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 mmtotal ST segment deviation sum in the anterior leads V1-V4 AND anterior wall motionabnormality noted on a diagnostic quality left ventriculogram or echocardiogram

4. Patient presents to the enrolling hospital where the index procedure will beperformed 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) hassigned Informed Consent

Exclusion Criteria:

1. Patient transferred from an outside hospital where invasive coronary procedure wasattempted (including diagnostic catheterization)

2. Unwitnessed cardiac arrest OR ≥30 minutes of CPR prior to enrollment OR any cardiacarrest with impairment in mental status, cognition, or any global or focalneurological 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 needfor inotropes/pressors to maintain a systolic BP >90mmHg) plus one of the following:any requirement for pressors/inotropes prior to arrival at the catheterizationlaboratory, clinical evidence of end organ hypoperfusion or use of IABP or any othercirculatory support device

5. Inferior STEMI or suspected right ventricular failure

6. Any contraindication or inability to place the Impella, including peripheralvascular disease, tortuous vascular anatomy, femoral bruits or absent pedal pulses

7. Severe aortic stenosis

8. Acute cardiac mechanical complication: LV free wall rupture OR Interventricularseptum 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 innon-anterior leads

15. Prior CABG or LAD PCI

16. History of heart failure (documented history of EF <40% or documentedhospitalization 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 IntracranialHemorrhage or any permanent neurological deficit

20. History of bleeding diathesis or known coagulopathy (including heparin-inducedthrombocytopenia), 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 studyof an investigational drug or device which has not reached its primary endpoint.

26. Any organ condition, concomitant disease (e.g., psychiatric illness, severealcoholism, or drug abuse, severe cancer, hepatic or kidney disease), with lifeexpectancy 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 theInvestigator and/or Sponsor's medical monitor, would pose an unacceptable risk tothe patient in the study.

27. Subject has other medical, social, or psychological problems that, in the opinion ofthe Investigator, compromises the subject's ability to give written informed consentand/or to comply with study procedures, including follow-up CMRs.

28. Subject belongs to a vulnerable population [Vulnerable patient populations aredefined as Individuals with mental disability, persons in nursing homes, children,impoverished persons, homeless persons, nomads, refugees, prisoners, and thosepermanently incapable of giving informed consent. Vulnerable populations also mayinclude members of a group with a hierarchical structure such as universitystudents, 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 byInstitutional Review Board (IRB), Regional Ethics Board (REB), local EthicsCommittee (EC) or competent authority.