title: Index-beat assessment of left ventricular systolic and diastolic function during atrial fibrillation using myocardial strain and strain rate.
abstract: BACKGROUND
  Accurate assessment of left ventricular (LV) function in patients with atrial fibrillation (AF) remains difficult, mainly because of the beat-to-beat variability of many echocardiographic parameters. The aim of this study was to assess the hypothesis that LV function can be estimated from an index-beat echocardiographic assessment in patients with AF using myocardial strain and strain rate.
  
  
  METHODS
  A prospective study was conducted to assess 25 patients with AF (mean age, 66 ± 10 years). Peak systolic longitudinal strain (LS) and peak diastolic longitudinal strain rate (dSR) were measured using two different methods: (1) mean LS and dSR, the averages of instantaneous LS and dSR over 10 sec, and (2) index-beat LS and dSR, calculated when the ratio of the preceding (RR1) to the pre-preceding (RR2) interval was 1 (range, 0.96-1.04). These variables were compared with simultaneously measured LV pressure parameters using Millar catheters.
  
  
  RESULTS
  There was a positive linear relationship between mean LS and index-beat LS at RR1/RR2 = 1 (r = 0.94, P < .001) and a positive linear relationship between mean dSR and index-beat dSR (r = 0.69, P < .001). Index-beat LS was correlated with the maximal positive derivative of LV pressure (peak +dP/dt) (r = -0.73, P < .001). Index-beat dSR was correlated with the time constant of isovolumic LV pressure decay (τ) (r = -0.63, P < .001). To investigate the independent predictors of τ, a stepwise multilinear regression analysis showed that index-beat dSR was the best predictor of τ.
  
  
  CONCLUSIONS
  Index-beat parameters accurately reflect the mean values of parameters in patients with AF. These noninvasively obtained index-beat parameters are useful to assess surrogate LV function even in patients with AF.
authors: Institute of Health Biosciences, Department of Cardiovascular Medicine, University of Tokushima Graduate School, Tokushima, Japan.
authors: Kenya
authors: K
authors: Kusunose
authors: Hirotsugu
authors: H
authors: Yamada
authors: Susumu
authors: S
authors: Nishio
authors: Noriko
authors: N
authors: Tomita
authors: Junko
authors: J
authors: Hotchi
authors: Mika
authors: M
authors: Bando
authors: Toshiyuki
authors: T
authors: Niki
authors: Koji
authors: K
authors: Yamaguchi
authors: Yoshio
authors: Y
authors: Taketani
authors: Takashi
authors: T
authors: Iwase
authors: Takeshi
authors: T
authors: Soeki
authors: Tetsuzo
authors: T
authors: Wakatsuki
authors: Masataka
authors: M
authors: Sata
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D003971:Diastole / Q000502:physiology; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology; D011446:Prospective Studies; D012044:Regression Analysis; D015203:Reproducibility of Results; D013599:Systole / Q000502:physiology