Age-related and blood pressure-independent reduction in aortic stiffness after kidney transplantation

High-resistance inspiratory muscle strength training: a promising strategy for improving vascular health in chronic kidney disease

Patients with chronic kidney disease (CKD) demonstrate accelerated vascular aging which contributes to an increased risk of cardiovascular disease (CVD). Impaired vascular health in CKD is characterized by both functional and structural alterations to the vasculature including hypertension, arterial stiffness, vascular endothelial dysfunction, and autonomic dysfunction. These detriments persist despite pharmacological intervention. Habitual aerobic exercise can be protective of vascular health; however, the feasibility in patients with CKD is low due to numerous barriers to exercise. In this perspective we emphasize the need for novel and non-pharmacological strategies that can rescue vascular health and reduce the development of CVD in patients with CKD, explain the unique barriers to aerobic exercise in CKD, present a novel physical training intervention-high-resistance inspiratory muscle strength training (IMST) that addresses the barriers to exercise, and provide our opinion on why this lifestyle intervention may be particularly efficacious for patients with CKD.

Improved Arterial Stiffness Indices 3 and 6 Months after Living-donor Renal Transplantation

Arterial stiffness is a non-traditional risk factor of cardiovascular disease and may explain part of the excess cardiovascular risk in chronic kidney disease patients. Successful renal transplantation (RT) may restore renal function and improve several metabolic abnormalities involved in arterial stiffness. This prospective study conducted non-invasive assessments of arterial stiffness indices [the augmentation index (AI) and pulse wave velocity (PWV)] in end-stage kidney disease (ESKD) patients before RT and 3 and 6 months after living-donor RT, alongside the effects of age and calcineurin inhibitors on arterial stiffness. The study included 26 ESKD patients (22 males and 4 females; mean age, 34.07 years; median duration of dialysis, 10 months) scheduled for RT and followed up for three visits (within 1 week before transplantation, and 3 and 6 months after transplantation). Six months after successful RT, the patients had nearly normal serum creatinine and significantly improved serum phosphate and intact parathyroid hormone levels. The pretransplant AI was 21.53% ± 13.61% which reduced significantly 6 months after RT to 16.19% ± 10.74% (P <0.05). Although there was a reduction in PWV 6 months after RT from the pre-transplant PWV, it was not significant. A significant correlation between age and the augmentation index was noted 3 and 6 months after RT. Patients on tacrolimus-based immunosuppression after RT showed significant improvements in the AI compared with patients on a cyclosporine-based regimen. RT helped to improve arterial stiffness indices, resulting in reduced cardiovascular risk.

Association between Long-Term Change in Arterial Stiffness and Cardiovascular Outcomes in Kidney Transplant Recipients: Insights from the TRANSARTE Study

(1) Background: Increased arterial stiffness is associated with cardiovascular (CV) diseases in end-stage renal disease (ESRD) patients, and CV mortality remains higher in kidney transplantation (KT) recipients compared to in the general population. KT is associated with an improvement in arterial stiffness in the early post-transplant period, followed by a potential re-worsening in the late period. In a cohort of KT patients, we evaluated the associations of pulse-wave velocity (PWV) measured at different time-points (pre-transplant, and early and late post-transplant periods) with CV morbi-mortality, as well as the evolution between these measurements with CV morbi-mortality. (2) Methods: Forty KT recipients with a 10-year follow-up were included. The association of PWV with CV events was assessed with multivariable cox analysis. Backward linear regressions were conducted to identify the determinants of PWV at 1 year and those of the long-term evolution of PWV after KT (delta PWV at 1 year—latest PWV). (3) Results: The absence of arterial stiffening during the long-term follow-up after KT is associated with a lower CV outcome rate (HR for the delta PWV = 0.76 (0.58−0.98), p = 0.036). Age at KT is associated with the worsening of arterial stiffness in the late post-transplantation period (β for the delta PWV = −0.104, p = 0.031). A high PWV at 1 year was associated with a potential for recovery during follow-up (β = 0.744, p < 0.0001). (4) Conclusions: The absence of PWV worsening in the late post-transplantation period was significantly associated with a lower risk of CV events, whereas early changes in PWV were not. Finding an intervention capable of reducing long-term PWV could improve the prognosis of KT recipients.

