Evaluation of left ventricular mechanical dyssynchrony in chronic heart failure patients by two-dimensional speckle tracking imaging

The purpose of this study was to evaluate left ventricular mechanical dyssynchrony (LVMD) in chronic heart failure (CHF) patients using two-dimensional speckle tracking imaging (2D-STI), and also to compare the usefulness of three patterns of myocardial deformation in mechanical dyssynchrony assessment. Furthermore, the relationships between left ventricular ejection fraction (LVEF), QRS duration (QRSd), and LVMD were explored. In total, 78 patients and 60 healthy individuals (group 3) were enrolled. The patients were classified into two subgroups: LVEF ≤ 35% (group 1), 35% < LVEF < 50% (group 2). All participants underwent two-dimensional echocardiography, and dyssynchrony indices derived from 2D-STI were calculated. According to statistical principles, the cut-off value of LVMD was defined as mean ± 1.645 SD of the normal population. Dyssynchrony rates were calculated in CHF subgroups and compared within each subgroup, respectively. Compared with group 3, all indices in group 1 were remarkably higher (p < 0.05), and some of the indices in group 2 were significantly higher (p < 0.05). A significant difference of dyssynchrony rate was noted within both group 1 and group 2 (χ2 = 25.55, p < 0.05 vs. χ2 = 23.88, p < 0.05), and the highest value was derived from the longitudinal index in both subgroups. LVEF was related to all three forms of strain/strain rate (p < 0.05), whereas no relationship existed between QRSd and dyssynchrony indices (p > 0.05). CHF patients have different extents of LVMD. Longitudinal deformation shows the best detectability of dyssynchrony motion. Left ventricular systolic function was closely related to mechanical dyssynchrony, whereas QRSd showed no significant correlation.