Ethnicity-Specific Changes in Cardiac Troponin T in Response to Acute Mental Stress and Ethnicity-Specific Cutpoints for the R Wave of the aVL Lead.

Acute mental stressor-induced cardiac stress responses might contribute to excessive myocardial strain and resultant cardiovascular episode risk. We assessed ethnicity-specific acute cardiac stress (by measuring cardiac troponin T (cTnT) and N-terminal prohormone of brain natriuretic peptide) related to hemodynamic activity. The prospective Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study was conducted during 2007-2008 in South Africa. In the cross-sectional phase of the SABPA study, 388 black and white participants underwent a 1-minute acute mental stressor, during which blood pressure was continuously measured. Fasting blood samples for cardiac stress markers were obtained before and 10 minutes after stress (% change). Resting 10-lead electrocardiogram measured the R wave of the aVL lead (RaVL). Black participants exhibited greater cardiac stress responses (P < 0.001), diastolic blood pressure, total peripheral resistance, and stroke volume compared with white participants, who displayed decreases in cardiac stress and increases in cardiac output. Prestress and stressor cTnT cutpoints of 4.2 pg/mL predicted 24-hour, daytime, and nighttime diastolic hypertension in black participants (P < 0.001). These cTnT cutpoints were associated with an ethnicity-specific RaVL cutpoint of 0.28 mV (odds ratio = 3.49, 95% confidence interval: 2.18, 5.83; P = 0.021). Acute mental stress elicited an α-adrenergic activation pattern and cardiac stress hyperreactivity only in black participants. Mental stress might increase the black population's risk for ischemic episodes and heart disease.

BDNF increases associated with constant troponin T levels and may protect against poor cognitive interference control: The SABPA prospective study.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) modulates brain health and cognition, which can interfere with executive cognitive function. BDNF was implicated with microcirculatory ischaemia and may reflect cardiomyocyte injury. We aimed to determine whether prospective changes (%Δ) in BDNF and cardiac troponin T (cTnT) will be associated with executive cognitive function in a bi-ethnic cohort. DESIGN: A prospective investigation was conducted over a three-year period in a bi-ethnic sex cohort (N = 338; aged 20-65 years) from South Africa. Fasting serum samples for BDNF and cTnT were obtained. The STROOP-color-word conflict test (CWT) was applied to assess executive cognitive function at baseline. RESULTS: In Blacks, BDNF (P < 0.001) increased over the three-year period while cTnT did not change. In contrast, in Whites, BDNF and cTnT decreased over three years. In Black men, no change in cTnT was associated with increased ΔBDNF (ß = 0.25; 95% CI 0.05-0.45; P = 0.02). In the Black men, constant cTnT levels were inversely associated with executive cognitive function (ß = -0.33; 95% CI -0.53 to -0.12; P = 0.003). Three-year increases in BDNF increased the likelihood for chronic lower cTnT levels at a pre-established cut-point of <4.2 ng/L [OR = 2.35 (1.12-4.94), P = 0.02]. The above associations were not found in the White sex groups. CONCLUSIONS: Central neural control mechanisms may have upregulated BDNF in Black men as a way to protect against myocardial stress progression and to possibly improve processes related to cognitive interference control. High-sensitive cTnT levels may act as an early predictor of disturbed neural control mechanisms.

Depression Symptoms Facilitated Fibrinolytic Dysregulation and Future Coronary Artery Disease Risk in a Black Male Cohort: The Sympathetic Activity and Ambulatory Blood Pressure in Africans Study.

