Platelet Reactivity in Stent Thrombosis Patients

St. Antonius Hospital187 enrolled

Overview

Recent studies have demonstrated a marked interindividual variability of clopidogrel's capacity to inhibit platelet aggregation with a substantial proportion (11-34%) of the patients considered non-responders to clopidogrel treatment. Variable intestinal absorption is suggested to contribute to the inconsistencies in response to clopidogrel. However, little is known about intestinal absorption in subjects who had suffered from a stent thrombosis. The MAPCAT-study has been designed to investigate whether plasma pharmacokinetics (represented by Cmax, Tmax and the AUC) after a 600 mg loading dose are significantly different between subjects who have suffered a stent thrombosis and subjects who have not suffered a stent thrombosis.

Objectives: The first objective of the MAPCAT-study is to investigate whether plasma pharmacokinetics (Cmax, Tmax and AUC) of an additional 600 mg loading dose are impaired in patients with a history of stent thrombosis. The second objective of the MAPCAT study is to investigate whether genetic polymorphisms in receptors, enzymes and ligands involved in the process of thrombosis and haemostasis as well in the conversion-process of clopidogrel into its metabolites do have influence on both the absolute magnitude of platelet inhibition and Cmax, Tmax and AUC.

Study Type

INTERVENTIONAL

Allocation

NON_RANDOMIZED

Purpose

DIAGNOSTIC

Masking

NONE

Enrollment

187

Conditions

Coronary Artery Stent Thrombosis

Eligibility

Sex: ALLMin age: 18 YearsMax age: 90 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Patients with a history of a stent thrombosis in the period 2004-2008. Exclusion Criteria: * Persistent acute ST-segment elevation * Successful revascularization during the qualifying hospitalization, prior to study entry * Acute pulmonary edema, hypotension, or evidence of cardiogenic shock * Clinically significant liver disease * End stage kidney disease requiring dialysis * Use at study entry of drugs that are strong inhibitors of cytochrome P450 3A4 and CYP3A5 (i.e. clarithromycin, erythromycin, itraconazole, ketoconazole) * Contraindications to antithrombotic/antiplatelet therapy * Failed coronary intervention in the previous 2 weeks * Malignancies * Increased risk of bleeding (previous stroke in the past months, active bleeding or bleeding diathesis, recent trauma or major surgery in the last month, suspected aortic dissection, oral anticoagulation therapy with coumarin derivate within 7 days, recent use of GPIIb/IIIa inhibitors within 14 days, severe uncontrolled hypertension \>180 mmHg unresponsive to therapy) * Relevant hematologic deviations (haemoglobin \<100g/L (6,2 mmol/L) or hematocrit \<34%, platelet count \<100 x 109 /L or platelet count \> 600 x 109/L) * Known allergy to clopidogrel * Pregnancy (present or suspected) * uncontrolled hypertension at time of randomization

Outcomes

Primary Outcomes

Plasma concentrations of unchanged clopidogrel, its active thiol metabolite and its inactive carboxyl metabolite between the different patient groups after the administration of a 600 mg loading dose of clopidogrel.

Time frame: 6 hours after the administration of a 600mg loading dose of clopidogrel

Secondary Outcomes

The magnitude of platelet reactivity as measured with several commercial available platelet function tests before and 6 hours after the ingestion of the loading dose.

Time frame: platelet reactivity measured at baseline and 6 hours after a 600 mg clopidogrel loading dose.

Exploratory Endpoint: prevalence of various genetic polymorphisms that might influence the pharmacokinetics of clopidogrel

Time frame: blood obtained for genetic sampeling at timepoint of first study blood collection