Mortality and Cardiovascular End Points In Relation to the Aortic Pulse Wave Components: An Individual-Participant Meta-Analysis.

BACKGROUND: Wave separation analysis enables individualized evaluation of the aortic pulse wave components. Previous studies focused on the pressure height with overall positive but differing results. In the present analysis, we assessed the associations of the pressure of forward and backward (Pfor and Pref) pulse waves with prospective cardiovascular end points, with extended analysis for time to pressure peak (Tfor and Tref). METHODS: Participants in 3 IDCARS (International Database of Central Arterial Properties for Risk Stratification) cohorts (Argentina, Belgium, and Finland) aged ≥20 years with valid pulse wave analysis and follow-up data were included. Pulse wave analysis was done using the SphygmoCor device, and pulse wave separation was done using the triangular method. The primary end points consisted of cardiovascular mortality and nonfatal cardiovascular and cerebrovascular events. Multivariable-adjusted Cox regression was used to calculate hazard ratios. RESULTS: A total of 2206 participants (mean age, 57.0 years; 55.0% women) were analyzed. Mean±SDs for Pfor, Pref, Tfor, and Tfor/Tref were 31.0±9.1 mm Hg, 20.8±8.4 mm Hg, 130.8±35.5, and 0.51±0.11, respectively. Over a median follow-up of 4.4 years, 146 (6.6%) participants experienced a primary end point. Every 1 SD increment in Pfor, Tfor, and Tfor/Tref was associated with 27% (95% CI, 1.07-1.49), 25% (95% CI, 1.07-1.45), and 32% (95% CI, 1.12-1.56) higher risk, respectively. Adding Tfor and Tfor/Tref to existing risk models improved model prediction (∆Uno's C, 0.020; P<0.01). CONCLUSIONS: Pulse wave components were predictive of composite cardiovascular end points, with Tfor/Tref showing significant improvement in risk prediction. Pending further confirmation, the ratio of time to forward and backward pressure peak may be useful to evaluate increased afterload and signify increased cardiovascular risk.

Role of atrial natriuretic peptide in the dissociation between flow relations with ventricular mass and function in a community with volume-dependent hypertension.

Background: Whether differential effects of volume load on left ventricular mass (LVM) and function occur in sustained volume-dependent primary hypertension, and the impact of atrial natriuretic peptide (ANP) on these effects, is unknown. Methods: From aortic pressure, velocity and diameter measurements and echocardiography, we determined in an African community (n = 772), the impact of systemic flow-induced increases in central pulse pressure (PPc) and circulating ANP (ELISA) on LVM and indexes of function. Results: Stroke volume (SV), but not aortic flow (Q), was associated with LVM and mean wall thickness (MWT) beyond stroke work and confounders (p < 0.0001). Adjustments for SV markedly decreased the relationships between PPc and LVMI or MWT. However, neither SV, nor Q were independently associated with either myocardial s', e', or E/e' (p > 0.14) and adjustments for neither SV nor Q modified relationships between PPc and s', e' or E/e' (p < 0.005 to <0.0001). SV was nevertheless strongly and independently associated with ANP (p < 0.0001) and ANP was similarly strikingly associated with s' (p < 0.0001) and e' (p < 0.0005), but not E/e', independent of confounders and several determinants of afterload. Importantly, ANP concentrations were inversely rather than positively associated with LV diastolic dysfunction (DD) (p < 0.005) and lower rather than higher ANP concentrations contributed markedly to the ability to detect DD in those with, but not without LV hypertrophy. Conclusion: In populations with sustained volume-dependent hypertension, flow (SV)-related increases in PP have a major impact on LV structure, but not on function, an effect attributed to parallel striking beneficial actions of ANP on myocardial function.

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.

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.

Proximal aortic stiffness modifies the relationship between heart rate and backward wave and hence central arterial pulse pressure.

