Facilitated defensive coping, silent ischaemia and ECG left-ventricular hypertrophy: the SABPA study

Coping strategies and resilience among patients with hypertension in Ghana

Background

Hypertension is associated with high morbidity and mortality and this has been linked to poor treatment and control rates. To optimize drug treatment, patient-centered strategies such as coping, resilience, and adherence to medication may improve control rates and decrease the morbidity and mortality associated with hypertension. This study, therefore, assessed coping skills and resilience among patients with hypertension in Ghana.

Methods

A cross-sectional study was conducted at Korle Bu Teaching Hospital. 224 consented patients with a diagnosis of hypertension were consecutively selected from the outpatient clinic. Questionnaires comprising socio-demographic characteristics, clinical parameters, Adult Resilience Measure, and the Africultural Coping Systems Inventory were administered. Data were analyzed using Stata version 16.1 and significance level was set at p-value of ≤ 0.05.

Results

The mean age of participants was 62.03 ± 11.40 years and the majority were female (63%). The overall coping strategy mean score was 43.13 ± 13.57. For resilience, median relational and personal resilience (PR) scores were 32 (IQR-7) and 39 (IQR-9), respectively. Increased systolic BP significantly increases the overall coping strategy score. Collective coping strategy and systolic BP significantly increased coping scores (95%CI = 0.05-3.69 vs. 95%CI = 0.58-5.31). Overall coping strategy significantly increased personal and relational resilience (RR) domain scores by 0.004 (95%CI = 0.002-0.01) and 0.005 (95%CI = 0.003-0.006) units, respectively. This study demonstrated that Cognitive and emotional debriefing coping strategy was mostly used by patients with hypertension.

Conclusion

Coping strategies had a positive and significant correlation with personal and RR, specifically collective and cognitive debriefing had a significant positive association with resilience among study participants. There is a need to actively put in measures that can improve the coping strategies and resilience among patients with hypertension to adjust to the long-term nature of the illness and treatment as this will promote better treatment outcomes.

Cardiorespiratory Fitness, Blood Pressure and Ethnicity Are Related to Salivary Cortisol Responses after an Exercise Test in Children: The ExAMIN Youth SA Study

BACKGROUND

Childhood elevated circulatory stress mediators such as cortisol seem to play an important role in the development of hypertension and metabolic disorders later in life. Little is known about the association of body composition, cardiorespiratory fitness (CRF), blood pressure (BP) and ethnicity with cortisol reactivity in young children.

METHODS

In this cross-sectional study, 324 black and 227 white school children (aged 7.4 ± 1.0 years) were screened for salivary cortisol reactivity, body mass index, BP and CRF (shuttle run) by standardised assessments for children.

RESULTS

Children in the lower cortisol reactivity percentile (<25th) had a higher heart rate (87.0 ± 12.9 bpm) and a lower CRF (3.1 ± 1.3 stages) compared to children in the upper (>25th) percentile (86.2 ± 11.5 bpm and 3.5 ± 1.7 stages, respectively). At baseline, children of black ethnicity had a higher cortisol level (p < 0.001). Immediately before the exercise test, no associations of obesity, BP, CRF and ethnicity with cortisol levels were found. In analysis of covariance (ANCOVA) we found that low CRF, high BP and black ethnicity were independently associated with lower cortisol reactivity by performing the shuttle run test (p < 0.01).

CONCLUSION

Low CRF and high BP were associated with lower cortisol reactivity after a cardiorespiratory exercise test. Black children showed a lower cortisol reactivity which may contribute to the earlier onset of hypertension reported in black compared to white populations. Primary prevention programs need to focus on improving physical fitness to reduce the growing prevalence of cardiometabolic disorders during childhood.

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.

Coping facilitated troponin T increases and hypo-responsivity in the copeptin-HPA-axis during acute mental stress in a black cohort: The SABPA study

BACKGROUND

Defensive coping (DefS) was associated with a vulnerable cardiovascular profile in blacks. The copeptin/vasopressin system is a manifestation of hypothalamic-pituitary-adrenal-axis activity and may act as an acute compensatory mechanism when there is a disruption in volume-loading homeostasis, i.e. when cardiac stress is evident. Whether DefS will influence associations between copeptin and cardiac stress markers, remains unclear. Here we aimed to determine associations between acute mental stress responses of copeptin, vascular responsiveness and biomarkers of cardiomyocyte injury [cardiac troponin T (cTnT)] and cardiac wall-stress [N-terminal pro-brain natriuretic peptide (NT-proBNP)] in DefS race groups.

