Variable platelet response to aspirin in patients with ischemic stroke

Area of Science:

• Cardiovascular Medicine
• Neurology
• Pharmacology

Background:

• Ischemic stroke patients often experience events despite aspirin (acetylsalicylic acid, ASA) treatment.
• The reasons for aspirin treatment failure, including normal response versus hyporesponsiveness, remain unclear in these patients.

Purpose of the Study:

• To investigate aspirin (acetylsalicylic acid, ASA) response in ischemic stroke patients.
• To differentiate between normal ASA response, poor compliance, and impaired platelet function in stroke patients.

Main Methods:

• Studied the effect of oral and in vitro aspirin (acetylsalicylic acid, ASA) on platelet aggregation and thromboxane (TX) synthesis.
• Analyzed collagen- and arachidonic-acid-induced TX formation in platelet-rich plasma from 90 ischemic stroke patients and 25 healthy controls.

Main Results:

• Identified aspirin (acetylsalicylic acid, ASA) nonresponse in 11% of stroke patients not on oral ASA, indicating impaired platelet response.
• Observed poor compliance or pharmacokinetic nonresponse in some patients treated with aspirin (acetylsalicylic acid, ASA).
• Found increased collagen-induced, TX-independent platelet aggregation in stroke patients compared to controls.

Conclusions:

• Distinct categories of aspirin (acetylsalicylic acid, ASA) nonresponders exist in ischemic stroke patients.
• These categories include poor bioavailability/noncompliance, impaired in vitro platelet response to aspirin (acetylsalicylic acid, ASA), and increased TX-independent hyperreactivity to collagen.