Abstract Background Aortic stenosis (AS) is the most common primary valve disease leading to surgery or catheter intervention with a growing prevalence due to the ageing population. Severe aortic stenosis with reduced transaortic flow and gradient although it is a common finding still remains diagnostic challenge. Purpose The aim of study was to analyse the outcomes of patients with high- and low-gradient aortic stenosis depending on the ejection fraction. Methods 621 patients hospitalized in the First Department of Cardiology, with severe aortic stenosis defined as aortic valve area <1cm2 were enrolled to the Aortic Stenosis Registry (ASRegistry). The high-gradient aortic stenosis (HG-AS) [mean transvalvular pressure gradient (PGmean) ≥40mmHg and peak transvalvular velocity (Vmax) ≥ 4 m/s] and low-gradient aortic stenosis (LG-AS) [mean transvalvular pressure gradient (PGmean) <40mmHg and peak transvalvular velocity (Vmax) <4 m/s] were observed in 54%(n = 340) and 45% (n = 281) patients, respectively. In the subgroup of HG-AS were 80% (n = 275) and in the subgroup of LG-AS were 61%(n = 174) of patients with preserved left ventricle ejection fraction (LVEF > 50%). The patients were observed for a period of 6 years (2012-2018). The primary end-point, all-cause mortality, was obtained from Nation Health Registry. Results Patients with LG-AS had a significantly higher risk of mortality compared to patients with HG-AS: 35% (n = 101) vs 26% (n = 87), p < 0,05. Mortality in both group with HG-AS and LG-AS was significantly higher in the subgroup with diminished left ventricle dysfunction than in the subgroup with preserved ejection fraction: HG-AS: 44%(n = 29) vs 21%(n = 58), p < 0,05 and LG-AS: 53%(n = 57) vs 25%(n = 44), p < 0,05. The highest mortality rates was observed in the LG-AS group with left ventricule dysfunction, p < 0,001. Conclusions The study shows the negative impact of left ventricle dysfunction in both groups of patients: high- and low-gradient severe aortic stenosis. The worst prognosis is in patients with LG-AS and low LVEF.