Optimal Coronary Flow After PCI for Myocardial Infarction - a Pilot Study

Criteria for randomization: 1\. IMR measured in culprit vessel \> 30 Criteria for IMR measurement: Inclusion Criteria: 1. Oral and signed informed consent 2. Males and females 18 - 85 years of age 3. Diagnosis of ST-elevation myocardial infarction (STEMI) including occlusion of culprit vessel on angiography 4. Onset of continuous symptoms within 12 hours 5. Have undergone PCI of culprit vessel 6. Subjects are willing to comply with scheduled visits and tests and are able and willing to provide informed consent Exclusion Criteria: 1. Previously known ejection fraction \<30% 2. Previous PCI in the culprit vessel 3. Chronic total occlusion in major vessel 4. Any history of bleeding diathesis, known coagulopathy, or will refuse blood transfusions 5. Recent history or known platelet count \<100.000 cells/mm3 or Hbg \< 10 g/dL 6. Known reduced kidney function with estimated glomerular filtration rate (GFR) \<30 ml/min/1.73m2. 7. Previous hemorrhagic stroke 8. Ongoing oral anticoagulation treatment 9. Severe asthma requiring daily treatment 10. Any mechanical complication (e.g. ventricular septal defect, papillary muscle rupture, cardiac tamponade) 11. Atrioventricular block grade III 12. Known inability to undergo MRI investigation Permanent pacemaker * Pronounced claustrophobia 13. Known intolerance to study drug 14. Known intolerance to adenosine 15. Pregnancy 16. Participation in another investigational drug study 17. Previous randomization in the OPTIMAL-PCI trial