Platelet function following acute cerebral ischemia.
BACKGROUND
Studies have previously identified increased levels of platelet activation following acute ischemic stroke. In order to evaluate new antiplatelet agents and their combinations, there is a need for accurate measures of platelet activation.


METHODS
Blood was taken from 17 patients within 24 hours of an acute ischemic stroke, and then at 3, 7, 14 and 42 days. For comparison, a group of 18 stable arteriopaths had identical tests performed. Platelet aggregation was measured using a free platelet counting technique, and platelet surface P-selectin and monocyte platelet aggregates (MPAs) were measured using flow cytometry. Soluble P-selectin and D-dimers were measured by an enzyme linked immune assay.


RESULTS
The initial level of MPAs was significantly raised in the stroke patients compared with the stable patients (p = 0.04, 14.2% vs. 9.3%); however, this difference was not significantly higher than later study points (14.2%, 10.1%, 9.3%, 11.9%, 11.3%; days 1, 3, 7, 14 and 42 respectively. Day 1 vs. day 7 p = 0.07 ANOVA). No changes in P-selectin or platelet aggregation were identified. D-dimer levels were significantly higher on day 7 than day 42 (p < 0.01), and fibrinogen levels were elevated on both days 3 and 14 compared with day 42. Fibrinogen levels were not elevated compared with stable patients.


CONCLUSIONS
MPA levels are elevated following an acute ischemic stroke compared to stable patients, but no significant change was seen with other platelet markers. This study suggests MPAs are a more sensitive marker of platelet activation than either P-selectin or aggregation.
Smout
Jonathan
J
Northern Vascular Centre Freeman Hospital, Northern Vascular Centre, Newcastle Upon Tyne, United Kingdom.
Dyker
Alexander
A
Cleanthis
Marcus
M
Ford
Gary
G
Kesteven
Patrick
P
Stansby
Gererd
G
D000368:Aged; D000369:Aged, 80 and over; D002544:Cerebral Infarction / Q000097:blood*; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000502:physiology*; D019007:P-Selectin / Q000097:blood*; D010865:Pilot Projects; D015539:Platelet Activation / Q000502:physiology; D010974:Platelet Aggregation / Q000502:physiology*; D010976:Platelet Count; D010979:Platelet Function Tests; D012016:Reference Values
D005338:Fibrin Fibrinogen Degradation Products; D019007:P-Selectin; C036309:fibrin fragment D; D005340:Fibrinogen