METHODS

South African black and white teachers (n = 378) of both sexes, participated in this target population study. Cases with a history of myocardial infarction, stroke and atrial fibrillation were excluded. We obtained coping scores (Coping Strategy Indicator), beat-to-beat blood pressure and fasting blood samples at rest and after 1-min exposure to the Stroop-Colour-Word-Conflict-test.

RESULTS

Interaction effects (p < .05) for copeptin percentage change (%) during the Stroop-Colour-Word-Conflict-test determined stratification of participants into race and DefS (≥26, above-median score) groups. In DefS blacks, Stroop-Colour-Word-Conflict-test exposure elicited increases in cTnT%, NT-proBNP% and diastolic-blood pressure%. Again, in these individuals, multiple regression analyses showed positive associations between copeptin% and total peripheral resistance%; with inverse associations between copeptin% and cTnT% (p < .05). None of these associations were found in DefS whites.

CONCLUSIONS

Utilisation of DefS in blacks provoked vascular hyper-responsiveness and cardiac wall stress (elevated cTnT and NT-proBNP); possibly mediated via the copeptin/vasopressin system. However, a presumably hypo-responsive hypothalamic-pituitary-adrenal-axis during stress exposure could not counteract coronary perfusion deficits via additional copeptin/vasopressin release. The presence of defensiveness may have clinical implications in preventive cardiology.

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.

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; β = 0.48; 95% CI 0.28-0.68, p < 0.001) and baseline SBP (Adj R² 0.43; β = 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.

Coping and Cardiac Troponin T - A Risk for Hypertension and Sub-Clinical ECG Left Ventricular Hypertrophy: The SABPA Study

BACKGROUND

Defensive coping (DefS) was associated with cardiovascular disease (CVD) susceptibility in Blacks. Whether coping strategies will associate with sub-clinical left ventricular hypertrophy (electrocardiographic-left ventricular hypertrophy [ECG-LVH] or Cornell product), cardiomyocyte injury and blood pressure (BP), is unclear. Therefore, we assessed relationships between ECG-LVH, cardiac troponin T (cTnT) and 24-hour BP in bi-ethnic groups when habitually utilising a certain coping style, and these groups when having a stress-related cTnT cut-point of 4.2ng/L.

METHODS

A target population study included a Black (n=190) and White (n=204) teachers' gender cohort (20-65years) from South Africa. The Coping Strategy Indicator determined DefS, social support and avoidance coping scores. Fasting blood samples, 10-lead ECG, 24-hour BP and ECG data were obtained.

RESULTS

Interaction effects showed no gender, social support and avoidance coping differences. Stratification of groups was done for ethnicity and DefS. Blacks sought more social support, used less avoidance coping and presented with higher CVD susceptibility. Hypertension prevalence and ECG-LVH levels in DefS Blacks (63%) were higher compared to DefS Whites (40%). Multivariate regression analyses showed positive associations between Cornell product, cTnT and BP [p≤0.05] in DefS Blacks only. Their 24-hour systolic blood pressure (SBP) was associated with time-domain depressed heart-rate-variability and prolonged ST-segment-depression especially when applying an established stress-related cTnT ≥ 4.2ng/L cut-point.

CONCLUSIONS

Defensive coping facilitated autonomic hyperactivity, myocardial injury and subsequent compensatory BP elevations as possible homeostatic reflexes to alleviate myocardial perfusion deficits. The resulting pressure overload increased sub-clinical wall remodelling and ischaemic heart disease risk in Blacks utilising habitual defensiveness. We therefore recommend regular ECG and high sensitivity cTnT screening in asymptomatic patients with emotional stress susceptibility. Longitudinal evidence is needed to confirm causality and progression of cardiomyopathy risk.

