Although percutaneous coronary interventions (PCIs) are an established therapeutic approach in patients presenting with acute coronary syndrome (ACS), it is still unclear which the best antithrombotic therapy to be applied periprocedurally is. The EPISTENT trial has shown that adding abciximab (a glycoprotein [GP] IIb/IIIa receptor inhibitor) to the therapy with ticlopidine plus aspirin significantly reduces the incidence of ischemic complications (death, myocardial infarction or reinterventions) after coronary stent implantation. Ticlopidine also reduces procedural complications but has a delayed onset of action after coronary stenting and has been replaced by clopidogrel, which provides similar efficacy and is associated with fewer side effects. Experimental studies have shown that a 600 mg loading dose of clopidogrel is safe and acts rapidly leading to a maximal inhibition of platelet aggregation within 2 hours after administration. In the ISAR-REACT trial, a 600 mg loading dose of clopidogrel was well tolerated, and associated with such a low frequency of early complications that the use of abciximab offered no clinically measurable benefit at 30 days. Although patients with ACS have frequently been treated with a "cooling-off" strategy for >48 hours before undergoing PCI, the ISAR-COOL trial demonstrated that patients undergoing PCI within 6-12 hours of presentation with an ACS actually suffer a lower rate of ischemic complications than those for whom an invasive approach is delayed. However, patients with ACS represent a higher risk subset and may need a more potent antithrombotic regimen periprocedurally. Therefore, the results of ISAR REACT, which was performed in low and intermediate risk patients, should not be generalized to high risk patients.