title: Impact of blood pressure variability on cardiac and cerebrovascular complications in hypertension.
abstract: BACKGROUND
  The independent prognostic value of daytime and night-time blood pressure (BP) variability estimated by noninvasive 24-h BP monitoring is unclear.
  
  
  METHODS
  We followed 2649 initially untreated subjects with essential hypertension for up to 16 years (mean, 6). Variability of BP was estimated by the standard deviation of daytime or night-time systolic BP (SBP) and diastolic BP (DBP). A BP variability either less than or equal to the group median or greater than the group median (12.7/10.4 mm Hg for daytime SBP/DBP and 10.8 and 8.9 mm Hg for night-time SBP/DBP) identified subjects at low or high BP variability.
  
  
  RESULTS
  During follow-up there were 167 new cardiac and 122 new cerebrovascular events. The rate of cardiac events (x100 person-years) was higher (all P < .05) in the subjects with high than in those with low BP variability (daytime SBP: 1.45 v 0.72, daytime DBP: 1.29 v 0.91; night-time SBP: 1.58 v 0.62; night-time DBP: 1.32 v 0.85). The rate of cerebrovascular events was also higher (all P < .05) in the subjects with high than in those with low BP variability. In a multivariate analysis, after adjustment for several confounders, a high night-time SBP variability was associated with a 51% (P = .024) excess risk of cardiac events. The relation of daytime BP variability to cardiac events and that of daytime and night-time BP variability to cerebrovascular events lost significance in the multivariate analysis.
  
  
  CONCLUSIONS
  An enhanced variability in SBP during the night-time is an independent predictor of cardiac events in initially untreated hypertensive subjects.
authors.affiliation: Clinical Research Unit-Preventive Cardiology, Hospital R. Silvestrini, Perugia, Italy. sheldon.tobe@sunnybrook.ca
authors.forename: Paolo
authors.initials: P
authors.lastname: Verdecchia
authors.forename: Fabio
authors.initials: F
authors.lastname: Angeli
authors.forename: Roberto
authors.initials: R
authors.lastname: Gattobigio
authors.forename: Cristian
authors.initials: C
authors.lastname: Rapicetta
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Reboldi
mesh_terms: D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D002318:Cardiovascular Diseases / Q000175:diagnosis* / Q000209:etiology; D002561:Cerebrovascular Disorders / Q000175:diagnosis* / Q000209:etiology; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications*; D007558:Italy; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012890:Sleep