Cardiopulmonary support (CPS) has been shown to be a useful addition to interventional cardiology when considering alternatives for high-risk patients. Cardiopulmonary support systems are capable of up to 6 liters/min output and can be used prophylactically to prevent hemodynamic collapse following balloon occlusions or acute vessel closure. The technique, supported angioplasty, results in reductions of preload and afterload and allows prolonged balloon inflations in critical coronary vessels. Although it provides excellent support for most high-risk patients, CPS is a technically challenging and expensive procedure associated with significant patient morbidity. Standby CPS patients are prepared for institution of CPS, but bypass is not actually initiated unless the patient sustains irreversible hemodynamic compromise. In this study, standby and prophylactic patients had comparable success and major complication rates, but procedural morbidity was more frequent in prophylactic patients. Further study will better define appropriate patient selection for standby versus prophylactic CPS.