T. Nagao et al., PLATELET ACTIVATION IS NOT INVOLVED IN ACCELERATION OF THE COAGULATION SYSTEM IN ACUTE CARDIOEMBOLIC STROKE WITH NONVALVULAR ATRIAL-FIBRILLATION, Stroke, 26(8), 1995, pp. 1365-1368
Background and Purpose It is generally accepted that the coagulation s
ystem is activated in ischemic stroke and that platelet activation is
involved in the pathogenesis of this disease. However, little is known
about how and to what extent platelet activity participates in coagul
ation system enhancement. We evaluated the hemostatic condition, espec
ially with regard to platelet function and the coagulation system, wit
hin 3 days of onset of acute stroke. The study participants were limit
ed to elderly patients with cardioembolic stroke due to nonvalvular at
rial fibrillation. Methods Seventeen elderly patients with acute cardi
oembolic stroke due to nonvalvular atrial fibrillation were investigat
ed, Within 3 days of stroke onset, beta-thromboglobulin (BTG), platele
t factor 4 (PF4), thrombin-antithrombin III complex (TAT), and D-dimer
from arterial blood were carefully evaluated in these patients. Blood
samples from 19 healthy age-and sex-matched control subjects were als
o examined. Results The two studied markers of platelet activity did n
ot change in the patients or the control subjects, and the between-gro
up differences between the stroke and control groups were not statisti
cally significant (BTG, 43.8 versus 31.9 ng/mL; PF4, 9.06 versus 5.78
ng/mL; respectively). In contrast, the two studied coagulation-system
indicators were markedly elevated in the patients compared with the co
ntrol subjects (TAT, 13.8 versus 3.5 ng/mL, P < .01 D-dimer, 366.3 ver
sus 147.2 ng/mL, P < .01; respectively). Conclusions Platelet function
was not enhanced in the acute stage of cardioembolic stroke with nonv
alvular atrial fibrillation. This result indicates that enhancement of
the coagulation system in cardioembolic stroke is not the result of p
latelet hyperfunction, ie, ''platelet-fibrin'' thrombi, but rather of
''stasis-related'' thrombi formation.