Incremental Value of Strain Rate Analysis as an Adjunct to Wall-Motion Scoring for Assessment of Myocardial Viability by Dobutamine Echocardiography

Abstract

Assessment of myocardial viability based on wall-motion scoring (WMS) during dobutamine echocardiography (DbE) is difficult and subjective. Strain-rate imaging (SRI) is quantitative, but its incremental value over WMS for prediction of functional recovery after revascularization is unclear. DbE and SRI were performed in 55 stable patients (mean age, 64+/-10 years; mean ejection fraction, 36+/-8%) with previous myocardial infarction. Viability was predicted by WMS if function augmented during low-dose DbE. SR, end-systolic strain (ESS), postsystolic strain (PSS), and timing parameters were analyzed at rest and with low-dose DbE in abnormal segments. Regional and global functional recovery was defined by side-by-side comparison of echocardiographic images before and 9 months after revascularization. Of 369 segments with abnormal resting function, 146 showed regional recovery. Compared with segments showing functional recovery, those that failed to recover had lower low-dose DbE SR, SR increment (DeltaSR), ESS, and ESS increment (DeltaESS) (each P<0.005). After optimal cutoffs for the strain parameters were defined, the sensitivity of low-dose DbE SR (78%, P=0.3), DeltaSR (80%, P=0.1), ESS (75%, P=0.6), and DeltaESS (74%, P=0.8) was better though not significantly different from WMS (73%). The specificity of WMS (77%) was similar to the SRI parameters. Combination of WMS and SRI parameters augmented the sensitivity for prediction of functional recovery above WMS alone (82% versus 73%, P=0.015; area under the curve=0.88 versus 0.73, P<0.001), although specificities were comparable (80% versus 77%, P=0.2). The measurement of low-dose DbE SR and DeltaSR is feasible, and their combination with WMS assessment improves the sensitivity of viability assessment with DbE.