[Inhibition of platelet aggregation for the secondary prevention after ACS: when clopidogrel instead of ASA, when clopidogrel and ASA?].

Long-term inhibition of platelet aggregation is essential for the secondary prevention after acute coronary syndromes (ACS). Inhibition of platelet aggregation with acetylsalicylic acid (ASA) has been established as a safe and effective therapy in this indication already end of the eighties in the preceding century. A decade later, with the introduction of the thieno-pyridines, combined platelet aggregation inhibition became possible. This opened the door for new treatment strategies in interventional cardiology. The first substance, ticlopidine was more or less replaced by the newer substance clopidogrel, which has improved pharmacological properties and less side effects. Low dose ASA (75 mg/d) is still regarded as the standard therapy for secondary prevention after ACS. However, large clinical trials established clopidogrel as at least as effective and safe as ASA in this indication. Following PCI with bare metal stent implantation, a combined therapy of ASA and clopidogrel should be given for at least 4 weeks. After ACS with non-ST-elevation myocardial infarction the combined therapy with ASA and clopidogrel gives a better outcome than ASA alone. Recently published clinical trials show superiority of this strategy in patients with ST-elevation myocardial infarction, too. If a combined long-term platelet aggregation inhibition with ASA and clopidogrel will be safe and more effective for secondary prevention is discussed.