Relationship Between Urinary Salt Excretion and Pulse Pressure and Central Aortic Hemodynamics Independent of Steady State Pressure in the General Population

Attenuated Relationships Between Indexes of Volume Overload and Atrial Natriuretic Peptide in Uncontrolled, Sustained Volume-Dependent Primary Hypertension

BACKGROUND

Whether systolic blood pressure (SBP) control in sustained volume-dependent primary hypertension is associated with blunted ANP (atrial natriuretic peptide) relationships with indexes of volume load is unknown.

METHODS

Systemic hemodynamics (central pressure, echocardiographic aortic velocity and diameter measurements in the outflow tract), circulating ANP concentrations (ELISA assays) and glomerular and tubular function (24-hour urine collections [n=519]) were determined in a community of African ancestry (n=772).

RESULTS

As compared with those with a controlled SBP, those with an uncontrolled SBP (n=198) showed lower ANP concentrations (P<0.005) despite higher stroke volume and cardiac output (P<0.0001) and renal differences consistent with enhanced fluid retention. In those with a controlled SBP, fractional Na⁺ excretion (FeNa⁺; P<0.0005) and creatinine clearance (glomerular filtration rate; P<0.005) were inversely associated with ANP concentrations independent of confounders. Moreover, in those with a controlled SBP, stroke volume and cardiac output (P<0.0001) were independently and positively associated with ANP concentrations. In addition, in those with a controlled SBP, ANP concentrations were independently and inversely associated with systemic vascular resistance (SVR; P<0.0001) and aortic characteristic impedance (Zc; P<0.005). By contrast, in those with uncontrolled SBP, no relationships between either stroke volume (P>0.25), cardiac output (P>0.29), FeNa⁺ (P>0.77), or glomerular filtration rate (P>0.47) and ANP concentrations were noted. Furthermore, in those with an uncontrolled SBP, no relationships between ANP concentrations and SVR or Zc were observed (P>0.34).

CONCLUSIONS

In a population where primary hypertension is strongly volume-dependent, those with an uncontrolled SBP have an attenuated relationship between ANP and both renal and hemodynamic indexes of volume overload and the vascular effects of ANP.

The International Database of Central Arterial Properties for Risk Stratification: Research Objectives and Baseline Characteristics of Participants

OBJECTIVE

To address to what extent central hemodynamic measurements, improve risk stratification, and determine outcome-based diagnostic thresholds, we constructed the International Database of Central Arterial Properties for Risk Stratification (IDCARS), allowing a participant-level meta-analysis. The purpose of this article was to describe the characteristics of IDCARS participants and to highlight research perspectives.

METHODS

Longitudinal or cross-sectional cohort studies with central blood pressure measured with the SphygmoCor devices and software were included.

RESULTS

The database included 10,930 subjects (54.8% women; median age 46.0 years) from 13 studies in Europe, Africa, Asia, and South America. The prevalence of office hypertension was 4,446 (40.1%), of which 2,713 (61.0%) were treated, and of diabetes mellitus was 629 (5.8%). The peripheral and central systolic/diastolic blood pressure averaged 129.5/78.7 mm Hg and 118.2/79.7 mm Hg, respectively. Mean aortic pulse wave velocity was 7.3 m per seconds. Among 6,871 participants enrolled in 9 longitudinal studies, the median follow-up was 4.2 years (5th-95th percentile interval, 1.3-12.2 years). During 38,957 person-years of follow-up, 339 participants experienced a composite cardiovascular event and 212 died, 67 of cardiovascular disease.

CONCLUSIONS

IDCARS will provide a unique opportunity to investigate hypotheses on central hemodynamic measurements that could not reliably be studied in individual studies. The results of these analyses might inform guidelines and be of help to clinicians involved in the management of patients with suspected or established hypertension.

Plasma sodium, extracellular fluid volume, and blood pressure in healthy men

In the general population we recently reported a consistent association between plasma sodium and volume markers, suggesting that individuals with higher plasma sodium have higher extracellular fluid volume (ECFV). To test this hypothesis, we analyzed the association between plasma sodium and directly measured ECFV (iothalamate distribution volume) in healthy men. Second, we studied whether plasma sodium is associated with blood pressure. We analyzed data from 70 men (age 24 ± 7 years) at the end of two 7-day periods on a low-sodium diet (LS, 50 mmol Na/24 h) and a high-sodium diet (HS, 200 mmol Na/24 h), respectively. The association of plasma sodium with blood pressure was assessed in the combined data of the different sodium intakes by linear mixed effects models. A positive univariable association between plasma sodium and ECFV was found during HS (β = 0.24, p = 0.042) and LS (β = 0.23, p = 0.058), respectively. Individual values of plasma sodium on LS and HS diet were strongly correlated (β = 0.68, p < 0.001), as were values for ECFV (β = 0.54, p < 0.001). In the combined data set plasma sodium level was significantly associated with ECFV (B [SE] = 0.10 [0.04], p = 0.02), and systolic blood pressure (SBP, B [SE] = 0.73 [0.26], p = 0.006), independent of ECFV. In conclusion, plasma sodium concentration is positively associated with ECFV on both LS and HS intake. Our data confirm and extend prior data on individual regulation of plasma sodium and suggest that this is associated with individuality of the regulation of ECFV. Finally, plasma sodium level is associated with SBP, independent of ECFV and diet.

Associations of urinary sodium excretion with central hemodynamics and changes in vascular structure and function at high altitude

Research reports on associations of urinary sodium excretion with central hemodynamic parameters and vascular changes are quite limited in general or non‐hypertensive population. The purpose of the current study was to explore such associations in Chinese general Tibetans living at high altitude. This cross‐sectional study was conducted in Luhuo County, Ganzi Tibetan Autonomous Prefecture with average elevation of 3800 meters from December 2018 to January 2019. A total of 294 Tibetans were included in the current study. Twenty‐four hour urinary sodium excretion was estimated by second fasting spot urine in the morning using Kawasaki formula. Central hemodynamic parameters, including central systolic blood pressure (CSBP), central diastolic blood pressure (CDBP), central pulse pressure (CPP), central mean arterial pressure (CMAP), augmentation pressure (AP), and augmentation index standardized for heart rate of 75 (AIx₇₅), were evaluated using the SphygmoCor system. Vascular structures and functions were assessed by carotid intima media thickness (CIMT) test and brachial ankle pulse wave velocity (baPWV), respectively. Estimated mean 24h urinary sodium excretion of Tibetans in Luhuo County was 5.26±1.61 g. After adjustment, estimated 24h urinary sodium was positively associated with CSBP (β = 1.15, p = .008) and CPP (β = 0.87, p = .013). Line graph of means across urinary sodium quartiles showed that associations of 24 h urinary sodium excretion with AIx₇₅ and baPWV presented approximate “J” shape after controlling for confounders. Estimated 24 h sodium excretion was independently and positively associated with CSBP and CPP. Moreover, association between urinary sodium excretion and arterial elasticity, as evaluated by baPWV and AIx₇₅, presented “J” shape. Further studies are needed to verify J‐shaped association and “safe” zone of sodium intake.

Albuminuria Intensifies the Link Between Urinary Sodium Excretion and Central Pulse Pressure in the General Population: The Wakuya Study

BACKGROUND

Central pulse pressure (cPP) is responsible for the hemodynamics of vital organs, and monitoring this parameter is important for cardiovascular disease (CVD) prevention. Excess sodium intake and (micro)albuminuria (a manifestation of renal microvascular damage) are known to be strong predictors of CVD. We sought to investigate the cross-sectional relationships among dietary sodium intake, albuminuria, and cPP in a general population cohort.

METHODS

The subjects were 933 apparently healthy adults (mean age, 56 ± 10 years). Radial pressure waveforms were recorded with applanation tonometry to estimate mean arterial pressure (MAP), cPP, forward and backward pressure amplitudes, and augmentation index. The urinary sodium/creatinine and albumin/creatinine ratios were measured in spot urine samples.

