Piracetam versus acetylsalicylic acid in secondary stroke prophylaxis. A double-blind, randomized, parallel group, 2 year follow-up study

Piracetam has been shown to inhibit platelet aggregation. Therefore, we per formed a double-blind, randomized, parallel group study to compare the effi cacy of daily 1600 mg piracetam t.i.d. vs. 200 mg acetylsalicylic acid (ASA ) t.i.d. in secondary stroke prophylaxis. 563 patients after stroke as conf irmed by computed tomography (CT) or magnetic resonance imaging (MRI) were enrolled and received either piracetam or ASA during a 2 year follow-up per iod. The primary endpoint was the rate of stroke, transient ischaemic attac k (TIA), or death from vascular cause. The secondary endpoint was the rate of adverse events leading to a premature discontinuation of the study medic ation. Patients were visited at home every 3 months and were examined in ho spital after 1 and 2 years. At every visit, the platelet function was evalu ated. No significant difference and no significant equivalence could be sho wn for the primary endpoint between the piracetam and the ASA group both in the intention-to-treat and in the per-protocol analysis. However, there wa s a not significant trend in favor of ASA (11.7 vs. 15.2%). After excluding those patients who did not respond to antiplatelet medication in vitro, ho wever, piracetam and ASA were equivalent in secondary stroke prophylaxis (s troke, TIA, or vascular death 10.1% in the piracetam group vs. 9.7% in the ASA group) Piracetam was significantly superior to ASA in the secondary end point (P = 0.0039). The data suggest that the overall efficacy of piracetam in secondary stroke prophylaxis is not as good as that of ASA but that pir acetam is better tolerated. However, our data furthermore show that nonresp onders to pharmacological inhibition of platelet function are more frequent under piracetam therapy and that they may influence the results of large s tudies: on secondary prophylaxis in vascular diseases. (C) 2000 Elsevier Sc ience B.V. All rights reserved.