Potential determinants of the E/e' ratio in non-dialysis compared with dialysis patients.

AIM: We hypothesized that arterial function and N-terminal natriuretic peptide (NT-proBNP) levels as a marker of volume overload, relate differently to E/e' as an index of diastolic function in dialysis compared with non-dialysis patients with chronic kidney disease. We further examined whether cardiovascular risk factors attenuated these relationships. METHODS: We assessed cardiovascular risk factors and determined arterial function indices by applanation tonometry using SphygmoCor software and E/e' by echocardiography in 103 (62 non-dialysis and 41 dialysis) patients. RESULTS: In established confounder adjusted analysis, dialysis status impacted the pulse wave velocity-E/e' relationship (interaction p = .01) but not the NT-proBNP level-E/e' association (interaction p = .1). Upon entering arterial function measures and NT-proBNP levels simultaneously in regression models, arterial function measures were associated with E/e' (p = .008 to .04) in non-dialysis patients whereas NT-proBNP levels were related to E/e' in dialysis patients (p = .009 to .04). Bivariate associations were found between diabetes (p < .0001) and E/e' in non-dialysis patients, and haemoglobin concentrations and E/e' (p = .02) in those on dialysis. Upon adjustment for diabetes in non-dialysis patients, only central pulse pressure remained associated with E/e' (p = .02); when haemoglobin concentrations were adjusted for in dialysis patients, NT-proBNP levels were no longer associated with E/e' (p = .2). In separate models, haemoglobin levels were associated with E/e' independent of left ventricular mass index and preload and afterload measures (p = .02 to .03). CONCLUSION: The main determinants of E/e' may differ in non-dialysis compared with dialysis patients. These include arterial function and diabetes in non-dialysis patients, and volume overload and anaemia in dialysis patients.

Arterial wave reflection and subclinical atherosclerosis in rheumatoid arthritis.

OBJECTIVES: Atherosclerotic cardiovascular disease risk is increased in rheumatoid arthritis (RA). Wave reflection occurs at arterial branching points, which are particularly prone to atherosclerosis. We explored the relationship of wave reflection with atherosclerosis in RA. METHODS: One hundred and sixty three RA patients (110 white, 31 Asian, 17 black and 5 of mixed ancestry) without cardiovascular disease participated. Arterial stiffness, wave reflection, pressure pulsatility, plaque in the extracranial carotid artery tree and the mean of the left and right common carotid arteries intima-thickness were determined. Associations were identified in multivariable regression models. RESULTS: One SD increase in reflected wave pressure (OR (95% CI) = 2.54 (1.41-4.44), p=0.001), reflection magnitude (OR (95% CI) = 1.84 (1.17-2.89), p=0.008), central pulse pressure (OR (95% CI) = 1.89 (1.12-3.22), p=0.02) and peripheral pulse pressure (OR (95% CI) = 2.09 (1.23-3.57), p=0.007) were associated with plaque. The association of wave reflection with plaque was independent of arterial stiffness and pressure pulsatility, and was present in both hypertensive and normotensive RA patients. In receiver operator characteristic curve analysis, the optimal cutoff value for reflected wave pressure in predicting plaque presence was 25 mmHg with a sensitivity, specificity, positive predictive value and negative predictive value of 45.2%, 89.3%, 78.6% and 66.2%, respectively; a reflected wave pressure of >25 mmHg was associated with plaque in univariate and adjusted analysis (p<0.0001 for both). Arterial function was not independently related to carotid intima-media thickness. CONCLUSIONS: Consideration and therapeutic targeting of wave reflection may improve cardiovascular disease prevention in RA.

The relative potential contribution of volume load and vascular mechanisms to hypertension in non-dialysis and dialysis chronic kidney disease patients.

