Comparison between initial and chronic response to clopidogrel therapy after coronary stenting for acute coronary
Thomas Cuisset1, Jacques Quilici, Marie Loosveld
1Département de Cardiologie, CHU Timone, Marseille, France. thomascuisset@voila.fr
Insights
Initial clopidogrel response in acute coronary syndrome patients is not a reliable predictor of maintenance therapy effectiveness. Platelet testing at one month better predicts bleeding events than initial response.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Medicine
Background:
- Tailored antiplatelet therapy using clopidogrel loading doses is studied.
- Optimal timing for platelet function testing remains unclear.
Purpose of the Study:
- To compare initial clopidogrel response after a 600 mg loading dose with one-month platelet response.
- To evaluate the relationship between these responses and ischemic events and bleeding complications.
Main Methods:
- 475 patients with non-ST-segment elevation acute coronary syndrome undergoing percutaneous coronary intervention were included.
- Patients received a 600 mg clopidogrel loading dose followed by 150 mg daily.
- High on-treatment platelet reactivity (HPR) was defined as vasoactive stimulated phosphoprotein >50%; hyperresponse was PRI VASP <95th percentile.
Main Results:
- Initial testing identified 44% with HPR and 5% with hyperresponse.
- At one month, 39% had HPR and 3% had hyperresponse, with a significant decrease in mean PRI VASP.
- Initial HPR patients were more likely to remain HPR at one month (60%) compared to initial responders (22%).
- Initial response correlated with stent thrombosis and bleeding; one-month response correlated only with bleeding.
Conclusions:
- Initial clopidogrel response is not a reliable predictor for maintenance therapy response.
- The predictive value of initial versus one-month clopidogrel response for clinical outcomes differs.
Background:
Studies have addressed the benefit of tailored therapy based on initial response to clopidogrel loading dose. However, the appropriate timing for platelet testing remains uncertain.
Methods:
The present study was performed to compare initial clopidogrel response after 600 mg loading dose and 1-month platelet response and their relationship with ischemic and bleedings events. A total of 475 patients with non-ST-segment elevation acute coronary syndrome undergoing percutaneous coronary intervention have been included in the present study. All patients were treated with 600 mg clopidogrel followed by 150 mg daily. Clopidogrel low response was defined by high on-treatment platelet reactivity (HPR) with vasoactive stimulated phosphoprotein >50%, and "hyperresponse," as platelet reactivity index vasoactive stimulated phosphoprotein (PRI VASP) <95th percentile after 600 mg.
Results:
After 600 mg, 210 patients were identified with HPR (44%), and 23 patients (5%), with hyperresponse (PRI VASP <8%). At 1 month on 150 mg clopidogrel daily, 184 patients (39%) had HPR (39%), 14 patients (3 %) had hyperresponse, and mean PRI VASP was significantly lower (43% ± 19% vs 46% ± 21%, P = .04). At 1 month, among the 210 patients with HPR after 600 mg, 127 (60%) remained, whereas among the 265 patients responders after 600 mg, only 57 (22%) remained with HPR (60% vs 22%, P < .0001). Initial response was significantly associated with risk of stent thrombosis and bleeding complications, whereas 1-month assessment was only linked with bleeding events.
Conclusion:
In conclusion, the present study showed that initial clopidogrel response in patients with acute coronary syndrome is not a reliable predictor of response to maintenance therapy and their values for prediction of clinical outcome are likely to be different.
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