Sex Differences in Subclinical Cardiovascular Organ Damage After Renal Transplantation: A Single-Center Cohort Study

Background: Cardiovascular disease (CVD) is the leading cause of death after renal transplantation (RT). Sex-specific differences in CVD in the general population are well known. The aim of this study was to evaluate sex-specific differences in prevalence and course of subclinical cardiovascular (CV) organ damage in RT recipients during the first year after RT. Methods: In a prospective longitudinal study, we enrolled 121 patients (male 64%, age 51 ± 15 years). CV risk factors, left ventricular mass index (LVMI), and pulse wave velocity (PWV) were assessed at time of RT and 1 year later. Results: Women showed less prediagnosed CVD and better blood pressure (BP) control, and were less likely to be treated with calcium channel blockers (CCBs). Despite similar transplant function, LVMI increased in women and decreased in men (p = 0.027). In multivariable analysis, changes in LVMI were independently associated with female sex and systolic BP. Importantly, women receiving CCBs showed a decrease in LVMI and PWV. Conclusions: Our findings indicate a sex-specific association between RT and changes in LVMI. CCBs seem to have a positive impact on CV risk after RT, especially in women. Further studies on the effect of sex and CCB use in RT recipients are warranted.

Would Oscillometry be Able to Solve the Dilemma of Blood Pressure Independent Pulse Wave Velocity - A Novel Approach Based on Long-Term Pulse Wave Analysis?

The utility of pulse wave velocity (PWV) as a surrogate parameter of arterial vessel damage (AVD) beyond the traditional brachial blood pressure (BP) measurement may be questioned as changes in BP are often accompanied by the corresponding changes in PWV. We sought to establish a new way for BP-independent estimation of AVD with PWV. We retrospectively analyzed data from 507 subjects with at least one available 24 h ambulatory BP- and pulse wave analysis, performed with Mobil-O-Graph (I.E.M., Stolberg, Germany). Individual relationship between eaPWV and central systolic BP (cSBP) was analyzed for every 24 h recording. The analysis revealed linear relation between eaPWV and cSBP in all subjects, which is described by equation eaPWV = a^∗cSBP + b. We termed “a” as PWVslope and “b” as PWVbaseline. All available demographic parameters and clinical data were correlated with eaPWV, PWVslope and PWVbaseline. 108 subjects had repeated 24 h recordings. Mean age was 60.7 years and 48.7% were female. 92.5% had hypertension, 22.9% were smoker, 20.5% had diabetes mellitus and 29.6% eGFR < 60 ml/min/1,73 m². Direct correlation was observed between age, SBP and eaPWV, while diastolic BP (DBP) and eGFR correlated inversely with eaPWV. PWVbaseline correlated directly with age and inversely with DBP, while PWVslope didn’t correlate with any inputted parameter. Using simple mathematical approach by plotting eaPWV and cSBP values obtained during ABPM, it is possible to visualize unique course of individual PWV related to BP. Using PWVslope and PWVbaseline as novel parameters could be a feasible way to approach BP-independent PWV, though their clinical relevance should be tested in future studies. Our data underline the importance of BP-independent expression of PWV, when we use it as a clinical surrogate parameter for the vascular damage.

Impact of kidney transplantation on aortic stiffness and aortic stiffness index β0

BACKGROUND

In chronic kidney disease, the enhanced aortic stiffness increases risk of cardiovascular events. Kidney transplantation (KTx) may improve aortic stiffness; however, it is unclear whether the improvement of aortic stiffness is merely the outcome of the reduction of blood pressure (BP) post-KTx. Furthermore, the long-term trajectory of aortic stiffness remains uncertain, as activation of the immune system may have a negative long-term impact on arterial wall property.

METHOD

Using aortic stiffness β0 as a BP-independent stiffness parameter, and a statistical adjustment for BP, we aimed to examine the early vs. late changes in aortic stiffness, and to define the characteristics of patients with favourable and unfavourable long-term trajectories of aortic stiffness. In this longitudinal study, aortic stiffness was assessed before, 3, 6 and 24 months after KTx in 79 individuals. Aortic stiffness was determined by carotid-femoral pulse wave velocity (cf-PWV), and aortic stiffness index β0 was obtained by applying the stiffness parameter β0 theory to cf-PWV based on Bramwell-Hill's equation using a reference pressure.

RESULTS

There was an early reduction of β0 3 months after KTx (29.0 ± 2.0 to 25.8 ± 1.2, P = 0.033) followed by a gradual increase at 6 (28.0 ± 1.4, P = 0.005 vs. 3 months) and 24 months (28.3 ± 1.3, P = 0.003 vs. 3 months). A late increase in β0 was associated with higher levels of the interleukin-6 (P = 0.029) even after adjustment for potential cofounders. Using statistical adjustments for BP showed similar results.

