Discontinuous contraction in the left ventricle assessed by 2‐D speckle tracking echocardiography benefits from CRT.

Background: Cardiac resynchronization therapy (CRT) improves the morbidity and mortality rate in patients with left bundle‐branch block (LBBB); however, some LBBB patients are non‐responders for CRT. Previous studies have shown that a transmural functional line block alters the left ventricular (LV) activation sequence, and that the presence of a line block is predictive for responders. We investigated whether responders could be predicted in patients with LBBB by 2‐dimensional (2‐D) speckle tracking strain imaging. Methods: We enrolled 54 patients with LBBB, who underwent echocardiography before and 6 months after CRT implantation. A responder was defined by a decrease in the LV end‐systolic volume >15% at the 6‐month follow‐up. We calculated a difference in the time from QRS onset to maximum strain between adjacent segments and defined the Tmax‐diff as the maximum difference among six intersegments. We compared the Tmax‐diff between responders and non‐responders. Results: Among 54 patients, 37 patients were identified as responders. The Tmax‐diff of the responders was significantly longer than that of the non‐responders (309.6 ± 168.6 ms vs 181.5 ± 138.4 ms, P = .009). Furthermore, Tmax‐diff ≥ 195 ms was higher in the septal and the anterior area. And patients with a Tmax‐diff ≥ 195 ms tended to be responders (P = .02). Conclusion: The present study showed that discontinuous contraction of the LV could be detected in CRT responders by 2‐D speckle tracking strain imaging, which may be a useful tool to identify the contraction pattern of patients with LBBB and predict CRT responders. [ABSTRACT FROM AUTHOR]