Abstract
The measurement of platelet reactivity in patients with stroke undergoing antiplatelet therapies is not commonly performed in clinical practice. We assessed the prevalence of therapy responsiveness in patients with stroke and further investigated differences between patients on prevention therapy at stroke onset and patients naive to antiplatelet medications. We also sought differences in responsiveness between etiological subtypes and correlations between Clopidogrel responsiveness and genetic polymorphisms. A total of 624 stroke patients on antiplatelet therapy were included. Two different groups were identified: "non-naive patients", and "naive patients". Platelet function was measured with multiple electrode aggregometry, and genotyping assays were used to determine CYP2C19 polymorphisms. Aspirin (ASA) responsiveness was significantly more frequent in naive patients compared with non-naive patients (94.9% versus 82.6%, P < .0010). A better responsiveness to ASA compared with Clopidogrel or combination therapy was found in the entire population (P < .0010), in non-naive patients (P < .0253), and in naive patients (P < .0010). Multivariate analysis revealed a strong effect of Clopidogrel as a possible "risk factor" for unresponsiveness (odds ratio 3.652, P < .0001). No difference between etiological subgroups and no correlations between responsiveness and CYP2C19 polymorphisms were found. In our opinion, platelet function testing could be potentially useful in monitoring the biological effect of antiplatelet agents. A substantial proportion of patients with stroke on ASA were "resistant", and the treatment with Clopidogrel was accompanied by even higher rates of unresponsiveness. Longitudinal studies are needed to assess whether aggregometry might supply individualized prognostic information and whether it can be considered a valid tool for future prevention strategies.
Highlights
Control of cerebrovascular risk factors and therapeutic secondary prevention are fundamental to prevent Q7 ischemic cerebrovascular events
(17.4%) among non-naive patients and 10 patients (5.1%). This observational study analyzed 624 consecutive patients with acute ischemic stroke referred to our stroke unit
Two different groups were identified: non-naive patients, including 278 patients who were already treated with antiplatelet therapy at stroke onset (219 patients were treated with ASA, 33 patients with Clopidogrel, and 26 patients with a combination of both [ASA plus Clopidogrel]), and naive patients, including 346 patients who started antiplatelet therapy because of the ischemic event (196 patients started ASA, 89 patients Clopidogrel, and 61 patients ASA plus Clopidogrel)
Summary
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