The clinical significance of abnormal diurnal blood pressure variation in healthy late middle-aged and older adults.

Objective. A fall in nocturnal blood pressure (BP) is generally observed in normotensive subjects as well as in those with mild to moderate essential hypertension, regardless of the level of daytime BP. Among elderly hypertensive subjects, extreme-dippers with a marked nocturnal fall in BP as well as non-dippers with nocturnal fall absence are at increased risk for cardiovascular and cerebrovascular complications. However, the relationship between these abnormal diurnal BP variation patterns in normotensive elderly subjects has not been investigated. Methods. We classified 45 healthy late middle-aged and older adults into three groups according to the nocturnal systolic BP fall pattern examined by 24-h ambulatory BP monitoring (dipper, non-dipper and extreme-dipper), and compared the parameters of initial atherosclerosis, endothelial function and autonomic function. As a parameter of atherosclerotic factors, the intima-media thickness (IMT) of the carotid artery was examined, and as a parameter of endothelial function, brachial artery endothelium-dependent flow-mediated dilation (FMD) was ultrasonographyically measured. Autonomic function was assessed by power spectral analysis of heart rate variability (HRV). Results. No difference was observed in the severity of IMT between the three groups. The percent change of FMD in subjects in the extreme-dipper group was significantly lower than that of subjects in the dipper group, indicating that extreme-dippers in healthy elderly subjects may be associated with endothelial dysfunction. Also, HRV due to sympathetic modulation of subjects in the extreme-dipper group was significantly higher than that of subjects in the dipper and non-dipper groups, suggesting the activation of sympathetic tone. Conclusion. In healthy elderly subjects, the extreme-dipper type may reflect a decrease in endothelial function, i.e. initial stage atherosclerosis, rather than the dipper type.