Impella LP2.5 vs. IABP in Cardiogenic SHOCK - ISAR-SHOCK


The goal of the trial was to evaluate treatment with an Impella percutaneous left ventricular assist device (LVAD) compared with an intra-aortic balloon pump (IABP) in patients with cardiogenic shock due to acute myocardial infarction (AMI). The Impella device is implanted through a 13 French sheath in the common femoral artery and inserted through the aortic valve into the left ventricle. It provides axial flow to the ascending aorta at a maximum flow rate of 2.5 L/min.


The percutaneous LVAD would be more effective in improving hemodynamic support.

Study Design

  • Randomized
  • Parallel

Patients Enrolled: 26
Mean Follow Up: 30 days
Mean Patient Age: Median 66 years
Female: 27
Mean Ejection Fraction: 27%

Patient Populations:

  • Patients with AMI within 48 hours and cardiogenic shock
  • Cardiogenic shock was defined as systolic blood pressure <90 mm Hg and heart rate >90 bpm or the need for inotropic drugs. Patients also needed evidence of end-organ hypoperfusion (cool extremities, low urine output, low cardiac index, or elevated pulmonary capillary wedge pressure).


  • Age <18 years
  • More than 30 minutes of resuscitation
  • Hypertrophic obstructive cardiomyopathy
  • Thrombus in the left ventricle
  • Treatment with an IABP
  • Severe valvular heart disease or a mechanical heart valve
  • Mechanical complication of AMI
  • Sepsis
  • Cerebral disease
  • Severe bleeding
  • Pulmonary embolus
  • Heparin allergy or coagulopathy
  • Inclusion in another clinical trial

Primary Endpoints:

  • Change in cardiac index from baseline to 30 minutes after device implantation

Secondary Endpoints:

  • Change in lactic acidosis
  • Hemolysis
  • Mortality at 30 days

Drug/Procedures Used:

Patients with cardiogenic shock due to AMI were randomized to an Impella LVAD (n = 13) versus an IABP (n = 13). The device was implanted after percutaneous coronary intervention (PCI) was performed.

Concomitant Medications:

For as long as the hemodynamic support device was implanted, patients were maintained on continuous heparin infusion to achieve a partial thromboplastin time of 60-80 seconds.

Principal Findings:

Overall, 26 patients were randomized, and baseline characteristics between the groups were well matched. In the Impella arm, the median age of participants was 65 years, LV ejection fraction was 27%, peak creatine kinase was 3,719, and time from symptoms until randomization was 4.5 hours. The time required to implant the Impella device was 22 minutes versus 14 minutes for the IABP (p = 0.40). PCI was performed in 92% of each group. One patient died in the Impella group prior to receiving the device.

In the Impella arm, cardiac index was 1.71 L/min/m2 at baseline and 2.20 L/min/m2 at 30 minutes (change 0.49 L/min/m2). In the IABP arm, cardiac index was 1.73 L/min/m2 at baseline and 1.84 L/min/m2 at 30 minutes (change 0.11 L/min/m2) (p = 0.02 for change in cardiac index with Impella compared with change in cardiac index with IABP; p = 0.18 for comparison of cardiac index between groups). After 30 hours, cardiac index was 2.51 L/min/m2 in the Impella group versus 2.40 L/min/m2 in the IABP group.

The mean arterial blood pressure increased by 9.0 mm Hg in the Impella arm versus decreased by 1.2 mm Hg in the IABP group (p = 0.09). The area under the curve for serum lactate during 48 hours was 123 hours · mmol/L versus 180 hours · mmol/L (p = 0.12), and 30-day mortality was 46% versus 46% (p = NS), respectively. The Impella device was used for 25 hours versus 23 hours for the IABP device.

There was one case of acute limb ischemia after the Impella device was removed versus no limb ischemia in the IABP group. The Impella group required transfusion of 2.6 U packed red blood cells versus 1.2 U in the IABP group (p = 0.18).


Among patients with cardiogenic shock due to AMI, the Impella device resulted in a greater change in 30-minute cardiac index compared with the IABP; however, at all measured time points, including 30 minutes and after 30 hours, cardiac index was similar between the groups. Although underpowered for clinical outcomes, 30-day mortality was the same in both groups.

A significant limitation of this trial was the lack of adjudication for major bleeding, which would likely not be trivial due to an indwelling 13 French catheter. This was partly evidenced by the greater need for packed red blood cell transfusion in the Impella group. Another safety signal was noted by the one episode of acute limb ischemia in the Impella group. Future studies will need to examine the clinical efficacy and safety of this device.


Seyfarth M, Sibbing D, Bauer I, et al. A randomized clinical trial to evaluate the safety and efficacy of a percutaneous left ventricular assist device (Impella LP2.5) versus intra-aortic balloon pumping for treatment of cardiogenic shock caused by myocardial infarction. J Am Coll Cardiol 2008:52:1584-1588.

Clinical Topics: Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Aortic Surgery, Cardiac Surgery and Heart Failure, Acute Heart Failure, Mechanical Circulatory Support

Keywords: Myocardial Infarction, Erythrocyte Transfusion, Creatine Kinase, Pulmonary Wedge Pressure, Arterial Pressure, Heart-Assist Devices, Femoral Artery, Heart Rate, Percutaneous Coronary Intervention, Lactates, Shock, Cardiogenic, Heart Failure, Intra-Aortic Balloon Pumping

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