Why is this study important?

• This is a much-awaited trial on the premise that ventricular unloading prior to primary percutaneous coronary intervention (PPCI) in anterior wall myocardial infarction improves myocardial salvage due to reduction in infarct size.
• A pilot clinical study had confirmed the safety and feasibility of mechanical left ventricular (LV) support with a TV-mAFP (Impella CP) plus delaying PCI for 30 minutes in patients with anterior STEMI without shock.

What question was this study supposed to answer?  

• Does the use of Impella CP for ventricular unloading for 30 minutes prior to PPCI in patients with anterior wall myocardial infarction without cardiogenic shock reduce infarct size as compared to immediate PPCI?

What did the study show?  

• Multicenter randomized trial, where 262 patients were randomized in the treatment arm to the Impella CP (via femoral access) for ventricular unloading prior to PPCI, and 265 patients in the control or PPCI arm. 
• Men constituted 79% of patients with a mean age of 60. 
• Left Anterior Descending (LAD) was the culprit vessel in > 97% of patients,
• Patients were followed for 12 months,
• Exclusions included:
  •   Unwitnessed cardiac arrest
  •   ≥30 minutes of CPR
  •   Any cardiac arrest with neurologic impairment
  •   Cardiogenic shock
  •   Acute cardiac mechanical complication
  •   Contraindication to Impella CP, drug-eluting stents, or contrast CMR
  •   Prior coronary angiogram or fibrinolysis or MCS for this admission
  •   Prior HF or severe Ao valve disease/intervention
  •   Prior Coronary Artery Bypass Grafting (CABG) PCI
• Cardiovascular magnetic resonance (CMR) was obtained to assess infarct size 
• There was a longer median total ischemic time at 47 min and median door-to-balloon time of 42 minutes in the treatment arm,
• At 12 months, ventricular unloading with TV-mAFP (Impella CP) plus a 30-minute delay to PCI did not reduce infarct size compared with immediate PPCI in patients with anterior STEMI without shock. There were no statistically significant differences in all-cause death (4% in the treatment arm vs 5.1% in the control arm, with p=0.51).
• Major bleeding (BARC 3-5) and vascular complications occurred in 34% of patients in the treatment arm vs 6% of the control patients.