RESULTS

Both the urinary sodium/creatinine and albumin/creatinine ratios were positively correlated with cPP, even after adjusting for MAP (P < 0.001). Moreover, both ratios had a synergistic influence on increasing the cPP independent of age, sex, estimated glomerular filtration rate, hyperlipidemia, and diabetes (interaction P = 0.04). A similar synergistic influence was found on the forward pressure amplitude, but not on the backward pressure amplitude or augmentation index. The overall results were not altered when the urinary albumin/creatinine ratio was replaced with the existence of chronic kidney disease (CKD).

CONCLUSIONS

(Micro)albuminuria strengthens the positive association between urinary sodium excretion and cPP and systolic forward pressure. Excess sodium intake may magnify the cardiovascular risk by widening the aortic pulsatile pressure, particularly in the presence of concomitant CKD.

Multiple metals exposure and arterial stiffness: A panel study in China

Chronic exposure to metals has been linked to arterial stiffness. However, the effects of exposure to multiple metals on arterial stiffness have rarely been studied. We aimed to investigate the associations of 23 urinary metals with arterial stiffness in a panel study of 127 Chinese adults with 3 repeated visits. Urinary metal measurements were conducted once a day for 4 consecutive days of each visit. Brachial-ankle pulse wave velocity (baPWV) and ankle-brachial index (ABI) were measured in health examinations during each visit. Linear mixed models, least absolute shrinkage and selection operator (LASSO) penalized regression models, and generalized linear models were applied to investigate the associations between multiple metals and arterial stiffness parameters. The odds ratio (OR) for peripheral arterial disease (PAD) was examined using generalized estimating equations. After adjusting for potential covariates and other metals, we found ABI reductions were associated with one unit increase in 4-day average (lag 0-3 day) of ln-transformed urinary titanium (Ti) [β = -0.019 (SE = 0.010), P = 0.045], and cobalt (Co) [β = -0.012 (SE = 0.006), P = 0.048], whereas no significant associations were observed for baPWV at different lag days. Stratified analyses revealed that urinary Ti was inversely related to ABI among never-smokers or in the winter. In addition, the current day or 4-day average of ln-transformed urinary Ti was associated with an increased OR of 1.94 (95% CI: 1.28, 2.92) or 3.30 (95% CI: 1.64, 6.63) for PAD, respectively. Our study showed significant associations of exposure to Ti and Co with arterial stiffness. Particularly, Ti may increase the risk of PAD.

Cardiovascular End Points and Mortality Are Not Closer Associated With Central Than Peripheral Pulsatile Blood Pressure Components

Supplemental Digital Content is available in the text.

Pulsatile blood pressure (BP) confers cardiovascular risk. Whether associations of cardiovascular end points are tighter for central systolic BP (cSBP) than peripheral systolic BP (pSBP) or central pulse pressure (cPP) than peripheral pulse pressure (pPP) is uncertain. Among 5608 participants (54.1% women; mean age, 54.2 years) enrolled in nine studies, median follow-up was 4.1 years. cSBP and cPP, estimated tonometrically from the radial waveform, averaged 123.7 and 42.5 mm Hg, and pSBP and pPP 134.1 and 53.9 mm Hg. The primary composite cardiovascular end point occurred in 255 participants (4.5%). Across fourths of the cPP distribution, rates increased exponentially (4.1, 5.0, 7.3, and 22.0 per 1000 person-years) with comparable estimates for cSBP, pSBP, and pPP. The multivariable-adjusted hazard ratios, expressing the risk per 1-SD increment in BP, were 1.50 (95% CI, 1.33–1.70) for cSBP, 1.36 (95% CI, 1.19–1.54) for cPP, 1.49 (95% CI, 1.33–1.67) for pSBP, and 1.34 (95% CI, 1.19–1.51) for pPP (P<0.001). Further adjustment of cSBP and cPP, respectively, for pSBP and pPP, and vice versa, removed the significance of all hazard ratios. Adding cSBP, cPP, pSBP, pPP to a base model including covariables increased the model fit (P<0.001) with generalized R² increments ranging from 0.37% to 0.74% but adding a second BP to a model including already one did not. Analyses of the secondary end points, including total mortality (204 deaths), coronary end points (109) and strokes (89), and various sensitivity analyses produced consistent results. In conclusion, associations of the primary and secondary end points with SBP and pulse pressure were not stronger if BP was measured centrally compared with peripherally.

Effects of added salt reduction on central and peripheral blood pressure

BACKGROUND

Although the effects of salt intake reduction on casual blood pressure have been extensively studied in hypertensive individuals, data on reductions of added salt on arterial stiffness in both normotensive and prehypertensive subjects are scarce.

OBJECTIVE

To evaluate the effects of progressive reduction in added salt intake (from 6 grams to 4 grams per day) on peripheral and central blood pressure and arterial stiffness in normotensive, prehypertensive and hypertensive individuals.

METHODS

This was a single-blinded clinical trial with 13 weeks of follow-up. Normotensive (≤ 130/85 mmHg), prehypertensive (≥ 130 e < 139/≥ 85 e < 90 mmHg) and stage 1 hypertensive individuals (< 139/≥ 85 and < 90 mmHg) were assessed. Casual blood pressure measurements and ambulatory blood pressure monitoring were performed using the automated OMRON 705CP device, and central blood pressure was measured using the Sphygmocor®. Twenty-four-hour urinary sodium excretion and the amounts of added salt consumed were measured. Statistically significance level was set at p < 0.05 for all analysis.

RESULTS

A total of 55 participants (18 normotensive, 15 prehypertensive and 22 hypertensive), median age 48 years (IQR:39-54) were studied. The groups were not different in age or sex. No difference was observed in blood pressure or sodium excretion levels before and after the intervention. No significant changes in arterial stiffness parameters were observed.

CONCLUSION

The progressive reduction in added salt intake during a period of 13 weeks did not cause significant reductions in peripheral and central blood pressure. (Arq Bras Cardiol. 2020; 114(3):554-561).

Increased Aortic Characteristic Impedance Explains Relations Between Urinary Na + /K + and Pulse or Systolic Blood Pressure

Alterations in sodium (Na + ) relative to potassium (K + ) intake increase systolic blood pressure, effects in-part attributed to enhanced pulsatile loads (pulse pressure) beyond steady-state pressures (mean arterial pressure). Whether this effect is through reversible changes (increases in blood volume and hence aortic flow [Q] or wave reflection [Pb]), or potentially irreversible structural changes in the proximal aorta, is unknown. In 581 black South Africans, we determined 24-hour urinary Na + and K + excretion and aortic function from central aortic pressure (radial pulse wave analysis [SphygmoCor software]), velocity, and diameter measurements. Proximal aortic function was assessed from characteristic impedance (Zc). Beyond mean arterial pressure and additional confounders, urinary Na + /K + was independently associated with Zc ( P <0.005) but not peak aortic Q ( P =0.30) or alternative aspects of Q or ejection volume. Although age was strongly associated with proximal aortic diameter, no independent relations between urinary Na + /K + and aortic diameter were noted ( P =0.17). Relations between urinary Na + /K + and Zc translated into independent relations with early systolic compression wave pressures (QxZc [P QxZc ]) and aortic forward wave pressures but not Pb. Moreover, neither reflected wave magnitude ( P =0.92) nor aortic pulse wave velocity were independently associated with urinary Na + /K + . In product of coefficient mediation analysis, the independent relations between urinary Na + /K + and peak aortic or brachial pulse pressure or systolic blood pressure were accounted for by Zc and P QxZc . In conclusion, abnormalities in Na + /K + intake determine pulse pressure or systolic blood pressure beyond mean arterial pressure mainly through potentially irreversible impacts on proximal aortic impedance rather than readily modifiable increases in aortic flow (blood volume) or wave reflection.