BACKGROUND: Hypercoagulation is associated with coronary artery disease (CAD). Whether depression symptoms dysregulate inflammatory and hemostatic markers in an African cohort is not known; therefore, we assessed the relationship between depressive symptoms and inflammatory and hemostatic markers as potential CAD risk markers in an African sex cohort. MATERIAL AND METHODS: We included 181 black African urban-dwelling teachers (88 men, 93 women; aged 25-60 years) from the Sympathetic Activity and Ambulatory Blood Pressure in Africans Study. The Patient Health Questionnaire was used to assess depressive symptoms. Fasting plasma concentrations of C-reactive protein, fibrinogen, D-dimer, plasminogen activator inhibitor-1 (PAI-1) and 24-hour blood pressure measures were obtained. RESULTS: Moderately severe depression symptom status was similar in the black sex groups. Both sex groups showed a mean hypertensive state and low-grade inflammation (C-reactive protein > 3 mg/L). Levels of PAI-1 were higher in depressed men, whereas D-dimer levels were lower in depressed women when considering concomitant confounders. In black men only, depressive symptoms were associated with levels of PAI-1 (adj. R = 0.12; ß = .22 [95% confidence interval, .0-.44]; P = .04) and D-dimer (adj. R = 0.12; ß = .28 [95% confidence interval, .08-.48]; P = .01), independent of confounders. CONCLUSION: In black men, depression symptoms accompanied by a mean hypertensive status may up-regulate inflammatory and thrombotic processes. Depression symptoms in black men facilitated hypercoagulation or fibrinolytic dysregulation and potentially increased their CAD risk. Early screening of fibrinolytic markers and for the presence of depressive symptoms is recommended.

The defense response and alcohol intake: A coronary artery disease risk? The SABPA Study.

The behavioral defense coping response (DefS) as a measure of coping with emotional stress may increase alcohol intake (gamma glutamyl transferase (γGT)), the risk for coronary artery disease (CAD) and insulin sensitivity (homeostasis model assessment, HOMA). We assessed associations between coping and cardiometabolic risk markers in a bi-ethnic cohort (N = 390) from South Africa. Ambulatory blood pressure (BP) and ECG, fasting blood and coping scores were obtained. Africans, and mostly when utilizing DefS, showed higher 24h BP, a low-grade inflammatory state, central obesity, increased HOMA [4.07 (3.66, 4.47)] and more ST events compared to their Caucasian counterparts. ROC γ-GT analyses predicting 24-h ambulatory hypertension showed a higher γ-GT cut-point in Africans (55.4 U/l) than in Caucasians (19.5 U/l). Odds ratios (ORs) of γ-GT cut-points predicting 24-h ambulatory hypertension was evident in DefS African men [OR: 7.37 (95% CI: 6.71-8.05), p = 0.003] and in DefS Caucasians, albeit at a lower γ-GT cut-point (19.5 U/l). Higher γ-GT cut-points in DefS Africans or Caucasians were not associated with HOMA > 3. DefS accompanied by alcohol abuse in taxing emotional situations, if no social support is forthcoming, underscores a profile of reduced coronary perfusion. It may enhance vasoconstriction of the coronary arteries, with compensatory increases in BP, and induce a risk for future coronary artery disease.

Fibrosis and coronary perfusion - a cardiovascular disease risk in an African male cohort: The SABPA study.

Low-grade inflammation has been correlated with risk factors of cardiovascular diseases (CVD). Whether the pro-inflammatory and thrombotic ratio (fibrosis) may contribute to CVD is not known. We therefore aimed to assess whether Cornell Product left ventricular hypertrophy (LVH) is associated with fibrosis and coronary perfusion (silent ischemia) in a bi-ethnic male cohort from South Africa. A cross sectional study was conducted including 165 African and Caucasian men between the ages of 20-65. Fasting blood samples were obtained to measure fibrinogen, C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor (TNF-α). Ambulatory blood pressure, ECG and 12 lead ECG measures were obtained to determine silent ischemic events (ST events) and LVH, respectively. Africans revealed more silent ischemia, higher 24 h blood pressure, inflammatory, coagulation as well as fibrosis levels than Caucasians. In a low-grade inflammatory state (CRP > 3 mg/l), Africans revealed higher fibrosis (p ≤ 0.01) values, but lower IL-6 and TNF-α values than Caucasians. Linear regression analyses in several models demonstrated positive associations between silent ischemia and fibrosis [Adj. R(2) 0.23; ß 0.35 (95% CI 0.13, 0.58), p ≤ 0.01]. In a low-grade inflammatory state (CRP>3mg/l), fibrinogen predicted AV-block in African men [OR 3.38 (95% CI 2.24, 4.53); p = 0.04]. Low-grade inflammation may induce AV-block through mechanisms involving fibrosis and ischemia to increase the burden on the heart in African men.

