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Purpose:In patients with low flow-low gradient aortic stenosis (LFAS) dobutamine stress echo allows discrimination between true and pseudosevere aortic stenosis but reduced left ventricular contractility needs further evaluation of the amount of residual viability (revealed by 18FDG-PET) to estimate the potential of improvement. We investigated the value of peak systolic longitudinal 2-D strain (PLS) for discrimination between different viability states in comparison to 18FDG-PET.Methods:22 patients with LFAS (valve area(AVA)≤1.2cm2(indexed AVA≤0.6cm2/m2),LVEF≤40%and mean pressure gradient≤40mmHg) were enrolled. All patients underwent N-13 ammonia (13) (perfusion scan) and 18FDG-PET (18) (metabolism scan) and were thus classified as follows: Normal (13 uptake>70%), perfusion/metabolism mismatch (13 uptake≤70% and 18>70%), perfusion/metabolism match (13 uptake≤70% and 18<70%) and scarred segments (S) (13uptake≤70% and 18<50%). Subsequently we arranged S into groups:viable (normal and mismatch) versus reduced viability (match and scar) and normal versus scar. PLS analysis was performed offline in the apical 4,3, and 2 chamber views for each step: echo at rest, 10mcg/kg/h (LDD) and peak dose (PDD) dobutamine. We used bull's eye analysis with an 18 segment model to compare 18FDG-PET with speckle tracking echo.Results:16male and 6female patients, age70±12years (mean±SD) were examined. LVEF was 29±11%, AVA-index 0,4±0,1cm2/m2. Segmental classification by 18FDG-PET: We found 324 viable S (Rest-6,5±6,8 LDD-7,6±7,1 PDD-7,3±6,9) and 72 (Rest-4,5±6,4 LDD-3,7±8,0 PDD-4,1±7,5) S with reduced viability (p= 0,023at Rest; p=0,000 at LDD and p=0,000 at PDD). Sub-analysis showed 262 (Rest-6,5±6,8 LDD-7,8±7,2 PDD-7,6±6,9) normal S and 22 (Rest-3,1±6,0 LDD-1,3±7,0 PDD-3,8±6,5) scarred S (p=0,025 at Rest; p=0,000 at LDD and p=0,014 at PDD). PLS values for different viability states and their sensitivity/ specificity: viable/reduced viability: Rest-6,8 56%; LDD-7, 62%; PDD-6,8 62%. Scar/normal: Rest-5,6, 65%; LDD-6, 70%; PDD-6, 68%. ROC AUCs for differentiation of viable from S with reduced viability: Rest0,59; LDD0,65, PDD0,63. ROC AUCs for differentiation of normal from scar S: Rest0,66; LDD0,76; PDD0,68.Conclusions:In patients with LFAS PLS is significantly impaired in S with reduced viability compared to viable S and even more impaired in scar compared to normal S. Dobutamine administration improves differentiation of viable from S with reduced viability by PLS with best performance at LDD levels. PLS in the setting of DSE in patients with LFAS may provide a new tool to discriminate different states of viability.