title: Prognostic implications of global LV dysfunction: a systematic review and meta-analysis of global longitudinal strain and ejection fraction.
abstract: BACKGROUND
  Global longitudinal strain (GLS) is a robust, well validated and reproducible technique for the measurement of LV longitudinal deformation. We sought to assemble evidence that GLS is an accurate marker in predicting cardiovascular outcomes, compared to LVEF.
  
  
  METHODS
  We undertook a systematic review of the evidence from observational studies which compared GLS against LVEF in predicting major adverse cardiac events. The primary outcome was all-cause mortality. The secondary outcome was a composite of cardiac death, malignant arrhythmia, hospitalisation due to heart failure, urgent valve surgery or heart transplantation, and acute coronary ischaemic event. A random effects model was used to combine HR and 95% CIs. A meta-regression was undertaken to assess the impact of potential covariates.
  
  
  RESULTS
  Data were collated from 16 published articles (n=5721 adults) comprising 15 prospective and 1 retrospective observational studies. The underlying cardiac conditions were heart failure, acute myocardial infarction, valvular heart disease, and miscellaneous cardiac diseases. Mortality was independently associated with each SD change in the absolute value of baseline GLS (HR 0.50, 95% CI 0.36 to 0.69; p<0.002) and less strongly with LVEF (HR 0.81, 95% CI 0.72 to 0.92; p=0.572). The HR per SD change in GLS was associated with a reduction in mortality 1.62 (95% CI 1.13 to 2.33; p=0.009) times greater than the HR per SD change in LVEF.
  
  
  CONCLUSIONS
  There is strong evidence of the prognostic value of GLS, which appears to have superior prognostic value to EF for predicting major adverse cardiac events.
authors.affiliation: Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Kashif
authors.initials: K
authors.lastname: Kalam
authors.affiliation: Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Petr
authors.initials: P
authors.lastname: Otahal
authors.affiliation: Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Marwick
mesh_terms: D002423:Cause of Death / Q000639:trends; D014943:Global Health; D006801:Humans; D064887:Observational Studies as Topic; D011379:Prognosis; D018570:Risk Assessment; D012307:Risk Factors; D013318:Stroke Volume / Q000502:physiology*; D015996:Survival Rate / Q000639:trends; D018487:Ventricular Dysfunction, Left / Q000401:mortality* / Q000503:physiopathology*
keywords: ejection fraction; mortality; outcome; speckle tracking