CONCLUSION

Reduction of aortic stiffness index β0 3 months after KTx suggests that KTx leads to an early de-stiffening of the intrinsic mechanical properties of aorta. However, this improvement is followed by a later stiffening, which is associated with increased interleukin-6, suggesting that activation of the immune system may be involved in arterial wall remodelling in kidney recipients.

Influence of Renal Transplantation and Living Kidney Donation on Large Artery Stiffness and Peripheral Vascular Resistance

BACKGROUND

Vascular status following renal transplantation (RT) may improve while living kidney donation (LKD) is possibly associated with an increased cardiovascular risk.

METHODS

We prospectively assessed glomerular filtration rate (mGFR, 51Chrome EDTA clearance) and intermediate vascular risk factors in terms of blood pressure (BP), pulse wave velocity (PWV), central augmentation index (AIx), excess pressure (Pexcess), and forearm vascular resistance in donors (n = 58, 45 ± 13 years) and recipients (n = 51, 50 ± 12 years) before and one year following LKD or RT.

RESULTS

After kidney donation, mGFR decreased by 33% to 65 ± 11 ml/min/1.73m2, while recipients obtained a mGFR of 55 ± 9 ml/min/1.73m.2 Ambulatory 24-hour mean arterial BP (MAP) remained unchanged in donors but decreased by 5 mm Hg in recipients (P < 0.05). Carotid-femoral PWV increased by 0.3 m/s in donors (P < 0.05) but remained unchanged in recipients. AIx was unaltered after LKD but decreased following RT (P < 0.01), and Pexcess did not change in either group. Resting forearm resistance (Rrest), measured by venous occlusion plethysmography, increased after LKD (P < 0.05) but was unaffected by RT, while no changes were seen in minimum resistance (Rmin). ΔPWV showed a positive linear association to Δ24-hour MAP in both groups. Multiple linear regression analysis (adjusting for age, gender, and the baseline value of the studied parameter) did not detect independent effects of graft function on 24-hour MAP, PWV, AIx, vascular resistance, or Pexcess, whereas low post-donation GFR was related to higher AIx and Rrest.

CONCLUSIONS

RT reduced BP and AIx without affecting PWV, whereas LKD resulted in increased PWV and Rrest, despite unchanged BP.

Kidney transplantation improves arterial stiffness in patients with end-stage renal disease

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of mortality among the patients with end-stage renal disease (ESRD). Arterial stiffness is a well-accepted predictor of cardiovascular mortality in general population and ESRD patients. The aim of this study was to compare the change of arterial stiffness in kidney transplant recipients (KTRs) and ESRD patients, and further investigate the impact of kidney transplantation (KT) on arterial stiffness.

METHODS

A total of 138 maintenance hemodialysis patients, 198 KTRs and 75 healthy volunteers were enrolled in this study. The carotid-femoral pulse wave velocity (CF-PWV) and carotid-radial PWV (CR-PWV) were determined, and the correlations of PWV with biochemical parameters were analyzed.

RESULTS

CF-PWV was highest in the maintenance hemodialysis patients, but similar between KTRs and healthy volunteers. Bivariate correlation analysis among KTRs demonstrated that CF-PWV was positively correlated with high level of peripheral diastolic blood pressure, pulse pressure, mean artery pressure, BUN and HDL, but negatively correlated with albumin. Univariate polytomous logistic regression analysis showed that age, BMI, systolic blood pressure, pulse pressure, length of KT and BUN were associated with the increase of CF-PWV value.

CONCLUSIONS

Aortic stiffness could be improved after KT. Meanwhile, age, BMI, systolic blood pressure, pulse pressure, length of KT and BUN were independent predictors of the increase of CF-PWV in KTRs.

Effect of spironolactone for 1 yr on endothelial function and vascular inflammation biomarkers in renal transplant recipients

