BACKGROUND: Left ventricular global longitudinal strain (GLS) is associated with long-term outcomes of patients with severe aortic stenosis. However, its prognostic value in patients with moderate aortic stenosis remains unknown. METHODS: Patients diagnosed with moderate aortic stenosis (1.0< aortic valve area </=1.5 cm(2)) and left ventricular ejection fraction >/=50% were identified. GLS was assessed by 2-dimensional strain imaging using speckle-tracking method. All-cause mortality was assessed according to the median GLS value. RESULTS: Two hundred eighty-seven patients were included (median age 76 years; 47% male). Mean aortic valve area was 1.25 cm(2), left ventricular ejection fraction 62%, and median GLS -15.2%. During a median follow-up of 3.9 years, there were 103 deaths (36%). Mortality was higher in patients with GLS>-15.2% (hazard ratio 2.62 [95% CI 1.69-4.06]) compared with patients with GLS </=-15.2% even after adjusting for confounders. Mortality rates at 1, 3, 5 years were 21%, 35%, 48%, respectively, in patients with GLS >-15.2%, and 6%, 15%, 19% in those with GLS </=-15.2%. Even among those with left ventricular ejection fraction >/=60%, GLS discriminated higher-risk patients (P=0.0003). During follow-up, 106 (37%) patients underwent aortic valve replacement with median waiting-time of 2.4 years, and their survival was better than patients without aortic valve replacement. Among those patients undergoing aortic valve replacement, prognosis was still worse in patients with GLS >-15.2% (P=0.04). Mortality rates at 1, 3, 5 years were 2%, 10%, 20%, respectively, in patients with GLS >-15.2% and 2%, 5%, 6% in those with GLS </=-15.2%. CONCLUSIONS: Impaired GLS in moderate aortic stenosis patients is associated with higher mortality rates even among those undergoing aortic valve replacement.