title: Novel measures of heart rate variability predict cardiovascular mortality in older adults independent of traditional cardiovascular risk factors: the Cardiovascular Health Study (CHS).
abstract: Novel HRV Predicts CV Mortality in the Elderly.
  
  
  BACKGROUND
  It is unknown whether abnormal heart rate turbulence (HRT) and abnormal fractal properties of heart rate variability identify older adults at increased risk of cardiovascular death (CVdth).
  
  
  METHODS
  Data from 1,172 community-dwelling adults, ages 72 +/- 5 (65-93) years, who participated in the Cardiovascular Health Study (CHS), a study of risk factors for CV disease in people >or=65 years. HRT and the short-term fractal scaling exponent (DFA1) derived from 24-hour Holter recordings. HRT categorized as: normal (turbulence slope [TS] and turbulence onset [TO] normal) or abnormal (TS and/or TO abnormal). DFA1 categorized as low (<or=1) or high (>1). Cox regression analyses stratified by Framingham Risk Score (FRS) strata (low = <10, mid = 10-20, and high >20) and adjusted for prevalent clinical cardiovascular disease (CVD), diabetes, and quartiles of ventricular premature beat counts (VPCs).
  
  
  RESULTS
  CVdths (N = 172) occurred over a median follow-up of 12.3 years. Within each FRS stratum, low DFA1 + abnormal HRT predicted risk of CVdth (RR = 7.7 for low FRS; 3.6, mid FRS; 2.8, high FRS). Among high FRS stratum participants, low DFA1 alone also predicted CVdth (RR = 2.0). VPCs in the highest quartile predicted CVdth, but only in the high FRS group. Clinical CV disease predicted CVdth at each FRS stratum (RR = 2.9, low; 2.6, mid; and 1.9, high). Diabetes predicted CVdth in the highest FRS group only (RR = 2.2).
  
  
  CONCLUSIONS
  The combination of low DFA1 + abnormal HRT is a strong risk factor for CVdth among older adults even after adjustment for conventional CVD risk measures and the presence of CVD.
authors.affiliation: Washington University School of Medicine, St Louis, Missouri 63108, USA. pstein@im.wustl.edu
authors.forename: Phyllis K
authors.initials: PK
authors.lastname: Stein
authors.forename: Joshua I
authors.initials: JI
authors.lastname: Barzilay
authors.forename: Paulo H M
authors.initials: PH
authors.lastname: Chaves
authors.forename: Stephanie Q
authors.initials: SQ
authors.lastname: Mistretta
authors.forename: Peter P
authors.initials: PP
authors.lastname: Domitrovich
authors.forename: John S
authors.initials: JS
authors.lastname: Gottdiener
authors.forename: Michael W
authors.initials: MW
authors.lastname: Rich
authors.forename: Robert E
authors.initials: RE
authors.lastname: Kleiger
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000401:mortality*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology*; D015716:Electrocardiography, Ambulatory / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008396:Maryland / Q000453:epidemiology; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D015996:Survival Rate