Prediction of response to cardiac resynchronization therapy combining two different three-dimensional analyses of left ventricular dyssynchrony

Abstract

Triplane tissue synchronization imaging (TSI) and real-time 3-dimensional echocardiography (RT3DE) provide different characterizations of left ventricular (LV) mechanics and dyssynchrony. Triplane TSI assesses differences in time to peak systolic segmental myocardial tissue velocities, whereas RT3DE evaluates differences in time to minimum end-systolic regional volumes. Whether an approach using the 2 3D techniques predicts better significant reverse remodeling after cardiac resynchronization therapy (CRT) remains unknown. In 166 patients (mean age 66 +/- 9 years, 78% men) treated with CRT, baseline LV dyssynchrony was assessed using RT3DE and triplane TSI. LV dyssynchrony was defined by a systolic dyssynchrony index >/=6.4% when assessed with RT3DE and SD of time to peak velocity of 12 segments (Ts-SD-12) >/=33 ms with triplane TSI. CRT response was defined by >/=15% decrease in LV end-systolic volume at 6-month follow-up. Mean LV dyssynchrony using Ts-SD-12 was 48 +/- 26 ms and mean systolic dyssynchrony index was 8.51 +/- 3.81%. Response to CRT was observed in 86.3% of patients showing LV dyssynchrony with the 2 methods. In contrast, 97% of patients who did not show significant LV dyssynchrony with any of the techniques were nonresponders (p <0.001). Importantly, systolic dyssynchrony index and LV dyssynchrony using Ts-SD-12 were independent predictors of response to CRT (p <0.001 for each technique). Assessment of LV dyssynchrony with the 2 techniques showed incremental value for prediction of significant LV reverse remodeling over its assessment with only 1 technique (chi-square 90.18, p <0.001). In conclusion, the combined use of 2 different 3D techniques to assess LV dyssynchrony permits accurate prediction of response to CRT.