Background: Hypertension is highly prevalent and particularly difficult to treat adequately in patients with chronic kidney disease (CKD). The relative contribution of volume overload and vascular mechanisms to blood pressure measures in CKD and whether these effects differ in non-dialysis compared to dialysis patients is unknown. Methods: We determined the potential impact of volume load (stroke volume) and vascular mechanisms (inverse of total arterial compliance (inv TAC) and systemic vascular resistance (SVR)) on mean and brachial and aortic systolic blood pressures in 67 non-dialysis and 48 dialysis chronic kidney disease (CKD) patients. Relationships were determined in confounder adjusted regression models. Results: Stroke volume (p value = 0.003) was more strongly associated with mean arterial pressure than SVR (p value = 0.9) (p value for difference = 0.03). When stroke volume and SVR were entered in the same regression model (model R2 = 0.324), they contributed equally to the variation in mean arterial pressure (p value for difference = 0.5). Stroke volume (p value ≤ 0.002) and inv TAC (p value ≤ 0.001) contributed equally to the variation in systolic pressures (p value for difference ≥ 0.9). When stroke volume and inv TAC were entered in the same regression model (model R2 = 0.752 to 0.765), they contributed equally to the variation in systolic blood pressures (p value for difference = 0.7). Stroke volume, TAC and SVR were similar (p value ≥ 0.5) and associated to the same extent with blood pressure measures in non-dialysis and dialysis CKD patients (p value for difference ≥ 0.1). In receiver operator characteristic curve analysis, elevated systolic blood pressure was determined by stroke volume (p value = 0.005) and inv TAC (p value = 0.03) but not SVR (p value = 0.8). The calculated power of the study was 0.999 based on α = 0.05. Conclusions: The present investigation suggests that both volume load and vascular mechanisms should be considered in the management of hypertension among patients with CKD. The extent and relative potential impact of volume load and vascular mechanisms on blood pressure measures are as large in non-dialysis compared to dialysis CKD patients.

Associations of Traditionally Determined Left Ventricular Mass Indices and Hemodynamic and Non-Hemodynamic Components of Cardiac Remodeling with Diastolic and Systolic Function in Patients with Chronic Kidney Disease.

We aimed to evaluate the extent to which different left ventricular mass parameters are associated with left ventricular function in chronic kidney disease (CKD) patients. We compared the associations between traditionally determined left ventricular mass indices (LVMIs) and hemodynamic (predicted LVMIs) and non-hemodynamic remodeling parameters with left ventricular function in patients with CKD; non-hemodynamic remodeling was represented by inappropriate left ventricular mass and inappropriate excess LVMIs (traditionally determined LVMIs-predicted LVMIs). Non-hemodynamic left ventricular remodeling parameters were strongly associated with impaired left ventricular systolic function (p < 0.001), whereas hemodynamic left ventricular remodeling was also related strongly (p < 0.001) but directly to left ventricular systolic function. Independent of one another, hemodynamic and non-hemodynamic left ventricular remodeling had associations in opposite directions to left ventricular systolic function and was associated directly with traditionally determined left ventricular mas indices (p < 0.001 for all relationships). Non-hemodynamic cardiac remodeling parameters discriminated more effectively than traditionally determined LVMIs between patients with and without reduced ejection fraction (p < 0.04 for comparison). Left ventricular mass parameters were unrelated to impaired diastolic function in patients with CKD. Traditionally determined LVMIs are less strongly associated with impaired systolic function than non-hemodynamic remodeling parameters (p < 0.04-0.01 for comparisons) because they represent both adaptive or compensatory and non-hemodynamic cardiac remodeling.

Aortic Stiffness and Pulsatile Pressures as Potential Mediators of Chronic Kidney Disease Induced Impaired Diastolic Function.

