Analysis of left ventricular circumferential strain in patients with left bundle branch block by layer-specific speckle tracking imaging

Abstract

Objective To evaluate the left ventricular systolic circumferential strain by layer-specific speckle tracking imaging in healthy volunteers and patients with left bundle branch block (LBBB). Methods Forty patients with LBBB were divided into two groups, LBBB1 group [left ventricular ejection fraction(LVEF≥50%] and LBBB2 group (LVEF<50%), and 25 healthy subjects were selected as the control group.High frame rate two-dimensional images were recorded from the left ventricular short-axis views at the levels of the mitral annulus, papillary muscle and apex respectively. The peak systolic circumferential strain of the endocardium, myocardium and epicardium were measured using layer-specific strain software. Results The circumferential strain of the epicardium and myocardium at the level of the apex showed a statistically significant difference between the LBBB1 group and the control group (P=0.004), while there was no statistically significant difference demonstrated at the levels of the mitral annulus and papillary muscle(P>0.01). The circumferential strain of the endocardium at the levels of the papillary muscle and apex showed a statistically significant difference between the LBBB1 group and the control group(P=0.000), while there was no statistically significant difference demonstrated at the level of the mitral annulus(P>0.01). The circumferential strain of the endocardium, myocardium and epicardium at the three short-axis view levels showed statistically significant differences between the LBBB2 group and the control or LBBB1 groups respectively(P=0.000). Conclusions The circumferential strain of the endocardium at the level of the apex can provide more information about disease prognosis, especially in LBBB patients with a LVEF of ≥50%. Key words: Echocardiography; Bundle branch block; Speckle tracking imaging; Circumferential strain