Endothelial-dependent flow-mediated dilation in african americans with masked-hypertension

BackgroundOffice-blood pressure (BP) measurements alone overlook a significant number of individuals with masked-hypertension (office-BP: 120/80-139/89mmHg and 24-h ambulatory BP monitoring (ABPM) daytime 135/85mmHg or night-time 120/70mmHg). Diminished endothelial function contributes to the pathogenesis of hypertension. To better understand the pathophysiology involved in the increased cardiovascular (CV) disease risk associated with masked-hypertension, we estimated the occurrence, assessed the endothelial function, compared plasma levels of inflammatory markers, white blood cell count (WBC count), tumor necrosis factor-α (TNF-α), and high sensitivity C-reactive protein (hsCRP) and examined the possible relationship between endothelial function and inflammatory markers in apparently healthy prehypertensive (office-BP: 120/80-139/89mmHg) African Americans.MethodsFifty African Americans who were sedentary, nondiabetic, nonsmoking, devoid of CV disease were recruited. Office-BP was measured according to JNC-7 guidelines to identify prehypertensives in whom ABPM was then assessed. Fasting plasma samples were assayed for inflammatory markers. Brachial artery flow-mediated dilation (FMD) at rest and during reactive hyperemia was measured in a subset of prehypertensives.ResultsSubjects in the masked-hypertension sub-group had a higher hsCRP (P = 0.04) and diminished endothelial function (P = 0.03) compared to the true-prehypertensive sub-group (office-BP: 120/80-139/89mmHg and ABPM: daytime 135/85mmHg or night-time 120/70mmHg). Regression analysis showed that endothelial function was inversely related to hsCRP amongst the masked-hypertensive sub-group (R 2 = 0.160; P = 0.04).ConclusionsMasked- hypertension was identified in 58% of African Americans which suggests that a masking phenomenon may exist in a sub-group of prehypertensives who also seem to have a diminished endothelial function that could be mediated by an elevated subclinical inflammation leading to the increased CV disease.