Original article
Global longitudinal strain: a novel index of left ventricular systolic function

https://doi.org/10.1016/j.echo.2004.02.011Get rights and content

Abstract

Background

Echocardiographic estimation of global left ventricular (LV) function is subjective and time consuming. Our aim was to develop a novel approach for assessment of global LV function from 2-dimensional echocardiographic images

Methods

Novel computer software for tissue tracking was developed and applied as follows: digital loops were acquired from apical 2-, 3-, and 4-chamber views and a line was loosely traced along the LV endocardium at the frame wherein it was best defined. Around this line, the software selected natural acoustic markers moving with the tissue. Automatic frame-by-frame tracking of these markers during the heart cycle yielded a measure of contractility along the selected region of interest. Global longitudinal strain (GLS) and GLS rate (GLSR) were calculated for the entire U-shaped length of LV myocardium (basal, mid, and apical segments of 2 opposite walls in each view). To test this software, computer-derived GLS and GLSR were analyzed by a nonechocardiographer, blinded to the echocardiographic interpretation, in 27 consecutive patients after myocardial infarction (MI) (age 64.4 ± 12.9 years; 19 men; mean wall-motion score index of 1.79 ± 0.44) and compared with those obtained in 12 consecutive control patients (age 59.0 ± 9.7 years; 8 women), with a normal echocardiographic study.

Results

GLS and GLSR, averaged from the 3 apical views, differed significantly in patients post-MI compared with control patients (GLS −14.7 ± 5.1% vs −24.1 ± 2.9% and GLSR −0.57 ± 0.21/s vs −1.02 ± 0.09/s for patients post-MI vs control patients, respectively; both P < .0001). There was a good linear correlation between the wall-motion score index and the GLS and GLSR (R = 0.68 and R = 0.67, respectively; both P < .0001). A cut-off value for GLS of −21% had 92% sensitivity and 89% specificity and a cut-off value for GLSR −0.9/s had 92% sensitivity and 96% specificity for the detection of patients post-MI.

Conclusions

GLS and GLSR are novel indices for assessment of global LV function from 2-dimensional echocardiographic images. Early validation studies with the method are suggestive of high sensitivity and specificity in the detection of LV systolic dysfunction in patients post-MI.

Section snippets

Echocardiography and acquisition of digital loops

Echocardiographic studies were performed using a commercially available machine (GE Vivid 3 Expert, General Electric Ultrasound, Milwaukee, Wis) equipped with a 1.5- to 1.7-MHz tissue harmonic imaging probe and a frame rate of 80 Hz. Digital loops were stored on the hard disk of the echocardiography machine for online or offline analysis, and transferred to a workstation (EchoPAC, Vingmed, General Electric, Horten, Norway) for offline analysis.

Selection of region of interest and tissue tracking

An innovative method for 2D strain analysis8 was

Results

In 4 patients post-MI and in 3 control patients, only 2 of the 3 apical views were available for analysis. In these patients GLS and GLSR was averaged from 2 apical views. The quality control program rejected 44 of the 660 segments (6.6%). In these loops GLS and GLSR was averaged from less than 6 segments.

Average GLS and GLSR differed significantly in patients post-MI compared with control patients (GLS −14.7 ± 5.1% vs −24.1 ± 2.9% and GLSR −0.57 ± 0.21/s vs −1.02 ± 0.09/s for patients post-MI

Discussion

The prognostic value of LV function is well recognized for patients who survive an acute MI.11 Because echocardiographic estimation of LV function is subjective, novel objective methods are obviously required.

Strain echocardiography is a promising method for assessing LV systolic and diastolic function.12 Doppler-derived tissue velocity imaging, the most commonly used method for the assessment of LV strain, is angle dependent.12 Other 2D echocardiography-based techniques, like color kinesis,

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