Patients undergoing percutaneous coronary intervention (PCI) who have severely compromised left ventricular systolic function and complex coronary lesions including multivessel disease, left main disease, or bypass graft disease are at higher risk of adverse outcomes from hemodynamic collapse. The TandemHeart percutaneous left ventricular assist device and the Impella Recover LP 2.5 System may provide rapid circulatory support in high-risk PCI patients and in those who have cardiogenic shock. Identification of patients who are at high risk for severe hemodynamic compromise and most likely to benefit from mechanical circulatory support is crucial to derive the most benefit from this therapy. Multicenter randomized clinical trials are needed to clearly define the role of these two devices in providing circulatory support in a variety of clinical settings.