Resistance to aspirin in secondary stroke prevention. A pilot study

INTRODUCTION: The purpose of the study was to establish the frequency of aspirin resistance in patients treated in the Department of Neurology in Zabrze with diagnosed transient ischaemic attack (TIA) or ischaemic stroke who used aspirin in the dose of 150 mg daily. MATERIAL AND METHODS: We examined 20 patients (14 female, 6 male), the mean age 66.8 +/- 11.1. The assessment of platelets' function was performed by Platelet Function Analyzer-100 (PFA-100) and optical aggregometry by Born. The examinations were done three times: in the acute phase, after 6 +/- 1 months and after 12 +/- 1 months. RESULTS: In the successive exams by PFA-100 following frequencies of aspirin resistance were observed: 0% (I), 37.5% (II), 23% (III). We found no correlation between results obtained by PFA-100 and optical aggregometry. Also no correlation was observed between aspirin resistance and age, sex, degree of motor incapability, total cholesterol, LDL, HDL, triglycerides and other drugs. CONCLUSIONS: Some patients treated with aspirin develop aspirin resistance. Sometimes the increase of aspirin dose results in antiplatelet state again. No consistency between results of both applied methods could be a consequence of heterogenity of the phenomenon of aspirin resistace, and indicates that laboratory method should carefully be chosen in purpose to monitoring antiplatelet therapy in prevention of vascular diseases. This was a pilot study and it will be continued in purpose to increase the examined group and prolong time of observation.