[Antithrombotic drugs in the prevention of ischemic stroke]

Stroke prevention cannot be dissociated from cardiovascular prevention in general. It is based on the correction of vascular risk factors, particularly hypertension and tobacco smoking, and on antithrombotic drugs which tackle the thrombo-embolic process which is the immediate cause of the ischemic event. Ischemic strokes exhibit considerable etiopathogenic diversity, the underlying cause modifying thrombus composition. In atherothrombotic brain infarction, platelets play a major role and antiplatelet drugs have a benefit/risk ratio better than that of oral anticoagulants, with a 25% reduction in the combined risk of ischemic stroke, myocardial infarction and vascular death. Antiplatelet drugs are also used in small artery diseases of the brain although the role of thrombosis is unknown and no specific trial has been devoted to this variety of cerebrovascular disease. In emboligenic cardiac diseases, atrial fibrillation in particular, stasis of the dilated left atrium favors coagulation phenomena, hence the much better efficacy of oral anticoagulants (presently vitamin K antagonists) both in primary and secondary prevention with a 70% risk reduction in cerebral infarction, compared with only 20% for aspirin. The expected benefit of antithrombotic drugs must be weighed against their inherent hemorrhagic risk, which is greatest for oral anticoagulants, slightly less for association of antiplatelet drugs and even less for each antiplatelet drug given alone. The use of antithrombotic drugs allows a targeted prevention of cerebral infarction. It is based on a triple case by case evaluation: that of the cause and of the risk it carries, that of the benefit expected from antithrombotic drugs, and that of their inherent hemorrhagic risk.