title: An echocardiographic study of the limitations of the Tei index in aortic stenosis.
abstract: BACKGROUND
  The omnibus Tei index, the sum of isovolumic contraction and relaxation times divided by the ejection time, is a good indicator of global cardiac function. However, these time intervals can be influenced by valvular heart disease and the role of the Tei index among patients with aortic stenosis (AS) and left ventricular systolic dysfunction remains incompletely defined.
  
  
  METHODS
  Doppler time intervals were measured retrospectively by two observers, and the Tei index were calculated on 80 patients with various degrees of left ventricular systolic dysfunction and severity of AS. Differences between observers were resolved by consensus. Ejection fraction (EF) was visually estimated, and the aortic valve area (AVA) was calculated using the continuity equation.
  
  
  RESULTS
  The mean AVA was 1.1+/-0.5 cm(2) and the mean EF was 0.39+/-0.15. Although correlation (r = 0.61, P < 0.001) and agreement (intraclass correlation coefficient=0.55) for the Tei index were satisfactory, there were significant differences between observers (P < 0.001). Using consensus data, the mean Tei index was 0.32+/-0.20 and significantly lower among patients with severe compared with less severe AS (P=0.01). The index varied inversely with left ventricular function (P=0.003). However, receiver operating characteristic analysis shows that the Tei index lacks discrimination in accurately identifying poor left ventricular function or severe AS or both.
  
  
  CONCLUSIONS
  The Tei index varies inversely with systolic ventricular function (low index with good EF) and positively with severity of AS (low index with smaller valve area). As such, it may have limited utility among individual patients with AS.
authors.affiliation: Department of Medicine, Division of Cardiology, London Health Sciences Centre, University Campus, University of Western Ontario, Ontario, Canada.
authors.forename: Sachin
authors.initials: S
authors.lastname: Sud
authors.forename: David
authors.initials: D
authors.lastname: Massel
mesh_terms: D001011:Aorta / Q000000981:diagnostic imaging*; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging*; D002170:Canada; D004452:Echocardiography / Q000379:methods* / Q000592:standards; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity