Effectiveness of Reloading to Overcome Clopidogrel Nonresponsiveness in Patients With Acute Myocardial Infarction

Whether increasing doses of clopidogrel can overcome nonresponsiveness was evaluated. Clopidogrel nonresponsiveness was found in up to 25% of treated patients and was associated with worse prognosis in patients with acute coronary syndrome and patients undergoing coronary intervention. Adenosine dip...

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Bibliographic Details
Published in:The American journal of cardiology 2008-09, Vol.102 (5), p.524-529
Main Authors: Matetzky, Shlomi, MD, Fefer, Paul, MD, Shenkman, Boris, MD, PhD, Varon, David, MD, Savion, Naphtali, MD, Hod, Hanoch, MD
Format: Article
Language:English
Subjects:
Biological and medical sciences
Blood Platelets - metabolism
Blood products
Cardiology
Cardiology. Vascular system
Cardiovascular
Cells
Coronary heart disease
Dose-Response Relationship, Drug
Electrocardiography
Female
Fibrinogen - drug effects
Fibrinogen - metabolism
Flow Cytometry
Follow-Up Studies
Heart
Heart attacks
Humans
Male
Medical prognosis
Medical sciences
Middle Aged
Myocardial Infarction - blood
Myocardial Infarction - drug therapy
Myocardial Infarction - physiopathology
Myocarditis. Cardiomyopathies
P-Selectin - biosynthesis
Platelet Aggregation - drug effects
Platelet Aggregation Inhibitors - administration & dosage
Prospective Studies
Ticlopidine - administration & dosage
Ticlopidine - analogs & derivatives
Treatment Outcome
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Summary:Whether increasing doses of clopidogrel can overcome nonresponsiveness was evaluated. Clopidogrel nonresponsiveness was found in up to 25% of treated patients and was associated with worse prognosis in patients with acute coronary syndrome and patients undergoing coronary intervention. Adenosine diphosphate (ADP)-induced platelet aggregation was prospectively determined on day 4 of acute myocardial infarction in 200 consecutive patients, who received clopidogrel 300 mg as a loading dose and 75 mg/day thereafter. Thirty patients (15%) had ADP-induced platelet aggregation ≥80% using light transmittance aggregometry and were considered clopidogrel nonresponders. Nonresponders were reloaded with clopidogrel 600 mg, followed by 150 mg/day for 4 weeks. A 75-mg/day dose was resumed thereafter. ADP-induced platelet aggregation was reassessed 4 hours after reloading and biweekly for 10 weeks. Flow cytometry was used to determine platelet P-selectin expression and fibrinogen binding before and 4 hours after reloading. ADP-induced platelet aggregation significantly decreased 4 hours after reloading (from 83 ± 6% to 56 ± 14%; p
ISSN:0002-9149
1879-1913
DOI:10.1016/j.amjcard.2008.04.028