PURPOSE: We assessed whether aortic stiffness and pulsatile pressures can mediate chronic kidney disease (CKD)-associated impaired diastolic function. PARTICIPANTS AND METHODS: In 276 black Africans including 46 CKD (19 non-dialysis; 27 dialysis) and 230 control subjects, pulse wave velocity (PWV) estimated aortic stiffness and pulsatile pressures (forward and backward wave pressure, central systolic blood pressure (CSBP) and pulse pressure (CPP)) were determined by applanation tonometry; e' as an index of left ventricular active relaxation and E/e' as a measure of left ventricular filling pressure or passive relaxation were evaluated by echocardiography. RESULTS: In age, sex, traditional cardiovascular risk factor and mean arterial pressure (MAP) adjusted regression models, CKD was inversely associated with e' (p = 0.03) and directly with E/e' (p < 0.01). The CKD-e' relationship was attenuated and no longer significant (p = 0.31) upon additional adjustment for aortic PWV but not pulsatile pressures (p = 0.03-0.05). In product of coefficient mediation analysis, PWV accounted for 47.6% of the CKD-e' association. CSBP (22.9%) and CPP (18.6%) but not PWV (11.3%) accounted for a significant and relevant proportion of the CKD-E/e' relationship. However, CKD remained strongly associated with E/e' independent of aortic function measures (p < 0.01). Treatable covariates that were or tended to be consistently associated with diastolic function included MAP (p < 0.01) and diabetes (p = 0.02-0.07) for the CKD-e' and CKD-E/e' relations, respectively. CONCLUSION: Aortic stiffness rather than pulsatile pressures mediates CKD-related impaired left ventricular active relaxation. By contrast, aortic pulsatile pressures (and not stiffness) contribute to CKD-related left ventricular filling pressures but do not fully account for the respective association.

Uric Acid, Ferritin, Albumin, Parathyroid Hormone and Gamma-Glutamyl Transferase Concentrations are Associated with Uremic Cardiomyopathy Characteristics in Non-Dialysis and Dialysis Chronic Kidney Disease Patients.

Introduction: Circulating uric acid, ferritin, albumin, intact parathyroid hormone and gamma-glutamyl transferase each participate in biochemical reactions that reduce or/and enhance oxidative stress, which is considered the final common pathway through which pathophysiological mechanisms cause uremic cardiomyopathy. We hypothesized that the respective biomarkers may be involved in the development of uremic cardiomyopathy characteristics and can be useful in their identification among chronic kidney disease patients. Methods: We assessed traditional and non-traditional cardiovascular risk factors including biomarker concentrations and determined central systolic blood pressure using SphygmoCor software and cardiac structure and function by echocardiography in 109 (64 non-dialysis and 45 dialysis) patients. Associations were evaluated in multivariate regression models and receiver operator characteristic (ROC) curve analysis. Results: Each biomarker concentration was associated with left ventricular mass beyond stroke work and/or inappropriate left ventricular mass in all, non-dialysis and/or dialysis patients. Ferritin, albumin and gamma-glutamyl transferase levels were additionally associated with E/e' in all, non-dialysis and/or dialysis patients. Dialysis status influenced the relationship of uric acid concentrations with inappropriate left ventricular mass and those of gamma-glutamyl transferase levels with left ventricular mass and inappropriate left ventricular mass. In stratified analysis, low uric acid levels were related to inappropriate left ventricular mass in dialysis but not non-dialysis patients (interaction p=0.001) whereas gamma-glutamyl transferase concentrations were associated with left ventricular mass and inappropriate left ventricular mass in non-dialysis but not dialysis patients (interaction p=0.020 to 0.036). In ROC curve analysis, uric acid (area under the curve (AUC)=0.877), ferritin (AUC=0.703) and albumin (AUC=0.728) concentrations effectively discriminated between dialysis patients with and without inappropriate left ventricular hypertrophy, left ventricular hypertrophy, and increased E/e,' respectively. Conclusion: Uric acid, ferritin, albumin, parathyroid hormone and gamma-glutamyl transferase were associated with uremic cardiomyopathy characteristics and could be useful in their identification. Our findings merit validation in future longitudinal studies.

