Incremental value of strain rate analysis as an adjunct to wall-motion scoring for assessment of myocardial viability by dobutamine echocardiography - A follow-up study after revascularization

Background - 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. Methods and Results - 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 (Delta SR), ESS, and ESS increment (Delta ESS) ( each P < 0.005). After optimal cutoffs for the strain parameters were defined, the sensitivity of low-dose DbE SR (78%, P = 0.3), Delta SR (80%, P = 0.1), ESS (75%, P = 0.6), and Delta ESS (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). Conclusions - The measurement of low-dose DbE SR and Delta SR is feasible, and their combination with WMS assessment improves the sensitivity of viability assessment with DbE.