Morning Blood Pressure Hyper-reactivity Is an Independent Predictor for Hypertensive Cardiac Hypertrophy in a Community-Dwelling Population

Background Morning blood pressure (BP) surge seems to be a risk factor for cardiovascular events. Although physical activity after arising significantly affects morning BP surge, it has remained unclear whether morning BP surge after controlling for physical activity (morning BP reactivity) is associated with target organ damage. Methods We performed ambulatory BP monitoring with simultaneous actigraphy and echocardiography in 120 community-dwelling Japanese subjects. We determined the waking time by actigraphy, and defined morning BP surge (MBPS) as the average of systolic BP during the 2 h after awakening minus the average of systolic BPs during the 1 h that included the lowest sleep BP. The ratio of MBPS/(sum of the 2-h physical activity after the arising time)0.5 was calculated as the morning BP reactivity (MBPR). Results In all the subjects studied (n = 120), MBPR was positively associated with left ventricular (LV) mass index (r = 0.30, P = .001). The MBPR had a positive association with both 24-h BP variability (SD) (r = 0.373, P< .001) and awake BP variability (r = 0.20, P< .05). The MBP hyper-reactive group (the highest quartile [Q4] of MBPR: n = 30) had significantly higher LV mass index than the nonreactive group (the other quartiles [Q1 to 3]: n = 90) (140 v 113 g/m2, P< .001). Even after controlling for age, body mass index, gender, and 24-h systolic BP, the MBP hyper-reactive status still remained a strong predictor for LV hypertrophy. Conclusions Exaggerated MBPS, adjusted for physical activity, is associated with cardiac hypertrophy independent of ambulatory BP level in a community-dwelling population.