Predictive Value of Platelet Aggregation Tests in Recurrent Cerebral Ischemia and Major Bleeding.

BACKGROUND Evaluating the efficacy of antiplatelet therapy is rarely performed in patients with cerebral ischemia, despite the underlying potential recurrence of ischemia and unexpected bleeding. This study aimed to evaluate the role of platelet aggregation tests, which can predict ischemic recurrence and major bleeding. MATERIAL AND METHODS We measured the platelet aggregation activity of 768 patients using a standardized turbidimetric technique. Ischemia recurred in 8 of 48 patients who received aspirin alone, and recurred in 68 of 142 patients administered more than 1 antiplatelet agent. Major bleeding occurred in 11 of the same 142 patients. Platelet aggregation was induced by the addition of 4.0 and 20 µmol/L of adenosine diphosphate (ADP). The correlations of the maximal aggregation (MaxAgg), disaggregation rate, and aggregation curve area with the recurrence of ischemia and major bleeding were analyzed. RESULTS The MaxAgg in patients without recurrence decreased significantly (74.9%±13.2 to 54.0%±11.3, P<0.001 for 4.0 µmol/L) compared with the values before aspirin treatment. The odds ratio for recurrence (n=68) of total ischemia to non-recurrence (n=74) was 1.057 (1.029-1.086, P<0.001) for 4.0 µmol/L stimulation. The odds ratio for patients with bleeding (n=11) to total ischemia cases (n=142) was 0.828 (0.742-0.924, P=0.001) with 4.0 µmol/L stimulation. CONCLUSIONS The recurrence of ischemia was correlated with the lack of decrease in MaxAgg. Major bleeding was correlated with an excessive decrease in MaxAgg.