All patients undergoing elective or sub-acute PCI are screened by MULTIPLATE test for clopidogrel low-responsiveness after receiving 600 mg clopidogrel the day before.

A cut off value has previously been established. Only low-responders with Multiplate values above the cut off value are included in the study. The patients are randomized to either clopidogrel 150 mg once daily or Prasugrel 10 mg (age > 75 og bodyweight < 60 kg 5 mg)once daily for 30 days after the procedure.

Follow up will be at 30 days after PCI were another MULTIPLATE test will be performed.

Primary endpoint:Platelet inhibition (by MULTIPLATE) after 30 days of intensified antiplatelet therapy.

Clinical endpoints such as bleeding complications (GUSTO, TIMI) during treatment, and major adverse cardiac events (MACE) at 30 days will be collected and reported but the study size does not allow for formal statistical analysis The study ends by the 30 days follow up visit and all patients continue with clopidogrel 75 mg once daily for another 11 months (not study related)

Inclusion Criteria:

• PCI with stenting and Multiplate hep-ADP > 70 U despite clopidogrel loading

Exclusion Criteria:

• need for vit K antagonist
• women with childbearing potential
• breastfeeding women
• Planned surgery within 6 months
• Intolerance to clopidogrel, prasugrel or aspirin
• previous stroke