Insulin Resistance and Renal Sodium Handling Influence Arterial Stiffness in Hypertensive Patients with Prevailing Sodium Intake

BACKGROUND

Insulin resistance and renal tubular sodium handling influence arterial structure and function and play an essential role in salt-sensitive forms of hypertension.

METHODS

In a population with prevailing sodium consumption, we assessed the relationship between cardiovascular phenotypes (peripheral and central blood pressures, elastic properties of large arteries, the left ventricular structure) and sodium handling parameters (daily urinary sodium excretion, fractional urinary lithium excretion in proximal-FELi and distal tubules), as a function of insulin sensitivity-measured by homeostasis model assessment-insulin resistance (HOMA-IR), leptin-to-adiponectin (L/A) ratio, and homeostasis model assessment-adiponectin (HOMA-AD).

RESULTS

In patients with FELi below the median value (corresponding to the group with increased proximal sodium reabsorption) and higher insulin resistance as measured by HOMA-IR, pulse wave augmentation indexes were significantly higher-AIxP (99.4% vs. 86.2%; P = 0.007), AIxC1 (159.4% vs. 144.2%; P = 0.04), and AIxC2 (36.1% vs. 28.3%; P = 0.02), than in patients with lower insulin resistance. The same trend was observed in relation to L/A ratio-AIxP (98.7% vs. 87.1%; P = 0.005), AIxC1 (158.6% vs. 144.5%; P = 0.02), and AIxC2 (35.6% vs. 28.5%; P = 0.01) and HOMA-AD-AIxP (99.7% vs. 83.8%; P = 0.001), AIxC1 (160.5% vs. 140.3%; P = 0.007), and AIxC2 (36.6% vs. 26.3%; P = 0.003). Such relationships were not observed in patients with FELi above the median value.

CONCLUSIONS

In the hypertensive population with prevailing sodium intake, insulin resistance and increased sodium reabsorption in proximal tubules may affect arterial wall function.

Association of Urinary Sodium Excretion with Vascular Damage: A Local Kidney Effect, Rather Than a Marker of Generalized Vascular Impairment

Evidence suggests that increased salt consumption induces blood pressure- (BP) mediated organ damage, yet it remains unclear whether it reflects a generalized micro- and macrovascular malfunction independent of BP. We studied 197 newly diagnosed and never-treated individuals with hypertension, intermediate hypertensive phenotypes, and normal BP, classified by use of 24-hour ambulatory BP monitoring. Sodium excretion and microalbuminuria were estimated in 24-hour urine samples, dermal capillary density was estimated from capillaroscopy, and arterial stiffness was estimated with pulse wave velocity (PWV) and augmentation index (AIx). Sodium excretion correlated with microalbuminuria (p<0.001) and 24-hour and day- and nighttime systolic BP, but not with office blood pressure, arterial stiffness, or capillary density. In the multivariate analysis, the association with microalbuminuria was maintained (p=0.007). In a population free from the long-standing effects of hypertension, increased salt intake appears to be associated with early signs of vascular kidney damage, rather than a diffuse micro- and macrovascular impairment.

Insulin resistance influences the impact of hypertension on left ventricular diastolic dysfunction in a community sample

Background

Although obesity‐associated metabolic abnormalities (insulin resistance‐IR) may not play as marked a role in determining left ventricular (LV) diastolic dysfunction (DD) as hypertension, the impact of combinations of these risk factors on DD is unknown.

Hypothesis

We hypothesized that IR influences the impact of hypertension on DD.

Methods

In 704 randomly selected participants from a community sample with a high prevalence of hypertension (50.6%) and obesity (46.5%), we determined adiposity indices, IR from the homeostasis model (HOMA‐IR) and LV diastolic function using standard echocardiographic techniques.

Results

HOMA‐IR was independently associated with lateral wall e' and E/e' (P < 0.05 to P < 0.005) as well as a diagnosis of DD (P < 0.02). Importantly, however, an enhanced relationship between HOMA‐IR and E/e' in hypertensives (n = 356, partial r = 0.15, P < 0.005) as compared to normotensives (n = 348, partial r = 0.02 P = 0.75) was noted. Consequently, as compared to normotensives, with adjustments for confounders, hypertension was independently associated with DD only in those with the highest tertile of HOMA‐IR (odds ratio = 2.65, 95% confidence interval = 1.29‐5.42, P < 0.01), while in those with the lowest tertile of HOMA‐IR, hypertension failed to show a higher prevalence of DD (P = 0.22).

Conclusions

Insulin resistance enhances the impact of hypertension on LV DD. Thus, DD is more likely to occur with the combination of hypertension and IR.

Large artery stiffness is associated with salt intake in young healthy black but not white adults: the African-PREDICT study

PURPOSE

There is global consensus on the benefits of reducing excessive salt intake. Indeed, lower salt intake associates with reduced arterial stiffness, a well-established predictor of cardiovascular risk, in older populations. Whether high habitual salt intake in healthy normotensive youth may already contribute to increased arterial stiffness is unknown. We, therefore, determined whether estimated salt intake is associated with large artery stiffness in young healthy black and white adults.

METHODS

We included 693 black and white adults (51% black; 42% men), aged 20-30 years. Participants were normotensive based on clinic blood pressure, and no previous diagnosed chronic illnesses. We measured carotid femoral pulse wave velocity (cfPWV) and determined estimated salt intake based on 24 h urinary sodium excretion.

RESULTS

We found estimated salt consumption of > 5 g/day in 47% of our population, whereas 21% consumed > 10 g/day. In multivariable-adjusted regression analyses a positive association existed between estimated salt intake and cfPWV in the total group (Adj. R² = 0.32; std. β = 0.10; p = 0.007), and black adults (Adj. R² = 0.37; std. β = 0.12; p = 0.029). This was independent of age, sex, mean arterial pressure, and other covariates. No association was evident in white individuals (p = 0.19).

CONCLUSION

Excessive salt intake is positively associated with large artery stiffness-independent of blood pressure-in young adults, especially in black individuals. Our results suggest a potential contributory role of salt consumption towards early vascular aging.

Associations of Urinary Caffeine and Caffeine Metabolites With Arterial Stiffness in a Large Population-Based Study

OBJECTIVE

To assess the influence of caffeine on arterial stiffness by exploring the association of urinary excretion of caffeine and its related metabolites with pulse pressure (PP) and pulse wave velocity (PWV).

PARTICIPANTS AND METHODS

Families were randomly selected from the general population of 3 Swiss cities from November 25, 2009, through April 4, 2013. Pulse pressure was defined as the difference between the systolic and diastolic blood pressures obtained by 24-hour ambulatory monitoring. Carotid-femoral PWV was determined by applanation tonometry. Urinary caffeine, paraxanthine, theophylline, and theobromine excretions were measured in 24-hour urine collections. Multivariate linear and logistic mixed models were used to explore the associations of quartiles of urinary caffeine and metabolite excretions with PP, high PP, and PWV.

RESULTS

We included 863 participants with a mean ± SD age of 47.1±17.6 years, 24-hour PP of 41.9±9.2 mm Hg, and PWV of 8.0±2.3 m/s. Mean (SE) brachial PP decreased from 43.5 (0.5) to 40.5 (0.6) mm Hg from the lowest to the highest quartiles of 24-hour urinary caffeine excretion (P<.001). The odds ratio (95% CI) of high PP decreased linearly from 1.0 to 0.52 (0.31-0.89), 0.38 (0.22-0.65), and 0.31 (0.18-0.55) from the lowest to the highest quartile of 24-hour urinary caffeine excretion (P<.001). Mean (SE) PWV in the highest caffeine excretion quartile was significantly lower than in the lowest quartile (7.8 [0.1] vs 8.1 [0.1] m/s; P=.03). Similar associations were found for paraxanthine and theophylline, whereas no associations were found with theobromine.