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 defensiveness and neuroendocrine dysfunction reflect a novel cardiac troponin T cut point: The SABPA study

BACKGROUND

Sympatho-adrenal responses are activated as an innate defense coping (DefS) mechanism during emotional stress. Whether these sympatho-adrenal responses drive cardiac troponin T (cTnT) increases are unknown. Therefore, associations between cTnT and sympatho-adrenal responses were assessed.

METHODS

A prospective bi-ethnic cohort, excluding atrial fibrillation, myocardial infarction and stroke cases, was followed for 3 years (N=342; 45.6±9.0years). We obtained serum high-sensitive cTnT and exposure measures [Coping-Strategy-Indicator, depression/Patient-Health-Questionnarie-9, 24h BP, 24h heart-rate-variability (HRV) and 24h urinary catecholamines].

RESULTS

Blacks showed moderate depression (45% vs. 16%) and 24h hypertension (67% vs. 42%) prevalence compared to Whites. A receiver-operating-characteristics cTnT cut-point 4.2ng/L predicting hypertension in Blacks was used as binary outcome measure in relation to exposure measures [AUC 0.68 (95% CI 0.60-0.76); sensitivity/specificity 63/70%; P≤0.001]. Bi-ethnic cTnT-incidence was similar (Blacks=27%, Whites=25%) with cTnT-recovery better in Blacks (9%) compared to Whites (5%), P=0.001. In cross-sectional analyses, elevated cTnT was related to DefS [OR 1.08 (95% CI 0.99-1.16); P=0.06]; 24h BP [OR 1.03-1.04 (95% CI 1.01-1.08); P≤0.02] and depressed HRV [OR 2.19 (95% CI 1.09-4.41); P=0.03] in Blacks, but not in Whites. At 3year follow-up, elevated cTnT was related to attenuated urine norepinephrine:creatinine ratio in Blacks [OR 1.46 (95% CI 1.01-2.10); P=0.04]. In Whites, a cut point of 5.6ng/L cTnT predicting hypertension was not associated with exposure measures.

CONCLUSION

Central neural control systems exemplified a brain-heart stress pathway. Desensitization of sympatho-adrenal responses occurred with initial neural- (HRV) followed by neuroendocrine dysfunction (norepinephrine:creatinine) in relation to elevated cTnT. Chronic defensiveness may thus drive the desensitization or physiological depression, reflecting ischemic heart disease risk at a novel 4.2ng/L cTnT cut-point in Blacks.

Cohort Study of ECG Left Ventricular Hypertrophy Trajectories: Ethnic Disparities, Associations With Cardiovascular Outcomes, and Clinical Utility

BACKGROUND

ECG left ventricular hypertrophy (LVH) is a well-known predictor of cardiovascular disease. However, no prior study has characterized patterns of presence/absence of ECG LVH ("ECG LVH trajectories") across the adult lifespan in both sexes and across ethnicities. We examined: (1) correlates of ECG LVH trajectories; (2) the association of ECG LVH trajectories with incident coronary heart disease, transient ischemic attack, ischemic stroke, hemorrhagic stroke, and heart failure; and (3) reclassification of cardiovascular disease risk using ECG LVH trajectories.

METHODS AND RESULTS

We performed a cohort study among 75 412 men and 107 954 women in the Northern California Kaiser Permanente Medical Care Program who had available longitudinal exposures of ECG LVH and covariates, followed for a median of 4.8 (range <1-9.3) years. ECG LVH was measured by Cornell voltage-duration product. Adverse trajectories of ECG LVH (persistent, new development, or variable pattern) were more common among blacks and Native American men and were independently related to incident cardiovascular disease with hazard ratios ranging from 1.2 for ECG LVH variable pattern and transient ischemic attack in women to 2.8 for persistent ECG LVH and heart failure in men. ECG LVH trajectories reclassified 4% and 7% of men and women with intermediate coronary heart disease risk, respectively.

CONCLUSIONS

ECG LVH trajectories were significant indicators of coronary heart disease, stroke, and heart failure risk, independently of level and change in cardiovascular disease risk factors, and may have clinical utility.

The protective role of oestradiol against silent myocardial ischemia and hypertension risk in South African men: The SABPA study

BACKGROUND

Oestradiol has a protective effect on coronary artery health in women but the effect it has on men, is controversial. A translational approach was followed to assess whether sex hormone levels are associated with silent myocardial ischemia (SMI) and hypertension risk over a 3year period.

