Echocardiographic strain imaging for myocardial viability: an improvement over visual assessment?

Echocardiographic strain imaging was introduced by Heimdal et al in 19981 as a means to calculate myocardial regional function from tissue Doppler velocity data.2,3 Strain imaging is a variation of the previous concept of tissue Doppler myocardial velocity gradient, which calculates regional thickening independent of passive whole heart motion.4,5 Because routine clinical evaluation of regional function is usually by visual wall-motion assessment, strain imaging has great promise to improve objective quantification of regional function. Strain imaging calculates deformation, which translates clinically to percent shortening in the longitudinal dimension (assessed from apical views) or percent thickening in the radial dimension (assessed from parasternal views).1,6,7 Theoretically, it has the important advantage of differentiating active myocardial motion from passive translational or tethering movements that other echocardiographic-Doppler approaches cannot differentiate. Indeed, there have been literally hundreds of publications over the last 10 years detailing a wide range of experimental and potential clinical applications of strain imaging; however, currently, few centers have adopted strain imaging in their routine clinical practice, preferring visual “eyeball” assessment, even though this is inherently subjective and requires a high level of experience and training.8 An important question remains: Is it now time for strain imaging to be adopted in a widespread clinical sense?