Related Experiment Video
Updated: Mar 17, 2026
Interventional Diagnostic Procedure: A Practical Guide for the Assessment of Coronary Vascular Function
Published on: March 15, 2022
Effect of long-term adherence to clopidogrel on the VASP-PRI after elective coronary stent implantation: a randomized
Valentina Forni Ogna1, Isabelle Menetrey1, Olivier Muller2
1Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland.
Insights
Monitoring adherence to clopidogrel therapy did not significantly alter platelet reactivity over six months. However, adherence impacts platelet inhibition, especially in initial good responders, highlighting the variability in clopidogrel biological response.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Trials
Background:
- Clopidogrel response varies significantly, with poor responsiveness linked to adverse cardiac events.
- Therapy adherence is a key factor in clopidogrel responsiveness, but its long-term impact on platelet inhibition is unclear.
Purpose of the Study:
- To assess the impact of different adherence monitoring programs on clopidogrel's long-term effect on platelet reactivity.
Main Methods:
- A randomized controlled trial involving 123 adults undergoing coronary stenting treated with clopidogrel.
- Participants were assigned to standard care, standard care with electronic monitoring, or integrated care with feedback.
- Platelet reactivity was measured using the vasodilator-stimulated phosphoprotein-platelet reactivity index (VASP-PRI) at baseline, 3, and 6 months.
Main Results:
- No significant difference in VASP-PRI was observed between groups at 6 months.
- Adherence and baseline VASP-PRI predicted VASP-PRI at 3 and 6 months.
- The association between adherence and VASP-PRI diminished in patients with high baseline VASP-PRI (>50%).
- Diabetes, CYP2C19*2 status, and BMI were significant predictors of VASP-PRI.
Conclusions:
- Platelet response to clopidogrel remains highly variable during chronic therapy, irrespective of adherence monitoring.
- Adherence monitoring programs did not alter VASP-PRI at 6 months.
- Poor adherence affects platelet inhibition primarily in patients who are initially good responders to clopidogrel.
Aims:
The biological response to clopidogrel is highly variable and a poor responsiveness is associated with major adverse cardiac events. Adherence to therapy is a major cause of poor responsiveness but its impact on long-term platelet inhibition is unknown. The objective of the present study was to evaluate the effect of different programmes monitoring adherence to clopidogrel on platelet reactivity.
Methods:
The study took the form of a monocentric, parallel group, randomized controlled trial. Adults treated with clopidogrel 75 mg after elective coronary stenting were randomized into one of three groups: (i) a standard of care group; (ii) a standard of care + adherence electronic monitoring group, in which drug intake was recorded but kept blinded until the study end; or (iii) an integrated care group, with regular feedback on recorded adherence. Clopidogrel response was assessed with the vasodilator-stimulated phosphoprotein-platelet reactivity index (VASP-PRI) at randomization, 3 months and 6 months.
Results:
A total of 123 adults were enrolled and randomized. Baseline VASP-PRI was highly variable, with a mean of 48 ± 18.8%. No difference between groups in VASP-PRI was found at 6 months (P = 0.761), despite better adherence to clopidogrel in the integrated care group. However, adherence (P = 0.035) and baseline VASP-PRI (P = 0.015) were associated with VASP-PRI at 3 months and 6 months. The association between adherence and VASP-PRI was lost in patients with baseline VASP-PRI > 50%. Diabetes, CYP2C19*2 carrier status and body mass index were significant predictors of VASP-PRI.
Conclusions:
The platelet response to clopidogrel during chronic therapy remained highly variable, despite high adherence. Different adherence monitoring programmes did not affect VASP-PRI at 6 months. Poor adherence is associated with lower VASP-PRI only in initial good responders to clopidogrel.
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...
01:27Coronary Artery Disease V: Interprofessional Care
01:27Peripheral Artery Disease III: Interprofessional Care