Assessment of left ventricular dyssynchrony by speckle tracking strain imaging comparison between longitudinal, circumferential, and radial strain in cardiac resynchronization therapy.

OBJECTIVES The objective of this study was to assess the usefulness of each type of strain for left ventricular (LV) dyssynchrony assessment and its predictive value for a positive response after cardiac resynchronization therapy (CRT). Furthermore, changes in extent of LV dyssynchrony for each type of strain were evaluated during follow-up. BACKGROUND Different echocardiographic techniques have been proposed for assessment of LV dyssynchrony. The novel 2-dimensional (2D) speckle tracking strain analysis technique can provide information on radial strain (RS), circumferential strain (CS), and longitudinal strain (LS). METHODS In 161 patients, 2D echocardiography was performed at baseline and after 6 months of CRT. Extent of LV dyssynchrony was calculated for each type of strain. Response to CRT was defined as a decrease in LV end-systolic volume >/=15% at follow-up. RESULTS At follow-up, 88 patients (55%) were classified as responders. Differences in baseline LV dyssynchrony between responders and nonresponders were noted only for RS (251 +/- 138 ms vs. 94 +/- 65 ms; p < 0.001), whereas no differences were noted for CS and LS. A cut-off value of radial dyssynchrony >/=130 ms was able to predict response to CRT with a sensitivity of 83% and a specificity of 80%. In addition, a significant decrease in extent of LV dyssynchrony measured with RS (from 251 +/- 138 ms to 98 +/- 92 ms; p < 0.001) was demonstrated only in responders. CONCLUSIONS Speckle tracking radial strain analysis constitutes the best method to identify potential responders to CRT. Reduction in LV dyssynchrony after CRT was only noted in responders.