Value of two-dimensional speckle tracking imaging in assessing left ventricular function and synchrony in patients with complete left bundle branch block

Abstract

Objective To explore the effect of different strain patterns on left ventricular systolic function and synchrony in complete left bundle branch block (CLBBB) patients using two-dimensional speckle tracking imaging (2D-STI). Methods Ninety patients with CLBBB were included from April 2016 to April 2018. The patients with CLBBB were divided into two groups based on the criteria of classic pattern of dyssynchrony (CPD) and non-classic pattern of dyssynchrony (n-CPD). Furthermore, patients with left ventricular ejection fraction (LVEF)> 50% were further selected and divided into a CPD group and n-CPD group as above. Thirty healthy subjects were included as controls. Common echocardiography and 2D-STI were performed. Left ventricular end-diastolic dimension and volume (LVEDD and LVEDV) as well as left ventricular ejection fraction (LVEF) were measured. Global left ventricular longitudinal strain (GLS), interventricular mechanical delay time (IVMD), basal-segment strain septal to lateral strain peak time delay (b-Ssl), mid-segment septal to lateral strain peak time delay (m-Ssl), and standard deviation of time to longitudinal strain peak for the left ventricular 18 segments (SDt) were measured and calculated. Results LAD, RVBD, E/e′, LVEDD, and LVEDV values in the CPD and n-CPD groups were significantly higher than those in the control group, and E/A and EDT in the CPD and n-CPD groups were significantly lower than those in the control group (t=5.12, 3.67, 7.29, 5.69, 5.89, 3.15, 2.05, 5.89, 5.22, and 3.83, P 50% were selected for comparisons, and there was no significant difference in LVEF between the two groups (P>0.05). Compared with the healthy control group, QRS, LVEDD, LVESD, LVEDV, LVESV, IVMD, b-Ssl, m-Ssl, and SDt values were significantly higher and Sept-LS, Lat-LS, and GLS values were significantly lower (t=19.44, 4.01, 5.21, 5.61, 4.73, 9.19, 5.27, 3.16, 3.25, 8.02, 4.15, and 5.42, respectively, P<0.001) in the CPD group; QRS, LVEDD, LVEDV, LVESV, IVMD, b-Ssl, m-Ssl, and SDt values were significantly higher and Sept-LS and GLS values were significantly lower (t=20.68, 2.46, 3.15, 3.10, 6.95, 3.00, 4.59, 6.53, 3.84, and 4.05, respectively, P<0.05) in the n-CPD group. Compared with the n-CPD group, QRS, LVEDD, LVESD, LVEDV, LVESV, IVMD, b-Ssl, and SDt values in CPD group were significantly higher and Sept-LS, Lat- LS, and GLS values were significantly lower (t=2.73, 2.13, 3.88, 3.06, 2.19, 3.94, 3.00, 3.25, 4.38, 2.90, and 2.30, respectively, P<0.05l) in the CPD group. Conclusion Conventional echocardiography combined with 2D-STI technology can early detect reduced systolic function and systolic synchronicity of the left ventricle in CLBBB patients, as well as the phenomenon that the systolic function and systolic synchronicity are further decreased in typical CLBBB compared with non-typical CLBBB, which can prompt clinical attention to typical CLBBB patients and timely treatment intervention. Key words: Echocardiography; Complete left bundle branch block; Systolic function; Systolic synchrony