Assessment of myocardial viability at dobutamine echocardiography by deformation analysis using tissue velocity and speckle-tracking

Objectives Comparison of myocardial tissue-velocity imaging (TVI) and speckle-tracking echocardiography (STE) for prediction of viability at dobutamine echocardiography (DbE). Background Use of TVI-based strain imaging during DbE may facilitate the prediction of myocardial viability but has technical limitations. STE overcomes these but requires evaluation for prediction of viability. Methods We studied 55 patients with ischemic heart disease and left ventricular systolic dysfunction (left ventricular ejection fraction <0.45) who were undergoing DbE for assessment of myocardial viability and who subsequently underwent myocardial revascularization. TVI was used to measure longitudinal end-systolic strain (longS) and peak systolic strain rate (SR) at rest and at low-dose dobutamine (LDD). Longitudinal, radial, and circumferential strain and strain rate were measured with STE. Segmental functional recovery was defined by improved wall-motion score on side-by-side comparison of echocardiographic images before and 9 months after revascularization and areas under the receiver operator characteristic curves were used to compare methods. Results Of the 375 segments with abnormal resting function, 154 (41%) showed functional recovery. Only circumferential resting and low-dose STE strain and low-dose longitudinal strain and SR predicted functional recovery independent of wall-motion analysis. Among different strain parameters, only TVI-based longitudinal end-systolic strain and peak systolic SR at LDD had incremental value over wall-motion analysis (areas under the receiver operator characteristic curves of 0.79, 0.79, and 0.74, respectively). STE measurements of strain and SR identified viability only in the anterior circulation, whereas TVI strain and SR accurately identified viability in both anterior and posterior circulations. Conclusions Combination of TVI or STE methods with DbE can predict viability, with TVI strain and SR at LDD being the most accurate. TVI measures can predict viability in both anterior and posterior circulations, but STE measurements predict viability only in the anterior circulation. The detection of myocardial viability in patients with ischemic left ventricular (LV) dysfunction has potential therapeutic and prognostic implications ( 1). Dobutamine echocardiography (DbE) has comparable accuracy to other approaches for the assessment of myocardial viability ( 2), but involves subjective assessment of wall-thickening responses to dobutamine stimulation and is highly operator-dependent ( 3). Measurement of myocardial deformation with tissue-velocity imaging (TVI) during DbE has comparable accuracy to expert wall-motion analysis for prediction of functional recovery ( 4). However, the wider application of Doppler strain in clinical practice has been constrained by its susceptibility to signal noise and dependence on the angle of insonation ( 5). Angle dependency is not a problem with 2-dimensional speckle-tracking echocardiography (STE), but this technique is dependent on image quality and operates at limited frame rate ( 6 7 ). STE-based myocardial strain has been validated against other techniques, used to measure the amplitude and timing of function at rest, and applied (with more difficulty) during stress ( 8 9 10 ). However, its utility in the DbE assessment of myocardial viability has not been studied. In the present study, we sought to determine the relative accuracy of TVI- and STE-based measurements of myocardial strain for the detection of myocardial viability.