title: Ejection fraction in patients with heart failure and preserved ejection fraction is greater than in healthy controls: a meta-analysis.
abstract: BACKGROUND
  Ejection fraction (EF) slightly declines with age in healthy control (HC) subjects. Yet, studies of heart failure with preserved ejection fraction (HFPEF) often report EF values which are surprisingly greater than those reported for HC of the same age. The goals of this study were to: (1) compare the EF, at rest, in subjects with HFPEF versus HC, and (2) compare how EF varies with age in HFPEF and HC.
  
  
  METHODS
  A systematic review and meta-analysis of the literature was performed. Studies were identified in the PUBMED and EMBASE databases until August 2013. A study reporting EF at rest in HFPEF and HC was included regardless of the aim of the primary study. In most of the primary studies (25 of 28 studies, 89%) EF was not a primary endpoint. A summary measure was the standardized mean difference (SMD) of the EF in HFPEF vs.
  Twenty eight studies (1529 HFPEF and 1068 HC subjects) were included. SMD was 0.71 (95% CI: 0.31, 1.12, P<0.001) demonstrating a greater EF in HFPEF. Effect size of HFPEF on EF was moderate. A meta-regression showed a statistically non-significant trend of increased SMD with older age.
  
  
  CONCLUSIONS
  This analysis showed that EF in HFPEF is on average "greater-than-normal". This phenomenon may be related to an underlying adaptive mechanism occurring in HFPEF. Further research is needed.
authors.affiliation: HaEmek Medical Center, Rabin Blvd., Afula 18101, Israel; Rappaport School of Medicine, Technion- Israel Institute of Technology, Efron St., P.O.B. 9649, Bat Galim, Haifa 31096, Israel. Electronic address: guydo@clalit.org.il.
authors.forename: Guy
authors.initials: G
authors.lastname: Dori
authors.affiliation: Carmel Medical Center, 7 Michal St., Haifa 34362, Israel.
authors.forename: Idriss
authors.initials: I
authors.lastname: Rajab
authors.affiliation: Rappaport School of Medicine, Technion- Israel Institute of Technology, Efron St., P.O.B. 9649, Bat Galim, Haifa 31096, Israel.
authors.forename: Kestenbaum
authors.initials: K
authors.lastname: David
authors.affiliation: HaEmek Medical Center, Rabin Blvd., Afula 18101, Israel.
authors.forename: Schwartz
authors.initials: S
authors.lastname: Naama
authors.affiliation: Harvard Clinical Research Institute, 930 Commonwealth Ave., Boston, MA 02215, USA.
authors.forename: Vardi
authors.initials: V
authors.lastname: Moshe
mesh_terms: D016022:Case-Control Studies; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D013318:Stroke Volume / Q000502:physiology*
keywords: Ejection fraction; Heart failure; Heart failure with preserved ejection fraction