Prise en charge pharmacologique (antiagrégants, anticoagulants) du syndrome coronarien aigu

During acute coronary syndromes (ACS), the role of platelet aggregation developing closely to a ruptured vulnerable atheroma plaque is the primary trigger promoting the formation of an occlusive thrombus during ST-segment elevation ACS (myocardial infarction), sometimes non-occlusive with distal emboli in the coronary bed (explaining troponin elevation) in non ST-segment elevation ACS (unstable angina). Aspirin and clopidogrel are mandatory during the acute phase. Indications of GP IIb/IIIa inhibitors have been restricted with the concomitant use of loading doses of clopidogrel in non ST-segment elevation ACS, these molecules are more readily introduced during high risk coronary angioplasty. During ST-segment elevation ACS, the GP IIb/IIIa inhibitors associated with heparin compete with bivalirudin alone (reduction of bleeding complications), but pre-hospital administration of bivalirudin has not yet been validated. Regarding anticoagulants, unfractionated heparin (UFH) has been replaced by low molecular weight heparins, then by fondaparinux in non ST-segment elevation ACS. In combination with fibrinolysis during ST-segment elevation ACS, enoxaparin has been validated, UFH may be a safer choice in elderly patients with poor renal function. In case of primary angioplasty, enoxaparin is currently evaluated in comparison with UFH. The development of new antiplatelet and anticoagulant agents will probably lead to some therapeutic changes in the near future. We must keep in mind that by increasing the efficacy of antithrombotic drugs, we most often also increase the hemorrhagic risk. We have to evaluate carefully for each new drug, each new strategy, the benefit/risk ratio.