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Published on: May 28, 2019
Clopidogrel response up to six months after acute myocardial infarction
Pablo Codner1, Muthiah Vaduganathan, Eldad Rechavia
1Department of Cardiology, Rabin Medical Center, Tel Aviv University, Petah-Tikva, Israel.
Insights
High on-treatment platelet reactivity (HTPR) after acute myocardial infarction (AMI) is linked to poor outcomes. This study found that the HTPR phenotype, indicating a reduced response to clopidogrel, remained relatively stable in patients for up to six months post-treatment.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Medicine
Background:
- High on-treatment platelet reactivity (HTPR) despite clopidogrel therapy is a known risk factor for adverse cardiac events in acute myocardial infarction (AMI) patients.
- Current understanding of HTPR is limited by assessments at single time points, leaving the stability of this phenotype over time unclear.
Purpose of the Study:
- To investigate the stability of clopidogrel response, specifically the phenotype of high on-treatment platelet reactivity (HTPR), in patients with acute myocardial infarction (AMI) over a six-month period following percutaneous coronary intervention (PCI).
Main Methods:
- Fifty-seven patients with AMI treated with PCI were evaluated for clopidogrel response at three time points: during hospitalization, at 30 days, and at 6 months post-discharge.
- Platelet reactivity was measured using the VerifyNow P2Y12 assay and multiple electrode aggregometry (MEA).
- HTPR was defined using established thresholds for both assays (≥235 P2Y12 response units or ≥47 aggregation units).
Main Results:
- The prevalence of HTPR was relatively consistent across the three time points, with no statistically significant differences observed between in-hospital, 30-day, and 6-month assessments for either assay.
- Specifically, HTPR by MEA was found in 22.8% (in-hospital), 26.3% (30 days), and 17.5% (6 months).
- HTPR by VerifyNow was observed in 38.6% (in-hospital), 28.1% (30 days), and 33.3% (6 months).
- The HTPR phenotype assignment demonstrated considerable stability, with 73.7% (MEA) and 70.2% (VerifyNow) of patients maintaining their phenotype at 6-month follow-up.
Conclusions:
- This study is the first to evaluate the temporal stability of clopidogrel response in AMI patients treated with PCI.
- The findings suggest that the HTPR phenotype in patients with AMI is relatively stable for up to six months after treatment.
- This stability has implications for understanding long-term risk stratification and potential therapeutic strategies in this patient population.
Abstract:
High on-treatment platelet reactivity (HTPR) despite clopidogrel therapy is associated with adverse cardiac events after acute myocardial infarction (AMI). Most studies to date have assessed clopidogrel response at a single time point before or after percutaneous coronary intervention (PCI). It is unclear, however, whether the HTPR phenotype is stable over time. Therefore, we aimed to examine response to clopidogrel in patients with AMI treated with PCI over a 6-month period. Patients (n = 57) with AMI treated with PCI were assessed for response to clopidogrel at 3 time points: in hospital, 30 days, and 6 months after index hospitalization. Response to clopidogrel was determined by the VerifyNow P2Y12 assay (reported as P2Y12 response units) and multiple electrode aggregometry (MEA; reported as aggregation units). HTPR was defined as ≥235 P2Y12 response units or ≥47 aggregation units. Patients' mean age was 54.5 ± 10.9 years, 91% were men, 19% had diabetes, and 74% were admitted with ST-segment elevation MI. HTPR based on MEA was observed in 22.8% of patients in hospital, 26.3% at 30 days, and 17.5% at 6 months (p = NS). HTPR based on the VerifyNow assay was observed in 38.6% of patients in hospital, 28.1% at 30 days, and 33.3% at 6 months (p = NS). Individual HTPR phenotypic assignment at baseline was stable in 73.7% (based on MEA) and 70.2% (based on VerifyNow) of patients at 6-month follow-up. In conclusion, this is the first study evaluating the stability of clopidogrel response over time after AMI. Rates of HTPR to clopidogrel therapy appear to be relatively stable up to 6 months after AMI.
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