Predictors of Target Organ Damage in Hypertensive Blacks and Whites

Abstract

Abstract-The purpose of this study was to evaluate the association of the insulin resistance syndrome with both blood pressure and target organ damage in blacks and whites with essential hypertension. Eighty-two black and 63 white French Canadian patients were studied. None had diabetes, and antihypertensive medications had been discontinued for Ն1 week. Key Words: hypertrophy Ⅲ glomerular filtration rate Ⅲ insulin resistance Ⅲ microalbumin Ⅲ race Ⅲ target organ damage R esistance to insulin-stimulated glucose uptake is a complex phenotype with both genetic and lifestyle contributory factors. The insulin resistance syndrome includes central obesity, hyperinsulinemia, dyslipidemia, hypertension, hypercoagulability, and an increased potential for developing atherosclerotic disease. 1 The possibility that insulin resistance and hyperinsulinemia may contribute to elevated arterial pressure in patients with essential hypertension has generated considerable interest, and a number of putative mechanisms have been proposed. 2-4 However, results of epidemiological and clinical studies describing the relationship of insulin resistance and/or hyperinsulinemia to hypertension or to the development of hypertension are conflicting. 5 Some reports suggest that the relationship between insulin resistance and hypertension is less striking in blacks than in whites. 6 Among hypertensives, both renal disease and cardiac disease have been related to the insulin resistance syndrome. Microalbuminuria is a strong predictor of cardiovascular and renal disease risk. 7 Several 8 -10 but not all 11,12 reports describe an association of plasma insulin concentrations and/or indexes of insulin resistance with microalbuminuria. Glomerular hyperfiltration, a functional renal change that precedes glomerulosclerosis, 13-15 is associated with obesity, 16 and obesity augments the effect of hypertension on albuminuria. 17 Furthermore, in obese hypertensives, higher glomerular filtration rate (GFR) is associated with insulin resistance. 18 Insulin exerts a growth-stimulating effect on cardiac myocytes and increases collagen production in fibroblasts. 19 Several studies suggest that insulin resistance and/or hyperinsulinemia also contribute to concentric left ventricular hypertrophy and diastolic dysfunction in normotensives and hypertensives. 20,21 Blacks are at greater risk for developing hypertension related target organ disease than whites. Hypertensive blacks have a greater rate of decline of renal function over time than do whites, 22 and black men have a 4-fold-higher incidence of

Determining ethnic-, gender-, and age-specific waist circumference cut-off points to predict metabolic syndrome: the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study

“…Higher renal risk in Africans has been documented by other researchers. 14,32 However, in the current study, ROC-developed WC cut-off points were not associated with ACR. This may imply that the albumin to creatinine ratio is not the best measurement of kidney dysfunction, and that the estimated glomerular filtration rate should rather be applied where different grades of renal function need to be assessed, independent of ethnicity and gender.…”

“…10 MetS can contribute to the strain of microalbuminuria as a marker of target organ damage. 8,9,[11][12][13][14] It has been found that various MetS risk factors have been associated with renal impairment with regard to target organ damage in the SABPA population. 8,15 Determining ethnic-, gender-, and age-specific waist circumference cut-off points to predict metabolic syndrome: the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study JEMDSA The aim of this study was firstly to develop a WC cutoff point for Africans and Caucasians in ethnic-, gender-and age-specific groups (25-45 years and 46-65 years) for MetS in this cohort.…”

Risk for Cardiovascular Outcomes among Subjects with Atherosclerotic Cardiovascular Disease and Greater-than-Normal Estimated Glomerular Filtration Rate

“…Although no previous study has demonstrated detrimental outcomes associated with higher GFR among patients with atherosclerotic cardiovascular disease, previous investigations have suggested that an elevated GFR is associated with other target organ damage (18,19). For example, among 111 hypertensive subjects with normal renal function, glomerular hyperfiltration was associated with the presence of left ventricular hypertrophy, after adjustment for age, BMI, body surface area, and arterial pressure (19).…”

“…For example, among 111 hypertensive subjects with normal renal function, glomerular hyperfiltration was associated with the presence of left ventricular hypertrophy, after adjustment for age, BMI, body surface area, and arterial pressure (19). The presence of cardiac hypertrophy, glomerular hyperfiltration, and sodium retention has particularly been noted among black subjects with hypertension (18). In addition, studies have suggested that the presence of glomerular hyperfiltration in subjects with hypertension and diabetes increases a patient's risk for progressive renal dysfunction (20 -24).…”

Increased nighttime blood pressure or nondipping profile for prediction of cardiovascular outcomes

“…On the contrary, a large number of cross-sectional studies in hypertensive subjects have established an almost constant association between nocturnal BP phenotypes with cardiac adaptations including abnormal LV mass and geometry. 7,8,12,21,22 In addition, nondippers and those with hypertensive nocturnal BP values demonstrated impaired LV diastolic function, abnormal aortic root diameters and left atrium structural properties compared with dippers and those with normotensive nocturnal BP levels, respectively. 23,24 However, other studies have reported no difference in cardiac adaptations among dippers and nondippers, [25][26][27][28] whereas nocturnal hypertension was constantly related to LV mass, an issue not addressed by absolute nocturnal systolic and diastolic BP.…”