Three-dimensional speckle tracking echocardiography: The future is now.

Cardiac ultrasound is an imaging modality that enables dynamic imaging of the heart and great vessels. The past decade has seen the development of two-dimensional speckle tracking echocardiography (2D-STE), a semiautomated technique based on frame-by-frame tracking of tiny echo-dense speckles within the myocardium that reveals the extent of lengthening and shortening relative to the baseline (Lagrangian strain). It enables assessment of motion and deformation parameters such as velocity, displacement, strain, and strain rate in the left ventricular longitudinal, radial, or circumferential axis. This non-Doppler methodology is therefore able to provide information on segmental and global myocardial deformation. Myocardial 2D-STE has been validated by comparison with sonomicrometry and tagged magnetic resonance imaging (MRI). With respect to left ventricular (LV) mechanics, global longitudinal strain (GLS) is the most-studied 2D-STE parameter and is part of routine assessment in many echocardiographic laboratories. This is in contrast to analysis of radial and circumferential LV mechanics, which are probably not sufficiently reproducible. By convention, GLS is presented as negative values representing shortening in the longitudinal LV axis. In a meta-analysis of 24 studies which included 2597 healthy subjects, GLS varied from