METHODS

Participants included 89 Black and 91 White men (aged 21-63years) participating in both phases of the Sympathetic activity and Ambulatory Blood Pressure in Africans prospective study. Fasting blood samples, ambulatory blood pressure and 2-lead ECG recordings were obtained.

RESULTS

No difference in the levels of the various baseline serum T fractions between the two ethnic groups occurred. Oestradiol of the Black men increased by 54.2% compared to a decrease of 24.1% in the White men. Changes in total oestradiol (adjusted R²=0.33, β=-0.31, p=0.023) and free oestradiol (adjusted R²=0.34, β=-0.33, p=0.019) were inversely associated with changes in SMI in the Black men but not in White men. Baseline serum nitric oxide metabolites were inversely associated with ΔSMI in the Blacks only (adjusted R²=0.33, β=-0.28, p=0.047). Chronic SMI was associated with 24h hypertension in Blacks [cut point 1.5 events: Area under the curve 0.71 (95% CI: 0.60, 0.82); p=0.006; with sensitivity/specificity 44%/94%].

CONCLUSIONS

Chronic SMI events facilitated future ischemic heart disease in Black men. Up-regulated free oestradiol seems to be involved in the protection of the heart against SMI and hypertension risk in Black but not in White men. A similar protective role for testosterone could however not be shown.

Recent advances in understanding hypertension development in sub-Saharan Africa

Consistent reports indicate that hypertension is a particularly common finding in black populations. Hypertension occurs at younger ages and is often more severe in terms of blood pressure levels and organ damage than in whites, resulting in a higher incidence of cardiovascular disease and mortality. This review provides an outline of recent advances in the pathophysiological understanding of blood pressure elevation and the consequences thereof in black populations in Africa. This is set against the backdrop of populations undergoing demanding and rapid demographic transition, where infection with the human immunodeficiency virus predominates, and where under and over-nutrition coexist. Collectively, recent findings from Africa illustrate an increased lifetime risk to hypertension from foetal life onwards. From young ages black populations display early endothelial dysfunction, increased vascular tone and reactivity, microvascular structural adaptions as well as increased aortic stiffness resulting in elevated central and brachial blood pressures during the day and night, when compared to whites. Together with knowledge on the contributions of sympathetic activation and abnormal renal sodium handling, these pathophysiological adaptations result in subclinical and clinical organ damage at younger ages. This overall enhanced understanding on the determinants of blood pressure elevation in blacks encourages (a) novel approaches to assess and manage hypertension in Africa better, (b) further scientific discovery to develop more effective prevention and treatment strategies and

Cortisol:brain-derived neurotrophic factor ratio associated with silent ischaemia in a black male cohort: the SA BPA study

Aim

Emotional distress has been associated with cardiovascular disease (CVD) in Africans. Cortisol and brain-derived neurotrophic factor (BDNF), as markers of emotional distress, increase cardiometabolic risk. We therefore aimed to investigate associations between cardiometabolic risk markers and the cortisol-to-BDNF ratio (cortisol:BDNF).

Methods

A cross-sectional study included a bi-ethnic gender cohort (n = 406) aged 44.7 ± 9.52 years. Ambulatory blood pressure (ABPM), ECG, fasting serum cortisol and BDNF levels and cardiometabolic risk markers were obtained.

Results

Africans had increased incidence of hyperglycaemia and 24-hour silent ischaemic events, and elevated 24-hour blood pressure (BP) and cortisol:BDNF ratios compared to Caucasians. Forward stepwise linear regression analysis underscored a similar trend with associations between hyperglycaemia, 24-hour BP [Adj R2 0.21–0.29; β 0.23 (0.1–0.4); p = 0.01], silent ischaemia [Adj R2 0.22; β 0.40 (0.2–0.6); p < 0.01] and cortisol:BDNF levels in Africans, mostly in the men.

Conclusion

Attenuated cortisol levels in this group may be indicative of emotional distress and if chronic, drive the cortisol:BDNF ratio to desensitise BDNF. Desensitised cortisol:BDNF may sustain cardiometabolic risk and induce neurodegeneration in African men via silent ischaemia. Compensatory increases in blood pressure to increase perfusion and maintain homeostasis may increase coronary artery disease risk.

