title: Accuracy and reproducibility of biplane two-dimensional echocardiographic measurements of left ventricular dimensions and function.
abstract: OBJECTIVE
  To investigate sources of variability in serial echocardiographic recordings in a core laboratory we assessed the impact of repeated echo recordings, repeated video measurements and measurements made by different investigators.
  
  
  METHODS
  Two investigators each recorded and analysed two-dimensional echos in 12 individuals (n = 24 in total) three times at one week intervals. Left ventricular end-diastolic and end-systolic volumes were measured using the biplane modified Simpson's rule. Ejection fraction was derived from these volumes and left ventricular mass estimated using the area-length method. The left ventricular spherity index was expressed as the ratio of the short axis area and the long axis area at end-diastole. A video recording from each examination was reexamined twice by both investigators.
  
  
  RESULTS
  Deviations between repeated echo recordings and repeated video measurements ranged from -5 to +5% between investigators. A three-way repeated analysis of variance indicated a small, but systematic difference between investigators. Reproducibility, measured by coefficients of variation, ranged from 3-9% for different investigators, 3-6% for repeated video measurements and 7-19% for repeated echo recordings across the different variables. The total variability of all three factors should be considered when the smallest detectable significant change in a variable is assessed. These ranged from 16-28% across the five variables studied, when a 10% error of classification was accepted for a one-sided change in a variable.
  
  
  CONCLUSIONS
  Repeated echo recordings were the dominant component of variation. Two-dimensional echo measurements are reproducible and accurate, but the same investigator should follow the same patients.
authors.affiliation: Division of Cardiology, Vestfold Central Hospital, Toensberg, Norway.
authors.forename: J E
authors.initials: JE
authors.lastname: Otterstad
authors.forename: G
authors.initials: G
authors.lastname: Froeland
authors.forename: M
authors.initials: M
authors.lastname: St John Sutton
authors.forename: I
authors.initials: I
authors.lastname: Holme
mesh_terms: D000328:Adult; D000368:Aged; D004452:Echocardiography / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging*; D008297:Male; D009203:Myocardial Infarction / Q000000981:diagnostic imaging; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D013318:Stroke Volume / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*