2% in the general population), inheritedor acquired clotting factor deficiencies (including factors VII, VIII [hemophilia A], IX [hemophilia B], and XI), or acquired antibodies to clottingfactors, 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) orsteroids for ≥30 days after PCI.

• patient affiliated to a social security system

• signed informed consent form

• For women of childbearing potential, an effective contraception method must be usedup to the visit V3

Exclusion Criteria:

• Enrolled in another clinical trial except non interventional studies

• Any prior documented intracerebral bleed

• Contra-indication, known allergy or expected interactions with clopidogrel. Baselinetreatment (at screening) should not include an antiplatelet therapy for which acontra-indication, known allergy or expected interactions is known (example historyof stroke and use of prasugrel, or concomitant use of ticagrelor and ritonavir)

• Patients on concomitant treatment with an anticoagulant agent (Vitamin-K antagonistsor 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