ELEVATED PLATELET MICROPARTICLES IN TRANSIENT ISCHEMIC ATTACKS, LACUNAR INFARCTS, AND MULTIINFARCT DEMENTIAS

Platelets release microparticles (PMP) upon activation. Elevated level s of PMP were observed in patients with immune thrombocytopenic purpur a (ITP), sometimes associated with a syndrome resembling transient isc hemic attack (TIA), suggesting a thrombogenic potential for PMP. To de termine if this association applies to TIA and other cerebrovascular a ccidents (CVA) without ITP, we studied PMP profiles in 71 patients wit h ischemic CVA: 28 with small vessel CVA (SCVA), either lacunar infarc ts or TIA; 24 with large vessel CVA (LCVA); 19 with multiinfarct demen tia (MID); 12 with Alzheimer's dementia (AD); and 31 healthy controls. The mean PMP values were: MID = 3.71 +/- 0.51; SCVA = 3.48 +/- 0.63; LCVA = 1.97 +/- 0.28; AD = 1.19 +/- 0.27; controls = 0.88 +/- 0.09, (a ll units x 10(7)/mL). PMP values in all groups except AD were signific antly above normal (p<0.01). However, the elevation in SCVA was more m arked than in LCVA (p<0.01). Administration of the calcium channel blo cker, nifedipine, to 11 TIA patients reduced PMP significantly.