CONCLUSION

Urinary caffeine, paraxanthine, and theophylline excretions were associated with decreased parameters of arterial stiffness, suggesting a protective effect of caffeine intake beyond its blood pressure-lowering effect.

Central Blood Pressure Responses to Dietary Sodium and Potassium Interventions

BACKGROUND

To explore how central hemodynamics respond to dietary sodium and potassium interventions, and whether the responses are associated with metabolic traits.

METHODS

We conducted a dietary intervention study including a 7-day low-sodium (51.3 mmol sodium/day) intervention, a 7-day high-sodium (307.8 mmol sodium/day) intervention, and a 7-day high-sodium with potassium supplementation (60.0 mmol potassium/day) intervention among 99 northern Chinese subjects aged 18-60 years. Five metabolic traits included abdominal obesity, high triglycerides, low HDL cholesterol, raised blood pressure (BP), and high glucose. Central hemodynamics were measured at baseline and during each intervention.

RESULTS

Central systolic BP (SBP), diastolic BP (DBP), pulse pressure (PP), and augmentation index (AIx@75) significantly decreased during low-sodium intervention, increased during high-sodium intervention, and then decreased during potassium supplementation. We observed potential linear trends toward significance of central SBP and PP responses to low-sodium intervention, and significant linear trends of responses to high-sodium intervention as the number of metabolic traits grows. For example, among participants with 0 or 1, 2 or 3, and 4 or 5 metabolic traits, central SBP responses to high-sodium intervention were 8.8 [95% confidence interval (5.8, 11.8)], 9.3 (7.1, 11.6), and 14.0 (11.6, 16.3) mmHg, respectively (P for trend = 0.009). Significant linear trends of central SBP and DBP responses to potassium supplementation were also observed.

CONCLUSIONS

Central BP and AIx@75 were lowered by sodium reduction and potassium supplementation, and elevated by sodium-loading. The responses of central BP were pronounced among individuals with metabolic traits clustering.

CLINICAL TRIALS REGISTRATION

Trial Number NCT00721721 (The current study is registered on ClinicalTrials.gov; https://clinicaltrials.gov).

Associations between dietary salt, potassium and blood pressure in South African adults: WHO SAGE Wave 2 Salt & Tobacco

BACKGROUND & AIMS

In June 2016, South Africa implemented legislation mandating maximum sodium levels in a range of processed foods with a goal of reducing population salt intake and disease burden from hypertension. Our aim was to explore the relationship between salt and blood pressure (BP) in a subsample of the World Health Organization Study on global AGEing and adult health (SAGE) Wave 2 before implementation of legislation in South Africa.

METHODS & RESULTS

Blood pressure (BP) was measured in triplicate (n = 2722; median age 56 years; 33% male) and 24-h urine collected in a nested subsample (n = 526) for sodium, potassium and creatinine analysis. Hypertension prevalence was 55% in older adults (50-plus years) and 28% in younger adults (18-49 years). Median salt intake (6.8 g/day) was higher in younger than older adults (8.6 g vs 6.1 g/day; p < 0.001), and in urban compared to rural populations (7.0 g vs 6.0 g/day; p = 0.033). Overall, 69% of participants had salt intakes above 5 g/day. Potassium intakes were generally low (median 35 mmol/day) with significantly lower intakes in rural areas and older adults. Overall, 91% of adults failed to meet the daily potassium recommendation of 90 mmol/d. Salt intakes above 5 g/day, and to a greater extent, a dietary sodium-to-potassium (Na:K) ratio above 2 mmol/mmol, were associated with significantly steeper regression slopes of BP with age.

CONCLUSION

These preliminary results indicate that high dietary Na:K ratio may lead to a greater increase in BP and hypertension risk with age. Interventions to increase potassium intakes alongside sodium reduction initiatives may be warranted.

Contribution of backward and forward wave pressures to age-related increases in aortic pressure in a community sample not receiving antihypertensive therapy

Reports on the contribution of aortic forward (Pf) and backward (Pb) wave pressures to age-related increases in central aortic pulse pressure (PPc) have been confounded by the use of participants receiving antihypertensive therapy. We assessed the relative contribution of Pf and Pb to age-related increases in PPc (radial applanation tonometry and SphygmoCor software using an assumed triangular wave for wave separation analysis) in 892 community participants not receiving antihypertensive therapy. We validated our results using aortic flow waves (echocardiography) for wave separation analysis in 254 of these participants. In multivariate regression models in those aged <50 years, adjustments for both Pb and a Pf-independent measure of reflected wave function (RM = Pb/Pf), but not Pf abolished the impact of age on PPc. However, in those aged >50 years, adjustments for Pf (β-coefficient: 0.25 ± 0.06 vs. 0.74 ± 0.08; P < .0001) and Pb (0.04 ± 0.04 vs. 0.74 ± 0.08; P < .0001), but not RM markedly decreased the relationship between age and PPc. On product of coefficient mediation analysis, whether assessed in men or in women, in those participants aged <50 years, independent of several confounders and mean arterial pressure, Pb (P < .005), but not Pf contributed to age-related increases in PPc. In contrast, in those participants aged ≥50 years, independent of several confounders and mean arterial pressure, Pb (P < .005) and Pf (P < .01) contributed to age-related increases in PPc, and Pb effects were markedly diminished by adjustments for Pf (0.26 ± 0.002 vs. 0.52 ± 0.003 mm Hg per year, P < .0001 for comparison). In conclusion, independent of the effects of antihypertensive therapy, aortic backward waves contribute to age-related increases in aortic PPc across the adult lifespan, but at an older age, this effect may be attributed in part to the impact of forward on backward wave pressures.

Chronic kidney disease epidemiology collaboration-derived glomerular filtration rate performs better at detecting preclinical end-organ changes than alternative equations in black Africans

AIM

To identify whether the more recently developed equation for estimated glomerular filtration rate (eGFR) [Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)] is more closely associated with end-organ changes than previous equations in a group of black African descent.

METHODS

In 1221 randomly recruited participants of black African ancestry in South Africa, we evaluated serum creatinine concentrations, echocardiographic left ventricular mass index (n = 833), carotid-femoral (aortic) pulse wave velocity (PWV) (n = 1053) and carotid intima-media thickness (n = 633). We calculated eGFR from the Jelliffe, five Cockcroft-Gault, Salazar-Corcoran, Modification of Diet in Renal Disease (MDRD) and CKD-EPI equations.

RESULTS

After multivariate adjustments, eGFR calculated from all formulae was inversely associated with left ventricular mass index (P < 0.0001) and PWV (P < 0.05 to <0.001), but not with carotid intima-media thickness (P > 0.08). However, although eGFR determined from all equations except Cockcroft-Gault lean body weight or adjusted body weight was independently associated with left ventricular hypertrophy (n = 390 of 833), CKD-EPI-derived eGFR, but not eGFR determined from alternative equations, was independently associated with an increased PWV (n = 88 of 1053). eGFR derived from the CKD-EPI and MDRD equations showed a better performance (area under the receiver operator characteristic curve) for the detection of left ventricular hypertrophy (P < 0.0005) than eGFR determined from alternative equations.

CONCLUSIONS

In black Africans, eGFR derived from the CKD-EPI equation is better at detecting end-organ measures than eGFR derived from either the MDRD or alternative equations. To enhance risk prediction in black African communities, eGFR calculated from the CKD-EPI equation may be preferred to other equations.

Enhanced Aortic Reflected Wave Magnitude Accounts for the Impact of Female Gender on Aortic Pressure Augmentation in a Group of African Ancestry

BACKGROUND

Aortic reflected wave magnitude (RM) may not account for sex-specific differences in aortic pressure augmentation in Caucasians. However, aortic reflected waves are greater in groups of African descent than other ethnic groups. We determined whether RM or alternative factors explain the impact of sex on aortic augmented pressure (Pa) in participants of African ancestry.

