Impact of age on the independent association of adiposity with pulse-wave velocity in a population sample of African ancestry

Association of the second derivative of photoplethysmogram with age, hemodynamic, autonomic, adiposity, and emotional factors

The second derivative of photoplethysmogram (SDPTG) is used as an arterial stiffness marker. This study aimed to examine the associations between SDPTG indices and age, in addition to hemodynamic, autonomic, adiposity, and emotional factors.This study had a cross-sectional chart review design, and electronic medical records of 262 women outpatients (mean ± SD,|38.57| ± |11.64 years) were reviewed. Among SDPTG measurements, b/a, c/a, d/a, and (b-c-d)/a were considered. Hemodynamic measurements included systolic and diastolic blood pressure (SBP and DBP) and cardiac output. Autonomic measurements included low and high frequency (LF and HF) values of the heart rate variability. Adiposity measurements included body mass index (BMI) and waist-hip ratio (WHR). Tension, anger, depression, fatigue, confusion, and vigor scores using the Profile of the Mood States were included as emotional markers. All data were normalized through the Box-Cox transformation, and 4 hierarchical regression models were constructed.Age was independently predictive of SDPTG, hemodynamic, autonomic, and adiposity factors (β; 0.143-0.648).After the adjustment for age, SBP and DBP showed negative correlations with d/a (r = -0.201, -0.262), whereas BMI, WHR, LF, and HF showed positive correlations with c/a (r = 0.126, 0.131, 0.151, 0.234). In the hierarchical regression modeling, age and hemodynamic factors were directly predictive of SDPTG indices (β; 0.103-0.626). Age had moderating effects between diastolic blood pressure, heart rate, depression scores, and SDPTG indices (β; 0.104-0.176).In conclusion, age, hemodynamic, adiposity, and autonomic factors may be independently associated with SDPTG indices for women. As age has moderating effects between hemodynamic, emotional factors, and SDPTG indices, its moderating effects should be considered when assessing arterial stiffness using SDPTG indices.

Interaction of Metabolic Health and Obesity on Subclinical Target Organ Damage

BACKGROUND

Metabolically healthy obese (MHO) individuals generally show better cardiovascular prognosis compared with metabolically unhealthy counterparts, which may be related to different patterns of target organ damage (TOD). We aimed to investigate the patterns of TOD related to obesity and metabolic unhealthiness.

METHODS

A total of 659 Korean adults (mean age, 60.0 ± 11.8 years; male, 51.1%) undergoing health examinations were stratified into four groups according to obesity (body mass index ≥25.0 kg/m²) and metabolic healthiness (meeting ≤1 criteria of metabolic syndrome excluding abdominal circumference): metabolically healthy nonobese (MHNO), metabolically unhealthy nonobese (MUNO), MHO, and metabolically unhealthy obese (MUO). Four measures of TOD were evaluated: arterial stiffness, renal dysfunction, left ventricular (LV) diastolic dysfunction, and LV hypertrophy (LVH).

RESULTS

In multivariable analyses, compared with the MHNO group, the MHO group showed 2.31 times higher odds for LVH, whereas, the MUNO group showed 3.14 and 6.28 times higher odds for increased arterial stiffness and renal dysfunction, respectively. Metabolic unhealthiness was associated with increased arterial stiffness [odds ratio (OR) 2.73; confidence interval (95% CI) 1.72-4.34], renal dysfunction (OR 4.02; 95% CI 1.54-10.49), and LV diastolic dysfunction (OR 2.28; 95% CI 1.14-4.55). Meanwhile, obesity showed weaker association with LVH and LV diastolic dysfunction, and was not associated with increased arterial stiffness and renal dysfunction in multivariable analyses.

CONCLUSIONS

Metabolic unhealthiness shows more association with TOD than obesity, which may contribute to the higher risk of cardiometabolic abnormalities in MUNO compared with MHO.

Association of Blood Pressure Variability Ratio With Glomerular Filtration Rate Independent of Blood Pressure and Pulse Wave Velocity

BACKGROUND

Blood pressure variability ratio (BPVR)(derived from within-subject SD of 24-hour ambulatory blood pressure [BP]) predicts all-cause mortality independent of BP and has a similar prognostic ability to ambulatory arterial stiffness (AASI). Whether BPVR, and AASI, offer prognostic information beyond measurements of arterial stiffness at a given pressure, as indexed by pulse wave velocity (PWV), is not known.

