Related Experiment Video
Updated: Aug 19, 2025
Microfluidics in Assessing Platelet Function
Published on: November 8, 2024
High On-Treatment Platelet Reactivity: Aspirin versus Clopidogrel
René M'Pembele1, Samantha Ahlbrecht2, Carolin Helten2
1Department of Anesthesiology, Heinrich Heine University Medical Center Düsseldorf, Düsseldorf, Germany.
Insights
High on-treatment platelet reactivity (HTPR) was more common with clopidogrel than aspirin in patients on oral anticoagulation post-PCI. This suggests aspirin may be a better choice for antiplatelet therapy in this patient group.
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.
Background:
Antithrombotic regimen in patients on oral anticoagulation (OAC) post-percutaneous coronary intervention (PCI) is challenging. At least, one antiplatelet agent in combination with OAC is recommended after PCI for 6-12 months. Clopidogrel is used most frequently in this setting. However, data comparing P2Y12 inhibition with clopidogrel versus cyclooxygenase inhibition by acetylsalicylic acid (ASA, aspirin) is missing. It is well known that the antiplatelet effects of ASA and clopidogrel are frequently impaired (high on-treatment platelet reactivity [HTPR]). In this pilot investigation, we compared the antiplatelet effects of clopidogrel versus ASA.
Methods:
In this retrospective single-center database analysis, we investigated platelet reactivity by light transmission aggregometry in patients under different antiplatelet regimes. Results were presented as maximum of aggregation (MoA). HTPR to ASA and to clopidogrel were assessed.
Results:
755 patients were enrolled. 677 were on ASA, 521 were on clopidogrel, and 198 had OAC. Overall mean age was 73 ± 13.4 years, and 458 (60.7%) were male. HTPR to ASA occurred in 94/677 patients (13.9%), and mean arachidonic acid-induced MoA was 14.15 ± 19.04%. HTPR to clopidogrel occurred in 241/521 patients (46.3%), and mean adenosine diphosphate-induced MoA was 50.06 ± 20.42%. HTPR to clopidogrel was significantly more frequent than HTPR to ASA; single antiplatelet therapy (SAPT)-mono ASA: 27/199 (13.6%) versus mono clopidogrel: 6/18 (33.3%); p = 0.037; SAPT with OAC-OAC with ASA: 8/35 (22.9%) versus OAC with clopidogrel: 27/60 (45%); p = 0.046. Same difference in HTPR contingency could be shown in subgroups of dual antiplatelet therapy and ASA + clopidogrel + OAC therapy.
Conclusion:
Impaired pharmacodynamic response to clopidogrel was more frequent as HTPR to ASA. Hence, ASA should be tested in combination with OAC post-PCI.
Related Concept Videos
01:20Antiplatelet Drugs: Prostaglandin Synthesis, P2Y12 and Glycoprotein IIb/IIIa Inhibitors
Prostaglandin synthesis inhibitors, exemplified by the widely known aspirin, wield their power by irreversibly acetylating...
01:22Formation of the Platelet Plug
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...
01:27Coronary Artery Disease V: Interprofessional Care