Assessment of Left Ventricular Mechanical Dyssynchrony Using Real Time Three-Dimensional Echocardiography: A Comparative Study to Doppler Tissue Imaging

Abstract

To assess left ventricular mechanical dyssynchrony (LVMD) using real time three-dimensional echocardiography (RT3DE) and comparing it with the different dyssynchrony indices derived from Doppler tissue imaging (DTI) for the same patient. The study included 60 consecutive patients who were considered candidates for CRT, i.e., having ejection fraction ≤35%, NYHA class III or ambulatory class IV, QRS duration ≥120 msec, on optimal pharmacological therapy. Apical RT3DE full volumes were obtained and analyzed to generate the systolic dyssynchrony index (SDI-16), which is the standard deviation of the time to minimal systolic volume of the 16 segments of LV. Color-coded DTI was performed for the three standard apical views with estimation of the mechanical dyssynchrony index (12 Ts-SD), which is the standard deviation of the time to peak systolic velocity at 12 segments of LV. SDI-16 was 10.96 ± 3.9% (cutoff value: 8.3%), while Ts-SD was 38 ± 10.2 msec (cutoff value: 32.6 msec). The concordance rate for both indices was 75%; however, there was no correlation between both indices (r = 0.14, P = 0.3). SDI-16 showed good correlation with QRS duration (r = 0.45, P < 0.001) and inverse correlation with left ventricular ejection fraction (LVEF) calculated by RT3DE (r =-0.37, P = 0.004), while 12 Ts-SD index showed no correlation with QRS duration (r =-0.0082, P = 0.51) or 2D LVEF (r =-0.26, P = 0.84). RT3DE can quantify LVMD by providing the SDI-16 and it may prove to be more useful than DTI as it shows increasing dyssynchrony with increased QRS duration and decreased LVEF.