Abstract
Abstract Background Evaluation of two-dimensional (2D) speckle-tracking longitudinal strain (LS) is useful for assessing global and regional left ventricular (LV) dysfunction. Purpose The purpose of this study was to test the hypothesis that temporal changes in regional 2D-LS distribution, (i.e., changes in area and intensity of the negative strain), during the systolic period may reflect the LV activation sequence. Methods We studied 52 patients with an ejection fraction <35% who were classified into four groups: complete left bundle branch block (LBBB, QRS 162±17 ms, n=17); right ventricular pacing from inferior septum (RVP, QRS 180±29 ms, n=16); left VP from lateral branch of the coronary sinus (LVP, QRS 182±21 ms, n=9); and no conduction block (Narrow QRS, QRS 100±9 ms, n=19). Longitudinal strain was evaluated in three standard apical views, and then bulls-eye distribution maps were constructed every 50 ms from the QRS onset to aortic valve closing (AVC) and at the time of the end of QRS. Segments indicating negative strain at the end of QRS were regarded as an early contraction site. Segments with intensifying negativity of strain as it got closer to the AVC were regarded as a late contraction site. Results In patients with LBBB, negative strain appeared initially in the septum region. Then, the contracted area enlarged including the apical region, and the basal lateral region contracted late. On the other hand, Narrow QRS showed a few regional differences in strain at the end of QRS (standard deviation in 17-segments: Narrow QRS 1.3±0.4%*, LBBB 3.3±1.1%, RVP 3.2±1.0%, LVP 3.3±1.1%, *p<0.001), and contracted homogeneously during the systolic period. RVP and LVP showed negative strain at the end of QRS in septum and lateral regions respectively, with the contracted area becoming enlarged towards the opposite regions of the early contracted regions. Conclusion The 2D-LS distribution during the systolic period reflects the LV contraction process in patients with an altered ventricular activation sequence, and may have potential for identifying the regions of early activation site and subsequent activation propagation. Funding Acknowledgement Type of funding source: None
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