Cardiovascular Risk Factor Profiles and Disease in Black Compared to Other Africans with Chronic Kidney Disease.

METHODS: Cardiovascular risk factors, aortic and cardiac function, atherosclerosis extent, and cardiovascular event rates were assessed in 115 consecutive predialysis (n = 67) and dialysis patients (n = 48) including 46 black and 69 other (32 Asian, 28 white, and 9 mixed race) participants. Data were analysed in multivariable regression models. RESULTS: Overall, black compared to other African CKD patients had less frequent carotid artery plaque (OR (95% CI) = 0.38 (0.16-0.91)) despite an increased cardiovascular risk factor burden. In receiver operator characteristic curve analysis, the Framingham score performed well in identifying non-black but not black CKD patients with carotid plaque (area under the curve (AUC) (95% CI) = 0.818 (0.714-0.921) and AUC (95% CI) = 0.556 (0.375-0.921), respectively). Black compared to other African predialysis patients experienced larger Framingham scores and more adverse nontraditional cardiovascular risk factors, impaired arterial and diastolic function but similar cardiovascular event rates (OR (95% CI) = 0.93 (0.22 to 3.87)). Among dialysis patients, black compared to other Africans had an overall similar traditional and nontraditional cardiovascular risk factor burden, similar arterial and diastolic function but increased systolic function (partial R = 0.356, p = 0.01 and partial R = 0.315, p = 0.03 for ejection fraction and stroke volume, respectively) and reduced cardiovascular event rates (OR (95% CI) = 0.22 (0.05 to 0.88)). CONCLUSION: Black compared to other African CKD patients have less frequent very high risk atherosclerosis and experience weaker cardiovascular risk factor-atherosclerotic CVD relationships. These disparities may be due to differences in epidemiological health transition stages. Among dialysis patients, black compared to other Africans have less cardiovascular events, which may represent a selection bias as previously documented in black Americans.

Association of Post Transplantation Anaemia and Persistent Secondary Hyperparathyroidism with Diastolic Function in Stable Kidney Transplant Recipients.

INTRODUCTION: We hypothesized that post transplantation anaemia and persistent secondary hyperparathyroidism are potential determinants of diastolic function in stable kidney transplant recipients. METHODS: We assessed traditional and non-traditional cardiovascular risk factors and determined carotid artery intima-media thickness and plaque by ultrasound, arterial function by applanation tonometry using SphygmoCor software and diastolic function by echocardiography in 43 kidney transplant recipients with a transplant duration of ≥6 months, no acute rejection and a glomerular filtration rate of ≥15 mL/min/1.73m2. RESULTS: Mean (SD; range) transplant duration was 12.3 (8.0; 0.5-33.8) years. Post transplantation anaemia and persistent secondary hyperparathyroidism were identified in 27.9% and 30.8% of the patients, respectively; 67.5% of the participants were overweight or obese. In established confounder adjusted analysis, haemoglobin (partial R=-0.394, p=0.01) and parathyroid hormone concentrations (partial R=0.382, p=0.02) were associated with E/e'. In multivariable analysis, haemoglobin (partial R=-0.278, p=0.01) and parathyroid levels (partial R=0.324, p=0.04) were independently associated with E/e'. Waist-height ratio (partial R=-0.526, p=0.001 and partial R=-0.355, p=0.03), waist circumference (partial R=-0.433, p=0.008 and partial R=-0.393, p=0.02) and body mass index (partial R=-0.332, p=0.04 and partial R=-0.489, p=0.002) were associated with both e' and E/A, respectively, in established confounder adjusted analysis. The haemoglobin-E/e' (partial R=-0.422, p=0.02), parathyroid hormone-E/e' (partial R=0.434, p=0.03), waist-height ratio-e' (partial R=-0.497, p=0.007) and body mass index-E/A (partial R=-0.386, p=0.04) relationships remained consistent after additional adjustment for left ventricular mass index and cardiac preload and afterload measures. CONCLUSION: Haemoglobin and parathyroid hormone concentrations as well as adiposity measures are independently associated with diastolic function in kidney transplant recipients. Whether adequate management of post transplantation anaemia, persistent secondary hyperparathyroidism and excess adiposity can prevent the development of heart failure with preserved ejection fraction in kidney transplant recipients merits further investigation.