Kidney transplantation is associated with increased cardiovascular risk. Endothelial dysfunction and vascular inflammation contribute to negative outcome. In experimental models, mineralocorticoid receptor antagonists improved endothelial function and reduced inflammation. The present study tested the hypothesis that the mineralocorticoid receptor antagonist spironolactone improves endothelial function and reduces vascular inflammation in renal transplant patients. Eighty prevalent renal transplant patients from an ongoing, double-blind randomized placebo-controlled trial were included. Paired plasma samples before and after 1 yr of treatment (n = 39 in the spironolactone-treated group and 41 in the placebo-treated group) were used to determine markers of endothelial dysfunction (nitrite, nitrate, cGMP, arginine, citrulline, ornithine, asymmetric dimethylarginine, symmetric dimethylarginine, N^G-monomethyl-l-arginine, von Willebrand factor, tissue-type plasminogen activator antigen, and plasminogen activator inhibitor 1 antigen) and markers of inflammation (intercellular adhesion molecule, vascular adhesion molecule, high-sensitivity C-reactive protein, and serum amyloid protein A). The median time since the transplantation was 4.6 (0.12-22.3) yr in the spironolactone-treated group and 2.1 (0.17-13.9) yr in the placebo-treated group (P > 0.05). Spironolactone increased plasma aldosterone (P < 0.001) and K⁺ (P < 0.001). Blood pressure did not change significantly. No significant differences were detected between groups in any of the measured markers of endothelial dysfunction or inflammation except in the subgroup analysis of patients with diabetes, where spironolactone decreased nitrite compared with placebo. In this study, mineralocorticoid receptor antagonism did not improve biomarkers of endothelial dysfunction or vascular inflammation in prevalent renal transplant patients. Further studies are needed to evaluate the potential beneficial effect of early or late mineralocorticoid receptor antagonism on vascular outcomes in renal transplant patients.

Arterial Stiffness in Patients With Renal Transplantation; Associations With Co-morbid Conditions, Evolution, and Prognostic Importance for Cardiovascular and Renal Outcomes

Patients with chronic kidney disease (CKD), particularly those with end-stage renal disease (ESRD), are at increased risk of cardiovascular events and mortality. The spectrum of arterial remodeling in CKD and ESRD includes atheromatosis of middle-sized conduit arteries and, most importantly, the process of arteriosclerosis, characterized by increased arterial stiffness of aorta and the large arteries. Longitudinal studies showed that arterial stiffness and abnormal wave reflections are independent cardiovascular risk factors in several populations, including patients with CKD and ESRD. Kidney transplantation is the treatment of choice for patients with ESRD, associated with improved survival and better quality of life in relation to hemodialysis or peritoneal dialysis. However, cardiovascular mortality in transplanted patients remains much higher than that in general population, a finding that is at least partly attributed to adverse lesions in the vascular tree of these patients, generated during the progression of CKD, which do not fully reverse after renal transplantation. This article attempts to provide an overview of the field of arterial stiffness in renal transplantation, discussing in detail available studies on the degree and the associations of arterial stiffness with other co-morbidities in renal transplant recipients, the prognostic significance of arterial stiffness for cardiovascular events, renal events and mortality in these individuals, as well as studies examining the changes in arterial stiffness following renal transplantation.

A Systematic Review and Meta-analysis of Nonpharmacologic-based Interventions for Aortic Stiffness in End-Stage Renal Disease

Introduction

Increased carotid-femoral pulse wave velocity (cf-PWV) in end-stage renal disease (ESRD) indicates enhanced aortic stiffness and mortality risk. We conducted a systematic review and meta-analysis of nonpharmacologic interventions in adults with ESRD to determine their effects on cf-PWV, systolic blood pressure (SBP), and intervention-associated adverse events.

Methods

MEDLINE, EMBASE, and EBM databases were searched. Study screening, selection, data collection, and methodological quality assessments were performed by 2 independent reviewers. Pooled-effect estimates from mean differences and 95% confidence intervals (CIs) were calculated using random effect models.

Results

A total of 2166 subjects with ESRD from 33 studies (17 randomized; 16 nonrandomized) were included. Four intervention-comparator pairs were meta-analyzed. Quality of evidence ranged from very low to moderate. Kidney transplantation decreased cf-PWV (−0.70 m/s; CI: –1.3 to −0.11; P = 0.02) and SBP (−8.3 mm Hg; CI: −13.2 to −3.3; P < 0.001) over pretransplantation. In randomized trials, control of fluid overload by bio-impedance reduced cf-PWV (−1.90 m/s; CI: −3.3 to −0.5); P = 0.02) and SBP (−4.3 mm Hg; CI: −7.7 to −0.93); P = 0.01) compared with clinical assessment alone. Cross-sectional studies also demonstrated significantly lower cf-PWV and SBP in normovolemia compared with hypervolemia (P ≤ 0.01). Low calcium dialysate decreased cf-PWV (−1.70 m/s; CI: −2.4 to −1.0; P < 0.00001) without affecting SBP (−1.6 mm Hg; CI: −8.9 to 5.8; P = 0.61). Intradialytic exercise compared with no exercise reduced cf-PWV (−1.13 m/s; CI: −2.2 to −0.03; P = 0.04), but not SBP (+0.5 mm Hg; CI: −9.5 to 10.4); P = 0.93).