End-organ damage in urbanized Africans with low plasma renin levels: the SABPA study.

The purpose of this study was to evaluate whether active renin concentration is associated with markers of end-organ damage in urbanized Africans. This study forms part of the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study. For this study, 81 men and 74 women were divided into low- and high-renin groups. Ambulatory blood pressure measurements were conducted. A resting 12-lead ECG was determined in order to determine the gender-specific Cornell voltage. Cardiovascular variables were continuously recorded with the Finometer. Carotid-dorsalis pedis pulse wave velocity was obtained with the Complior acquisition system. The carotid intima-media thickness (CIMT) was obtained with the SonoSite MicroMaxx. Blood samples were collected; serum and plasma were stored at -80 °C for analysis. Anthropometric measurements were taken using standard methods. A general health questionnaire was also completed. The urinary creatinine was determined with a calorimetric method and albumin with a turbidimetric method. The serum sodium and potassium were determined by making use of the Konelab TM 20i Sequential Multiple Analyzer Computer (SMAC). The concentration of active renin in the plasma was analyzed by making use of a high-sensitivity radio-immunometric assay. A negative association (r=-0.29, p<0.01) exists between renal function (ACR) and plasma renin in the low-renin group (<6.18 pg/mL), which was not observed in Africans with high-renin levels. It seems evident that low renin in black South Africans may result in sub-clinical renal damage and impaired vascular function in a group of urbanized black South Africans.

Effects of acute and chronic stress on the L-arginine nitric oxide pathway in black and white South Africans: the sympathetic activity and ambulatory blood pressure in Africans study.

OBJECTIVE: This study investigated the impact of stress on effectors of the L-arginine/nitric oxide (NO) system including the endogenous inhibitor asymmetric dimethylarginine (ADMA). METHODS: Black (n = 168) and white (n = 206) South African teachers were exposed to a mental and a physical stressor for 1 minute, respectively. Serum samples for determination of l-arginine, NO metabolites, ADMA, and symmetric dimethylarginine (SDMA) were obtained at rest and during stress exposure. Perception of task stressfulness was assessed on a 7-point Likert scale, and psychological distress was estimated by the General Health Questionnaire. RESULTS: Black South Africans exhibited higher resting levels of NO metabolites (adjusted mean [standard error of the mean] = 11.3 [1.3] versus 3.9 [1.1] µmol/l, p < .001) but lower circulating ADMA (0.62 [0.02] versus 0.70 [0.02] µmol/l, p = .004) and SDMA (0.41 [0.01] versus 0.53 [0.01] µmol/l, p < .001) than did white South Africans. Ethnicity-by-psychological distress interaction was observed for resting levels of ADMA (p = .002), SDMA (p = .038), and L-arginine (p = .048). Ethnic differences in responses to experimental stress were evident for NO metabolites (blacks versus whites: 5.94 [1.55] versus -0.74 [1.25] µmol/l, p = .004) and SDMA (blacks versus whites: -0.02 [0.01] versus 0.02 [0.01] µmol/l, p = .004). Ethnicity-by-psychological distress interaction for stress responses was found for l-arginine/ADMA ratio (p = .027). CONCLUSIONS: The l-arginine/NO system is affected by psychosocial distress with higher susceptibility in black South Africans. This interaction may contribute to the higher cardiovascular disease risk in black South Africans.

Low testosterone and hyperkinetic blood pressure responses in a cohort of South African men: the SABPA Study.

