With advances in devices and techniques of percutaneous coronary intervention (PCI), interventional cardiologists are managing patients with coronary artery disease of increasing complexity. For patients with prohibitive operative risk or who refuse bypass surgery, PCI may provide a reasonable alternative. Procedural haemodynamic stress often poses a significant challenge and is poorly tolerated in patients with reduced myocardial reserve, such as those with advanced heart failure or extreme frailty. The emergence of new mechanical circulatory support (MCS) devices has made PCI a more viable option for these high-risk patients. In this article, the authors review the existing evidence on the use of MCS in non-emergency complex and high-risk PCI, the optimal timing of initiating MCS and barriers to MCS use.