Defensive coping and essential amino acid markers as possible predictors for structural vascular disease in an African and Caucasian male cohort: The SABPA study

Defensive coping (DefS), oxidative stress, inflammation, and related amino acids (phenylalanine [Phe] and tyrosine [Tyr]) have been implicated in cardiovascular disease. This study assessed whether inflammation, oxidative stress, changes in essential amino acids, and altered coping strategies are correlated with subclinical vascular changes in African (n = 82) and Caucasian (n = 100) men from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study. The Coping Strategy Indicator questionnaire identified DefS participants. Ambulatory blood pressure (BP) was monitored for 24 h, whereas carotid intima media thickness (CIMT) and cross-sectional wall area (CSWA) were determined ultrasonically. Essential amino acids were analyzed with a liquid chromatography tandem mass spectrometry method. Oxidative-inflammatory markers were measured by spectrophotometry. African men had poorer health than Caucasian men, including higher alcohol abuse, elevated BP, abdominal obesity, physical inactivity, and elevated inflammation. Phe (p < .001) and Phe/Tyr ratio (p = .006) as well as CIMT (p = .032) were higher in African men. DefS African men had higher levels of Phe (p = .002) and Phe/Tyr (p = .009) compared to DefS Caucasian men; these differences were not observed in non-DefS men. Systolic BP and inflammation (C-reactive protein) were positively associated with left (L-) CSWA, while Phe/Tyr was negatively associated with L-CSWA in DefS African men. African males presented with elevated Phe and Phe/Tyr ratio, catecholamine precursors, worsening during DefS-possibly driven by inflammation and BP contributing to structural vascular abnormalities.

Hypothalamic-pituitary-adrenal-axis dysregulation and double product increases potentiate ischemic heart disease risk in a Black male cohort: the SABPA study

Emotional distress has been associated with a poorer prognosis in myocardial infarction patients. Elevated adrenocorticotrophic hormone (ACTH), lower cortisol, dehydroepiandrosterone sulfate (DHEAS) and cortisol:DHEAS, as measures of emotional distress, might correlate with silent myocardial ischemia (SMI) and workload. Thus, we assessed the relationship between emotional distress, SMI and double product (systolic blood pressure (SBP) × heart rate). Cross-sectional South African biethnic single-set cohorts (N=378), aged 44.7±9.52 years, were investigated. Depressive symptoms (Patient Health Questionnaire-9), anthropometric, fasting blood, 24-h double product and 24-h 2-lead electrocardiogram (ST-segment depression) values were obtained. Blacks, mostly men, had increased depressive symptoms, hyperglycemia, SMI, double product, SBP hypertension and ACTH but lower cortisol, DHEAS and cortisol:DHEAS than their White counterparts. Black men had the highest combined SBP hypertension and below-median cortisol prevalence, 38%, compared with 5.9-13.8% in the other groups. Their SMI was associated with ACTH and cortisol:DHEAS (adj. R² 0.29; β 0.27-0.31 (0.12-0.64); P⩽0.05), double product (adj. R² 0.29; β 0.38 (0.18-0.57); P=0.050) and SBP hypertension (area under the curve: 0.68 (95% CI: 0.56, 0.80); P=0.042; sensitivity/specificity 49/85%). Double product was positively associated with central obesity in all sex groups and with cortisol in the Black men (P<0.05). A dysregulated hypothalamic-pituitary-adrenal-axis (HPAA) showed signs of a hyporesponsive adrenal cortex, suggesting chronic emotional stress in the Black male cohort. In this cohort, HPAA dysregulation and compensatory increases in double product occur as a potential defense mechanism to alleviate perfusion deficits, thereby potentiating ischemic heart disease risk.