Hypertension (HT) and the metabolic syndrome are major problems in Africa. The role of sex hormones in the cardiovascular profile of black Africans in South Africa has not been studied. Our objective was to study the association between the sex hormones and ambulatory blood pressure and the heart rate (HR) in black and white South Africans. The 24-hour ambulatory blood pressure measurements were performed and the blood samples were taken between 07:00 and 09:00 hours. A total of 80 black and 98 white South African teachers between 25 and 65 years of age from similar socioeconomic backgrounds from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study were included. As a result, a more vulnerable cardiovascular profile was observed in Africans compared with Caucasians. In the African group, low testosterone (T) explained 19%-36% of the variance in systolic blood pressure (SBP), diastolic blood pressure (DBP), and HR, whereas in the Caucasian group non-sex-hormone-binding globulin (non-SHBG)-bound T explained 27% of the variance in HR. In the African males, inverse associations between blood pressure and T (SBP: P = .08; DBP: P = .02) and non-SHBG-bound T (SBP: P < .001; DBP: P < .01) and HR (P < 0.01) were observed. Ambulatory HR predicted a prediabetic state in Africans. In conclusion, low T levels may predispose or result in impaired cardiovascular function in African men. The possibility exists that a prediabetic state, vagal-impaired HR, and hyperkinetic blood pressure responses may predispose or result in low T levels in African men.

Low grade inflammation and ECG left ventricular hypertrophy in urban African males: The SABPA study.

BACKGROUND: Hypertension and vascular hyperresponsiveness have been associated with structural wall abnormalities in black Africans. Whether low grade inflammation would have an additive effect is uncertain. Therefore, a novel investigation aimed to assess whether inflammation and pressure overload would have an additive association with ECG left ventricular hypertrophy (LVH). METHODS: We included 75 African and 87 Caucasian males. Ambulatory blood pressure monitoring was done in the working week. A resting 12-lead ECG recording was used for the determination of LVH with the Cornell product formula. Fasting blood samples were obtained for high sensitivity C-reactive protein (hs-CRP) analyses after a controlled overnight stay. Men were stratified into low (≤3 mg/L) and high (>3 mg/L) hs-CRP groups. RESULTS: African men revealed higher ambulatory blood pressure levels compared to Caucasian men independent of hs-CRP levels after adjustment for age, physical activity, cotinine, log γ-GT and body surface area. In forward stepwise linear regression analyses, SBP was positively associated with ECG LVH in all Africans. Considering low grade inflammatory status (>3 mg/L hs-CRP), SBP [Adj R(2)=0.49 (ß=0.99, 0.45, 1.44), p≤0.01] and pulse pressure [Adj R(2)=0.61 (ß=0.0.34, 0.88), p≤0.01] respectively, predicted ECG LVH in African but not in Caucasian men. CONCLUSIONS: Hyperdynamic blood pressure and inflammation acted in tandem as possible promoting factors to structural wall abnormalities in African men.

Arterial stiffness profiles: investigating various sections of the arterial tree of African and Caucasian people.

In Africans, arterial stiffness progression seems more pronounced compared to Caucasians. We compared the arterial stiffness profiles of different age groups and focused on muscular arteries and two more central arterial segments in African and Caucasian people from South Africa. In African (N = 374) and Caucasian (N = 376) participants (20-70 years), we measured carotid-radial (C-R) and carotid-dorsalis pedis (C-DP) pulse wave velocity (PWV) and aortic characteristic impedance (Zao). Major findings were that normotensive and high-normal/hypertensive (HT) Caucasians indicated increased trends of C-R PWV with aging (P = .029 and P = .067), not seen in the African groups (P = .122 and P = .526). Both ethnic groups showed significant increases of C-DP PWV and Zao with aging. High-normal/hypertensive Africans had significantly stiffer arteries than hypertensive Caucasians for almost all age groups, and for all stiffness measures. African C-R PWV correlated significantly with blood pressure (BP), but not with age. Opposite results were observed for Caucasians. In conclusion, the stiffness of muscular arteries is already elevated in young Africans, in both those with normal or elevated BP. This is possibly due to an earlier deterioration during childhood, or perhaps already present from birth. Also, in Caucasians stiffness seems more age-related, while in Africans it seems to be more pressure-related.

