Background Elective intraaortic balloon pump (IABP) may reduce acute complications during unprotected left main (ULM) stenting. However, few data exist on criteria for elective IABP support during ULM stenting. Methods Since January 1993, 219 consecutive patients underwent elective ULM stenting: 69 had elective IABP support (elective IABP group), whereas 150 patients had conventional procedure (conservative group). Criteria for elective IABP support were (1) lesion located in the distal segment of the left main (bifurcation lesion), (2) left ventricular ejection fraction 6 (identifying high-risk patients) occurred in 38% in the elective IABP group and 13% in the conservative group (P 6 plus bifurcation lesion (OR 5.49; 95% CI 1.47-20.5 1; P = .011) were the independent predictors of. intraprocedural events. Conclusions Elective IABP may prevent intraprocedural events in elective ULM stenting, especially in patients at higher risk.