Conclusions

Several nonpharmacologic interventions effectively decrease aortic stiffness in ESRD. The impact of these interventions on cardiovascular outcomes and mortality risk reduction in ESRD requires further study.

A Pilot Trial to Examine the Changes in Carotid Arterial Inflammation in Renal Transplant Recipients as Assessed by 18F-Fluorodeoxyglucose (18F-FDG) Positron Emission Tomography Computed Tomography (PET/CT)

BACKGROUND Inflammatory activity of the artery can be assessed by measuring 18F-fluorodeoxyglucose (18F-FDG) uptake with positron emission tomography computed tomography (PET/CT). Improvement in vascular function after renal transplantation has been reported, but no studies have used 18F-FDG PET/CT to examine the changes in vascular inflammation. This study investigated the changes in the inflammatory activity in the carotid artery after renal transplantation in patients with chronic kidney disease (CKD). MATERIAL AND METHODS 18F-FDG PET/CT was performed before and at 4 months after transplantation. We quantified 18F-FDG uptake as the target-to-background ratio (TBR) in the carotid artery in 10 CKD patients. TBR was evaluated in the whole carotid artery (WH) and most-diseased segment (MDS), and the mean and maximum values were analyzed. The concentrations of inflammatory cytokines, including tumor necrosis factor-alpha, interleukin-6, plasminogen activator inhibitor-1, and endothelin-1, were measured. RESULTS Eight patients showed a decrease in mean or maximum TBR. The average mean or maximum TBRs in the WH and MDS of the right and left arteries were all reduced after transplantation. The average mean TBR for the right WH decreased significantly (% reduction [95% CI]) by -5.74% [-15.37, -0.02] (p=0.047). TBRs did not correlate significantly with cytokine concentrations. The changes in cytokine concentrations after transplantation varied. CONCLUSIONS 18F-FDG uptake by the WH and MDS tended to reduce after renal transplantation. Therefore, renal transplantation may confer an anti-inflammatory effect on carotid atherosclerosis in patients with CKD; however, this effect is not large enough to be demonstrated in this study with small sample size.

Reduction of Arterial Stiffness After Kidney Transplantation: A Systematic Review and Meta-Analysis

Background

End‐stage kidney disease is associated with increased arterial stiffness. Although correction of uremia by kidney transplantation (KTx) could improve arterial stiffness, results from clinical studies are unclear partly due to small sample sizes.

Method and Results

We conducted a systematic review and meta‐analysis of before‐after design studies performed in adult KTx patients with available measures of arterial stiffness parameters (pulse wave velocity [PWV], central pulse pressure [PP], and augmentation index) before and at any time post‐KTx. Mean difference of post‐ and pre‐KTx values of different outcomes were estimated using a random effect model with 95% confidence interval. To deal with repetition of measurement within a study, only 1 period of measurement was considered per study by analysis. Twelve studies were included in meta‐analysis, where a significant decrease of overall PWV by 1.20 m/s (95% CI 0.67‐1.73, I²=72%), central PWV by 1.20 m/s (95% CI 0.16‐2.25, I²=83%), peripheral PWV by 1.17 m/s (95% CI 0.17‐2.17, I²=79%), and brachial‐ankle PWV by 1.21 m/s (95% CI 0.66‐1.75, I²=0%) was observed. Central PP (reported in 4 studies) decreased by 4.75 mm Hg (95% CI 0.78–10.28, I²=50%). Augmentation index (reported in 7 studies) decreased by 10.5% (95% CI 6.9‐14.1, I²=64%). A meta‐regression analysis showed that the timing of assessment post‐KTx was the major source of the residual variance.

Conclusions

This meta‐analysis suggests a reduction of the overall arterial stiffness in patients with end‐stage kidney disease after KTx.

Impact of immunosuppressive therapy on arterial stiffness in kidney transplantation: are all treatments the same?