Associations of cholesterol and glucose with cardiovascular dysfunction in black Africans: the SABPA study.

The aim was to determine whether blood glucose or cholesterol is the more prominent contributor to cardiovascular dysfunction in 101 African men and 99 African women. We measured ambulatory daytime blood pressure (BP), carotid intima-media thickness (CIMT), and determined blood glucose and lipids in serum. High-density lipoprotein cholesterol (HDL) (p = 0.002) and HDL: total cholesterol (HDL:TC) (p ≤ 0.001) were significantly lower, while serum glucose (p ≤ 0.001) was significantly higher in men. In single, partial, and multiple regression analysis, BP correlated positively with blood glucose in men. Furthermore, CIMT (B = -0.50; p = 0.009) correlated negatively with HDL:TC in men. While in women CIMT (B = 0.346; p = 0.015) correlated positively with glucose. In conclusion, subclinical atherosclerosis is significantly related to an unfavorable HDL profile in men, whereas in women, this link is stronger with fasting glucose.

Heart rate variability, the dynamic nature of the retinal microvasculature and cardiac stress: providing insight into the brain-retina-heart link: the SABPA study.

BACKGROUND AND AIMS: Decreased heart-rate-variability (HRV) indicates increased sympathetic nervous system (SNS) activity and modulation with a shift in the sympatho-vagal balance towards SNS predominance. Increased SNS activity may precede volume-loading hypertension, contribute to increases in cardiac troponin T (cTnT), endothelial dysfunction and small vessel disease. Therefore, we investigated the retinal vasculature, HRV during flicker-light-induced-provocation (FLIP) and systemic cTnT, a marker of cardiac stress, to provide further evidence in support of the brain-retina-heart link. METHODS: Cross-sectional observations were obtained from a bi-ethnic cohort (N = 264), aged 23-68 years. Fasting serum samples for cTnT were obtained. Retinal vascular calibres were quantified from mydriatic eye fundus images and dynamic retinal vessel calibre responses were determined during FLIP. Time-and frequency domain parameters of HRV were calculated during FLIP for each participant. RESULTS: Africans had wider venules and attenuated time domain parameters during FLIP. In Africans, inverse associations emerged between arteriolar dilation and both cTnT and root-mean squared of the standard deviations of successive RR-intervals (rMSSD) (p = 0.030), and between arteriolar constriction and both low-frequency expressed in normalised units (LFnu) (p = 0.003) and high-frequency expressed in normalised units (p = 0.021). Wider venules inversely associated with standard deviation of the NN intervals (SDNN) as well as LFnu (p = 0.009) in Africans. An opposite profile was observed in Caucasians with both time-and frequency domain parameters of HRV in relation to retinal vessel structure and function. CONCLUSION: FLIP elicited increased SNS activity and modulation in this bi-ethnic cohort. In Africans, decreased HRV during FLIP accompanied arteriolar and venular responses and elevated systemic levels of cTnT, implying that the SNS exerted a significant effect on the smooth muscle tone of the retinal vasculature. Disrupted retinal autoregulation may imply general autonomic nervous system dysfunction; exemplifying central control by the brain on all systemic regulatory functions, across different vascular beds.

Correction to: Heart rate variability, the dynamic nature of the retinal microvasculature and cardiac stress: providing insight into the brain-retina-heart link: the SABPA study.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Ambulatory blood pressure monitoring and morning surge in blood pressure in adult black and white South Africans.

