Platelets play an important role in the pathogenesis of atherothrombosis. Platelet activation is associated with increased mean platelet volume (MPV) and platelet distribution width (PDW). In this study, we investigated the relation of MPV and PDW with the risk of stroke in patients with intermediate (50%-70%) carotid artery stenosis. A total of 254 patients (115 symptomatic and 139 asymptomatic) with intermediate carotid artery stenosis were enrolled in this study. Symptomatic and asymptomatic patients were compared in regard to MPV and PDW. Mean platelet volume was significantly greater in the symptomatic group compared with the asymptomatic group (11.1 and 9.4 fL, respectively; P < .001). Platelet distribution width was significantly greater in the symptomatic group compared with the asymptomatic group (15.0% and 11.9%, respectively; P < .001). Multivariate regression analysis showed that an MPV 10.2 fL and a PDW 14.3% were independent predictors of developing symptomatic carotid artery stenosis. Mean platelet volume and PDW are increased in the presence of symptomatic intermediate carotid artery stenosis. Increased MPV and PDW may be independent predictors of developing symptomatic carotid artery plaque
