[Modified platelet aggregation test in patients on ASA and/or clopidogrel]

Area of Science:

• Cardiology
• Pharmacology
• Hematology

Background:

• Antiplatelet therapy with aspirin (ASA) and clopidogrel is crucial for preventing arterial thrombosis.
• Monitoring the efficacy of these drugs in inhibiting platelet aggregation is essential for patient management.

Purpose of the Study:

• To evaluate the effectiveness of aggregometry in assessing platelet inhibition by various doses of ASA and clopidogrel, alone or in combination.
• To determine the failure rates of achieving adequate platelet inhibition in patients with arterial thrombosis.

Main Methods:

• A modified platelet aggregation test was employed to measure maximum aggregation in response to ADP, collagen, adrenalin, and arachidonic acid.
• Reference values were established from healthy individuals, and a scoring system was developed to detect inadequate platelet inhibition.
• Patients received ASA (30-300 mg/d), clopidogrel (75 mg/d), or combination therapy (ASA 100 + clopidogrel 75 mg/d).

Main Results:

• Significant delays in maximum platelet aggregation were observed in patients on ASA and combination therapy compared to controls.
• Patients on clopidogrel alone showed prolonged aggregation when induced by ADP, collagen, and arachidonic acid.
• Failure rates for adequate platelet inhibition were 27% for ASA 100 mg/d, 26% for clopidogrel 75 mg/d, and 7% for combination therapy.

Conclusions:

• Platelet inhibition monitoring via aggregometry is vital as many patients with arterial thrombosis do not achieve adequate inhibition with standard antiplatelet therapies.
• The study highlights potential limitations in achieving consistent therapeutic effects with individual antiplatelet agents, underscoring the need for personalized monitoring.