title: Short-term variability of heart rate turbulence in chronic heart failure.
abstract: BACKGROUND
  Heart rate turbulence (HRT) is associated with risk in chronic heart failure (CHF). The objective of this study was to assess the short-term variability of HRT and to compare the diagnostic yield of 7-day (7DH) versus 24-hour (1DH) Holter monitoring for calculating HRT in a CHF population.
  
  
  RESULTS
  Forty-nine consecutive patients with CHF were studied. At inclusion, 7DH was performed to evaluate the variability of HRT parameters. For categorized analyses, turbulence onset (TO) ≥0% and turbulence slope (TS) ≤2.5 ms/RR were defined as abnormal, and patients were classified into subgroups based on the number of abnormal HRT parameters.The cumulative percentage of patients with calculable HRT increased from 69.4% with 1DH to 93.9% with 7DH. The intraclass correlation coefficients across the 7-day monitoring were 0.81 (95% confidence interval [CI] 0.70-0.89) for TO and 0.90 (95% CI 0.84-0.95) for TS. When comparing 2 randomly selected days, TO and TS values were similar (P > .1) and showed a strong correlation (TO: r = 0.79; TS: r = 0.84: P < .001). Bland-Altman plots showed a mean difference of 0.31% (95% CI -0.07 to 0.70) for TO and 0.44 ms/RR (95% CI -1.37 to 0.48) for TS. In contrast, categorized analyses showed that up to 16% of patients changed their HRT subgroup score from day 1 to day 2 of comparison.
  
  
  CONCLUSIONS
  In this population, 7DH significantly increased the percentage of patients with calculable HRT parameters. The short-term variability of the quantitative HRT values was good, but when patients were categorized into the established HRT subgroups, the concordance was suboptimal.
authors.affiliation: Cardiology Department, University Hospital Virgen de la Arrixaca, Murcia, Spain. sergiosmf13@hotmail.com
authors.forename: Sergio
authors.initials: S
authors.lastname: Manzano-Fernández
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Pastor-Pérez
authors.forename: Óscar
authors.initials: Ó
authors.lastname: Barquero-Pérez
authors.forename: Domingo A
authors.initials: DA
authors.lastname: Pascual-Figal
authors.forename: Rebeca
authors.initials: R
authors.lastname: Goya-Esteban
authors.forename: José Luis
authors.initials: JL
authors.lastname: Rojo-Álvarez
authors.forename: Antonio
authors.initials: A
authors.lastname: Caamaño-Fernández
authors.forename: María Dolores
authors.initials: MD
authors.lastname: Martínez Martínez-Espejo
authors.forename: James Louis
authors.initials: JL
authors.lastname: Januzzi
authors.forename: Mariano
authors.initials: M
authors.lastname: Valdés
authors.forename: Arcadio
authors.initials: A
authors.lastname: García-Alberola
mesh_terms: D000328:Adult; D002908:Chronic Disease; D015331:Cohort Studies; D015716:Electrocardiography, Ambulatory / Q000379:methods; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors