title: The left atrial function index: a rhythm independent marker of atrial function.
abstract: OBJECTIVE
  This study evaluates a simple echocardiographic rhythm independent expression of left atrial (LA) function, 'the left atrial function index' (LAFI).
  
  
  BACKGROUND
  Quantitation of LA function is challenging and often established parameters including peak A are limited to sinus rhythm (SR). We hypothesized that atrial function could be characterized independent of rhythm by combining analogues of LA volume, reservoir function and LV stroke volume.
  
  
  METHODS
  Seventy-two patients with chronic atrial fibrillation (CAF) were followed for six months post cardioversion (CV). Thirty-seven age matched healthy subjects were controls. The LAFI = LAEF x LVOT-VTI/LAESVI (LAEF = LA emptying fraction, LAESVI = maximal LA volume indexed to BSA, LVOT-VTI = outflow tract velocity time integral).
  
  
  RESULTS
  The LAFI pre-CV in the CAF group was depressed vs controls (0.10 +/- 0.05 vs 0.54 +/- 0.17; P = 0.0001). Post-CV, LAFI was lower in persistent AF than in those restored to SR (AF vs SR: 0.08 +/- 0.03 vs 0.15 +/- 0.08; P = 0.0001), improved progressively in SR and was unchanged when AF persisted.
  
  
  CONCLUSIONS
  The LAFI, a simple, rhythm independent expression of atrial function, appears sensitive to differences between individuals in AF and those restored to SR and justifies clinical and investigative applications.
authors: Department of Cardiology, University of Sydney, Westmead Hospital, Darcy Road, Sydney 2145, NSW, Australia. lizat@westgate.wh.usyd.edu.au
authors: Liza
authors: L
authors: Thomas
authors: Michelle
authors: M
authors: Hoy
authors: Karen
authors: K
authors: Byth
authors: Nelson B
authors: NB
authors: Schiller
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D016279:Atrial Function, Left; D006325:Heart Atria / Q000000981:diagnostic imaging*; D006801:Humans; D008875:Middle Aged; D014463:Ultrasonography