Aims: A lower heart rate (HR) increases central blood pressure through enhanced backward wave pressures (Pb). We aimed to determine whether these relationships are modified by increases in aortic stiffness. Methods: Using non-invasive central pressure, aortic velocity and diameter measurements in the outflow tract (echocardiography), we assessed the impact of aortic stiffness on relationships between HR and arterial wave morphology in 603 community participants < 60 years of age, 221 ≥ 60 years, and in 287 participants with arterial events [stroke and critical limb ischemia (CLI)]. Results: As compared to community participants < 60 years, those ≥ 60 years or with events had increased multivariate adjusted proximal aortic characteristic impedance (Zc) and carotid femoral pulse wave velocity (PWV) (p < 0.05 to < 0.0001). Community participants ≥ 60 years and those with events also had a greater slope of the inverse relationship between HR and Pb (p < 0.001 for comparison). While in community participants < 60 years, no interaction between indexes of aortic stiffness and HR occurred, in those ≥ 60 years (p < 0.02) and in those with arterial events (p = 0.001), beyond aortic root diameter, an interaction between Zc and HR, but not between PWV and HR independently associated with Pb. This translated into stepwise increases in the slope of HR-Pb relationships at incremental tertiles of Zc. Although HR was inversely associated with the systemic reflection coefficient in community participants ≥ 60 years (p < 0.0001), adjustments for the reflection coefficient failed to modify HR-Pb relations. Conclusion: Beyond the impact on systemic wave reflection, increases in proximal aortic stiffness enhance the adverse effects of HR on Pb and hence central BP.

Contribution of Increases in Late Systolic Ejection Volume to the Impact of Heart Rate on Central Arterial Pulse Pressure in a Community Sample.

BACKGROUND: A lower heart rate (HR) increases left ventricular (LV) ejection volume. Whether this contributes to the adverse effects of HR on central pulse pressure (PPc) through reservoir volume effects is uncertain. METHODS: Using noninvasive central pressure, aortic velocity, and diameter measurements in the outflow tract (echocardiography), we assessed the role of LV ejection volume as a determinant of HR relations with PPc in 824 community participants. RESULTS: A lower HR was independently associated with both stroke volume (SV) (P < 0.001) and a shift in ejection volume from early (until the first systolic shoulder) to late (from first systolic shoulder to peak PP) systole (P < 0.05 to P < 0.005). Adjustments for LV end diastolic volume markedly diminished HR relations with SV and indexes of the shift in ejection volume to late systole. A lower HR was also independently associated with increases in forward traveling pressure waves (Pf) and PPc (P < 0.0001). However, adjustments for neither SV, nor indexes of a shift in ejection volume to late systole modified HR-Pf or PPc relations. This was despite relationships between indexes of a shift in ejection volume to late systole and both Pf and PPc (P < 0.0001). In contrast, adjustments for the increases in re-reflected and backward traveling wave pressures with a lower HR, eliminated HR-Pf and PPc relations. CONCLUSIONS: In contrast to current thought, a lower HR is not associated with increases in PPc through an impact of increases in late systolic ejection volume on aortic reservoir volume, but rather through increases in backward wave pressures.

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.

Increased Backward Wave Pressures Rather than Flow Explain Age-Dependent Heart Rate Effects on Central, But not Peripheral Arterial Pressure.

Through both backward (Pb) and forward (Pf) wave effects, a lower heart rate (HR) associates with increased central (PPc), beyond brachial pulse pressure (PP). However, the relative contribution to Pf of aortic flow (Q) versus re-reflection of Pb, has not been determined. Using central pressure, aortic velocity and diameter measurements in the outflow tract (echocardiography), we constructed central pressure waveforms that account for the relative contribution of Q versus re-reflection to Pf. We thus evaluated the mechanisms of HR-PPc relations in a community sample (n=824) and the impact of age thereon. Inverse HR-PPc (P<0.0001), but not HR-brachial PP (P=0.064) relations were noted. The slope of HR-PPc relation was increased in older adults (P<0.005). HR was inversely associated with ventricular filling time, ejection duration, stroke volume, and peak Pf (P<0.001 to P<0.0001). However, an increased Q and hence pressures generated by the product of aortic characteristic impedance and Q did not account for Pf effects. Age-dependent HR-PPc and Pf relations were both accounted for by enhanced Pb (P<0.0001) with an increased Pf mediated by increments in wave re-reflection (P<0.0001). The lack of impact of ejection duration on PPc was explained by an increased time to peak Pb (P<0.0001). In conclusion, increases in PPc and Pf at a decreased HR are accounted for by an enhanced Pb rather than by a prolonged ejection or filling duration and hence flow (Q). These effects at a young-to-middle age are of little clinical significance, but at an older age, are of clinical importance.

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.

Metformin Prevents Low-dose Isoproterenol-induced Cardiac Dilatation and Systolic Dysfunction in Male Sprague Dawley Rats.