The Optimal Haemoglobin Target in Dialysis Patients May Be Determined by Its Contrasting Effects on Arterial Stiffness and Pressure Pulsatility.

INTRODUCTION: It remains unclear why the optimal haemoglobin target is lower in patients with chronic kidney disease (CKD) than in non-CKD persons. Arteriosclerosis and consequent impaired arterial function comprise a central cardiovascular risk mechanism in CKD. We hypothesized that the optimal haemoglobin target depends on its opposing effects on arterial stiffness and pressure pulsatility in CKD. METHODS: Arterial stiffness (aortic pulse wave velocity), wave reflection (augmentation index, reflected wave pressure and reflection magnitude), and pressure pulsatility (central systolic and pulse pressure, peripheral pulse pressure, pressure amplification and forward wave pressure) were assessed in 48 dialysis patients. RESULTS: In established confounder and diabetes adjusted linear regression models, haemoglobin levels were directly associated with arterial stiffness (partial R=0.366, p=0.03) and inversely with central systolic pressure (partial R=-0.344, p=0.04), central pulse pressure (partial R=-0.403, p=0.01), peripheral pulse pressure (partial R=-0.521, p=0.001) and forward wave pressure (partial R=-0.544, p=0.001). The presence of heart failure and use of angiotensin converting enzyme inhibitors or angiotensin receptor blockers and erythropoietin stimulating agents did not materially alter these relationships upon further adjustment for the respective characteristics in the models, and in sensitivity analyses. In receiver operator characteristic curve analysis, the optimal haemoglobin concentration cut-off values in predicting arterial stiffness and increased central pulse pressure were remarkably similar at 10.95 g/dl and 10.85 g/dl, respectively, and with clinically useful sensitivities, specificities and positive and negative predictive values. In logistic regression models, a haemoglobin value of >10.9 mg/dl was associated with both arterial stiffness (>10 m/sec; OR (95% CI) = 10.48 (1.57-70.08), p=0.02) and normal central pulse pressure (>50 mmHg; OR (95% CI) = 7.55 (1.58-36.03), p=0.01). CONCLUSION: This study suggests that the optimal haemoglobin target in dialysis patients is ~11g/dl and determined by its differential and contrasting effects on arterial stiffness and pressure pulsatility.

Nesfatin-1 and visfatin expression is associated with reduced atherosclerotic disease risk in patients with rheumatoid arthritis.

Nesfatin is an anti-inflammatory molecule that reduces atherosclerotic cardiovascular risk. By contrast, visfatin has pro-inflammatory properties and is pro-atherogenic. We examined the potential impact of nesfatin and visfatin on atherosclerotic disease in 232 (113 black and 119 white) consecutive rheumatoid arthritis (RA) patients from 2 centers. Independent relationships of nesfatin and visfatin concentrations with metabolic risk factors, endothelial activation, carotid atherosclerosis and altered plaque stability were determined in multivariable regression models. Rheumatoid factor (RF) positivity was associated with both nesfatin (ß = 0.650, p < 0.0001) and visfatin levels (ß = 0.157, p = 0.03). Visfatin concentrations were related to increased diastolic blood pressure (ß = 4.536, p = 0.01) and diabetes prevalence (ß = 0.092, p = 0.04). Nesfatin levels were associated with reduced carotid intima-media thickness (ß = -0.017, p = 0.008). Nesfatin (ß = 0.116, p = 0.001) and visfatin concentrations (ß = 0.234, p = 0.001) were related to those of matrix metalloproteinase-2 (MMP-2), a plaque stability mediator. Nesfatin and visfatin concentrations were directly correlated (Spearman's rho = 0.516). The nesfatin-MMP-2 and visfatin-MMP-2 relations were both stronger in RF negative compared to RF positive patients (interaction p = 0.01 and p = 0.04, respectively). Nesfatin is associated with reduced atherosclerosis and increased plaque stability mediator levels in RA. Visfatin is related to adverse cardio-metabolic risk in RA. Increased MMP-2 expression in relation to visfatin may represent a compensatory mechanism aimed at reducing cardiovascular risk in RA.