The association between seven-day objectively measured habitual physical activity and 24 h ambulatory blood pressure: the SABPA study

Few studies have examined objective physical activity in relation to 24 h ambulatory blood pressure (BP). We aimed to assess the association of 7-day objectively measured habitual physical activity with ambulatory BP in a sample of African and Caucasian school teachers (n=216, age 49.7 years) from the sympathetic activity and blood pressure in Africans prospective cohort study. Hypertension (ambulatory systolic BP⩾130 and/or diastolic BP⩾80 mm Hg) was prevalent in 53.2% of the sample, particularly in black Africans. The hypertensive group spent significantly more awake time in sedentary activity (51.5% vs 40.8% of waking hours, P=0.001), as well as doing less light- (34.1% vs 38.9%, P=0.043) and moderate-intensity (14.0% vs 19.7%, P=0.032) activities compared with normotensives, respectively. In covariate adjusted models, light-intensity activity time was associated with lower 24 h and daytime ambulatory systolic BP (β=-0.15, 95% confidence interval (CI): -0.26, -0.05, P=0.004; β=-0.14, CI: -0.24, -0.03, P=0.011) and diastolic BP (β=-0.14, CI: -0.25, -0.03, P=0.015; β=-0.13, CI: -0.24, -0.01, P=0.030), as well as resting systolic BP (β=-0.13, CI: -0.24, -0.01, P=0.028). Sedentary time was associated only with 24 h systolic BP (β=0.12; CI: 0.01, 0.22), which was largely driven by night-time recordings. Participants in the upper sedentary tertile were more likely to be 'non-dippers' (odds ratio=2.11, 95% CI: 0.99, 4.46, P=0.052) compared with the lowest sedentary tertile. There were no associations between moderate to vigorous activity and BP. In conclusion, objectively assessed daily light physical activity was associated with ambulatory BP in a mixed ethnic sample.

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.

Hyperpulsatile pressure, systemic inflammation and cardiac stress are associated with cardiac wall remodeling in an African male cohort: the SABPA study

Inflammation may contribute to an increase in cardiac wall stress through pathways related to cardiac remodeling. Cardiac remodeling is characterized by myocyte hypertrophy, myocyte death and modifications of the extracellular matrix. We sought to explore associations among cardiac remodeling, inflammation and myocardial cell injury in a bi-ethnic cohort of South African men and women. We included 165 men (76 African and 89 Caucasian) and 174 women (80 African and 94 Caucasian) between 20 and 65 years of age. Inflammatory markers used were C-reactive protein (CRP), interleukin-6 and tumor necrosis factor-alpha (TNF-α), whereas troponin T (Trop T) and the N-terminal of pro B-type natriuretic peptide (NT-proBNP) were used as cardiac markers. The frequency of ischemic events (ST segment depression) and left ventricular strain (left ventricular hypertrophy: LVH) were monitored by a 24-h recording of ambulatory blood pressure (BP), ECG and 12-lead standard ECG. Hypertension diagnosed with ambulatory monitoring was more frequent in Africans (53.85 vs. 24.59%; P<0.001), as was the number of ischemic events (6±15 (1; 5) vs. 3±6 (0; 3)). Inflammatory markers (CRP, IL-6 and TNF-α) and the degree of LVH were all significantly higher in Africans (P<0.05). BP was associated (P<0.05) with Trop T in men across ethnic groups. In African men, cardiac stress (NT-proBNP) was associated with TNF-alpha (P<0.001), Trop T (P<0.001) and pulse pressure (P=0.048; adjusted R(2)=0.45). The susceptibility for cardiac wall remodeling appears to increase with hyperpulsatile pressure, low-grade systemic inflammation and ventricular stress, and may lead to the development of future cardiovascular events in African men.

Chronic depression symptoms and salivary NOx are associated with retinal vascular dysregulation: The SABPA study

BACKGROUND

Depression has been associated with impaired nitric oxide (NO)-mediated vasodilation and vascular dysregulation (VD). Whether depression and NO levels will disturb retinal haemodynamics is not clear.

OBJECTIVES AND METHODS

Associations between the retinal vasculature, diastolic ocular perfusion pressure (DOPP) as measure of hypoperfusion, NO metabolites (NOx) and depression symptoms were assessed. Chronic VD risk markers [depression symptoms (Patient Health Questionnaire/PHQ-9 ≥ 10) and 24 h pulse pressure] were determined in a bi-ethnic cohort (n = 313; 48.6 ± 9 years; 53.9% men). At 3 year follow-up, retinal vessel calibre and retinopathy signs were quantified from digital images. Salivary NOx was obtained pre- and post-flicker light-induced provocation (FLIP). DOPP was defined as diastolic blood pressure minus intraocular pressure.

