Impact of Blood Pressure Variability on Cardiac and Cerebrovascular Complications in Hypertension

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 (×100 person-years) was higher (all P 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 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.