METHODS

We assessed aortic function (radial applanation tonometry, SphygmoCor) in 1,197 randomly recruited community participants of African ancestry (age ≥ 16 years). Aortic forward (Pf) and backward (Pb) wave separation was performed assuming an aortic triangular flow wave validated against aortic velocity measurements.

RESULTS

Across the adult lifespan, women had greater multivariate-adjusted augmentation index (AIx) and Pa. This was associated with multivariate-adjusted age-related increases in Pb, RM (Pb/Pf), and time to the peak of Pf and decreases in backward wave foot time; but not increases in Pf. With adjustors, Pa was associated with female gender (β-coefficient = 3.81 ± 0.34), a relationship which was markedly attenuated by adjustments for RM (β-coefficient = 1.78 ± 0.31, P < 0.0001 vs. without adjustments for RM), and Pb (β-coefficient = 2.05 ± 0.19, P < 0.0001 vs. without adjustments for Pb), but not by adjustments for Pf, time to the peak of Pf, or backward wave foot time. Similarly, AIx was associated with female gender, a relationship which was markedly attenuated by adjustments for RM, Pb, and backward wave foot time, but not alternative factors.

CONCLUSIONS

In contrast to reports in alternative populations, the relationship between aortic pressure augmentation and female gender in participants of African descent is accounted for mainly by increases in RM.

Contributions of aortic pulse wave velocity and backward wave pressure to variations in left ventricular mass are independent of each other

Aortic pulse wave velocity (PWV) and backward waves, as determined from wave separation analysis, predict cardiovascular events beyond brachial blood pressure. However, the extent to which these aortic hemodynamic variables contribute independent of each other is uncertain. In 749 randomly selected participants of African ancestry, we therefore assessed the extent to which relationships between aortic PWV or backward wave pressures (Pb) (and hence central aortic pulse pressure [PPc]) and left ventricular mass index (LVMI) occur independent of each other. Aortic PWV, PPc, forward wave pressure (Pf), and Pb were determined using radial applanation tonometry and SphygmoCor software and LVMI using echocardiography; 44.5% of participants had an increased left ventricular mass indexed to height^1.7. With adjustments for age, brachial systolic blood pressure or PP, and additional confounders, PPc and Pb, but not Pf, were independently related to LVMI and left ventricular hypertrophy (LVH) in both men and women. However, PWV was independently associated with LVMI in women (partial r = 0.16, P < .001), but not in men (partial r = 0.03), and PWV was independently associated with LVH in women (P < .05), but not in men (P = .07). With PWV and Pb included in the same multivariate regression models, PWV (partial r = 0.14, P < .005) and Pb (partial r = 0.10, P < .05) contributed to a similar extent to variations in LVMI in women. In addition, with PWV and Pb included in the same multivariate regression models, PWV (P < .05) and Pb (P < .02) contributed to LVH in women. In conclusion, aortic PWV and Pb (and hence pulse pressure) although both associated with LVMI and LVH produce effects which are independent of each other.

Insulin resistance-associated decreases in left ventricular diastolic function are strongly modified by the extent of concentric remodeling in a community sample

BACKGROUND

Whether excess adiposity, associated metabolic abnormalities or alternative risk factors for left ventricular (LV) diastolic function are modified rather than mediated by geometric LV remodeling, is uncertain.

METHODS

Echocardiographic LV mass index (LVMI), relative wall thickness (RWT) and diastolic function (lateral and septal wall myocardial tissue lengthening at the level of the mitral annulus [e'] [n=430], ratio of early-to-late transmitral blood flow velocity (E/A), and E/e' [n=430]) were determined in 737 randomly recruited participants of a community-based study (43% obese).

RESULTS

Independent of LVMI and confounders, indexes of adiposity and the homeostasis model of insulin resistance (HOMA-IR) were independently associated with LV diastolic function (p<0.05). In addition, RWT was independently associated with LV diastolic function (p<0.002). Importantly, an independent interaction between HOMA-IR and RWT, but not between blood pressure or age and RWT, was related to LV diastolic function (p<0.05). This translated into an independent relationship between HOMA-IR and lateral e' (partial r=-0.17, p<0.02), septal e' (partial r=-0.14, p=0.05), E/A (partial r=-0.17, p<0.005) and E/e' (partial r=0.19, p<0.01) in those with RWT above, but a lack of relationship between HOMA-IR and LV diastolic function (p>0.59) in those with RWT below the median for the sample. Similarly, HOMA-IR was independently associated with LV diastolic dysfunction in those with RWT above (p<0.05) but not below (p>0.19) the median for the sample.

CONCLUSIONS

The relationship between insulin resistance, but not alternative risk factors and LV diastolic function is markedly modified by the presence of a more concentrically remodeled LV.

Blood pressure, arterial stiffness and endogenous lithium clearance in relation to AGTR1 A1166C and AGTR2 G1675A gene polymorphisms

Introduction:

Although recently a matter of epidemiologic controversy, sodium overload and its interaction with genetic factors predispose to hypertension and related target organ complications.

Methods:

In 131 (66 male) treated hypertensives, we measured peripheral and central arterial pressures and pulse wave augmentation indexes (AIx_P, AIx_C1, AIx_C2), pulse wave velocity (PWV), daily urinary sodium excretion and did genetic studies of AGTR1 A1166C and AGTR2 G1675A polymorphisms. Proximal (FE_Li) and distal (FDR_Na) sodium reabsorption measurements were performed using endogenous lithium clearance.

Results:

In men, we found interaction between FDR_Na and AGTR2 G1675A polymorphism with respect to AIx_C1 (p_INT=0.01), AIx_C2 (p_INT=0.05) and AIx_P (p_INT=0.006). Arterial stiffness increased with higher sodium reabsorption in the distal tubule, in the presence of AGTR2 G allele with the opposite tendency in A allele carriers. In the subgroup with FDR_Na below median, as compared to those with FDR_Na above median, the AIx_C1 (139.6±3.8 vs 159.1±5.7%; p=0.009), AIx_C2 (26.3±1.8 vs 33.3±1.7%; p=0.016) and AIx_P (83.4±2.5 vs 96.5±2.6%; p<0.0001) were lower, in the G allele carrying men and GG homozygous women.

Conclusions:

The relation between sodium reabsorption in the distal tubule and the development of arterial stiffness depends on the AGTR2 G1675A polymorphism in blood pressure independent fashion.

Novel Approach to the Detection of Left Ventricular Hypertrophy Using Body Mass Index-Corrected Electrocardiographic Voltage Criteria in a Group of African Ancestry

BACKGROUND

Electrocardiographic (ECG) QRS voltages used to generate criteria for left ventricular hypertrophy (LVH) detection are considerably attenuated by obesity. This effect renders the utility of ECG criteria to detect LVH in obese individuals of African ancestry to be of limited value.

HYPOTHESIS

A novel approach to correcting QRS voltages for the attenuating effect of body mass index (BMI) will improve the ability of ECG criteria to detect LVH in a group of African descent.

METHODS

Left ventricular mass was determined from echocardiography in 661 randomly selected participants (43.0% obese) of black African ancestry in South Africa.

RESULTS

As compared with Cornell and Sokolow-Lyon voltage criteria, BMI best correlated with RaVL , Gubner-Ungerleider, and Lewis QRS complex voltages, but these relations were noted only in those with BMI <29 kg/m(2) . Correcting RaVL and Lewis voltages by the difference in the slope of BMI-voltage relations in those with BMI <29 kg/m(2) vs those with BMI ≥29 kg/m(2) showed the greatest performance for LVH detection (uncorrected RaVL : 0.695 ± 0.025, corrected RaVL : 0.733 ± 0.022; P < 0.0001), and also increased the sensitivity (uncorrected RaVL : 30.6%, corrected RaVL : 42.4%; P < 0.0005) with no significant change in specificity (uncorrected RaVL : 86.3%, corrected RaVL : 83.0%; P = 0.28).