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.

Kidney function, endothelial activation and atherosclerosis in black and white Africans with rheumatoid arthritis.

OBJECTIVE: To determine whether kidney function independently relates to endothelial activation and ultrasound determined carotid atherosclerosis in black and white Africans with rheumatoid arthritis (RA). METHODS: We calculated the Jelliffe, 5 Cockcroft-Gault equations, Salazar-Corcoran, Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimated glomerular filtration rate (EGFR) equations in 233 (112 black) RA patients. RESULTS: The CKD-EPI eGFR was <90 ml/min/1.73m2 in 49.1% and 30.6% of black and white patients, respectively (odds ratio (95% confidence interval) = 2.19 (1.28-3.75), p = 0.004). EGFRs were overall consistently associated with monocyte chemoattractant protein-1 and angiopoietin 2 concentrations in white patients, and with carotid intima-media thickness and plaque in black participants. Amongst black patients, plaque prevalence was 36.7% and the area under the curve (AUC) of the receiver operating characteristic (ROC) curve was not associated with plaque presence for the MDRD equation (p = 0.3), whereas the respective relationship was significant or borderline significant (p = 0.003 to 0.08) and of similar extent (p>0.1 for comparisons of AUC (SE)) for the other 8 equations. Based on optimal eGFR cutoff values with sensitivities and specificities ranging from 42 to 60% and 70 to 91% respectively, as determined in ROC curve analysis, a low eGFR increased the odds ratio for plaque 2.2 to 4.0 fold. CONCLUSION: Reduced kidney function is independently associated with atherosclerosis and endothelial activation in black and white Africans with RA, respectively. CKD is highly prevalent in black Africans with RA. Apart from the MDRD, eGFR equations are useful in predicting carotid plaque presence, a coronary heart disease equivalent, amongst black African RA patients.

Diabetogenic effect of tacrolimus in South African patients undergoing kidney transplantation1.

BACKGROUND: Diabetes mellitus (DM) is a complication of tacrolimus therapy. This prospective study evaluated the prevalence of DM in South African black and white patients receiving tacrolimus after kidney transplantation and factors that could identify patients before transplantation who may be at risk of developing DM. METHODS: Fasting blood samples from 17 patients (11 black, 6 white) were analyzed immediately pretransplantation and at 1 and 3 months posttransplantation for glucose, HbAIC, insulin, C-peptide, free fatty acids, lipids, urea, and creatinine. Insulin resistance (IR) was calculated using the homeostasis model assessment (HOMA) and quantitative insulin sensitivity check index (QUICKI) formulas. RESULTS: Eight patients (47%) became diabetic (six black, two white), and nine patients (five black, four white) remained nondiabetic. Mean glucose concentrations in the diabetic group were significantly higher at 1 month (P=0.03) and 3 months (P=0.01). Mean insulin level was also significantly raised at 3 months (P=0.01) as was HbAIC (P=0.001). C-peptide concentrations did not change significantly in either group. Significant correlations emerged between fasting glucose concentrations at 3 months posttransplantation and initial HOMA (r=0.486; P=0.048) and initial QUICKI (r=-0.582; P=0.014). CONCLUSIONS: Occurrence of DM was high and somewhat greater in black patients. IR was the main mechanism involved, together with inadequate beta-cell compensation. IR pretransplantation predicts the subsequent development of DM.