Arterial stiffness is a biologic process related to ageing and its relationship with cardiovascular risk is well established. Several methods are currently available for non-invasive measurement of arterial stiffness that provide valuable information to further assess patients’ vascular status in real time. In kidney transplantation recipients, several factors could accelerate the stiffness process, such as the use of calcineurin inhibitors (CNIs), the presence of chronic kidney disease and other classical cardiovascular factors, which would explain, at least in part, the high cardiovascular mortality and morbidity. Despite the importance of arterial stiffness as a biomarker of cardiovascular risk, and unlike other cardiovascular risk factors (e.g. left ventricular hypertrophy), only a few clinical trials or retrospective studies of kidney recipients have evaluated its impact. In this review we describe the clinical impact of arterial stiffness as a prognostic marker of cardiovascular disease and the effects of different immunosuppressive regimens on its progression, focusing on the potential benefits of CNI-sparing protocols and supporting the rationale for individualization of immunosuppression in patients with lower arterial elasticity. Among the immunosuppressive drugs, a belatacept-based regimen seems to offer better vascular protection compared with CNIs, although further studies are needed to confirm the preliminary positive results.

Association of interleukin-6 with aortic stiffness in end-stage renal disease

Cardiovascular disease (CVD) is the leading cause of mortality in patients with chronic kidney disease (CKD). Aortic stiffness, a nontraditional risk factor, is associated with high rate of mortality in CKD. Using a CKD animal model with medial vascular calcification, we previously reported increased mRNA expression of interleukin-6 (IL-6), tumor necrosis factor (TNF), and interleukin-1β (IL-1β) in calcified aorta. The aim of the study was to investigate the association between IL-6, TNF, IL-1β, and aortic stiffness in end-stage renal disease patients. In a cross-sectional study, we enrolled 351 patients on dialysis. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (cf-PWV), while central pulse pressure and augmentation index were assessed using generalized transfer function applied to the radial artery pressure wave form. Plasma IL-6, TNF, and IL-1β were measured by enzyme-linked immunosorbent assay. IL-6 was associated with cf-PWV adjusted for mean blood pressure (MBP) (standardized β = 0.270; P < .001). In a multivariate adjusted model for age, diabetes, hypertension, CVD, and MBP, IL-6 was still associated with cf-PWV (standardized β = 0.096; P = .026). The impact of age, diabetes, and CVD on cf-PWV was partially mediated by IL-6 in a mediation analysis. However, there were no associations between TNF, IL-1β, and aortic stiffness. While IL-6 was associated with augmentation index (standardized β = 0.224; P < .001) and central pulse pressure (standardized β = 0.162; P = .001) when adjusted for MBP and heart rate, this relationship was not significant after adjusting for potential confounders.This study suggests a potential role of IL-6 for CKD-related aortic stiffness.

Levels of Angiopoietin-Like-2 Are Positively Associated With Aortic Stiffness and Mortality After Kidney Transplantation

BACKGROUND

Angiopoietin-like-2 (ANGPTL2) is a secreted proinflammatory glycoprotein that promotes endothelial dysfunction, atherosclerosis, and cardiovascular disease (CVD). Circulating ANGPTL2 is increased in chronic kidney disease (CKD), where the risk of CVD is amplified. The objectives of the present study were to (i) examine whether kidney transplantation (KTx) reduces ANGPTL2 levels, (ii) identify the determinants of ANGPTL2 after KTx, (iii) study the association of ANGPTL2 with aortic stiffness, and (iv) assess the impact of ANGPTL2 on mortality after KTx.

METHODS

In 75 patients, serum ANGPTL2 levels were measured at baseline and 3 months after KTx. Aortic stiffness was determined by carotid-femoral pulse wave velocity, glomerular filtration rate was estimated by CKD-EPI formula, and serum cytokines and endothlin-1 levels were determined 3 months after KTx. Survival analysis was performed using Kaplan-Meier and Cox regression after a median follow-up of 90 months.

RESULTS

After 3 months of KTx, ANGPTL2 levels decreased from 71 ng/ml (53-95) to 11 ng/ml (9-15) (P < 0.001). In multivariate analysis, age, lower renal function, and endothelin-1 were independently associated with higher post-KTx ANGPTL2 levels. ANGPTL2 was positively associated with aortic stiffness after KTx, even when adjusted for mean blood pressure (standardized β = 0.314; P = 0.008). During follow-up, 13 deaths occurred. The group of patients with higher post-KTx ANGPTL2 levels had a hazard ratio for mortality of 3.9 (95% confidence interval: 1.07-14.4; P = 0.039).

CONCLUSION

KTx significantly reduced serum ANGPTL2 levels. The positive association between post-KTx ANGPTL2, aortic stiffness and mortality, suggests that ANGPTL2 may play a biological role in CKD-related CVD.

Hypertension and arterial stiffness in heart transplantation patients

OBJECTIVES

Post-transplantation hypertension is prevalent and is associated with increased cardiovascular morbidity and subsequent graft dysfunction. The present study aimed to identify the factors associated with arterial stiffness as measured by the ambulatory arterial stiffness index.

