Ongoing and Planned Trials of Antiplatelet Therapy in the Acute and Long-Term Management of Patients with Ischaemic Brain Syndromes: Setting a New Standard of Care

Abstract

Among high vascular risk patients, acetylsalicylic acid (ASA) reduces the relative risk of serious vascular events by about one fifth. However, because ASA fails to prevent four fifths of serious vascular events, more effective, yet equally safe and affordable, antiplatelet regimens are desired. Compared with ASA, clopidogrel alone reduces the odds of serious vascular events by about 10%, and the combination of dipyridamole and ASA reduces the odds of serious vascular events by about 6%. Combining ASA with an orally administered platelet glycoprotein (GP) IIb/IIIa blocker is not effective, and indeed more hazardous than ASA alone. Among patients with non-ST-segment acute coronary syndromes (ACS), the addition of an intravenously administered GP IIb/IIIa receptor antagonist to ASA reduces the risk of vascular events by about 10% compared with ASA, and the addition of clopidogrel to ASA reduces the risk of vascular events by 20% compared with ASA alone. Among patients undergoing percutaneous coronary intervention (PCI), both the addition of an intravenously administered GP IIb/IIIa receptor antagonist to ASA, and the addition of clopidogrel to ASA reduce the risk of vascular events by 30% compared with ASA alone. The greater efficacy of the combinations of ASA with clopidogrel, and ASA with an intravenously administered GP IIb/IIIa receptor antagonist, in patients with ACS and those undergoing PCI has fostered several ongoing and planned trials of these regimens in the acute and long-term management of patients with ischaemic brain syndromes. The combination of ASA and clopidogrel is being compared with ASA alone within 12 h of onset of symptoms of TIA in two trials (FASTER, ATARI), and the use of an intravenously administered GP IIb/IIIa receptor antagonist is being compared with placebo within 6 h of onset of acute ischaemic stroke in two trials (AbESST, AbESST-2). Six trials are assessing the combination of clopidogrel and ASA in the long-term management of patients with ischaemic brain syndromes due to atherothrombosis (MATCH, CHARISMA, ARCH, CARESS, SPS3) or atrial fibrillation (ACTIVE). The MATCH trial of clopidogrel and ASA versus clopidogrel alone in patients with recent TIA or ischaemic stroke is the first which is likely to report its results – in mid 2004. The combination of dipyridamole and ASA is being compared with ASA in the ESPRIT trial and with the combination of clopidogrel and ASA in the planned PRoFESS trial. These ongoing and planned clinical trials of antiplatelet therapy promise to further define the role of combination antiplatelet therapy in the acute and long-term management of patients with ischaemic brain syndromes.