METHODS

We assessed whether BPVR and AASI were associated with indices of subclinical organ damage (TOD) [estimated glomerular filtration rate (eGFR), left ventricular mass index, early-to-late transmitral velocity (E/A), carotid intima-media thickness (IMT)] independent of BP, and whether BPVR-TOD and AASI-TOD relations were independent of PWV (applanation tonometry) in 772 randomly selected participants from an urban, developing community. AASI was derived from 24-hour diastolic BP vs. systolic BP standard linear regression.

RESULTS

On bivariate analyses, BPVR, AASI, and PWV were correlated with all indices of TOD (P < 0.0005). However, after adjustments for potential confounders including age and 24-hour mean BP, BPVR, and PWV (P < 0.005 to P < 0.0001), but not AASI (P > 0.25), were independently associated with eGFR, but not other indices of TOD. Importantly, the BPVR-eGFR relation was independent of BP variability (P < 0.005) and PWV (P < 0.001).

CONCLUSIONS

BPVR was negatively associated with eGFR independent of mean BP, BP variability, and PWV. Therefore, in the prediction of cardiovascular risk, measurements of arterial stiffening (BPVR) may provide information beyond the impact of arterial stiffness.

Influence of obesity in central blood pressure

BACKGROUND

Obesity is an important risk factor for cardiovascular disease and has become a major concern in healthcare due to its high prevalence worldwide. The aim of the present study was to investigate the impact of BMI on central blood pressure (BP) and pulse wave velocity (PWV) in normotensive and hypertensive patients.

PATIENTS AND METHODS

Normotensive and hypertensive adult patients who attended the outpatient clinic of cardiovascular risk were included. Peripheral BP was obtained in the brachial artery by using an oscillometric device (OMRON M-6). Central aortic BP waveform was reconstructed from the radial artery pressure waveforms (SphygmoCor, AtCor Medical, Sydney, Australia) and central BP was calculated. Carotid-femoral PWV was measured by an automatic device (Complior, Artech, France).

RESULTS

We examined a total of 351 patients [50.7% women; 77 patients normal-weight (BMI < 25 kg/m)], 274 patients overweight or obese (BMI ≥25 kg/m). Central SBP showed a positive association with male sex and mean BP, but a negative association with overweight/obesity. PWV was positively associated with age, male sex, central BP, peripheral BP and BP treatment, whereas BMI of at least 25 kg/m led to a decrease in PWV in patients with the same central SBP levels. Likewise, PWV was lower in the overweight/obese group compared to the normal-weight group at the same central SBP.

CONCLUSION

Overweight and obesity tend to have lower central SBP as compared to lean patients, mainly in women. Further research is required to assess the interaction between body weight and vascular dynamics and their clinical implications.

Pulse pressure amplification in relation to body fatness

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Aortic-brachial pulse pressure amplification (PPA) is a measure of arterial elasticity and it is also an independent cardiovascular risk factor. The PPA is mainly determined by age, height, central and peripheral pressure waveforms characteristics, including measures of arterial stiffness and wave reflection.

WHAT THIS STUDY ADDS

In this study, however, we demonstrate that PPA is also significantly associated with indirect indices of body fatness. As the body fatness is treatable, our findings might be used as a reference for future studies on the effects of body fat reduction on PPA and the PPA-related cardiovascular risk. AIMS Arterial pressure transfer to the periphery is accompanied by pulse pressure amplification (PPA). Pulse pressure is influence by body fat. The purpose of the present study was to evaluate any possible inter-relation between body fatness and PPA in healthy subjects.

METHODS

Haemodynamic and wave reflection indices were estimated by pulse wave analysis. Body fat was measured by bio-impedance.

RESULTS

A total of 367 healthy volunteers (136 men and 231 women) was studied. Pulse pressure amplification correlated significantly with percentage of body fat (r=-0.53, P < 0.0001), age (r=-0.62, P < 0.0001), height (r= 0.43, P < 0.0001), heart rate (r= 0.28, P < 0.0001) and mean blood pressure (r=-0.29, P < 0.0001). The association of PPA with body fat was also significant in a multiple linear regression model. Age was an independent predictor of PPA and analysis of study subjects subdivided into two groups, those <50 years and those >50 years showed that body fatness correlated inversely and significantly with PPA in individuals both younger and older than 50 years (r=-0.44, P < 0.0001, r=-0.37, P < 0.0001 respectively). Augmentation pressure was also associated significantly with percentage of body fat in both subgroups (r= 0.48, P < 0.0001 and r= 0.49, P < 0.0001 respectively).

CONCLUSIONS

This study performed on healthy subjects showed that pulse pressure amplification is related to body fatness over a wide age range. Percentage body fat is significantly associated with augmentation pressure, a component of central pulse pressure.