METHODS

The current study used a prospective, observational, analytical design to evaluate a group of adult heart transplantation patients. Arterial stiffness was obtained by monitoring ambulatory blood pressure and using the ambulatory arterial stiffness index as the surrogate outcome. Multivariate logistic regression analyses were performed to control confounding.

RESULTS

In a group of 85 adult heart transplantation patients, hypertension was independently associated with arterial stiffness (OR 4.98, CI 95% 1.06-23.4) as well as systolic and diastolic blood pressure averages and nighttime descent.

CONCLUSIONS

Measurement of ambulatory arterial stiffness index is a new, non-invasive method that is easy to perform, may contribute to better defining arterial stiffness prognosis and is associated with hypertension.

Assessment of Arterial Stiffness, Volume, and Nutritional Status in Stable Renal Transplant Recipients

Reduction of cardiovascular death might have a significant effect on the long-term survival rates of renal transplant recipients (RTRs). The aim of the study was to assess the relation between arterial stiffness and graft function, adipose tissue content, and hydration status in patients after kidney transplantation (KTx).The study included 83 RTR patients (mean age: 55 ± 13 years) who had been admitted to a nephrology-transplantation outpatient clinic 0.5 to 24 years after KTx. Clinical and laboratory data were analyzed and eGFR was calculated with the CKD-EPI formula. Arterial stiffness was assessed in all RTRs with pulse wave propagation velocity (PWV) with the use of a complior device. In addition, fluid and nutritional status was assessed with a Tanita BC 418 body composition analyzer. The control group consisted of 31 hospital workers who received no medication and had no history of cardiovascular disease.Multivariable linear regression analysis, with PWV as a dependent variable, retained the following independent predictors in the final regression model: red blood cell distribution width (RDW) (B = 0.323; P = 0.004), age (B = 0.297; P = 0.005), tacrolimus therapy (B = -0.286; P = 0.004), and central DBP (B = 0.185; P = 0.041). Multivariable linear regression analysis with eGFR as a dependent variable retained the following independent predictors in the final regression model; creatinine concentration (B = -0.632; P = 0.000), hemoglobin (B = 0.280; P = 0.000), CRP (B = -0.172; P = 0.011), tacrolimus therapy (B = 0.142; P = 0.039), and triglycerides (B = -0.142; P = 0.035).Our data indicates that: kidney transplant recipients can present modifiable CVD risk factors linked to increased arterial stiffness, DBP, waist circumference, SCr, time on dialysis, CyA therapy, and visceral fat mass; RDW is a parameter associated with arterial stiffness; and parameters such as CyA therapy, time on dialysis, PWV, RDW, and triglycerides show negative associations with the allograft function assessed with eGFR.

Assessment of arterial stiffness using pulse wave velocity in tacrolimus users the first year post kidney transplantation: a prospective cohort study

BACKGROUND

The leading cause of death in end stage renal disease is cardiovascular disease (CVD). Kidney transplantation is associated with improved survival over dialysis. We hypothesized that arterial stiffness, a marker of CVD, would improve in patients post kidney transplant, potentially explaining one mechanism of survival benefit from transplant.

METHODS

After obtaining Institutional Review Board approval and informed consent, we performed a longitudinal prospective cohort study of 66 newly transplanted adult kidney transplant recipients, using aortic pulse wave velocity (PWV) to assess arterial stiffness over a 12 month period. All patients were assessed within one month of transplant (baseline) and 12 months post transplant. The primary outcome was change in PWV score at 12 months which we assessed using Wilcoxon Signed Rank test. Secondary analyses included correlation of predictors with PWV score at both time points.

RESULTS

The median age of the cohort was 49.7 years at transplant, with 27 % Black and 27 % female. At baseline, 43 % had tobacco use, 30 % had a history of CVD, and 42 % had diabetes. Median baseline calcium was 9.1 mg/dL and median phosphorus was 5.1 mg/dL. Median PWV score was 9.25 and 8.97 m/s at baseline versus month 12, respectively, showing no significant change (median change of -0.07, p = 0.7). In multivariable regression, subjects with increased age at transplant (p = 0.008), diabetes (p = 0.002), and a higher baseline PWV score (p < 0.001) were at increased risk of having a high PWV score 12 months post transplant.

CONCLUSION

Aortic arterial stiffness does not progress in the first year post kidney transplant. Increasing age, diabetes, and higher baseline PWV score identify patients at risk for increased arterial stiffness. Further research that assesses patients for greater than one year and includes a control dialysis group would be helpful in further understanding the change in arterial stiffness post transplantation.

