High On-Treatment Platelet Reactivity: Aspirin versus Clopidogrel

Area of Science:

• Cardiology
• Pharmacology
• Thrombosis

Background:

• Managing antithrombotic therapy in patients on oral anticoagulation (OAC) after percutaneous coronary intervention (PCI) presents challenges.
• Current guidelines recommend combining OAC with at least one antiplatelet agent for 6-12 months post-PCI.
• Clopidogrel is frequently used, but direct comparisons with aspirin regarding P2Y12 and cyclooxygenase inhibition are limited.

Purpose of the Study:

• To compare the antiplatelet effects of clopidogrel versus aspirin in patients undergoing PCI.
• To assess the incidence of high on-treatment platelet reactivity (HTPR) with both agents.

Main Methods:

• Retrospective analysis of platelet reactivity using light transmission aggregometry.
• Assessment of maximum aggregation (MoA) to evaluate HTPR to aspirin and clopidogrel.
• Inclusion of patients on single antiplatelet therapy, OAC, and dual antiplatelet therapy.

Main Results:

• HTPR to clopidogrel occurred in 46.3% of patients, significantly higher than HTPR to aspirin (13.9%).
• This difference was consistent across various antiplatelet regimens, including those with OAC.
• Mean MoA for clopidogrel was 50.06 ± 20.42% compared to 14.15 ± 19.04% for aspirin.

Conclusions:

• Impaired pharmacodynamic response, indicated by HTPR, is more frequent with clopidogrel than aspirin.
• Aspirin warrants further investigation for use in combination with OAC post-PCI.
• These findings highlight potential differences in antiplatelet efficacy between clopidogrel and aspirin in specific patient populations.