• Myocardial infarction
  
• Unstable angina
  
• Cerebral infarction
  
• Transitory cerebral ischaemia
  
• Percutaneous or surgical vascular intervention
  
• Sudden deterioration of symptoms
  
• Amputation
  
• Death
  

Patients with atherosclerosis of the lower limbs are at high risk of atherothrombosis, mainly heart attack and stroke. The medical treatment of these patients include platelet inhibiting drugs, usually aspirin, to reduce the risk of blood clot formation. Clopidogrel is another platelet inhibiting drug, which is prescribed less often, primarily because of the high costs compared to aspirin.

Phenomena of 'resistance' to these drugs have been described by numerous investigators. Essentially resistance means that the effect of the drug described is less than expected or missing, when described by various laboratory methods. We still do not know which way resistance is best described, and we still do not know if patients who are 'resistant' to either drug are less protected against future heart attacks or strokes.

Main objectives:

• To measure the activity of platelets in these patients during aspirin treatment.
• To measure the activity of platelets in a minor population of these patients during clopidogrel treatment.
• To evaluate the prognostic significance of resistance to aspirin in these patients.

Secondary objectives:

• To describe the relation between drug resistance and the level of inflammatory markers in the blood.

Methods:

Platelet activity is measured by the PFA-100 (Dade Behring) and by traditional turbidimetric aggregation.

Patients:

Number needed is 1000.

Follow up:

6 years

Endpoints:

Myocardial infarction, unstable angina, cerebral infarction, transitory cerebral ischaemia, sudden deterioration of symptoms, percutaneous or surgical vascular intervention, amputation, death.