CONCLUSIONS

We offer a novel approach to correcting ECG voltages for the attenuating effects of obesity in individuals of African ancestry, and this improves the performance and sensitivity for LVH detection.

Aortic Pulse Pressure Amplification Imputed From Simple Clinical Measures Adds to the Ability of Brachial Pressure to Predict Survival

BACKGROUND

Although aortic-to-brachial pulse pressure amplification (PPamp) may offer prognostic information beyond brachial blood pressure (BP), this approach is limited in resource-limited settings. We aimed to derive an equation to impute central aortic PP (PPc) from simple clinical measures and assess whether imputed PPamp adds to the ability of brachial BP to predict mortality.

METHODS

An imputation equation for PPc, incorporating brachial PP, age, mean arterial pressure, and pulse rate, was identified from multivariate modeling of the factors associated with radial applanation tonometry-derived (measured) PPc in 1,179 community participants and validated in a clinical sample of 351 patients. We applied the equation to ambulatory awake BP and pulse rate values in a separate group of 4,796 patients referred for ambulatory monitoring and evaluated the impact on all-cause mortality.

RESULTS

Imputed PPc values closely approximated measured PPc (r (2) = 0.96, mean difference ± (2 × SD) = 1.4±6.2mm Hg). In adjusted Cox proportional models including adjustments for awake brachial PP during 47,111 person-years of follow-up, where 648 patients died, hazards ratio for all-cause mortality per SD of awake PPamp was 0.79 (95% confidence interval (CI): 0.68-0.93, P < 0.005). The hazards ratio for brachial PP with (1.49, CI = 1.36-1.64, P < 0.0001) or without (1.46, CI = 1.35-1.59, P < 0.0001) PPamp in the model was similar. Awake PPamp also predicted survival independent of awake brachial systolic BP (P < 0.0001).

CONCLUSIONS

PPc imputed from simple clinical assessments closely approximates measured PPc. PPamp derived from imputed PPc adds to the ability of brachial BP to predict survival. In resource-limited settings, an imputation equation may be employed to approximate aortic BP and enhance risk prediction.

Intrafamilial aggregation and heritability of tissue Doppler indexes of left ventricular diastolic function in a group of African descent

Although several indexes of left ventricular (LV) diastolic function show heritability, the genetic influence on the tissue Doppler index, E/e' (early transmitral velocity/velocity of myocardial tissue lengthening), an index of LV filling pressures in those of black African descent is currently unknown. Furthermore, whether any genetic influences on E/e' are through an impact of LV remodeling or aortic function is unknown. Intrafamilial aggregation and heritability (SAGE software) of E/e' (echocardiography) were assessed in 129 nuclear families (29 spouse pairs, 216 parent-child pairs, and 113 sibling-sibling pairs) from an urban developing community of black Africans, independent of LV mass index (LVMI), LV relative wall thickness (RWT), central aortic systolic pressure (SBPc), and backward wave pressures (Pb) (applanation tonometry, SphygmoCor software). Independent of confounders including LVMI and RWT, E/e' was correlated in parent-child (r = 0.23; P < .001) and sibling-sibling (r = 0.29; P < .005), but not in spouse (r = 0.13; P = .51) pairs. The relationships between parent-child (r = 0.22; P < .001) and sibling-sibling (r = 0.29; P < .005) pairs persisted with adjustments for SBPc. The relationships between parent-child (r = 0.22; P < .001) and sibling-sibling (r = 0.26; P < .01) pairs also persisted with adjustments for Pb. Independent of confounders including LVMI and RWT, E/e' showed significant heritability (h(2) ± standard error of the mean [SEM] = 0.51 ± 0.11; P < .0001) which similarly persisted with adjustments for SBPc (h(2) ± SEM = 0.50 ± 0.11; P < .0001) and Pb (h(2) ± SEM = 0.49 ± 0.11; P < .0001). In conclusion, in a group of African ancestry, independent of LV remodeling and aortic function, E/e' shows significant intrafamilial aggregation and robust heritability. Hence, genetic factors may play an important role in determining moderate-to-severe LV diastolic dysfunction independent of cardiac remodeling or aortic function in groups of black African ancestry.

Brachial Pressure Control Fails to Account for Most Distending Pressure-Independent, Age-Related Aortic Hemodynamic Changes in Adults

BACKGROUND

Although several characteristics of aortic function, which are largely determined by age, predict outcomes beyond brachial blood pressure (BP), the extent to which brachial BP control accounts for age-related variations in aortic function is uncertain. We aimed to determine the extent to which brachial BP control in the general population (systolic/diastolic BP < 140/90 mm Hg) accounts for age-related aortic hemodynamic changes across the adult lifespan.

METHODS

Central aortic pulse pressure (PPc), backward wave pressure (Pb), pulse wave velocity (PWV), and PP amplification (PPamp) (applanation tonometry and SphygmoCor software) were determined in 1,185 participants from a community sample (age >16 years; 36.4% uncontrolled BP).

RESULTS

With adjustments for distending pressure (mean arterial pressure, MAP), no increases in PPc, Pb, or PWV and decreases in PPamp were noted in those with an uncontrolled brachial BP younger than 50 years. In those older than 50 years with an uncontrolled brachial BP, MAP-adjusted aortic hemodynamic variables were only modestly different to those with a controlled brachial BP (PPc, 46±14 vs. 42±15 mm Hg, P < 0.02, Pb, 23±8 vs. 21±8 mm Hg, PWV, 8.42±3.21 vs. 8.19±3.37 m/second, PPamp, 1.21±0.17 vs. 1.21±0.14). Nonetheless, with adjustments for MAP, marked age-related increases in PPc, Pb, and PWV and decreases in PPamp were noted in those with uncontrolled and controlled brachial BP across the adult lifespan (P < 0.0001).

CONCLUSION

Brachial BP control in the general population fails to account for most distending pressure-independent, age-related changes in aortic hemodynamics across the adult lifespan.

Salt intakes in sub-Saharan Africa: a systematic review and meta-regression

Background

High sodium intake increases the risk of hypertension and cardiovascular diseases. For this reason the World Health Organization recommends a maximum intake of 2 g per day and a 30 % reduction in population sodium intake by 2025. However, in global reviews, data on sodium intake in sub-Saharan Africa have been limited.

Methods

A systematic review was conducted to identify studies reporting sodium intake in sub-Saharan African populations. Meta-regression analyses were used to test the effect of year of data collection and method of data collection (urinary/dietary), as well as any association between sex, urban/rural status or a country’s economic development, and population sodium intake.

Results

We identified 42 papers reporting 67 estimates of adult population sodium intakes and 12 estimates of child population sodium intakes since 1967. Of the 67 adult populations, 54 (81 %) consumed more than 2 g sodium/day, as did four of the 12 (33 %) child populations. Sixty-five adult estimates were included in the meta-regression, which found that urban populations consumed higher amounts of salt than rural populations and that urine collection gave lower estimates of sodium intake than dietary data.

Conclusions

Sodium intake in much of sub-Saharan Africa is above the World Health Organization’s recommended maximum intake and may be set to increase as the continent undergoes considerable urbanization. Few identified studies used stringent measurement criteria or representative population samples. High quality studies will be required to identify where and with whom to intervene, in order to meet the World Health Organization’s target of a 30 % reduction in population sodium intake and to demonstrate progress towards this target.

Intrafamilial Aggregation and Heritability of Aortic Reflected (Backward) Waves Derived From Wave Separation Analysis

BACKGROUND

Although aortic wave reflection may be inherited, the extent to which indexes of wave reflection derived from wave separation analysis (reflected (backward) wave index (RI) and pressure (Pb)) show intrafamilial aggregation and heritability is uncertain. We therefore aimed to determine the intrafamilial aggregation and heritability of RI and Pb and compare these with indexes of pressure augmentation.

