Consecutive STEMI patients, admitted within 12 hours of symptom onset and scheduled for primary PCI are randomly assigned to two treatment strategies: standard PCI including stenting and abciximab (group1) or thrombus aspiration with Pronto™ extraction catheter (Vasc.solutions, Minneapolis) before standard PCI (group2). Patients with cardiogenic shock, previous infarction or thrombolytic therapy are excluded.