(A) The RT3DE images obtained in a normal subject shown with the LV-cast from 3 different perspectives (from left to right: septal, inferolateral, and anterolateral) and the segmentation using the 17-segment model. (B) The corresponding 17 regional volume curves showing relatively synchronized motion reaching end-ejection between 30% and 40% of the RR interval, with the exception of the basal anteroseptal segment (arrows), which showed reduced amplitude of motion and seems to reach end-ejection at 50%. (C) Exclusion of this segment from analysis (arrow) reduced the calculated LVDI from 4.4% to 2.6% (cyan circles). EDV = end-diastolic volume; EF = ejection fraction; ESV = end-systolic volume; LV = left ventricle; LVDI = left ventricular dyssynchrony index; RT3DE = real-time 3-dimensional echocardiography; SDI = systolic dyssynchrony index; SV = stroke volume.

The LVDI values (expressed in percent of RR interval) measured in 135 normal subjects (orange circles) over the wide range of ages, shown with mean ± SD values for different age decades (brown circles with error bars), calculated for 17 (A) and 16 myocardial segments (B). Abbreviations as in Figure 1.

Evaluation of LV dyssynchrony in 1 patient of each group, which shows the effects of reduced ejection fraction and LBBB in 4 patients with: (A) normal LV function without LBBB (group 4), (B) normal LV function and LBBB (group 3), (C) dilated cardiomyopathy (DCM) without LBBB (group 2), and (D) DCM with LBBB (group 1). See text for details. LBBB = left bundle branch block; other abbreviations as in Figure 1.

Mean + SD (error bars) of the left ventricular function (LVF) parameters (end-diastolic volume [EDV] and end-systolic volume [ESV]; ejection fraction [EF]) and left ventricular dyssynchrony index (LVDI) obtained in the 4 groups of patients (same as in Fig. 3) in protocol 2. All intergroup comparisons showed significant differences in EDV, ESV, and LVDI, whereas ejection fraction was significantly different only between normal (NL) and dilated cardiomyopathy, irrespective of left bundle branch block. Abbreviations as in Figure 3.

An LVDI obtained in individual patients in the 3 groups (same as in Fig. 3) in protocol 2, shown with those of all normal (NL) control subjects against age in the same format as in Figure 2. Data are shown for both 17-segment analysis (A) and 16-segment analysis (B). The dashed horizontal lines represent the abnormality threshold defined as 2 SD above the mean of the normal control subjects. Abbreviations as in Figures 1, 3, and 4.

An LVDI obtained in individual patients in the 4 groups in protocol 2, shown against EF with the results of linear regression analysis. The dashed horizontal line represents the abnormality threshold defined as 2 SD above the mean of the 135 normal (NL) control subjects in protocol 1, with the nonpopulated cross-hatched rectangular area showing that none of the patients with DCM and EF <35% had dyssynchrony within normal limits as defined in this study. The dotted line represents the 8.3% threshold used by Kapetanakis et al. (6), with the hatched rectangular area showing that there are a considerable number of patients with DCM and EF <35% whose LVDI would be considered within normal limits (see text for details). DCM = dilated cardiomyopathy; EF = ejection fraction; other abbreviations as in Figure 1.