RESULTS

Chronic VD risk was evident in Blacks opposed to acute risk in Whites (P < 0.05). At follow-up, retinopathy (Blacks 60.4%/Whites 39.6%), lower pre-FLIP (μM) and higher post-FLIP NOx (changes from baseline, %), arteriolar narrowing and wider venular calibre values were evident in Blacks compared to Whites, independent of confounders. A wider venular calibre, an index of stroke risk, was associated with chronic depression symptoms [cut point 248 MU: Area under the curve 0.61 (95% CI: 0.51, 0.72); 71% sensitivity; 55% specificity] as well as with hypoperfusion in the Blacks. In this group, arteriolar narrowing was associated with hypoperfusion; and attenuated arteriolar dilation with increased post-FLIP NOx responses.

CONCLUSIONS

Chronic depression symptoms may alter NO regulation and facilitate VD. NO-mediated vasoconstriction presumably impeded perfusion, retinal haemodynamics and -remodelling; potentiating stroke risk in Blacks.

Hypercoagulation and hyperkinetic blood pressure indicative of physiological loss-of-control despite behavioural control in Africans: The SABPA study

OBJECTIVES

A dissociation between behavioural (in-control) and physiological parameters (indicating loss-of-control) is associated with cardiovascular risk in defensive coping (DefS) Africans. We evaluated relationships between DefS, sub-clinical atherosclerosis, low-grade inflammation and hypercoagulation in a bi-ethnic sex cohort.

METHODS

Black (Africans) and white Africans (Caucasians) (n = 375; aged 44.6 ± 9.7 years) were included. Ambulatory BP, vascular structure (left carotid cross-sectional wall area (L-CSWA) and plaque counts), and markers of coagulation and inflammation were quantified. Ethnicity/coping style interaction was revealed only in DefS participants.

RESULTS

A hypertensive state, less plaque, low-grade inflammation, and hypercoagulation were more prevalent in DefS Africans (27-84%) than DefS Caucasians (18-41%). Regression analyses demonstrated associations between L-CSWA and 24 hour systolic BP (R(2) = 0.38; β = 0.78; p < 0.05) in DefS African men but not in DefS African women or Caucasians. No associations between L-CSWA and coagulation markers were evident.

CONCLUSION

Novel findings revealed hypercoagulation, low-grade inflammation and hyperkinetic BP (physiological loss-of-control responses) in DefS African men. Coupled to a self-reported in-control DefS behavioural profile, this reflects dissociation between behaviour and physiology. It may explain changes in vascular structure, increasing cerebrovascular disease risk in a state of hyper-vigilant coping.

Emotional Stress as a Risk for Hypertension in Sub-Saharan Africans: Are We Ignoring the Odds?

Globally most interventions focus on improving lifestyle habits and treatment regimens to combat hypertension as a non-communicable disease (NCD). However, despite these interventions and improved medical treatments, blood pressure (BP) values are still on the rise and poorly controlled in sub-Saharan Africa (SSA). Other factors contributing to hypertension prevalence, such as chronic emotional stress, might provide some insight for future health policy approaches.Currently, Hypertension Society guidelines do not mention emotional stress as a probable cause for hypertension. Recently the 2014 World Global Health reports, suggested that African governments should consider using World Health Organization hypertension data as a proxy indicator for social well-being. However, the possibility that a stressful life and taxing environmental factors might disturb central neural control of BP regulation has largely been ignored in SSA.Linking emotional stress to vascular dysregulation is therefore one way to investigate increased cardiometabolic challenges, neurotransmitter depletion and disturbed hemodynamics. Disruption of stress response pathways and subsequent changes in lifestyle habits as ways of coping with a stressful life, and as probable cause for hypertension prevalence in SSA, may be included in future preventive measures. We will provide an overview on emotional stress and central neural control of BP and will include also implications thereof for clinical practice in SSA cohorts.

