Author + information
- Li-Tan Yang1
Dobutamine stress echocardiography (DSE) is the best modality for CAD detection in patients who cannot exercise adequately. The visual estimation of stress-induced transient regional wall motion abnormalities are subjective and require expertise to achieve high accuracy. Disagreement in expert diagnostic results has been reported in an inter-institutional study. Following the advent of tissue Doppler and 2-dimensional (2D) speckle tracking analysis, several investigators have attempted to apply deformation imaging to obtain quantitative information to enhance diagnostic accuracy. There is currently no consensus regarding which parameter and which cut-off value of strain and/or strain rate is most appropriate for high diagnostic accuracy.
Although the bull’s eye map of longitudinal strain (LS) provides one look recognition of the severity and extent of longitudinal dysfunction, no studies have determined its potential utility during DSE. Furthermore, the effect of expertise on the diagnostic accuracy has not been determined. Accordingly, the aim of this study was 1) to compare diagnostic accuracy between visual analysis and strain assessment using a bull’s eye map for detecting significant CAD, and 2) to investigate the effect of expertise (expert and fellow physicians) on the diagnostic accuracy of strain analysis against visual assessment during DSE.
We retrospectively selected 37 patients who underwent both DSE and coronary angiography within 6 months. Three experts and two fellows performed visual and 2D speckle tracking analysis using vendor-dependent (GE) software on three apical views. A bull’s eye map of longitudinal strain (LS) and the post-systolic shortening (PSS) map were generated at baseline and peak stress. We defined significant coronary stenosis as >1% reduction in LS with an increase in the PSS of at least 2 contiguous segments in the specific coronary artery territory at peak stress compared with baseline.
Twenty-five patients had significant CAD (>70% stenosis on coronary angiography), including 17 with left anterior descending coronary artery (LAD) stenosis and 19 with non-LAD stenosis. Overall, strain imaging provides no additional benefit over visual analysis in detecting significant stenosis in patient basis as well as vessel basis for experts and fellows. Strain analysis by the fellow had a significantly lower specificity and accuracy compared with the expert.
Figures 1 and 2 shows two representative cases, including one case with concordant LAD abnormality in all 5 examiners (Figure 1), and one case with discordant results (Figure 2).
Strain analysis with a bull’s eye map had no obvious benefits over visual analysis for CAD diagnosis during DSE. Expertise affects not only visual wall motion estimation but also deformation analysis for detecting significant CAD.