• Cardiac index [ Time Frame: within 1 hour after device implantation ]
  

• Hemodynamic and metabolic parameters [ Time Frame: until to hospital discharge ]
  
• Mortality [ Time Frame: within 30 and 180 days ]
  
• device-related complications:hemolysis and major bleedings [ Time Frame: during hospitalization ]
  

Cardiogenic shock due to a left ventricular failure after myocardial infarction (MI) is associated with a mortality rate of 50-70 % despite all efforts such as immediate PCI of the occluded vessel, positive inotropic drugs, and the use of intraaortic balloon counterpulsation (IABP). While urgent heart transplantation or the surgical implantation of high-volume left ventricular assist devices are possible treatment options, a widespread use of these techniques for this common complication of myocardial infarction is limited. Because of the easy, percutaneous use of an intraaortic balloon pump, IABP is the method of choice for mechanical assistance in these patients. Despite a lack of randomized data, the ACC/AHA guidelines recommend the use of an intraaortic balloon counterpulsation (Level of evidence IB) in patients with a cardiogenic shock after myocardial infarction. However, improvement of the hemodynamic state by the use of an IABP is limited and the lack of an active cardiac support remains the major limitation of this treatment. Percutaneous left ventricular assist devices may both overcome the limitation of a surgical approach and offer the potential benefit of an active cardiac support during recovery of the failing left ventricle after PCI.

Previous studies have demonstrated a significant improvement of hemodynamic parameters by the use of a catheter-based miniaturized rotary blood pump (Impella LP2.5, Abiomed-Impella CardioSystems GmbH, Aachen, Germany), that is placed retrogradely through the aortic valve. The microaxial pump aspirates blood from the left ventricle and expels it to the ascending aorta with a maximal flow of 2.5 L/min. Randomized data comparing the LVAD with IABP are missing. Therefore, this trial will primarily compare the hemodynamic improvement of the LVAD (Impella LP2.5) with the hemodynamic improvement of an intraaortic balloon counterpulsation (IABP), while secondarily feasibility, safety and mortality will be compared.