We examined whether there were differences in the circadian variation in blood pressure and the morning surge in blood pressure between black and white Africans. Clinic and ambulatory blood pressure data obtained from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study was examined (n = 406; 49% black African). Ambulatory blood pressure readings were fitted to a six-parameter double logistic equation to determine the power and rate of the morning surge in blood pressure. Multiple linear regression analysis was used to examine differences in blood pressure between black and white participants. Clinic and ambulatory blood pressure were higher in black participants throughout the day and night. In those taking medications, blood pressure was less well controlled in black subjects. Despite the higher systolic blood pressure, the day-night difference estimated by the logistic function was similar in black and white participants. However, the rate of rise and power in the morning surge in blood pressure was lower in black participants. We conclude that black participants of the SABPA study present with higher blood pressure throughout the day and night but have a lower power of the morning surge in blood pressure due to a slower morning rate of increase. Moreover, they had an increased prevalence of undiagnosed hypertension and, in those taking medication, were less likely to have their blood pressure controlled than their white counterparts.

Retinal Vasculature Reactivity During Flicker Light Provocation, Cardiac Stress and Stroke Risk in Africans: The SABPA Study.

Structural and functional similarities exist between the retinal, cerebral and, as previously suggested, the coronary microvasculature. Retinal microvascular structure and functionality (in response to flicker-light-induced-provocation (FLIP)) may relate to coronary artery disease risk and possible stroke risk. We investigated associations between retinal vessel structure, functionality and cardiac stress markers (cardiac troponin T [cTnT], amino-terminal B-type natriuretic peptide [NT-proBNP]) to translate these retina-heart relationships to stroke risk. We included 317 African and Caucasian teachers' (aged 23-68 years), who participated in the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study. Fasting plasma and serum samples for cTnT and NT-proBNP were collected. Retinal vascular calibres were quantified from fundus images and dynamic retinal vessel calibre responses during FLIP. The University of California stroke risk score was applied to assess sub-clinical 10-year stroke risk. cTnT levels were similar in Africans and Caucasians, whereas NT-proBNP levels were lower in Africans. In Africans, a reduced arteriolar calibre and attenuated arteriolar dilation during FLIP was associated with higher cTnT (p < 0.01). Their larger retinal-venular calibre (p < 0.02) and attenuated arteriolar dilation during FLIP (p < 0.05) were associated with lower NT-proBNP. Again, exclusively in Africans, increased cardiac stress, wider venular calibres and retinal arteriovenous nicking predicted an increased 10-year stroke risk with odds ratios of 1.57 (95% CI, 1.34; 1.68, p = 0.031), 1.51 (95% CI, 1.26; 1.59, p = 0.002), 1.10 (95% CI, 0.94; 2.85, p = 0.002) and 1.06 (95% CI 0.83; 1.56, p = 0.052), respectively. None of these associations were evident in the Caucasian group. Investigating the retinal vasculature may serve as a tool to approximate sub-clinical coronary and cerebral microvasculature damage or dysfunction. These cardiac stress-retinal associations additionally predicted a greater stroke risk in the SABPA African cohort. Observable changes in the retinal vasculature may serve as markers for the identification and prediction of cardio-systemic and cerebral vascular morbidities and risks, thereby establishing a brain-heart link. Graphical Abstract Proposed series of events during which sustained high pressure and increased cardiac stress may alter retinal reactivity and link to increased stroke risk.

Longitudinal changes of cardiac troponin and inflammation reflect progressive myocyte stretch and likelihood for hypertension in a Black male cohort: The SABPA study.

