BACKGROUND In asymptomatic patients with severe aortic stenosis, guidelines recommend left ventricular ejection fraction (LVEF) of <50% as the threshold for referral for aortic valve replacement. We investigated the importance of LVEF on long-term outcome after aortic valve replacement in symptomatic and asymptomatic patients with severe aortic stenosis. RESULTS We retrospectively identified 2017 patients with severe aortic stenosis (aortic valve area<1 cm(2), mean gradient≥40 mm Hg, or indexed aortic valve area<0.6 cm(2)/m(2)) who underwent surgical aortic valve replacement from January 1995 to June 2009. Patients were divided into 4 groups depending on preoperative LVEF (<50% in 300 [15%] patients, 50%-59% in 331 [17%], 60%-69% in 908 [45%], and ≥70% in 478 [24%]). During follow-up of 5.3±4.4 years, 1056 (52%) patients died. A decrease in mortality was observed with increasing LVEF, P<0.0001; 5-year mortality estimates (95% confidence interval) were 0.41 (0.35-0.47), LVEF<50%; 0.35 (0.29-0.41), LVEF 50% to 59%; 0.26 (0.23-0.29), LVEF 60% to 69%; and 0.22 (0.18-0.26), LVEF≥70%. Compared with patients with LVEF≥60%, patients with LVEF 50% to 59% had increased mortality (hazard ratio [HR], 1.58; P<0.001), with similar risk increase in both symptomatic (HR, 1.56; P<0.001) and asymptomatic patients (HR, 1.58; P=0.006). Correcting for risk factors, LV mass index, aortic valve area, and stroke volume index, LVEF was independently predictive of mortality (HR, 0.88 per 10%; P<0.001). When this analysis was repeated in the subset of 1333 patients without history of coronary artery disease, LVEF remained associated with mortality (HR, 0.90 per 10%; P=0.009). CONCLUSIONS LVEF is a powerful predictor of outcome in patients with severe aortic stenosis undergoing aortic valve replacement, independent of the presence of valve-related symptoms.