Clopidogrel Resistance in Acute Ischemic Stroke

Jeon, Sung Man; Cha, Jae Kwan; Kim, Sang Ho; Kim, Jae Woo

Abstract

BACKGROUND: Clopidogrel has been widely used in the treatment of acute atherothrombosis. However, until now, there has been little information about its resistance during the acute stage of ischemic stroke. In this study, we investigated platelet responsiveness after using clopidogrel in acute ischemic stroke.
METHODS
ADP (10 uM) induced platelet aggregation was serially measured in 81 acute ischemic stroke patients at initial, after 24 hrs and 5 days since using clopidogrel. We defined Clopidogrel resistance as less than 30% decrease in platelet aggregation by clopidogrel and investigated the differences of clinical and laboratory findings between the Clopidogrel response and resistance groups.
RESULTS
The baseline ADP induced platelet aggregation was 10.2+/-5.5 ohm and was significantly (p<0.05) reduced to 4.0+/-4.5 ohm after the use of Clopidogrel. After 5 days of treatment, the clopidogrel resistance was observed in 18.5% of patients. Of the 15 patients with clopidogrel resistance, 12 patients (80%) had large artery atherosclerotic infarctions, 2 others had an unknown type of stroke, and 1 patient had small vessel disease. The patients with clopidogrel resistance showed significantly higher initial clinical severity (p=0.015), C-reactive protein levels (p=0.001) and WBC counts (p<0.001) than those with good responsiveness. In multiple logistic regression analysis, the WBC count was significantly correlated with the clopidogrel resistance (p=0.01).
CONCLUSIONS
Our results indicate that the clopidogrel resistance was observed in up to 18.5% of patients with acute ischemic stroke and might be affected by enhanced inflammatory reactions.