Impella left ventricular assist device (Abiomed). Impella 2.5 circulatory support system (Abiomed) can be inserted percutaneously via femoral artery and can pump up to 2.5 L of blood from left ventricle into aorta. Source: AJR 2009;193(1):W14-W24

The 30-day incidence of major adverse events (MAE) was not different for patients with intra-aortic balloon (IABP) or Impella 2.5 hemodynamic support; however, trends for improved outcomes were observed for Impella 2.5-supported patients at 90-days, according to a PROTECT II study published online Aug. 30 in Circulation.

While CABG is generally preferred in symptomatic patients with severe, complex multivessel or left main disease, some patients present with clinical features that make CABG clinically unattractive. PCI with hemodynamic support may be feasible for these patients, wrote the study authors. Currently, there is no systematic comparative evaluation of hemodynamic support devices for this indication.

PROTECT II was a prospective multicenter randomized trial conducted in 112 sites in the U.S., Canada and Europe. The study was designed to assess whether a high-risk percutaneous revascularization strategy with the support of the Impella 2.5 device would result in a better outcome than a revascularization strategy with IABP support.  

For this study, William W. O’Neill, MD, of the division of cardiology at the Leonard M. Miller School of Medicine at the University of Miami, and colleagues randomly assigned 452 symptomatic patients with complex three-vessel disease or unprotected left main coronary artery disease and severely depressed left ventricular function to IABP (226 patients) or Impella 2.5 (226 patients) support during non-emergent high-risk PCI.

The primary endpoint was the 30-day incidence of MAE. A 90-day follow-up was required as well by protocol.

The researchers reported that the Impella 2.5 provided superior hemodynamic support compared to IABP, with maximal decrease in cardiac power output from baseline of -0.04 Watts compared with -0.14 Watts for IABP.

The primary endpoint (30-day MAE) was not statistically different between groups, according to the study authors: 35.1 percent for Impella 2.5 vs. 40.1 percent for IABP in the intent-to-treat (ITT) population and 34.3 percent vs. 42.2 percent in the per patient protocol population.

At 90 days, they discovered a strong trend toward decreased MAE was observed in Impella 2.5-supported patients compared to IABP: 40.6 percent vs. 49.3 percent in the ITT population, 40 percent vs. 51 percent in PP populations, respectively.

“Our results suggest that PCI is a reasonable revascularization strategy for this high-risk population since it improves heart failure symptoms and the quality of life of patients with limited therapeutic options,” O’Neill et al wrote.

The ITT analysis did not show a statistically significant difference in MAE at 30 days with 69 percent of the planned enrollment whereas a trend toward better outcomes was observed at 90 days for the Impella 2.5-supported patients, the study authors pointed out.

There was no difference in mortality between groups in either the ITT or per protocol populations. Patients randomized into the IABP arm had a significantly higher rate of repeat revascularization procedures. “It is noteworthy that the rate of vascular operations in the Impella 2.5 arm was not different than that of the IABP arm, so there was no burden associated with the use of the larger sheath,” the researchers wrote. “Similarly, we did not observe any aortic or mitral valve dysfunction or left ventricular injury which confirms the safety profile of the Impella 2.5 device with respect to ventricular and valve function and integrity, which is consistent with prior reports.”

In the PROTECT II patients, PCI resulted in a marked reduction of symptoms and increased left ventricular function, O’Neill et al concluded. “Hemodynamic support with Impella 2.5 did not result in a superior outcome of the primary endpoint at 30 days but showed a strong trend to superior outcome at 90 days in the total cohort and a significant improvement in the per protocol analysis at 90 days,” they wrote. “Important adverse events continued to occur after 30-day follow-up suggesting that intense medical observation is required for at least 90 days in these patients.”

Abiomed, the maker of Impella 2.5, sponsored the trial.