title: Validation of echocardiographic left atrial parameters in atrial fibrillation using the index beat of preceding cardiac cycles of equal duration.
abstract: BACKGROUND
  The clinical assessment of left atrial function during atrial fibrillation is challenging and often inaccurate because of the beat-to-beat variability in the cycle length. The aim of this study was to validate the use of an index beat, the beat following two preceding cardiac cycles of equal duration, for the measurement of left atrial functional indices, including area, volume, and expansion index. The index beat was compared with the conventional but time-consuming method of averaging multiple consecutive cardiac cycles.
  
  
  METHODS
  Thirty patients with persistent or permanent atrial fibrillation were studied using two-dimensional echocardiography, and left atrial indices were measured from the average of 17 consecutive cardiac cycles compared with that of an index beat taken from outside of these 17 cycles.
  
  
  RESULTS
  The index beat showed good correlation with the averaging technique, and comparison of the two methods showed them to be interchangeable. Clinically, the differences in left atrial functional indices between the two methods were minor.
  
  
  CONCLUSIONS
  Use of the index beat to measure dynamic left atrial function in atrial fibrillation can easily be performed and is as accurate as and less time consuming than the onerous method of averaging of multiple cardiac cycles.
authors.affiliation: Division of Cardiac and Vascular Sciences, St. Georges University of London, London, United Kingdom. m.govindan@sgul.ac.uk
authors.forename: Malini
authors.initials: M
authors.lastname: Govindan
authors.forename: Anatoli
authors.initials: A
authors.lastname: Kiotsekoglou
authors.forename: Samir K
authors.initials: SK
authors.lastname: Saha
authors.forename: Gabor
authors.initials: G
authors.lastname: Borgulya
authors.forename: Abhay
authors.initials: A
authors.lastname: Bajpai
authors.forename: Bart H
authors.initials: BH
authors.lastname: Bijnens
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Sagnella
authors.forename: John A
authors.initials: JA
authors.lastname: Camm
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016279:Atrial Function, Left / Q000502:physiology*; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D013318:Stroke Volume / Q000502:physiology*