title: Nocturnal nondipping of heart rate predicts cardiovascular events in hypertensive patients.
abstract: OBJECTIVE
  It has not been established whether nocturnal nondipping of heart rate (HR) predicts future cardiovascular disease (CVD). We performed this study to test the hypothesis that nocturnal nondipping of HR predicts the risk of incident CVD independent of nocturnal blood pressure dipping pattern.
  
  
  METHODS
  Ambulatory blood pressure monitoring was performed in 457 uncomplicated patients, who were being treated or evaluated for hypertension. They were followed for an average of 72 +/- 26 months. Nondipping HR was defined as a night/day HR ratio greater than 0.90. We chose two outcomes for this analysis: CVD events (defined as stroke, myocardial infarction, or sudden cardiac death) and all-cause mortality. Cox regression analyses (stepwise method) were used to estimate hazard ratios and their 95% confidence interval after adjusting for covariates.
  
  
  RESULTS
  In univariate analysis, increased sleep HR and nondipping of HR were associated with increased risk of CVD and all-cause mortality, but awake HR was not. In multivariable analyses, HR nondipping status significantly predicted an increased risk of CVD events (hazard ratio, 2.37; 95% confidence interval, 1.22-4.62; P = 0.01), but not for all-cause mortality. Increased 24-h HR was significantly associated with increased risk of all-cause mortality (hazard ratio, 1.67; 95% confidence interval, 1.11-2.51; P = 0.01).
  
  
  CONCLUSIONS
  The risk of future CVD was shown to be 2.4 times higher in those whose HR does not exhibit the typical nocturnal decline. The relationship was independent of nondipping of SBP and was not dependent on diabetes status or blood pressure level.
authors.affiliation: Department of Cardiology, International University of Health and Welfare Hospital, Nasushiobara, Japan. ke112@jichi.ac.jp
authors.forename: Kazuo
authors.initials: K
authors.lastname: Eguchi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hoshide
authors.forename: Joji
authors.initials: J
authors.lastname: Ishikawa
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Pickering
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Schwartz
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Shimada
authors.forename: Kazuomi
authors.initials: K
authors.lastname: Kario
mesh_terms: D000368:Aged; D018660:Blood Pressure Monitoring, Ambulatory; D002318:Cardiovascular Diseases / Q000503:physiopathology*; D002940:Circadian Rhythm; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies