Prognostic Significance of Variability in Ambulatory and Home Blood Pressure from the Ohasama Study

Ambulatory and home blood pressure (BP) can be measured over an extended period, thus generating information about BP variability. We have monitored a Japanese general population (Ohasama) for 20 years with respect to morbidity and mortality based on ambulatory and home BP, and have demonstrated the unique prognostic significance of variability in these values. A disturbed nocturnal decline in BP is associated with cerebral infarction and heart diseases, 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. A high BP at various times of the day is associated with different subtypes of cerebrovascular and cardiovascular disease risk. Home BP in the morning and in the evening provide equally useful information for stroke risk, whereas morning hypertension, which is that specifically observed only in the morning, might be a good predictor of stroke, particularly among individuals using anti-hypertensive medication. The BP and heart rate variabilities estimated as standard deviation measured every 30 minutes by ambulatory monitoring are independent predictors. That is, a higher short-term BP variability with a lower short-term heart rate variability leads to a worse cardiovascular prognosis. These variations in BP also bias the diagnosis and treatment of hypertension, which can be managed effectively by considering the phasic, as well as the tonic, component of BP.