Prognostic significance for stroke of a morning pressor surge and a nocturnal blood pressure decline - The Ohasama study

There is continuing controversy over whether the pattern of circadian blood pressure ( BP) variation that includes a nocturnal decline in BP and a morning pressor surge has prognostic significance for stroke risk. In this study, we followed the incidence of stroke in 1430 subjects aged >= 40 years in Ohasama, Japan, for an average of 10.4 years. The association between stroke risk and the pattern of circadian BP variation was analyzed with a Cox proportional hazards model after adjustment for possible confounding factors. There was no significant association between total stroke risk and the nocturnal decline in BP ( percentage decline from diurnal level) or between total stroke risk and the morning pressor surge. The cerebral infarction risk was significantly higher in subjects with a < 10% nocturnal decline in BP as compared with subjects who had a >= 10% nocturnal decline in BP ( P = 0.04). The morning pressor surge was not associated with a risk of cerebral infarction. On the other hand, an increased risk of cerebral hemorrhage was observed in subjects with a large morning pressor surge ( >= 25 mm Hg; P = 0.04). Intracerebral hemorrhage was also observed more frequently in extreme dippers ( those with a >= 20% nocturnal decline in BP) than dippers ( those with a 10% to 19% decline; P = 0.02). A disturbed nocturnal decline in BP is associated with cerebral infarction, whereas a large morning pressor surge and a large nocturnal decline in BP, which are analogous to a large diurnal increase in BP, are both associated with cerebral hemorrhage.