Diagnostic value of aortic valve displacement by tissue tracking for identification of aortic valve stenosis severity

Abstract

Abstract Background The assessment of aortic stenosis (AS) severity on transthoracic echocardiography (TTE) may be challenging, especially in normal flow, low gradient (NF LG) group with preserved ejection fraction (EF), where reclassification of AS severity after initial TTE was observed in 52% pts (1). Calcifications and fibrosis of valve leaflets result in increased stiffness and impaired mobility, which can be quantified by tissue tracking (TT). TT is an echocardiographic modality that displays longitudinal displacement of selected area by integrating tissue velocity over time. Purpose Assessment of the diagnostic value of aortic valve displacement (AVD) by TT as a test that may increase accuracy of AS severity diagnosis in TTE. Methods 205 pts (aged 71±10 yrs, men 43%) without more than mild aortic regurgitation, mitral or tricuspid valve disease, EF ≤55%, indexed stroke volume (SVI) ≤35 ml/m2, cardiac rhythm disturbances and poor acoustic window were selected out of 842 pts screened for AS in our institution between 2020 and 2023. Based on aortic valve area (AVA) value, moderate (n=51, AVA >1.0 cm2) or severe (n=154, AVA ≤1.0 cm2) AS was diagnosed. In severe AS group, 45 pts were classified as NF LG AS (mean gradient <40 mmHg). Additionally 30 pts (aged 68±10 yrs, men 46%) without abnormalities on TTE entered control group. During TTE in five- and three-chamber views, TT was applied and region of interest was adjusted to cover whole aortic valve (AV) during cardiac cycle. Single loop was analysed with Q-analysis software. The measurement in millimetres (mm) of positive wave representing displacement of AV was performed in both views by two independent echocardiographers (Figure 1). AVD was calculated by summing up results from both views. Receiver-operating characteristic curves for AVD in the whole study group and NF LG AS to diagnose severe AS were plotted. Results AVD was already significantly decreased in moderate AS compared with age- and sex-matched healthy controls, being 22.8±2.8 mm and 24.3±2.1 mm respectively (P=0.01). In pts with severe AS, AVD was further significantly reduced compared to moderate AS pts, being 19.3±3.2 mm (P<0.0001). In the whole study group, AVD with a cut-off point <19.6 mm provided 55.8% sensitivity but 96.1 % specificity to diagnose severe AS (Figure 2B). In pts with NF LG AS, AVD with a cut-off point <20.6 mm provided 71.4% sensitivity and a specificity of 79.6% (Figure 2A). Intraclass correlation coefficient of 0.87; 95% CI (0.84–0.89) indicated good interobserver reproducibility of AVD measurement. Conclusions Aortic valve displacement by tissue tracking in TTE is a valuable, new echocardiographic tool for identification of AS severity and may improve diagnostic accuracy of AS severity in NF LG AS.Figure 1Figure 2