Clopidogrel resistance in cerebrovascular disease – results of one-year follow-up

INTRODUCTION: In an earlier study the authors reported short-term benefits of clopidogrel treatment in patients with cerebrovascular disease. AIM: The aim of the authors was to analyze findings during a 12-month follow-up period. METHOD: 100 patients with a history of acute stroke or transient ischaemic attack have been included in the study. The efficacy of the therapy was assessed 7 and 28 days as well as 3, 6 and 12 months after initiation of medical therapy. Patients were divided into two parts (clopidogrel responder and resistant) based on their initial laboratory findings. Risk profiles, medical therapy, laboratory parameters and vascular events were compared between the two patient groups. RESULTS: After 7 days of treatment, clopidogrel seemed to be ineffective in 11 patients (11%). Strong, clinically significant correlations were found among blood pressure values, blood glucose and lipid parameters, serum C-reactive protein levels and platelet aggregation levels. An aggressive secondary preventive therapy resulted in a decrease of clopidogrel resistance and improvement in laboratory parameters. Patients who were clopidogrel resistant at baseline had significantly higher rate of vascular events compared to those who were clopidogrel responders (18.1 vs. 4.5%, p<0.01), although clopidogrel resistance was not an independent risk factor of unfavourable vascular outcome using a multivariate analysis. No adverse events or hemorrhagic complications were observed. CONCLUSIONS: Clopidogrel resistance and unfavourable outcome seems to be associated with "classical" risk factors underlying the importance of aggressive secondary prevention.