Antithrombotic therapy following cerebral ischaemia

Following cerebral ischaemia a recurrent stroke must be avoided in most patients by means of antithrombotic agents. Based on the results reviewed here of new therapy studies, we discuss the presently available antithrombotic treatment options for prophylaxis in ischaemic stroke. TASS (Ticlopidine Aspirin Stroke Study) and CATS (Canadian American Ticlopidine Study) are two multicentre studies investigating the effect of ticlopidine, a new antiplatelet agent of the thienopyridine family, compared to acetylsalicylic acid (ASA) respectively placebo, in the secondary prophylaxis of ischaemic stroke. A significant relative risk reduction of ticlopidine against ASA (21%) and against placebo (28.1%) was shown. CAPRIE (Clopidogrel vs. Aspirin in Patients with Risk of Ischemic Events) evaluated clopidogrel and ASA in the secondary prophylaxe of stroke, myocardial infarction and peripheral vascular occlusive disease. Clopidogrel has been shown to be as effective as ticlopidine compared to ASA in the secondary prevention of vascular disease but had the advantage of a far less severe side effect profile as ticlopidine. ESPS 2 (2(nd) European Stroke Prevention Study) compared dipyridamole and ASA alone and in combination against placebo in stroke prevention. The combination of agents showed a 24.4% relative risk reduction to suffer ischaemic stroke as opposed to placebo. The ranking of heparin and heparinoids in the secondary prevention of ischaemic stroke has not been completely established but seems to diminish according to recently published data from three major trials. The American TOAST study (Trial of Org 10172 in Acute Stroke Treatment) failed to prove any advantage of intravenous Orgaran compared to placebo. In IST (International Stroke Trial) and CAST (Chinese Acute Stroke Trial) the benefits of heparin are invalidated by a higher bleeding rate of patients on intravenous heparin therapy. Furthermore, the results of IST have to be judged critically because of significant methodical inadequacies. When applying antithrombotic agents, therapeutic effect and presumed better outcome should be weighed against the risk of associated bleedings. The indication for an antithrombotic treatment should be reevaluated in regular control examinations and the possibility of a less aggressive treatment should be considered.