Inflammation was cross-sectionally associated with subclinical wall remodeling and hypertension. Whether longitudinal changes (∆) in inflammation, myocyte injury (troponin T), and stretch (N-terminal-pro-B-type natriuretic peptide) are associated with hypertension and ECG left ventricular hypertrophy (ECG-LVH) is unclear. The first prospective analysis in Africa assessing these associations included a cohort of Black and White teachers (N = 338; aged 20-63 years). Fasting blood samples were obtained to measure tumor necrosis factor-alpha (TNF-α), cardiac troponin T (cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP). Ambulatory blood pressure, 2-lead ECG and resting 10-lead ECG values were obtained. A higher mean hypertensive status (62%) was evident in Blacks compared to Whites (44%, p < 0.001). Over 3-years, NT-proBNP increased in both ethnic groups. No associations were evident in women or in White men. In Black men, ECG-LVH at follow-up was positively associated with baseline cTnT (Adj R2 0.43; ß = 0.48; 95% CI 0.28-0.68, p < 0.001) and baseline SBP (Adj R2 0.43; ß = 0.29; 95% CI 0.09-0.49, p = 0.006). In Black men, baseline TNF-α (OR = 1.49, 95% CI 1.05-2.14, p = 0.03) and decreased ΔTNF-α (OR = 2.07, 95% CI 1.26-3.40, p = 0.004) increased the likelihood for cTnT levels ≥ 4.2 ng/L. Here, baseline NT-proBNP (OR = 1.12, 95% CI 1.01-1.23, p = 0.03) and ΔNT-proBNP progression (OR = 1.09, 95% CI 1.00-1.81, p = 0.04) increased the likelihood for 24-h hypertension. In conclusion, chronically increased levels of markers of myocyte injury accompanied by progressive myocardial stretch, reflective of cardiac metabolic overdemand, may ultimately increase hypertension and ischemic heart disease risk in a cohort of Black males.

Prospective associations between cardiac stress, glucose dysregulation and executive cognitive function in Black men: The Sympathetic activity and Ambulatory Blood Pressure in Africans study.

OBJECTIVE: Glucose dysregulation is an independent risk factor for cardiovascular and neurodegenerative disease development through synaptic dysfunction resulting in cognitive decline. The aim of this study was to study the interplay between impaired glycaemic metabolism (hyperglycaemia and insulin resistance), cardiac stress (cardiac troponin T and N-terminal brain natriuretic peptide) and executive cognitive function prospectively, in a bi-ethnic sex cohort. METHODS: Black and White teachers (N = 338, aged 20-63 years) from the Sympathetic activity and Ambulatory Blood Pressure in Africans study were monitored over a 3-year period. Fasting blood samples were obtained for cardiac troponin T, N-terminal brain natriuretic peptide, glycated haemoglobin and the homeostatic model assessment-insulin resistance for insulin resistance. The Stroop colour-word conflict test was applied to assess executive cognitive function at baseline. RESULTS: Over the 3-year period, Black men revealed constant high levels of cardiac troponin T (⩾4.2 ng/L), pre-diabetes (glycated haemoglobin > 5.7%) and insulin resistance (homeostatic model assessment-insulin resistance >3). %Δ Glycated haemoglobin was associated with %Δ insulin resistance (p < 0.001) and increases in %ΔN-terminal brain natriuretic peptide (p = 0.02) in Black men only. In the latter, baseline Stroop colour-word conflict test was inversely associated with %Δ cardiac troponin T (p = 0.001) and %Δ insulin resistance levels (p = 0.01). CONCLUSION: Progressive myocyte stretch and chronic myocyte injury, coupled with glucose dysregulation, may interfere with processes related to interference control in Black men.

The influence of cardiac and vascular responses on baseline cardiovascular parameters in Black African children.

BACKGROUND: The prevalence of hypertension among Black adults in South Africa is high. Because cardiovascular reactivity can be used to predict hypertension in later life, we attempted to determine whether cardiac and vascular responses to a task in Black South African children influence their cardiovascular parameters. DESIGN: This study was embedded in the Transition and Health during Urbanization in South Africa in Children study, which studied the health status of children. During the study, cardiovascular reactivity was determined with a hand dynamometer in 670 Black African children. Systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, stroke volume, cardiac output, total peripheral resistance, and Windkessel compliance of the arterial system were obtained by means of the Finapres (finger arterial pressure) apparatus and the Fast Modelflow software program. Anthropometric measurements were performed according to standard methods. Cardiac and vascular responders were classified with a regression-based approach. RESULTS: Cardiac responders had higher stroke volume; a trend to higher cardiac output; lower diastolic blood pressure; and a tendency toward lower systolic blood pressure, heart rate, and total peripheral resistance. Vascular responders showed no significant changes in cardiovascular parameters when responders and nonresponders were compared. CONCLUSIONS: Cardiac responders had higher stroke volume and a trend toward higher cardiac output, which may be an early indication of hypertension.

