Reproduced from O'Neill WW et al. A Prospective, Randomized Clinical Trial of Hemodynamic Support With Impella 2.5 Versus Intra-Aortic Balloon Pump in Patients Undergoing High-Risk Percutaneous Coronary Intervention: The PROTECT II Study. Circulation 2012;126(14):1717–1727. With permission from Lippincott, Williams and Wilkins.