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.

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