Platelet Inhibition in the Acute Phase of STEMI

Study Overview
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Brief Summary
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Background: Dual antithrombotic treatment with aspirin and clopidogrel is recommended in patients with ST elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). The European Society of Cardiology (ESC) Guidelines recommend a bolus dose of aspirin of 250-500 mg and a 600 mg bolus dose of clopidogrel as soon as STEMI is suspected. Studies have shown that more newly produced platelets are present in the acute phase of STEMI, and it is likely that these immature platelets are haemostatically more active and might be of importance in thrombus formation. The enhanced platelet reactivity may reduce the effect of aspirin and clopidogrel in the acute phase of STEMI compared to measurements made in the same patients 3 months after primary PCI. Aim: This study aims to compare platelet response to aspirin and clopidogrel in the acute phase of STEMI with the platelet response in the same patients 3 months after STEMI . Design: This study is an observational follow-up study. Materials and methods: 46 patients with STEMI referred to primary PCI at Aarhus University Hospital, Skejby will be included in the study. A total of 3 blood samples are obtained in the acute phase of STEMI: Prior to primary PCI (Blood sample 1), at 4 hours (Blood sample 2) and at 12 hours (Blood sample 3) after administration of loading dose aspirin and clopidogrel. When patients are in a stable phase 3 month later, a final blood sample is taken (Blood sample 4). The blood is analyzed 30 minutes after withdrawal of blood by the platelet aggregation test Multiplate® aggregometry (agonists: Collagen, arachidonic acid and adenosinediphosphate) and VerifyNow® arachidonic acid and P2Y12 aggregometry. Platelet count, volume and the immature platelet fraction (IPF) will be measured using Sysmex® flowcytometry.

Official Title
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Platelet Inhibition in the Acute Phase of ST-segment Elevation Myocardial Infarction

Conditions
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Acute Myocardial Infarction, Antiplatelet Therapy, ST-segment Elevation Myocardial Infarction (STEMI)

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Above 18 years of age Patients with ST-segment elevation myocardial infarction (STEMI) referred to primary PCI at University Hospital of Aarhus, Skejby. Exclusion Criteria: Treatment with NSAID, ticlopidine and dipyramidole. Treatment with anticoagulants (Vitamin K antagonists) Patients diagnosed with platelet disease or haemophilia. Patients unable to give written, informed consent to participation in this project.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| STEMI<br>Patients with STEMI according to ESC STEMI guidelines: Age above 18 years and able to give written, informed consent to participation in the project. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference between aggregation induced by agonist collagen (1 μg/ml) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 1: Obtained immediately before primary PCI in the catherization laboratory. The blood sample is obtained from the femoral artery catheter. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist collagen (1 μg/ml) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 2: 4 hours after administration of loading dose (LD) aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist collagen (1 μg/ml) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 3: 12 hours after administration of LD aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist arachidonic acid (1,0 mM) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 1: Obtained immediately before primary PCI in the catherization laboratory. The blood sample is obtained from the femoral artery catheter. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist arachidonic acid (1,0 mM) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 2: 4 hours after administration of loading dose (LD) aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist arachidonic acid (1,0 mM) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 3: 12 hours after administration of LD aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist adenosine diphosphate (6,4 µM) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 1: Obtained immediately before primary PCI in the catherization laboratory. The blood sample is obtained from the femoral artery catheter. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist adenosine diphosphate (6,4 µM) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 2: 4 hours after administration of loading dose (LD) aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist adenosine diphosphate (6,4 µM) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 3: 12 hours after administration of LD aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist adenosine diphosphate (20 µM) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 1: Obtained immediately before primary PCI in the catherization laboratory. The blood sample is obtained from the femoral artery catheter. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist adenosine diphosphate (20 µM) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 2: 4 hours after administration of loading dose (LD) aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation induced by agonist adenosine diphosphate (20 µM) measured by Multiplate® Aggregometry (Unit=AUC). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 3: 12 hours after administration of LD aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation measured by VerifyNow® Aggregometry using the ASPI-kit (Unit = ARU). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 1: Obtained immediately before primary PCI in the catherization laboratory. The blood sample is obtained from the femoral artery catheter. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation measured by VerifyNow® Aggregometry using the ASPI-kit (Unit = ARU). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 2: 4 hours after administration of loading dose (LD) aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation measured by VerifyNow® Aggregometry using the ASPI-kit (Unit = ARU). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 3: 12 hours after administration of LD aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation measured by VerifyNow® Aggregometry using the P2Y12-kit (Unit = PRU). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 1: Obtained immediately before primary PCI in the catherization laboratory. The blood sample is obtained from the femoral artery catheter. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation measured by VerifyNow® Aggregometry using the P2Y12-kit (Unit = PRU). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 2: 4 hours after administration of loading dose (LD) aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference between aggregation measured by VerifyNow® Aggregometry using the P2Y12-kit (Unit = PRU). | Outcome is the difference between aggregation measurements. In this case between: Blood sample 3: 12 hours after administration of LD aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in immature platelet fraction measured by Sysmex® flowcytometry. | Outcome is the difference between measurements. In this case between: Blood sample 1: Obtained immediately before primary PCI in the catherization laboratory. The blood sample is obtained from the femoral artery catheter. Blood sample 4: 2-3 months after administration of LD aspirin and clopidogrel. | Approximately 2-3 months | 
| Difference in serum P-selectin | Outcome is the difference between measurements. In this case between: Blood sample 1: Obtained immediately before primary PCI in the catherization laboratory. The blood sample is obtained from the femoral artery catheter. Blood sample 4: 2-3 months after administration of LD aspirin and clopidogrel. | Approximately 2-3 months | 
| Difference in serum trombopoietin | Outcome is the difference between measurements. In this case between: Blood sample 1: Obtained immediately before primary PCI in the catherization laboratory. The blood sample is obtained from the femoral artery catheter. Blood sample 4: 2-3 months after administration of LD aspirin and clopidogrel. | Approximately 2-3 months | 
| Difference in serum thromboxane B2 | Outcome is the difference between measurements. In this case between: Blood sample 1: Obtained immediately before primary PCI in the catherization laboratory. The blood sample is obtained from the femoral artery catheter. Blood sample 4: 2-3 months after administration of LD aspirin and clopidogrel. | Approximately 2-3 months | 
| Difference in immature platelet fraction measured by Sysmex® flowcytometry. | Outcome is the difference between measurements. In this case between: Blood sample 2: 4 hours after administration of loading dose (LD) aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 
| Difference in immature platelet fraction measured by Sysmex® flowcytometry. | Outcome is the difference between measurements. In this case between: Blood sample 3: 12 hours after administration of LD aspirin and clopidogrel. Blood sample 4: 2-3 months after primary PCI. | Approximately 2-3 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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STEMI, Acute myocardial infarction, Antiplatelet therapy, aspirin, clopidogrel, VerifyNow aggregometry, Multiplate aggregometry