QTc prolongation, increased NT-proBNP and pre-clinical myocardial wall remodeling in excessive alcohol consumers: The SABPA study.

Alcohol contributes greatly to vascular and structural modifications. Due to differences in the metabolism and tolerance of alcohol between ethnic groups, the manner of these modifications may differ. We investigated the association between alcohol consumption - measured via ethnic-specific gamma glutamyl transferase (γ-GT) cut-points - and markers of cardiac perfusion, electrical activity, and pre-clinical structural alterations. A South African target population study was performed in a bi-ethnic cohort (n = 405). Alcohol consumption was determined according to previously defined ethnic-specific γ-GT cut-points, where γ-GT ≥ 19.5 U/L and γ-GT ≥ 55 U/L indicated excessive alcohol consumption in Caucasians and Africans, respectively. Ambulatory 24-h blood pressure and electrocardiograms (ECG), 10-lead ECG left ventricular hypertrophy (LVH), ischemic events, N-terminal pro-brain natriuretic peptide (NT-proBNP), and QTc prolongation were assessed. Fasting blood samples were obtained. A poorer cardio-metabolic profile and mean 24-h hypertensive and ECG-LVH values were evident in high γ-GT groups of both ethnicities, when compared to their low counterparts. The African high γ-GT group reported a higher intake of alcohol and presented significant increases in NT-proBNP (p < 0.001), QTc prolongation (p = 0.008), and ischemic events (p = 0.013). Regression analyses revealed associations between ECG-LVH and NT-proBNP, QTc prolongation, ischemic events, and SBP, in the African high γ-GT group exclusively. High alcohol consumers presented delayed electrical conduction in the heart accompanied by ECG-LVH, ischemic events, and increased vaso-responsiveness, predominantly in Africans. Ultimately, increased left ventricular distension on a pre-clinical level may elevate the risk for future cardiovascular events in this population.

Chronic depression symptoms desensitize renin activity to protect against volume-loading hypertension in Blacks: The SABPA study.

BACKGROUND: Low-renin levels in Blacks have been associated with volume-loading hypertension (HT). Depression symptoms, frequently co-occurring with vascular dysregulation, might reflect a disturbed renin-angiotensin-aldosterone-system (RAAS). We aimed to assess prospective changes (∆) in depression symptoms, RAAS (renin, aldosterone), diastolic blood pressure (DBP), and estimated glomerular filtration rate (eGFR) in a bi-ethnic sex cohort. METHODS: We included 195 Black and White teachers (43.7 ±â€¯9 years) from a South African 3-year prospective study. Hypertension medication users, diabetics and human immunodeficiency virus infected individuals were excluded. Depression symptoms (Patient-Health-Questionnaire-9/PHQ-9), 24 h blood pressure measurements and fasting blood samples were obtained. RESULTS: Blacks had lower renin but higher DBP and eGFR levels at baseline (p ≤ .01) when compared to Whites. Blacks and Whites with depression (PHQ-9 ≥ 10) at baseline developed co-morbidity for having both depression plus DBP-HT at follow-up (Blacks, 49.1%; Whites, 13.1%). At 3-year follow-up, chronic depression symptoms were related to chronic lower renin in Blacks [Adjusted R2 0.20; ß -0.37 (-0.66, -0.08), p = .02]. Chronic depression symptoms also predicted DBP hypertension in Blacks [ROC AUC = 0.61 (0.48-0.75); sensitivity/specificity 78.1/46.3%]. No prospective associations existed between depression symptoms, aldosterone and eGFR. CONCLUSION: Chronic depression symptoms in Blacks activated the RAAS system activity with apparent desensitization of renin activity. Chronic depression could be causal to hypertension and in turn, lowers renin activity as a protective mechanism against volume-loading. These findings emphasize the potential impact of depression on the low renin-hypertension phenotype in Blacks in terms of diagnosis and treatment.