Waist circumference modifies the relationship between the adipose tissue cytokines leptin and adiponectin and all-cause and cardiovascular mortality in haemodialysis patients

BACKGROUND

the relationships between the adipose tissue cytokines leptin and adiponectin (ADPN) and clinical outcomes have not been well studied in haemodialysis (HD) patients and remain highly controversial. As central obesity is an important modifier of the effect of various risk factors for clinical outcomes, we tested the hypothesis that waist circumference (WC) modifies the link between these cytokines and both overall and cardiovascular death in HD patients.

METHODS

a total of 537 HD patients participated in a prospective cohort study.

RESULTS

leptin and ADPN were inversely related to each other and robustly associated with WC (P < 0.001). During follow-up (average 29 months, range 1-47 months) 182 patients died, including 115 from cardiovascular causes. In analyses adjusting for potential confounders, there were strong interactions between leptin and WC in relationship to both all-cause (P < 0.001) and cardiovascular death (P = 0.002). Accordingly, a fixed excess of leptin signalled a gradually increasing risk for all-cause and cardiovascular mortality in patients with a large WC but an opposite effect in those with a relatively small WC. An interaction between ADPN and WC for all-cause (P = 0.01) and cardiovascular mortality (P = 0.01) emerged only in models excluding the leptin-WC interaction, suggesting that these adipokines share a common pathway leading to adverse clinical events in HD patients.

CONCLUSIONS

the predictive value of leptin and ADPN for all-cause and cardiovascular death in HD patients appears to be critically dependent on WC. These findings support the hypothesis that disturbances in adipokine levels are involved in adverse clinical outcomes in HD patients with abdominal obesity.

Global cardiovascular risk profiles of untreated hypertensives in an urban, developing community in Africa

Introduction

Blood pressure (BP) control in people of African descent is poor, largely because of a lack of treatment. Although the requirements for immediate initiation of antihypertensive drug therapy are defined by global cardiovascular risk, the global cardiovascular risk profiles of untreated hypertensives at a community level are uncertain.

Aim

To identify the distribution of global cardiovascular risk profiles of untreated hypertensives in an urban, developing community of African descent in South Africa.

Methods

As part of the African Programme on Genes in Hypertension, we assessed nurse-derived clinic BP (the mean of five standardised BP values obtained according to guidelines), current antihypertensive therapy, and total cardiovascular risk in 1 029 participants older than 16 years of age from randomly selected nuclear families from the South West Township of Gauteng (SOWETO).

Results

Approximately 46% of participants had systolic/diastolic BP values ≥ 140/90 mmHg and ~23% of participants were hypertensives not receiving antihypertensive medication. Approximately 12% of untreated hypertensives had a high added risk and ~18% a very high added risk (6.7% of the total sample). In untreated hypertensives, in contrast to the absence of severe hypertension and diabetes mellitus in those with lower risk profiles, a high cardiovascular risk profile in this group was characterised by severe hypertension in ~52% and diabetes mellitus in ~33%. Based on a high added risk carrying at least a 20% chance and a very high added risk at least a 30% chance of a cardiovascular event in 10 years, this translates into 1 740 events per 100 000 of the population within 10 years, events that could be prevented through antihypertensive drug therapy.

Conclusions

In an urban, developing community of African ancestry, a significant proportion (6.7%) of people may have untreated hypertension and a global cardiovascular risk profile that suggests a need for antihypertensive drug therapy. Cardiovascular risk in this group is driven largely by the presence of severe hypertension or diabetes mellitus.

Insulin resistance independently influences arterial stiffness in normoglycemic normotensive postmenopausal women

OBJECTIVE

Cardiovascular disease risk increases after menopause, which may be related to insulin resistance, and arterial stiffness is a significant predictor of atherosclerosis. We investigated the relationships among insulin resistance, adiponectin, and arterial stiffness in normoglycemic normotensive postmenopausal women.

METHODS

From 9,555 participants who had routine health checkups, 455 normoglycemic normotensive postmenopausal women were enrolled. Serum concentrations of glucose, total cholesterol, triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C) and adiponectin were measured. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment (HOMA-IR). Pulse wave velocity (PWV) was evaluated to assess arterial stiffness.

