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Differential Myocardial Fibre Involvement by Strain Analysis in Patients With Aortic Stenosis. BACKGROUND: Aortic stenosis (AS) is the most common valvular heart disease and can result in left ventricular (LV) systolic impairment. LV myocardial fibres are organised in layers: the subendocardial layer is orientated longitudinally and the subepicardial layer circumferentially. We hypothesised that there is differential involvement of myocardial fibres in patients with aortic stenosis. METHODS: We performed multi-directional, multi-layered systolic strain analysis in 70 patients (aged 72±10.7years) with varying grades of AS severity (mean gradient 32.3±20mmHg, aortic valve area 1.1±0.6cm2) and in 30 controls. Clinical, demographic and resting echocardiographic data were recorded. Left ventricular subendocardial and subepicardial systolic strains were measured in the longitudinal, radial and circumferential axes. RESULTS: Systolic subendocardial strain was significantly higher than subepicardial strain in all three axes in patients and in controls. There were significant differences in longitudinal, but not in circumferential and radial strain, or left ventricular ejection fraction (LVEF), between patient groups. Aortic valve mean gradient (MG) and valve area (AVA) correlated better with subendocardial longitudinal strain (r=0.548, p<0.001; r=-0.54, p<0.001 respectively) than with subepicardial longitudinal strain (r=0.496, p<0.001, r=-0.544, p<0.001 respectively). Correlations between circumferential and radial strain and MG or AVA were poor. CONCLUSIONS: There was differential impairment in LV systolic strain in all three cardiac axes in patients with AS. Left ventricular longitudinal strain impairment was proportional to AS severity. Subendocardial longitudinal strain correlated better with AS severity than subepicardial longitudinal strain while correlations between circumferential and radial strain and AS severity were weak.