title: Quantification of the variability associated with repeat measurements of left ventricular two-dimensional global longitudinal strain in a real-world setting.
abstract: BACKGROUND
  Global longitudinal strain (GLS) derived from two-dimensional speckle-tracking is an emerging technology, but lack of industry standards limits its application. Prior studies support using this tool to identify subclinical disease through serial changes, but the variability introduced by a change in vendor or reader is not well defined.
  
  
  METHODS
  Fifty study subjects were prospectively identified to include four subgroups to ensure a broad range of GLS: normal (n = 20), left ventricular hypertrophy (n = 10), ST-segment elevation myocardial infarction (n = 10), and systolic heart failure (n = 10). Raw data were obtained using equipment from two vendors during the same session, and GLS was analyzed using an offline workstation. Intraobserver and interobserver variation was measured using correlation coefficients, intraclass correlation coefficients, and Bland-Altman plots.
  
  
  RESULTS
  GLS measurements were highly reproducible by the same reader or a different reader using vendor 1 and vendor 2 or comparing vendors (correlation coefficients and intraclass correlation coefficients ≥ 0.95). However, the Bland-Altman plots suggested that the variation in repeat GLS measurements may range from ± 2% to ± 5% on the basis of a change in vendor, reader, or both.
  
  
  CONCLUSIONS
  The expected variation in GLS measurements associated with a change in vendor, reader, or both should be considered when making conclusions about significant changes in serial measurements.
authors.affiliation: Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire. Electronic address: salvatore.p.costa@hitchcock.org.
authors.forename: Salvatore P
authors.initials: SP
authors.lastname: Costa
authors.affiliation: Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Beaver
authors.affiliation: Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire.
authors.forename: Joyce L
authors.initials: JL
authors.lastname: Rollor
authors.affiliation: Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire; Siriraj Hospital, Mahidol University, Bankok, Thailand.
authors.forename: Pantila
authors.initials: P
authors.lastname: Vanichakarn
authors.affiliation: Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire.
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Magnus
authors.affiliation: Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Palac
mesh_terms: D004452:Echocardiography / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging*
keywords: 2D; 2D strain; CHF; Congestive heart failure; Echocardiography; GLS; Global longitudinal strain; ICC; Intraclass correlation coefficient; LOA; LV; LVEF; Left ventricular; Left ventricular ejection fraction; Limits of agreement; STE; Speckle-tracking echocardiography; Two-dimensional