Primary Unloading and Delayed Reperfusion in ST-Elevation Myocardial Infarction: The STEMI-DTU Trial

Inclusion Criteria: 1. Age 18-85 years 2. First myocardial infarction 3. Acute anterior STEMI with ≥2 mm in 2 or more contiguous anterior leads or ≥ 4 mm total ST segment deviation sum in the anterior leads V1-V4 AND anterior wall motion abnormality noted on a diagnostic quality left ventriculogram or echocardiogram 4. Patient presents to the enrolling hospital where the index procedure will be performed between 1 - 6 hours after onset of continuous ischemic pain 5. Patient indicated for Primary PCI 6. Patient or the patient's Legally Authorized Representative (where applicable) has signed Informed Consent Exclusion Criteria: 1. Patient transferred from an outside hospital where invasive coronary procedure was attempted (including diagnostic catheterization) 2. Unwitnessed cardiac arrest OR ≥30 minutes of CPR prior to enrollment OR any cardiac arrest with impairment in mental status, cognition, or any global or focal neurological deficit 3. Administration of fibrinolytic therapy within 24 hours prior to enrollment 4. Cardiogenic shock defined as: systemic hypotension (systolic BP \<90 mmHg or the need for inotropes/pressors to maintain a systolic BP \>90mmHg) plus one of the following: any requirement for pressors/inotropes prior to arrival at the catheterization laboratory, clinical evidence of end organ hypoperfusion or use of IABP or any other circulatory support device 5. Inferior STEMI or suspected right ventricular failure 6. Any contraindication or inability to place the Impella, including peripheral vascular disease, tortuous vascular anatomy, femoral bruits or absent pedal pulses 7. Severe aortic stenosis 8. Acute cardiac mechanical complication: LV free wall rupture OR Interventricular septum rupture OR Acute mitral regurgitation 9. Suspected or known pregnancy 10. Suspected systemic active infection 11. History or known hepatic insufficiency prior to catheterization 12. On renal replacement therapy 13. COPD with home oxygen therapy or on chronic steroid therapy 14. Known or evidence of prior myocardial infarction, including pathologic Q waves in non-anterior leads 15. Prior CABG or LAD PCI 16. History of heart failure (documented history of EF \<40% or documented hospitalization for HF within one (1) year prior to screening) 17. Prior aortic valve surgery or TAVR 18. Left bundle branch block (new or old) 19. History of stroke/TIA within the prior 3 months, any history of Intracranial Hemorrhage or any permanent neurological deficit 20. History of bleeding diathesis or known coagulopathy (including heparin-induced thrombocytopenia), any recent GU or GI bleed, or will refuse blood transfusions 21. Patient on systemic anticoagulation pre-procedure (including factor Xa inhibitors, thrombin inhibitors, warfarin) Known contraindication to: 22. Undergoing MRI or use of gadolinium, \[CrCl\<30 ml/min, non-compatible implant, claustrophobia\] 23. Heparin, pork, pork products or contrast media 24. Receiving a drug-eluting stent 25. Participation in the active treatment or follow-up phase of another clinical study of an investigational drug or device which has not reached its primary endpoint. 26. Any organ condition, concomitant disease (e.g., psychiatric illness, severe alcoholism, or drug abuse, severe cancer, hepatic or kidney disease), with life expectancy of ≤2 years or other abnormality that itself, or the treatment of which, could interfere with the conduct of the study or that, in the opinion of the Investigator and/or Sponsor's medical monitor, would pose an unacceptable risk to the patient in the study. 27. Subject has other medical, social, or psychological problems that, in the opinion of the Investigator, compromises the subject's ability to give written informed consent and/or to comply with study procedures, including follow-up CMRs. 28. Subject belongs to a vulnerable population \[Vulnerable patient populations are defined as Individuals with mental disability, persons in nursing homes, children, impoverished persons, homeless persons, nomads, refugees, prisoners, and those permanently incapable of giving informed consent. Vulnerable populations also may include members of a group with a hierarchical structure such as university students, subordinate hospital and laboratory personnel, employees of the Sponsor, and members of the armed forces. * A pregnancy test will be conducted prior to enrollment if required by Institutional Review Board (IRB), Regional Ethics Board (REB), local Ethics Committee (EC) or competent authority.