title: Reversal of deteriorated fractal behavior of heart rate variability by beta-blocker therapy in patients with advanced congestive heart failure.
abstract: BACKGROUND
  The slope of the power spectrum in heart rate variability (HRV) reflects the fractal or scaling behavior in HR dynamics and recently was confirmed as an independent predictor of postmyocardial infarction survival. Whether or not the new measurement in HRV foresees the functional evolution in patients with advanced congestive heart failure treated by beta blockers is unclear.
  
  
  RESULTS
  Sequential 24-hour Holter ECG recordings were obtained at baseline, and 1 and 3 months after addition of atenolol therapy for advanced congestive heart failure in 10 patients. The slope and intercept of the regression line of power-law behavior, the short- and intermediate-term of detrended fluctuated analysis (DFA), the approximate entropy (ApEn), and the standard frequency spectra of the 24-hour HRV were compared sequentially as well as with those in 12 age-matched normal controls. The results showed that the slope (-1.70 +/- 0.45 vs -1.22 +/- 0.21; P < 0.05) and the intercept (5.11 +/- 0.46 vs 5.62 +/- 0.24; P < 0.05) of the regression line of power-law behavior and the short-term DFA (for 4 to 11 beats) (0.78 +/- 0.18 vs 1.13 +/- 0.21; P < 0.05) increased after 3 months of atenolol treatment. However, the change in intermediate-term DFA (>11 beats) and ApEn was not apparent (1.24 +/- 0.21 vs 1.22 +/- 0.15 and 1.34 +/- 0.14 vs 1.36 +/- 0.11; both P > 0.05). The evolution of the slope or intercept of the regression line of the HRV power spectrum did not correlate with the echocardiographic or clinical cardiac function, or with the frequency spectral components of the HRV (P > 0.05).
  
  
  CONCLUSIONS
  Additional beta-blocker therapy upregulated the fractal behavior control of the HRV in patients with advanced congestive heart failure. The improvement was independent of subjective and objective global cardiac performance.
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, Taipei.
authors.forename: L Y
authors.initials: LY
authors.lastname: Lin
authors.forename: J L
authors.initials: JL
authors.lastname: Lin
authors.forename: C C
authors.initials: CC
authors.lastname: Du
authors.forename: L P
authors.initials: LP
authors.lastname: Lai
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Tseng
authors.forename: S K
authors.initials: SK
authors.lastname: Huang
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D001262:Atenolol / Q000627:therapeutic use*; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D019277:Entropy; D005260:Female; D017709:Fractals; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics
chemical_list: D000319:Adrenergic beta-Antagonists; D001262:Atenolol