Short-Axis 2D Strain from Speckle Tracking Predicts Echocardiographic Response to Cardiac Resynchronization Therapy

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Two-dimensional (2D) strain imaging from speckle tracking is a Doppler independent technique allowing assessment of left ventricular (LV) strain (ɛ); systolic strain rate (SRs') and early diastolic strain rate (SRe') in the radial and circumferential planes. We set out to investigate whether (i) these parameters facilitated assessment of dyssynchronous contraction and (ii) these measures could predict response to cardiac resynchronization therapy (CRT). Forty-one patients with severe, symptomatic heart failure on optimal medical therapy were recruited. Thirty-two healthy subjects were used as controls. Time to peak ɛ, SRs', and SRe' of 6 LV segments were measured in the parasternal short axis prior to and 6 weeks post CRT implantation. Time delays between segments were then calculated and ANOVA assessed for prediction of response, classified as reduction in LV end systolic volume of >15%. 2D strain demonstrated significantly more dyssynchronous contraction in the heart failure population at baseline compared to healthy controls. Significant reduction in dyssynchrony was seen in ɛ and SRs' following CRT, largely confined to those with evidence of remodeling. The time delay between peak circumferential SRs' of opposing walls was the best predictor of reverse remodeling. 2D strain imaging appears to be a useful measure to predict response to CRT. The time to peak circumferential SR is a new predictor of response.