Cardiovascular characteristics in American youth with prehypertension.

BACKGROUND Cardiovascular structure and function in youth with prehypertension have been incompletely investigated. METHODS Casual and ambulatory blood pressure (BP) measurement, arterial stiffness, noninvasive hemodynamic profiles, and cardiac structure were studied in a twin cohort of American black and white youth (n = 942; mean age, 17.6 +/- 3.3 years SD). A family history of essential hypertension was used as a proxy to study genetic susceptibility to prehypertension. RESULTS The occurrence of prehypertension was approximately 12% in the entire sample. Body mass index and waist circumference were significantly greater in prehypertensive subjects than in normotensive subjects. The 24-h ambulatory systolic BP (SBP), 24-h ambulatory diastolic BP (DBP), nighttime ambulatory SBP, and nighttime ambulatory DBP were significantly elevated in prehypertensive subjects compared with normotensive subjects. In whites, prehypertensive subjects compared with normotensive subjects showed increased radial (6.8 +/- 0.1 v 6.2 +/- 0.1 m/sec, P < .001) and foot pulse-wave velocity (PWV) (7.4 +/- 0.1 v 7.0 +/- 0.1 m/sec, P = .001). In whites, the total peripheral resistance index was greater in prehypertensive subjects than in normotensive subjects (P = .005). White prehypertensive subjects had a significantly greater heart rate than white normotensive subjects (69.0 +/- 1.4 v 64.0 +/- 0.6 bpm). In contrast, in blacks, the cardiac index was higher in prehypertensive subjects than in normotensive subjects (3.3 +/- 0.1 v 3.0 +/- 0.1 L/min/m2, P = .004). In blacks and whites, there were no statistical differences in the parameters of left-ventricular structure between normotensive subjects and prehypertensive subjects. Finally, prehypertensive subjects were more likely to have a positive family history of essential hypertension, especially in blacks. CONCLUSIONS Prehypertension compared with normotension exhibited unfavorable cardiovascular phenotypes. Cardiovascular characteristics of prehypertension appear to be race-dependent.