Abstract: Objective To explore the relationship of platelet activation markers and vitamin D to antiplatelet drug resistance in ischemic stroke patients.Methods From June, 2017 to June, 2018, 190 patients with ischemic stroke were tested their maximum platelet aggregation rate (MPAR) induced by adenosine diphosphate (ADP) and arachidonic acid (AA), activation of platelet CD_62P and P-selectin vitamin D seven to ten days after dual antiplatelet treatment (aspirin 100 mg/d + clopidogrel 75 mg/d). According to the MPAR induced by ADP and AA, the patients were divided into resistance group and sensitive group. Results The prevalence of aspirin resistance was 1.2%, while the prevalence of clopidogrel resistance was 24.7% (47 in the resistance group and 143 in the sensitive group). The activation of platelet CD_62P (t = -5.232, P < 0.001) and the prevalence of hypertension (χ² = 4.878, P < 0.05) were more in the resistance group than in the sensitive group, while the vitamin D concentration was less (t = 3.052, P < 0.01). There was no significant difference in P-selectin between the resistance and sensitive groups (t = -0.684, P = 0.253). Logistic regression analyses showed that hypertension (OR = 5.538, 95% CI: 1.204-25.470, P < 0.05), activation of platelet CD_62P (OR = 1.082, 95% CI: 1.041-1.092, P < 0.05) and vitamin D (OR = 0.848, 95% CI: 0.755-0.953, P < 0.01) were the independent related factors for clopidogrel resistance. Conclusion Inhibition of platelet activation and supplementation of vitamin D may help to overcome the resistance of clopidogrel.

Key words: ischemic stroke, platelet activation, vitamin D, antiplatelet therapy, drug resistance