RESULTS

The women were stratified into three groups according to their HOMA-IR values, and comparisons were made among the three groups. There were significant differences in metabolic parameters between the groups. The mean age, body mass index, waist circumference, fasting plasma glucose, TG, systolic blood pressure (SBP), diastolic blood pressure (DBP), aortic PWV, and peripheral PWV increased sequentially with the degree of insulin resistance. Meanwhile, HDL-C and adiponectin levels decreased with the worsening of insulin resistance. Age, body mass index, fasting plasma glucose, TG, insulin, SBP, HOMA-IR, aortic PWV, and peripheral PWV were significantly higher in women with central obesity, and HDL-C and adiponectin were significantly lower in women with central obesity. Aortic PWV and peripheral PWV were significantly correlated with age, waist circumference, total cholesterol, SBP, DBP, insulin, and HOMA-IR, but adiponectin was not associated with PWV. The results of multiple regression analysis indicated that SBP, DBP, and insulin resistance were independently correlated with PWV.

CONCLUSIONS

Insulin resistance was independently associated with PWV in normoglycemic normotensive postmenopausal women.

Contribution of central and general adiposity to abnormal left ventricular diastolic function in a community sample with a high prevalence of obesity

The relative independent contribution of excess adiposity, as indexed by measures of central, general, or peripheral adiposity, toward abnormal cardiac diastolic chamber function at a community level is unclear. In 377 randomly selected participants >16 years old from a community sample with a high prevalence of excess adiposity ( approximately 25% overweight and approximately 43% obese), we assessed the independent contribution of the indexes of adiposity to the variation in early-to-late (atrial) transmitral velocity (E/A). After adjustments for a number of confounders, including age, gender, pulse rate, conventional diastolic (or systolic) blood pressure, antihypertensive treatment, left ventricular mass index, and the presence of diabetes mellitus or a hemoglobin A1c level >6.1%; waist circumference was an independent predictor of a reduced E/A (p = 0.0038). Body mass index (p = 0.07), waist-to-hip ratio (p = 0.23), and skinfold thickness (p = 0.37) were not independently associated with E/A, whereas waist circumference was independently associated with E/A, even after adjustments for other adiposity indexes, including body mass index (p <0.05 to 0.005). In contrast to the effects on diastolic function, the waist circumference did not correlate with the left ventricular ejection fraction (p = 0.23). The independent relation between the waist circumference and E/A (standardized beta coefficient -0.14 +/- 0.05, p = 0.0038) was second only to age (standardized beta coefficient -0.57 +/- 0.05, p <0.0001) and similar to blood pressure (standardized beta coefficient -0.11 +/- 0.04, p = 0.0075) in the magnitude of the independent effect on E/A. The inclusion of the relative wall thickness rather than the left ventricular mass index in the regression equation produced similar outcomes. The exclusion of the left ventricular mass index and relative wall thickness from the regression equations or the inclusion of carotid-femoral pulse wave velocity or 24-hour blood pressure as confounders failed to modify the relation between waist circumference and E/A. In conclusion, the waist circumference was second only to age in the impact on an independent association with E/A in a population sample with a high prevalence of excess adiposity. This effect was not accounted for by left ventricular hypertrophy or remodeling, the 24-hour blood pressure, or arterial stiffness.

Dietary-induced obesity hastens the progression from concentric cardiac hypertrophy to pump dysfunction in spontaneously hypertensive rats

We explored whether dietary-induced obesity hastens the transition from concentric left ventricular (LV) hypertrophy to pump dysfunction in spontaneously hypertensive rats (SHRs) and the mechanisms thereof. After feeding rats a diet for 4 to 5 months, obesity was induced in SHRs and Wistar-Kyoto (WKY) control rats. Obesity was not associated with abnormal blood glucose control (glycosylated hemoglobin) or with increases in systolic blood pressure. However, in SHRs, but not in WKY rats, obesity was associated with a reduced LV chamber systolic function, as determined by echocardiography, and in isolated perfused heart studies. A marked increase in LV end diastolic diameter and a right shift in the LV diastolic pressure-volume relation were noted in obese SHRs but not in obese WKY rats. Moreover, LV intrinsic myocardial systolic function, as determined from the slope of the linearized LV systolic stress-strain relationship (LV myocardial end systolic elastance), was markedly reduced in obese as compared with lean SHRs, whereas LV myocardial end systolic elastance was maintained in obese WKY rats. Obesity increased LV weight, cardiomyocyte width, cardiomyocyte apoptosis (TUNEL), the activity of myocardial matrix metalloproteinases (zymography), and serum leptin concentrations in SHRs but not in WKY rats. In conclusion, SHRs are susceptible to the adverse effects of dietary-induced obesity on the heart, an effect that hastens the progression from concentric LV hypertrophy to pump dysfunction independent of blood pressure changes or alterations in glycosylated hemoglobin. This effect may be mediated through a proclivity of SHRs to developing both obesity-induced effects on cardiomyocyte apoptosis and activation of myocardial collagenases through leptin resistance and obesity-induced hypertrophy.