ABSTRACT: Myocardial metabolic abnormalities are well-recognized alterations in chronic heart failure, effects that may contribute to progressive cardiac dysfunction. However, whether metabolic alterations in-part mediate their deleterious effects by modifying the chronic impact of excess low-dose sympathetic stimulation on cardiac chamber dilatation is uncertain. We therefore aimed to determine the effect of metformin administration on cardiac function and mitochondrial architectural changes in a rat model of chronic sympathetic-induced left ventricular (LV) remodeling and systolic dysfunction [daily subcutaneous isoproterenol (ISO) injection at a low dose of 0.02 mg/kg for 7 months]. Echocardiography was used to assess in vivo LV dimensions and function, and mitochondrial and myofibril arrangement was assessed using transmission electron microscopy. Seven months of low-dose ISO administration increased LV diastolic diameter (in mm) [control (CONT): 7.29 ± 0.19 vs. ISO: 8.76 ± 0.21; P = 0.001], an effect that was attenuated by metformin (ISO + MET: 7.63 ± 0.29 vs. ISO: P = 0.001) administration. Similarly, ISO increased LV end-systolic diameter (CONT: 4.43 ± 0.16 vs. ISO: 5.49 ± 0.16: P < 0.0001), an effect prevented by metformin (ISO + MET: 4.04 ± 0.25 vs. ISO: P < 0.0001). Moreover, chronic ISO administration reduced LV endocardial fractional shortening (P = 0.0001), midwall fractional shortening (P = 0.0001), and ejection fraction (P = 0.0001), effects similarly prevented by metformin administration. Furthermore, changes in mitochondrial arrangement and relative mitochondrial area (CONT: 37.7 ± 2.2 vs. ISO: 28.1 ± 2.9; P = 0.05) were produced by ISO administration, effects prevented by metformin. In conclusion, metformin offers cardiac protection against chronic sympathetic-induced LV dilatation and systolic dysfunction. These data support a role for myocardial metabolic changes in mediating LV dilatation and LV dysfunction produced by chronic neurohumoral activation in cardiac disease.

Marked intrafamilial aggregation and heritability of aortic flow in a community with prevalent volume-dependent hypertension in Africa.

AIMS: Although peak aortic flow (Q) is now recognized as a major determinant of hypertension in Africa, current therapy has no proven ability to target this change. The mechanisms of this effect, therefore, require elucidation. We compared the intrafamilial aggregation and heritability of Q to that of the vascular determinants of pulse pressure (PP) and SBP in Africa. METHODS: The intrafamilial aggregation and heritability of Q and aortic characteristic impedance (Zc) or total arterial compliance (TAC) was determined in 669 participants of 194 families (69 father-mother, 385 parent-child, 157 sibling-sibling pairs) in a community in Africa with prevalent flow-dependent primary hypertension. Haemodynamics were determined from velocity and diameter measurements in the outflow tract (echocardiography) and central arterial pressures. RESULTS: No mother-father correlations were noted for either Q or Zc. However, with adjustments for confounders, parent-child (P < 0.0001) and sibling-sibling (P < 0.0001) correlations were noted for Q. Parent-child and/or sibling-sibling correlations were also noted for Zc or TAC but were weaker for Zc and mother-father correlations were noted for TAC. Moreover, Q showed markedly stronger multivariate adjusted heritability estimates (h2 = 0.82 ±â€Š0.07, P < 0.0001) than Zc (h2 = 0.44 ±â€Š0.10, P < 0.0001)(P < 0.005 for comparisons) and TAC (h2 = 0.47 ±â€Š0.08, P < 0.0001)(P < 0.005 for comparisons). Importantly, the heritability of Q was also greater than that for PP (h2 = 0.12 ±â€Š0.09, P = 0.11) (P < 0.0001 for comparisons), or SBP (h2 = 0.13 ±â€Š0.10, P = 0.08) (P < 0.0001 for comparisons). CONCLUSION: Of the haemodynamic determinants of SBP, peak aortic flow is the most strongly inherited in Africa. Peak aortic flow, therefore, represents an important target for identifying novel therapeutic approaches to controlling SBP in Africa.

Independent relationships between renal mechanisms and systemic flow, but not resistance to flow in primary hypertension in Africa.

