PREVENTION OF MYOCARDIAL-INFARCTION AND STROKE BY ASPIRIN - DIFFERENTMECHANISMS - DIFFERENT DOSAGE

More than 50 randomized trials have documented the efficacy and safety of aspirin as an antiplatelet agent and a cardiovascular drug. Howeve r, the optimal dose for preventing coronary and cerebral thrombosis ha s long been a cause of debate, For patients with ischaemic heart disea se the range recommended for the prevention of a secondary event, base d on strong clinical evidence, is 75-160 mg aspirin/day. For patients with cerebrovascular disease, recommendations range from 30-1300 mg/da y, If these patients require a higher dose of aspirin it suggests that a different mechanism of action is involved. This paper considers hyp otheses and reports the findings of recent clinical trials. The SALT s tudy compared aspirin with placebo in 1360 patients with TIA or minor ischaemic stroke. It showed an 18% reduction in the risk of stroke or death in patients receiving 75 mg aspirin/day, Five other trials of 55 ,000 patients with ischaemic cerebrovascular disease compared the prot ective effect of aspirin (range 30-300 mg/day) with placebo, clopidogr el, or oral anticoagulants, Aspirin was better than placebo, safer tha n oral anticoagulants, and no different from clopidogrel, The implicat ions of these findings are discussed. Mechanistic studies and randomiz ed clinical trials strongly suggest that the mechanism of action and d ose requirement of the antithrombotic effect of aspirin in patients wi th cerebrovascular dis ease is the same as that for ischaemic heart di sease, (C) 1998 Elsevier Science Ltd.