Endothelial-Dependent Flow-Mediated Dilation in African Americans With Masked-Hypertension

Abstract

BACKGROUND Office-blood pressure (BP) measurements alone overlook a significant number of individuals with masked-hypertension (office-BP: 120/80 -139/89 mmHg & 24-hr ambulatory BP monitoring, ABPM: daytime >135/85 mmHg or nighttime >120/70 mmHg). Diminished endothelial function contributes to the pathogenesis of hypertension. To better understand the pathophysiology involved in the increased cardiovascular disease (CVD) risk associated with masked-hypertension, we estimated the occurrence, assessed the endothelial function, compared plasma levels of inflammatory markers, white blood cell count, tumor necrosis factor-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: 120/80-139/89 mmHg) African-Americans. METHODS 50 African-Americans who were sedentary, non-diabetic, non-smoking, devoid of CVD 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 at rest and during reactive hyperemia was measured in a subset of prehypertensives. RESULTS Subjects 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: 120/80-139/89 mmHg & ABPM: daytime <135/85 mmHg or nighttime <120/70 mmHg). Regression analysis showed that endothelial function was inversely related to hsCRP amongst the masked-hypertensive sub-group (R2=0.160; P=0.04). CONCLUSIONS Masked-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 CVD.

Masked Hypertension and Elevated Nighttime Blood Pressure in CKD

“…In CRIC, masked hypertension was associated with low eGFR, and masked and sustained hypertension were associated with elevated urine protein, independent of other risk factors. It is possible that ABP is affected more than clinic BP by endothelial function, for which elevated urine protein is a surrogate marker (34)(35)(36). In summary, our data indicate that patients with masked hypertension are more likely to have low eGFR and proteinuria.…”

The Role of Microalbuminuria in Arterial Endothelial Dysfunction in Hypertensive Patients With Carotid Plaques

“…However, there is still some difference of opinion about NMD among several studies. In Veerabhadrappa's 14) study, masked-hypertensive patients had a diminished FMD compared to the true prehypertensive patients, but did not have a diminished NMD. However, another study 15) involving 800 subjects demonstrated that both FMD and NMD were impaired in these patients although they had no symptoms but did have risk factors for atherosclerosis.…”

What Is the Significance of Masked Hypertension Versus Incident Hypertension in Blacks?

“…1 However, there are at least 5 other aspects of masked hypertension of clinical importance: (1) it has been considered an intermediate phenotype between sustained normotension and sustained hypertension, which most frequently arises from antecedent high-normal BP (130-139/85-89 mm Hg), less frequently from antecedent normal BP (120-129/80-84 mm Hg); and least frequently from antecedent optimal BP (<120/<80 mm Hg) 1 (note that normal and high-normal BP when combined are called prehypertension); (2) it frequently is associated with hypertensive target organ damage even without progressing to hypertension, perhaps because of increased pressure burden in daily life, and despite a long-dormant period before transitioning to sustained hypertension 1 ; (3) it has been associated with many cardiometabolic abnormalities, including obesity, metabolic syndrome, diabetes mellitus, obstructive sleep apnea, and chronic renal disease 1 ; (4) it frequently has been associated with nocturnal hypertension and impaired nocturnal dipping of BP-a particularly high-risk phenotype 2 ; and (5) there is an especially high prevalence of masked hypertension in people of African descent, approaching 30% to 50% in some series. [3][4][5][6] It is with this background that the present investigators used ABPM to define masked hypertension as a possible precursor of incident clinic hypertension in 317 treatment-naive participants from the Jackson Heart Study, a prospective cohort of blacks. 7 The mean age of this group was 54.8 years, mean body mass index was 30.1 U, prevalence of diabetes mellitus was 11.7%, any masked hypertension subtype was 45.4%, and the presence of left ventricular hypertrophy was 11.1%.…”

“…[3][4][5][6] It is with this background that the present investigators used ABPM to define masked hypertension as a possible precursor of incident clinic hypertension in 317 treatment-naive participants from the Jackson Heart Study, a prospective cohort of blacks. 7 The mean age of this group was 54.8 years, mean body mass index was 30.1 U, prevalence of diabetes mellitus was 11.7%, any masked hypertension subtype was 45.4%, and the presence of left ventricular hypertrophy was 11.1%.…”