Global longitudinal strain (GLS) <16 percent likely indicates significant myocardial dysfunction, according to results of a meta-analysis presented Aug. 31 at ESC Congress 2019 and simultaneously published in JACC: Cardiovascular Imaging.

While the prognostic and diagnostic value of GLS has been recognized, its inclusion in clinical guidelines has been slowed because, according to the authors, of difficulties in defining the lower limit of normal (LLN). Their patient-level meta-analysis sought to define the distribution of normal GLS values and the LLN.

A PubMed search yielded 1,084 papers published from 20100 to 2018, of which 16 were included in the meta-analysis. No relevant papers were identified from Cochrane or EMBASE. All included studies reported speckle tracking-based GLS. Histograms were used to assess variable distributions and all data were presented as the median [25th centile, 75th centile].

Results showed the mean GLS was 20.7 percent, with only minor funnel plot asymmetry. Eight of the papers included individual data for 2,396 participants who had a mean age of 42 years.

The normal GLS was 21.0 percent, but varied significantly with age. GLS was significantly lower in participants >60 years (20.0 percent) vs. those <60 years (21.0 percent; p< 0.01). A GLS <16.0 percent was observed in 66 (2.8 percent) participants, with a mean age of 54.3 years.

The normal GLS range varied according to age, weight, systolic blood pressure and a non-General Electric platform. Among platform vendors, the normal GLS range was highest with TomTec (n=644; 22.1 percent; LLN 18.0 percent), followed by General Electric (n=1,013; 21.2 percent; LLN, 18.2 percent), Toshiba (n=278; 19.9 percent; LLN, 15.8 percent), Philips (n=379; 19.6 percent; LLN, 15.5 percent) and Siemens (n=82; 16.9 percent; LLN, 14.0 percent).

The investigators concluded that regardless of clinical covariate or vendor, a GLS <16 percent likely indicates significant myocardial dysfunction. However, they note the current results may be unreliable in older populations, because of the difficulty in excluding all forms of cardiac disease with the screening investigations used by most of the included studies. "This is the first study to reliably define GLS variance in a normal population and may now support the routine use of GLS as a clinical decision-making tool."

Clinical Topics: Noninvasive Imaging, Echocardiography/Ultrasound

Keywords: ESC 19, ESC Congress, Echocardiography, Heart Ventricles

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