Usefulness of dyssynchrony indices based on two-dimensional speckle tracking echocardiography in a canine model of left bundle branch block.

INTRODUCTION: Determine the usefulness of dyssynchrony indices derived from two-dimensional speckle tracking echocardiography for the detection of mechanical dyssynchrony in a canine model of left bundle branch block.

ANIMALS: Ten healthy beagles.

MATERIALS AND METHODS: Segmental, time-radial strain curves were obtained using two-dimensional speckle tracking echocardiography. The maximum difference and standard deviation of the time to peak radial strain for six predefined segments (MaxD-TpSR and 6SD-TpSR) were calculated, together with the left ventricular dyssynchrony by radial strain (DysSR), before and after ablation of the left bundle branch block. Receiver operating characteristic curve analysis was performed using dogs after ablation as positive controls.

RESULTS: After ablation, all dogs showed multiple peaks in at least one segment on the time-radial strain curve, while all dyssynchrony indices increased significantly (MaxD-TpSR from 16.25 ± 16.04 [mean ± standard deviation] to 44.4 ± 26.18 ms, 6SD-TpSR from 7.59 ± 7.40 to 19.62 ± 11.91 ms, and DysSR from 4.20 ± 2.12 to 10.87± 2.92%, p<0.05). In receiver operating characteristic curve analysis, the areas under the curve for MaxD-TpSR, 6SD-TpSR, and DysSR were 0.825, 0.800, and 0.980, respectively.

CONCLUSIONS: Left ventricular dyssynchrony by radial strain can detect mechanical dyssynchrony with higher sensitivity and specificity than dyssynchrony indices, based on the time to peak radial strain.