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

PURPOSE: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.