Does orthostatic testing have any role in the evaluation of the young subject with mild hypertension?: an insight from the HARVEST study.

The aim of the study was to assess the clinical significance of the blood pressure (BP) reaction to standing in 1029 stage I hypertensives. Office BP was measured six times in the supine position and six times after 2 min of standing. All subjects underwent 24-h ambulatory BP monitoring, and measurements of 24-h urinary epinephrine and norepinephrine excretion. Echocardiography was performed in 636 patients. With use of mixture analysis we could single out a population with abnormal diastolic BP response to standing (hyperreactors, n = 95). These subjects had a diastolic BP increase from lying to standing of >11 mm Hg. The other subjects were defined as normoreactors (n = 934). Office systolic BP was similar in the two groups. Diastolic BP was lower (91 +/- 6 mm Hg v 95 +/- 5 mm Hg, P < .0001) and heart rate was higher in the hyperreactors (77 +/- 10 beats/min v 75 +/- 9 beats/min, P = .004). After adjusting for age, gender, and smoking habits the statistical significance did not change. Adjusted 24-h systolic BP (P = .02) and diastolic BP (P = .02) were higher in the hyperreactors than in the normoreactors. Hyperreactors were characterized by higher cardiac index (3.2 +/- 0.8 L/min/m2 v 3.0 +/- 0.7 L/min/m2, P = .008 for adjusted values), lower total peripheral resistance (1420 +/- 330 dyne/sec/cm(-5) v 1600 +/- 380 dyne/sec/cm(-5), P = .003), and higher urinary norepinephrine output (114.9 +/- 80.3 microg/24 h v 90.6 +/- 78.5 microg/24 h, P = .03). Dimensional echocardiographic data and albumin excretion rate did not differ between the two groups. In conclusion, mixture analysis allowed us to identify a population of young mild hypertensives with exaggerated BP response to standing. Hyperreactors were characterized by higher whole-day BP and by a hyperkinetic hemodynamic pattern as a result of increased sympathetic tone.