Platelet behavior in patients with TIA: responsiveness to small doses of aspirin.

To study platelet role in cerebrovascular disease, beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) plasma levels, indices of in vivo platelet activation, were assayed in a group of patients affected by cerebral ischemic attack (transient ischemic attack; TIA). Determinations were carried out within 1 month from the ischemic event and following short-term (1 month) and long-term (1 year) daily administration of low doses (50 mg) of aspirin (ASA). After the cerebral ischemic event, beta-TG and PF4 plasma levels were elevated. beta-TG and PF4 plasma levels did not decrease after 1 month of treatment with ASA and significantly increased in all the patients after 1 year. Such a trend can perhaps be related to the natural course of the disease and associated with the possible occurrence of collagen-induced platelet activation in cerebrovascular patients. Data suggest that although platelet activation occurs in TIA-affected patients, the high levels of beta-TG and PF4 may not be adequate parameters for evaluation of TIA relapses and ASA efficacy.