Cohort Profile: Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) prospective cohort study

Adapting to an over-demanding stressful urban environment may exhaust the psychophysiological resources to cope with these demands, and lead to sympathetic nervous system dysfunction. The evidence that an urban-dwelling lifestyle may be detrimental to the cardiometabolic health of Africans motivated the design of the Sympathetic activity and Ambulatory Blood Pressure in African Prospective cohort study. We aimed to determine neural mechanistic pathways involved in emotional distress and vascular remodelling. The baseline sample included 409 teachers representing a bi-ethnic sex cohort from South Africa. The study was conducted in 2008–09 and repeated after 3-year follow-up in 2011–12, with an 87.8% successful follow-up rate. Seasonal changes were avoided and extensive clinical assessments were performed in a well-controlled setting. Data collection included sociodemographics, lifestyle habits, psychosocial battery and genetic analysis, mental stress responses mimicking daily life stress (blood pressure and haemostatic, cardiometabolic, endothelial and stress hormones). Target organ damage was assessed in the brain, heart, kidney, blood vessels and retina. A unique highly phenotyped cohort is presented that can address the role of a hyperactive sympathetic nervous system and neural response pathways contributing to the burden of cardiometabolic diseases in Africans.

Attenuated brain-derived neurotrophic factor and hypertrophic remodelling: the SABPA study

Brain-derived neurotrophic factor (BDNF) has been linked to neurological pathologies, but its role in cardiometabolic disturbances is limited. We aimed to assess the association between serum BDNF levels and structural endothelial dysfunction (ED) as determined by cross-sectional wall area (CSWA) and albumin/creatinine ratio (ACR) in black Africans. Ambulatory blood pressure (BP) and ultrasound CSWA values were obtained from 82 males and 90 females. Fasting blood and 8 h overnight urine samples were collected to determine serum BDNF and cardiometabolic risk markers, that is, glycated haemoglobin (HbA1c), lipids, inflammation and ACR. BDNF median split × gender interaction effects for structural ED justified stratification of BDNF into low and high (⩽/>1.37 ng ml(-1)) gender groups. BDNF values (0.86-1.98 ng ml(-1)) were substantially lower than reference ranges (6.97-42.6 ng ml(-1)) in the African gender cohort, independent of age and body mass index. No relationship was revealed between BDNF and renal function and was opposed by an inverse relationship between BDNF and CSWA (r=-0.17; P=0.03) in the African cohort. Linear regression analyses revealed a positive relationship between systolic BP and structural remodelling in the total cohort and low-BDNF gender groups. In the high-BDNF females, HbA1C was associated with structural remodelling. Attenuated or possible downregulated BDNF levels were associated with hypertrophic remodelling, and may be a compensatory mechanism for the higher BP in Africans. In addition, metabolic risk and hypertrophic remodelling in women with high BDNF underpin different underlying mechanisms for impaired neurotrophin homeostasis in men and women.

Psychosocial stress but not hypertensive status associated with angiogenesis in Africans

AIM

Increased angiogenic factors [vascular endothelial growth factor-A (VEGF-A) and angiopoietin-2 (Ang-2)] have been associated with vascular dysfunction and hypertension. Black Africans undergoing rapid urbanization present with elevated blood pressure (BP) and we aimed to determine whether angiogenic factors are elevated in urban versus rural Africans with normal and elevated BP.

METHODS AND MATERIALS

Africans (n = 272), matched for gender and age, were recruited from rural and urban communities in South Africa. Omron HEM-757 BP data were obtained and angiogenic markers in plasma and serum were determined.

RESULTS

Urban African men displayed a higher (43.90%) hypertension prevalence compared with their rural counterparts (18.52%) and disturbed angiongenic factors. Adjusted VEGF-A concentrations were higher in urban men and women compared with their rural counterparts. Similar VEGF-A levels were observed in rural and urban hypertensives. Logistic regression analysis demonstrated that VEGF-A and Ang-2 levels were associated with psychosocial stress but not with hypertensive status in Africans [odds ratios 1.01-1.09 (95% CI 1.01-1.15), p ≤ 0.05].

CONCLUSION

Psychosocial stress per se was associated with disturbed VEGF-A and Ang-2. We suggest that hyperkinetic BP may act as compensatory mechanism when chronic psychosocial stress prevails, affecting vascular functioning and subsequent increased cardiovascular disease risk.