Background-The age, creatinine, and ejection fraction (ACEF) score (age/left ventricular ejection fractionϩ1 if creatinine Ͼ2.0 mg/dL) has been established as an effective predictor of clinical outcomes in patients undergoing elective coronary artery bypass surgery; however, its utility in "all-comer" patients undergoing percutaneous coronary intervention is yet unexplored. Methods and Results-The ACEF score was calculated for 1208 of the 1707 patients enrolled in the LEADERS trial. Post hoc analysis was performed by stratifying clinical outcomes at the 1-year follow-up according to ACEF score tertiles: ACEF low Յ1.0225, 1.0225Ͻ ACEF mid Յ1.277, and ACEF high Ͼ1.277. At 1-year follow-up, there was a significantly lower number of patients with major adverse cardiac event-free survival in the highest tertile of the ACEF score (ACEF low ϭ92.1%, ACEF mid ϭ89.5%, and ACEF high ϭ86.1%; Pϭ0.0218). Cardiac death was less frequent in ACEF low than in ACEF mid and ACEF high (0.7% vs 2.2% vs 4.5%; hazard ratioϭ2.22, Pϭ0.002) patients. Rates of myocardial infarction were significantly higher in patients with a high ACEF score (6.7% for ACEF high vs 5.2% for ACEF mid and 2.5% for ACEF low ; hazard ratioϭ1.6, Pϭ0.006). Clinically driven target-vessel revascularization also tended to be higher in the ACEF high group, but the difference among the 3 groups did not reach statistical significance. The rate of composite definite, possible, and probable stent thrombosis was also higher in the ACEF high group (ACEF low ϭ1.2%, ACEF mid ϭ3.5%, and ACEF high ϭ6.2%; hazard ratioϭ2.04, PϽ0.001). Conclusions-ACEF score may be a simple way to stratify risk of events in patients treated with percutaneous coronary intervention with respect to mortality and risk of myocardial infarction. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00389220. (Circ Cardiovasc Interv. 2011;4:47-56.)