NONLINEAR RELATION OF THE CIRCADIAN BLOOD PRESSURE AMPLITUDE TO CARDIOVASCULAR

A b s t r a c t Data from two independent studies are reanalyzed to determine how the MESOR and the circadian amplitude (A) of blood pressure (BP) as well as the 24-hour standard deviation (SD) of heart rate (HR) relate to vascular disease risk. In one prospective study, risk is quantified by the actual number of events that occurred within 6 years. In the other retrospective study, the left ventricular mass index (LVMI) was used as a surrogate outcome measure available for all subjects. The BP MESOR is found to be linearly related to risk. By contrast, the circadian BP-A and the 24-hour SD of HR show a nonlinear relation with risk, which is elevated only after a threshold value for BP-A or HR-SD is exceeded. For the diagnosis of a deviation in BP and HR, the recommendation to monitor for 7 days at the outset seems as reliable an assessment as practical, but it may not be sufficient, and the patient must be advised that further monitoring may be needed. K e y w o r d s: Cardiovascular disease risk, circadian blood pressure amplitude, essential hypertensio