Utility of strain-echocardiography in current clinical practice.

Myocardial strain measurement with two-dimensional speckle-tracking echocardiography (2D-STE) is of paramount importance in the early detection of subclinical left ventricular (LV) systolic dysfunction and the prediction of patient outcomes in various types of heart disease, especially when assessed with global longitudinal strain (GLS). The routine application of myocardial strain parameters requires the definition of normal values and an understanding of their reliabilities. One of the most important potential limitations to widespread clinical application of this technique is inter-vendor differences in normal strain values. Recent clinical reports indicate that the smallest differences were noted in GLS measurements among three orthogonal directions. Because the contribution of circumferential fibers to LV myocardial thickening is greater than that of longitudinal fibers, patients who have a reduced LV ejection fraction can have impaired global circumferential strain (GCS), which reflects more advanced intrinsic myocardial systolic dysfunction and is thus closely related to a poor prognosis. Since STE-derived strain analysis allows us to define the timing of the regional myocardial peak systolic deformation, it permits the assessment of LV mechanical dyssynchrony. The severity of LV mechanical dyssynchrony in the short axis plane, i.e., radial and/or circumferential strain imaging, is favorable for predicting the clinical response to cardiac resynchronization therapy. GLS in the right ventricular (RV) four-chamber view has recently been used as a surrogate for global RV function because longitudinal shortening is the major contributor to overall RV performance. Finally, 2D-STE can be used to quantify and characterize RV mechanical dyssynchrony in various diseases including acute pulmonary thromboembolism and chronic pulmonary hypertension.