Introduction: Mean platelet volume (MPV) has been associated with the prognosis in stroke patients. However, its spontaneous variability during the acute phase of the disease is unknown. Materials and Methods - One hundred and thirty-seven patients with ischemic stroke, aged 75.4+/-11.0 (SD) years, were classified according to several criteria: National Institutes of Health Stroke Scale (NIHSS) score, maximum lesion diameter on CT scan, Oxfordshire Community Stroke Projects (OCSP) and Trial of ORG 10172 in Acute Stroke Treatment (TOAST) categories. Platelet parameters were determined 1.2 days after the onset of symptoms, and after 3.0 further days.
Results: The initial MPV was higher in non-lacunar than lacunar strokes (8.30+/-1.10 vs. 7.95+/-0.79 fl, P=0.04), and correlated with the sampling delay with respect to the onset of symptoms, especially in the strokes with lesions >=4 cm (r=0.39, P=0.009), NIHSS >=11 (r=0.35, P=0.02) and of cardioembolic origin (r=0.35, P=0.01). Subsequently a late MPV increment was observed in the remaining categories: from 8.20 to 8.38 fl (P=0.02) in the strokes with lesions <4 cm, from 8.11 to 8.31 fl (P=0.01) in the presence of an NIHSS<11 and from 8.20 to 8.61 fl (P=0.03) when the occlusion of a large artery was involved.
Conclusions: Platelet volume is not stable during the acute phase in non-lacunar ischemic strokes, as it increases early in the most severe forms, and later in the remaining subtypes. The release of large and more reactive platelets may contribute to the thrombophilic state associated with ischemic events.