AIMS: Whether renal mechanisms of hypertension primarily translate into increases in systemic vascular resistance (SVR) in all populations is uncertain. We determined whether renal mechanisms associate with either increases in SVR (and impedance to flow) or systemic flow in a community of African ancestry. METHOD: In a South African community sampled across the full adult age range (n = 546), we assessed stroke volume (SV), peak aortic flow (Q), SVR, characteristic impedance (Zc) and total arterial compliance (TAC) from velocity and diameter measurements in the outflow tract (echocardiography) and central arterial pressures. Renal changes were determined from creatinine clearance (glomerular filtration rate, GFR) and fractional Na+ excretion (FeNa+) (derived from 24-h urine collections). RESULTS: Independent of confounders (including MAP and pressures generated by the product of Q and Zc), SV (and hence cardiac output) (P < 0.0001) and Q (P < 0.01), but not SVR, Zc or TAC (P = 0.09-0.20) were independently associated with decreases in both GFR (index of nephron number) and FeNa+. Through an interactive effect (P < 0.0001), the impact of GFR on SV or Q was strongly determined by FeNa+ and vice versa. The relationship between the GFR-FeNa+ interaction and either SV or Q was noted in those above or below 50 years of age, although neither GFR, FeNa+ nor the interaction were independently associated with SVR, Zc or TAC at any age. CONCLUSION: Across the full adult lifespan, in groups of African ancestry, renal mechanisms of hypertension translate into increases in systemic flow rather than into resistance or impedance to flow.

Hemodynamic and Functional Correlates of Concentric vs. Eccentric LVH in a Community-Based Sample With Prevalent Volume-Dependent Hypertension.

BACKGROUND: Whether in volume-dependent primary hypertension, concentric left ventricular (LV) remodeling beyond hypertrophy (LVH) represents the impact of a pressure rather than a volume overload, is unclear. METHODS: Using central arterial pressure, and aortic velocity and diameter measurements in the outflow tract (echocardiography), we determined the factors that associate with concentric LVH or remodeling in a community of African ancestry (n = 709) with prevalent volume-dependent primary hypertension. RESULTS: Both left ventricular mass index (LVMI) and relative wall thickness (RWT) were positively and independently associated with end diastolic volume (EDV), stroke volume (SV), and peak aortic flow (Q) (P < 0.05 to <0.0001). However, neither LVMI nor RWT were positively and independently associated with systemic vascular resistance (SVR), or aortic characteristic impedance (Zc) or inversely associated with total arterial compliance (TAC). Consequently, both concentric (P < 0.0001) and eccentric (P < 0.0001) LVH were associated with similar increases in EDV, SV, and either office brachial, central arterial, or 24-hour blood pressures (BP), but neither increases in SVR or Zc nor decreases in TAC. LV RWT, but not LVMI was nevertheless independently and inversely associated with myocardial systolic function (midwall shortening and s') (P < 0.05 to <0.005) and decreases in LV systolic function were noted in concentric (P < 0.05), but not eccentric LVH. CONCLUSIONS: In volume-dependent primary hypertension, concentric LVH is determined as much by volume-dependent increases in systemic flow and an enhanced BP as eccentric LVH. Concentric remodeling nevertheless reflects decreases in systolic function beyond LVH.

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.

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.

Impact of stroke work on the ability of left ventricular mass to account for pressure effects on function in a community with prevalent systemic flow-dependent hypertension.

AIMS: To determine whether the confounding influence of stroke work on left ventricular mass (LVM) limits the ability of LVM to detect hypertensive LV dysfunction in systemic flow-dependent hypertension. METHODS: In a community with prevalent systemic flow-dependent hypertension (n = 709), arterial haemodynamics, LVM and LV function were determined using central arterial pressure, aortic velocity and diameter measurements in the outflow tract, and echocardiography with tissue Doppler imaging. RESULTS: In multivariate models, stroke work showed markedly stronger relations with LVM index (LVMI) than blood pressure load [central arterial SBP (SBPc), backward wave pressure (Pb), 24-h SBP] (P < 0.0001 for comparisons). In contrast, although SBPc, Pb, and 24-h SBP were inversely associated with myocardial tissue shortening (s') and lengthening (e') velocity, stroke work was not. With adjustments for stroke work, positive relationships between SBPc, Pb, or 24-h SBP and LVMI were eliminated (P = 0.20 to P = 0.89), but strong relations between BP and s', e' or E/e' (P = 0.009 to P < 0.0001) remained. In mediation analysis, stroke work fully accounted for BP effects on LVMI, but explained none of the effects of BP on LV function. Hence LVMI accounted for little of the impact of BP load on LV function. Although LVMI beyond stroke work (inappropriate LVM) improved on relations between LVMI and s', it failed to improve on relations with e' or E/e' and contributed little beyond LVMI to the impact of BP on LV function. CONCLUSION: In systemic flow-dependent hypertension, the impact of stroke work markedly limits the ability of LVM to account for adverse effects of hypertension on LV function.