METHODS

Aortic Pb, RI, augmented pressure (Pa), and augmentation index (AIx) were determined using radial applanation tonometry and SphygmoCor software in 1,152 participants of 315 families (111 father-mother, 705 parent-child, and 301 sibling-sibling pairs) from an urban developing community of black Africans. Heritability estimates were determined from Statistical Analysis for Genetic Epidemiology software.

RESULTS

With appropriate adjustments, significant correlations were noted between parent-child pairs for Pb and Pa (P < 0.05 for all), but not for RI (P = 0.50) or AIx (P = 0.90) and between sib-sib pairs for Pb and Pa (P < 0.05), but not for RI (P = 0.54) or AIx (P = 0.14). No correlations for indexes of wave reflection were noted between fathers and mothers (P > 0.57). After adjustments, Pb (h2 = 0.24±0.07) and Pa (h2 = 0.23±0.07) (P < 0.001 for both) but not RI (h2 = 0.04±0.06, P = 0.27) or AIx (h2 = 0.10±0.07, P = 0.07) showed significant heritability.

CONCLUSIONS

Aortic reflected (backward) waves derived from either wave separation (Pb) or pulse wave analysis (Pa) show a similar degree of intrafamilial aggregation and heritability, but the use of RI or AIx may underestimate reflected wave effects.

Intrafamilial aggregation and heritability of left ventricular geometric remodeling is independent of cardiac mass in families of African ancestry

BACKGROUND

Whether left ventricular (LV) geometric remodeling, as indexed by relative wall thickness (RWT), aggregates in families and is inherited independent of LV mass (LVM) and additional confounders is uncertain.

METHODS

We determined whether RWT as assessed from 2D targeted M-mode echocardiography shows intrafamilial aggregation and heritability independent of LVM in 181 nuclear families (73 spouse pairs, 403 parent-child pairs, and 177 sibling-sibling pairs) with 16 families including 3 generations from an urban developing community of black Africans. Intrafamilial aggregation and heritability estimates (S.A.G.E. software) were assessed independent of confounders, including central aortic systolic blood pressure (SBPc) (radial applanation tonometry and SphygmoCor software).

RESULTS

Independent of confounders including SBPc, LV RWT was correlated in parent-child (r = 0.32, P < 0.0001) and sibling-sibling (r = 0.29, P < 0.0001), but not in spouse (r = 0.11, P = 0.33) pairs. The relationships between parent-child (r = 0.28, P < 0.0001) and sibling-sibling (r = 0.24, P < 0.001) pairs persisted with further adjustments for LVM or LVM indexed to height(2.7) (LVMI). Similarly, independent of confounders, LV RWT showed significant heritability (h(2) ± SEM = 0.56 ± 0.09, P < 0.0001) and this persisted with further adjustments for LVM (h(2) ± SEM = 0.48 ± 0.09, P < 0.0001) or LVMI (h(2) ± SEM = 0.49 ± 0.09, P < 0.0001).

CONCLUSIONS

In a group of African ancestry, independent of LVM, LV geometric remodeling shows significant intrafamilial aggregation and heritability. Genetic factors may in-part determine the LV geometric remodeling process independent of the extent of cardiac hypertrophy.

Impact of gender and menopausal status on relationships between biological aging, as indexed by telomere length, and aortic stiffness

BACKGROUND

Telomere length predicts cardiovascular disease (CVD) possibly through an impact of telomere attrition on aortic stiffness. Whether reduced biological aging and a lack of telomere length-aortic stiffness relationships in women contribute to the lower prevalence of CVD in women, prior to menopause, is uncertain.

METHODS

We evaluated the relationship between telomere length and carotid-femoral (aortic) pulse wave velocity (PWV) in 580 randomly recruited participants of Black African descent (age = 44 ± 19 years; women: n = 361; premenopausal: n = 195). PWV was determined using carotid and femoral applanation tonometry (SphygmoCor). Relative leukocyte telomere length (T/S) was measured using quantitative real-time polymerase chain reaction assays.

RESULTS

Men and women had similar T/S. T/S was inversely correlated with age (r = -0.14, P < 0.001) and this association was similar in all (r = -0.14, P < 0.01) and premenopausal (r = -0.17, P < 0.05) women as in men (r = -0.14, P < 0.05). An inverse relationship between T/S and PWV was noted both before (r = -0.20, P < 0.0001) and after (partial r = -0.14, P < 0.001) adjustments for confounders. No interaction between T/S and either sex or menopausal status was independently associated with PWV, and T/S was independently correlated with PWV in all (partial r = -0.14, P < 0.01) and premenopausal (partial r = -0.18, P < 0.05) women and in men (partial r = -0.15, P < 0.05).

CONCLUSIONS

Gender and premenopausal status do not affect age-related decreases in T/S and associations between T/S and PWV. In participants of African descent in whom telomere length did not differ by gender, the impact of gender prior to menopause on CVD is unlikely to be attributed to differences in the effect of biological aging on aortic stiffness.

Independent associations of circulating galectin-3 concentrations with aortic pulse wave velocity and wave reflection in a community sample

Although the profibrotic inflammatory substance galectin-3 predicts outcomes in the general population, the mechanisms responsible for this effect are uncertain. We aimed to determine whether circulating galectin-3 concentrations are associated with carotid femoral (aortic) pulse wave velocity and aortic reflective wave index (applanation tonometry and SphygmoCor software) in 966 randomly selected participants from a community sample. Galectin-3 concentrations were not independently associated with office (n=966) or 24-hour (n=661) systolic (P=0.88-0.92) or diastolic (P=0.65-0.94) blood pressure. In contrast, with adjustments for age, sex (in all participants), office or 24-hour mean arterial pressure (or systolic blood pressure and pulse pressure), pulse rate, body mass index, regular smoking, regular alcohol intake, total cholesterol concentrations, diabetes mellitus or an glycohemoglobin >6.1%, treatment for hypertension, and estimated glomerular filtration rate, galectin-3 was independently associated with aortic pulse wave velocity in all participants (partial r=0.15, P<0.0001) and reflective wave index in men (partial r=0.13, P<0.02). In 745 participants who had never received antihypertensive therapy, galectin-3 concentrations were similarly independently associated with pulse wave velocity in all participants (partial=0.16, P<0.0001) and reflective wave index in men (partial r=0.15, P<0.02). The blood pressure-independent relations between galectin-3 concentrations and aortic hemodynamics persisted with further adjustments for C-reactive protein concentrations (pulse wave velocity in all participants: partial r=0.14, P<0.0001; reflective wave index in men: partial r=0.12, P<0.05). In conclusion, despite a lack of independent association with brachial blood pressure, the profibrotic inflammatory substance galectin-3 may contribute toward adverse outcomes through an effect on aortic stiffness, an effect that cannot be attributed to general inflammatory changes.

Sodium-to-potassium ratio and blood pressure, hypertension, and related factors

The potential cost-effectiveness and feasibility of dietary interventions aimed at reducing hypertension risk are of considerable interest and significance in public health. In particular, the effectiveness of restricted sodium or increased potassium intake on mitigating hypertension risk has been demonstrated in clinical and observational research. The role that modified sodium or potassium intake plays in influencing the renin-angiotensin system, arterial stiffness, and endothelial dysfunction remains of interest in current research. Up to the present date, no known systematic review has examined whether the sodium-to-potassium ratio or either sodium or potassium alone is more strongly associated with blood pressure and related factors, including the renin-angiotensin system, arterial stiffness, the augmentation index, and endothelial dysfunction, in humans. This article presents a systematic review and synthesis of the randomized controlled trials and observational research related to this issue. The main findings show that, among the randomized controlled trials reviewed, the sodium-to-potassium ratio appears to be more strongly associated with blood pressure outcomes than either sodium or potassium alone in hypertensive adult populations. Recent data from the observational studies reviewed provide additional support for the sodium-to-potassium ratio as a superior metric to either sodium or potassium alone in the evaluation of blood pressure outcomes and incident hypertension. It remains unclear whether this is true in normotensive populations and in children and for related outcomes including the renin-angiotensin system, arterial stiffness, the augmentation index, and endothelial dysfunction. Future study in these populations is warranted.

