The aim of this case match study was to compare the outcome of patients with paradoxical low-flow (left ventricular ejection fraction [LVEF] ≥50% but stroke volume index 1.0 cm(2) and MG <40 mm Hg) (MAS group).In patients with preserved LVEF, a discordance between the AVA (in the severe range) and the gradient (in the moderate range) raises uncertainty with regard to the actual severity of the stenosis and thus the therapeutic management of the patient.In a prospective cohort of AS patients with LVEF ≥50%, we identified 187 patients in the PLG-SAS group. These patients were retrospectively matched: 1) according to the gradient, with 187 patients with MAS; and 2) according to the AVA, with 187 patients with HG-SAS.Patients with PLG-SAS had reduced overall survival (1-year: 89 ± 2%; 5-year: 64 ± 4%) compared with patients with HG-SAS (1-year: 96 ± 1%; 5-year: 82 ± 3%) or MAS (1-year: 96 ± 1%; 5-year: 81 ± 3%). After adjustment for other risk factors, patients with PLG-SAS had a 1.71-fold increase in overall mortality and a 2.09-fold increase in cardiovascular mortality compared with the 2 other groups. Aortic valve replacement was significantly associated with improved survival in the HG-SAS group (hazard ratio: 0.18; p = 0.001) and in the PLG-SAS group (hazard ratio: 0.50; p = 0.04) but not in the MAS group.Prognosis of patients with paradoxical low-flow, low-gradient severe AS was definitely worse than those with high-gradient severe AS or those with moderate AS. The finding of a low gradient cannot exclude the presence of a severe stenosis in a patient with a small AVA and preserved LVEF and should mandatorily prompt further investigation.