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.

Contribution of systemic blood flow to untreated or inadequately controlled systolic--diastolic or isolated systolic hypertension in a community sample of African ancestry.

AIMS: Age-related increases in systemic blood flow [stroke volume (SV), cardiac output (CO), and aortic flow (Q)] contribute substantially to untreated or inadequately controlled (uncontrolled) blood pressure (BP) in Africa. We aimed to identify the haemodynamic determinants of uncontrolled systolic--diastolic (Syst--diast HT) versus uncontrolled isolated systolic (ISH) or diastolic (IDH) hypertension. METHODS: Using central arterial pressure and aortic outflow tract velocity and diameter measurements (echocardiography), the haemodynamic correlates of BP were determined in 725 community participants of African ancestry (19.6% uncontrolled Syst--diast HT, 9.2% uncontrolled ISH, 11.3% uncontrolled IDH). RESULTS: Independent of confounders, compared with those with a normotensive BP, those with uncontrolled Syst--diast HT had increases in SV, CO, Q, systemic vascular resistance (SVR) and aortic characteristic impedance (Zc) and decreases in total arterial compliance (TAC) (P < 0.05--P < 0.0001). In multivariate regression models, uncontrolled Syst--diast HT was as strongly associated with Q, SV or CO as with SVR (P = 0.04--P = 0.20), Zc (P = 0.74--P < 0.0005) and TAC (P = 0.43--P < 0.005). Independent of confounders, compared with normotensive individuals those with uncontrolled ISH had increases in SV, CO, Q and Zc but not SVR, and decreases in TAC (P < 0.05-P < 0.0001), and those with IDH only had increases in SVR (P < 0.0001). Uncontrolled ISH was more strongly associated with Q, SV and CO than with SVR (P < 0.0005), but less than with TAC (P < 0.05--P < 0.0005). CONCLUSION: In groups of African ancestry living in Africa, hypertension because of increases in either SBP or DBP is as strongly associated with increases in systemic flow (SV, Q) as with arterial and arteriolar effects (Zc, TAC, SVR).

Relations of aortic stiffness with arterial damage beyond brachial pressure are both dependent and independent of central arterial pulsatile load.

AIM: We aimed to determine whether the impact of aortic stiffness on atherosclerotic or small vessel end organ damage beyond brachial blood pressure depends in-part on stiffness-induced increases in central arterial pressures produced by an enhanced resistance to flow (characteristic impedance, Zc). METHODS: We studied 1021 participants, 287 with stroke or critical limb ischaemia, and 734 from a community sample with atherosclerotic or small vessel end organ measures. Central arterial haemodynamics were determined from arterial pressure (SphygmoCor) and velocity and diameter assessments in the outflow tract (echocardiography). RESULTS: Although Zc and carotid-femoral pulse wave velocity (PWV) were correlated (P < 0.0001), these relations were not independent of confounders (P = 0.90). Both Zc and hence central arterial pressures generated by the product of Zc and aortic flow (Q) (PQxZc), as well as PWV were independently associated with carotid intima-media thickness, estimated glomerular filtration rate (eGFR), endothelial activation markers [vascular cell adhesion molecule-1 (V-CAM-1)] and events. With further adjustments for brachial pulse pressure (PP) or SBP, PWV and PQxZc were both associated with eGFR and V-CAM-1. Relationships between PWV and eGFR or V-CAM-1 were independent of PQxZc (P < 0.05) and relationships between PQxZc and eGFR and V-CAM-1 were independent of PWV (P < 0.005). Similarly, with adjustments for confounders and brachial PP or SBP, across the full adult lifespan, both aortic PWV and PQxZc were increased in those with arterial events (P < 0.005). Relationships between PWV and events were again independent of PQxZc (P < 0.005) and between PQxZc and events were independent of PWV (P < 0.0001). CONCLUSION: Beyond brachial blood pressure, the impact of aortic stiffness on arterial damage involves effects that are both dependent (proximal aortic Zc and hence PQxZc) and independent (full aortic length indexed by PWV) of central arterial pulsatile load. Hence, PWV and brachial PP may be insufficient to account for all of the damage mediated by increases in aortic stiffness.