Urinary angiotensinogen excretion is associated with blood pressure independent of the circulating renin-angiotensin system in a group of african ancestry

Although the circulating renin-angiotensin system (RAS) is suppressed in salt-sensitive populations, the role of the intrarenal RAS in blood pressure (BP) control in these groups independent of the circulating RAS is uncertain. We evaluated the relationship between 24-hour urinary angiotensinogen excretion and either office (mean of 5 measurements; n=425) or 24-hour ambulatory (n=340) BP independent of the circulating RAS in a community-based sample of African descent that had never received antihypertensive drug therapy. Circulating RAS activity was determined from plasma renin and angiotensinogen and serum aldosterone concentrations. Urinary angiotensinogen to creatinine ratio (angiotensinogen/creat) was correlated with plasma angiotensinogen concentrations (P<0.0005) but not with indexes of salt intake. However, urinary angiotensinogen/creat was independently associated with office systolic BP (partial r=0.16; P<0.001), whereas plasma angiotensinogen (partial r=0.07; P=0.14) was not independently associated with office systolic BP. Urinary angiotensinogen/creat was also associated with 24-hour systolic BP (partial r=0.11; P<0.05). The relationships between urinary angiotensinogen/creat and BP survived further adjustments for plasma angiotensinogen and serum aldosterone concentrations, plasma renin concentrations, estimated glomerular filtration rate, urinary Na(+)/K(+), or 24-hour urinary Na(+) excretion rates (P<0.005 for all). Participants with the highest compared with the lowest quartile of urinary angiotensinogen/creat showed an 8.2-mm Hg higher office (P<0.005) and 4.6-mm Hg higher 24-hour (P=0.01) systolic BP. In conclusion, independent of the systemic RAS, including plasma angiotensinogen concentrations, urinary angiotensinogen excretion is associated with BP in a salt-sensitive, low-renin group of African descent. These data lend further support for a role of the RAS in BP control in salt-sensitive groups of African ancestry.

Isolated increases in in-office pressure account for a significant proportion of nurse-derived blood pressure-target organ relations

AIMS

We determined the extent to which relationships between nurse-derived blood pressures (BPs) and cardiovascular damage may be attributed to isolated increases in in-office SBP independent of ambulatory BP.

METHODS

In 750 participants from a community sample, nurse-derived office BP, ambulatory BP, carotid-femoral pulse wave velocity (PWV; applanation tonometry and SphygmoCor software; n=662), and left ventricular mass indexed to height (LVMI; echocardiography; n=463) were determined.

RESULTS

Nurse-derived office BP was associated with organ changes independent of 24-h BP (LVMI; partial r=0.15, P<0.005, PWV; partial r=0.21, P<0.0001) and day BP. However, in both unadjusted (P<0.0001 for both) and multivariate adjusted models (including adjustments for 24-h BP; LVMI; partial r=0.14, P<0.01, PWV; partial r=0.21, P<0.0001), nurse office-day SBP (an index of isolated increases in in-office BP) was associated with target organ changes independent of ambulatory BP and additional confounders, with the highest quartile (≥15 mmHg) showing the most marked increases in LVMI (P<0.0005) and PWV (P<0.0001) as compared to the lowest quartile (<-5 mmHg). These relationships were reproduced in those with normotensive day BP values and the quantitative effect of nurse office-day BP on target organ changes was at least equivalent to that of ambulatory BP.

CONCLUSION

Nurse-elicited isolated increases in in-office BP account for a significant proportion of the relationship between nurse-derived BP and target organ changes independent of ambulatory BP. Therefore, high quality nurse-derived BP measurements do not approximate the impact of BP effects per se on cardiovascular damage.

Relations between white coat effects and left ventricular mass index or arterial stiffness: role of nocturnal blood pressure dipping

BACKGROUND

Whether independent relationships between white coat effects (office minus day (office-day blood pressure (BP))) and organ damage or arterial stiffness may be explained by associations with an attenuated nocturnal BP dipping, has not been determined.

METHODS

In 750 participants from a sample of African ancestry, office and 24-hour BP, carotid-femoral pulse wave velocity (PWV) (applanation tonometry and SphygmoCor software) (n = 662), and left ventricular mass indexed to height(2.7) (LVMI) (echocardiography) (n = 463) were determined.

RESULTS

Office-day systolic BP (SBP) was correlated with day minus night (day-night) SBP, percentage night divided by day (night/day) SBP, and night SBP (P < 0.0005), and these relationships persisted with adjustments for confounders, including day SBP (P < 0.005). With adjustments for 24-hour SBP and additional confounders, office-day SBP was associated with LVMI (P < 0.01) and PWV (P < 0.0001). With adjustments for day SBP and additional confounders, day-night SBP, percentage night/day SBP, and night SBP were related to PWV (P < 0.05) but not to LVMI (P > 0.44). The relationships between office-day SBP and LVMI or PWV persisted with adjustments for either day-night or percentage night/day SBP (LVMI: P = 0.01; PWV: P < 0.0001) or night SBP (LVMI: P < 0.01; PWV: P = 0.0001), and in product of coefficient mediation analysis with appropriate adjustments, neither indexes of nocturnal BP dipping nor nocturnal BP per se contributed toward the impact of office-day BP on LVMI or PWV (P > 0.09).

CONCLUSIONS

In a group of African ancestry, although white coat effects are independently associated with an attenuated nocturnal decrease in SBP, neither decreased BP dipping nor nocturnal BP contribute toward the independent relationships between white coat effects and LVMI or arterial stiffness.

Relationship between glomerular dysfunction and left-ventricular mass independent of haemodynamic factors in a community sample

AIM

To evaluate whether the relationship between early glomerular dysfunction and left-ventricular mass (LVM) occurs in a community sample and whether this relationship depends on haemodynamic factors.

METHODS

In 621 randomly selected participants from a community sample (332 were normotensive), estimated glomerular filtration rate (eGFR), LVM and dimensions were determined using echocardiography, and aortic blood pressure (BP) assessed from applanation tonometry and SphygmoCor software. Aortic pulse wave velocity (PWV) and high-quality 24-h BP values were available from 554 and 437 participants, respectively.

RESULTS

With adjustments for confounders (including clinic SBP), eGFR was associated with LVM index (LVMI) and LVM in excess of that predicted from stroke work (inappropriate LVM, LVMinappr) in all participants (LVMI: partial r = -0.18, P < 0.0001; LVMinappr: partial r = -0.17, P < 0.0001) and normotensive (LVMI: partial r = -0.23, P < 0.0001; LVMinappr: partial r = -0.22, P < 0.0001) separate from hypertensive patients. Marked differences in LVMinappr were noted in the eGFR range below 132 compared to at least 132 ml/min per 1.73 m (P < 0.0005). When replacing clinic BP with either aortic SBP, 24-h BP, PWV, stroke work (for LVMI), left-ventricular end-diastolic diameter (LVEDD), or circumferential wall stress in the regression models, eGFR retained strong associations with LVMI (P = 0.01 to <0.0001) and LVMinappr (P < 0.005 to <0.0001) and these effects were replicated in normotensive separate from hypertensive patients.

CONCLUSIONS

Strong relationships between eGFR and LVM occur at a community level irrespective of the presence of hypertension and independent of 24-h and aortic BP, PWV, LVEDD, stroke work and wall stress. Non-haemodynamic factors explain a considerable proportion of the relationship between early glomerular dysfunction and left-ventricular hypertrophy.