Abstract Background Assessment of pressure recovery adjusted indexed aortic valve area (AVAi) – energy loss index (ELI) – has been shown of prognostic interest for patients with asymptomatic and/or mild aortic stenosis (AS), but limited data are available in the setting of low gradient aortic stenosis (LG-AS). Purpose We hypothesized that among these patients with LG-AS, reclassification of AS severity as moderate by ELI may help to identify a subgroup of patients with moderate AS. Methods 379 patients with low gradient severe AS (defined by AVAi ≤0.6 cm2/m2 and mean aortic pressure gradient (MPG) <40 mmHg) and preserved left ventricular ejection fraction (LVEF ≥50%) were prospectively included. Reclassification as moderate AS by ELI was defined as AVAi ≤0.6 cm2 /m2 but an ELI >0.6 cm2/m2. Clinical and echocardiographic features of patients reclassified by ELI were studied. Clinical outcomes were all-cause and cardiac mortality. Results 148 patients (39%) were reclassified as moderate AS by ELI. By multivariable logistic regression analysis, patients being reclassified as moderate AS by ELI were associated with increased stroke volume index (SVi), absence of documented coronary artery disease and decreased body surface area, left indexed ventricular mass (all p<0.05). During a median follow-up of 34 months (30–38 months), 119 patients died, 52 of them from cardiac causes. Three-year survival free from all-cause or cardiac death were 76±4%, 96±2% for patients with moderate AS by ELI and 71±3%, 84±3% for patients with severe AS by ELI (p=0.178 and p=0.013, respectively). After adjustment for variables of prognostic interest including aortic valve replacement as a time-dependent covariable, there was a significant reduction of risk of cardiac mortality in patients with moderate AS by ELI (adjusted HR 0.44 [95% CI, 0.23–0.85]; p=0.014) but not for all-cause mortality (adjusted HR 0.85 [95% CI, 0.58–1.25]; p=0.403) Conclusion In patients with low gradient “severe” AS and preserved ejection fraction, calculation of ELI permits to reclassify almost 40% of patients as having moderate AS. Patients reclassified as moderate AS by ELI had a reduction of risk of cardiac mortality during follow-up but not for all-cause mortality. Calculation of ELI may be useful for decision making in AS patients with discordant grading and preserved ejection fraction. Acknowledgement/Funding Local funding