Active vitamin D and accelerated progression of aortic stiffness in hemodialysis patients: a longitudinal observational study

BACKGROUND

We hypothesized that high-dose active vitamin D therapy in the form of alphacalcidol (α-calcidol), used to treat secondary hyperparathyroidism in chronic kidney disease, could lead to vascular calcification and accelerated progression of aortic stiffness.

METHODS

We conducted an observational study in 85 patients on chronic hemodialysis, among which 70 were taking a weekly dose of α-calcidol of <2 µg and 15 were taking a weekly dose of ≥2 µg (pharmacological dose). Parathyroid hormone, 25-hydroxyvitamin D, fibroblast growth factor 23, and α-klotho were determined. Aortic stiffness was assessed by determination of carotid-femoral pulse wave velocity (cf-PWV) at baseline and after a mean follow-up of 1.2 years. A multivariable regression model was used to evaluate the impact of pharmacological dose of α-calcidol on the progression of aortic stiffness.

RESULTS

At baseline, clinical, biological, and hemodynamic parameters were similar. At follow-up, cf-PWV increased more in patients with pharmacological dose of α-calcidol (0.583±2.291 m/s vs. 1.948±1.475 m/s; P = 0.04). After adjustment for changes in mean blood pressure and duration of follow-up, pharmacological dose of α-calcidol was associated with a higher rate of progression of cf-PWV (0.969 m/s; 95% confidence interval = 0.111-1.827; P = 0.03), and this association persisted after further adjustments for parameters of mineral metabolism.

CONCLUSIONS

In this study, pharmacological dose of α-calcidol was associated with accelerated progression of aortic stiffness. This study suggest that the vascular safety of active vitamin D posology may need to be specifically addressed in the treatment of chronic kidney disease-related bone mineral disorder.

Aortic calcifications and arterial stiffness as predictors of cardiovascular events in incident renal transplant recipients

Renal transplant recipients have an increased risk of cardiovascular (CV) disease. Arterial stiffness (AS) and aortic calcifications (ACs) are well-known CV risk factors in patients with chronic kidney disease. We aimed to determine the prognostic value of AS and AC in incident renal transplant recipients (RTRs). We conducted a prospective study in 253 single RTR. AC were scored by means of lumbar X-ray. Carotid-femoral pulse wave velocity (PWV) was assessed in a subgroup of 115 patients. AC were present in 61% of patients. After a mean follow-up of 36 months, 32 CV events occurred in the overall group and 13 events in the PWV subgroup. When we accounted for age, gender, and CV history, AC score (HR, hazard ratio 1.09 per 1 unit increase; 95% CI 1.02-1.17) and PWV (HR 1.45 per 1 m/s; 95% CI 1.16-1.8) remained an independent predictor of CV events in Cox-regression analyses. Using receiver operating characteristics, the area under the curve for predicting CV events amounted to 0.80 and 0.72 for sum AC and PWV, respectively. Both AS and AC are strong predictors of future CV events in an incident RTR population. These vascular assessments are readily available and easy to perform, making them ideal tools for further risk stratification. (ClinicalTrials.gov number: NCT00547040).

Renal transplantation normalizes baroreflex sensitivity through improvement in central arterial stiffness

BACKGROUND

In end-stage renal disease (ESRD) patients, the most common cause of mortality and morbidity are cardiovascular events. This could be attributed to the impaired baroreflex function observed in this group of patients. The effect of renal transplantation (RT) on the baroreflex sensitivity (BRS) in ESRD patients has been inadequately addressed. Therefore, we investigated baroreflex function and its relation to arterial stiffness indices and cardiovascular variability parameters (heart rate and blood pressure variability--HRV and BPV) in ESRD patients before and after transplantation to decipher the underlying mechanism of attenuated BRS in ESRD patients.

METHODS

We studied 23 ESRD patients (mean age; 36 years) prospectively before and at 3 and 6 months after RT. Baroreflex function was determined by spontaneous method (sequence and spectral indices). Short-term HRV and BPV were assessed using power spectrum analysis of RR intervals and systolic blood pressure by frequency domain analysis. Arterial stiffness indices were assessed by carotid-femoral pulse-wave velocity (PWV), augmentation index (AI) and central pulse pressure using Sphygmocor Vx device (AtCor Medical, Australia).

RESULTS

RT was associated with the normalization of BRS by 6 months. Arterial stiffness indices, such as AI and central pulse pressure, showed a significant reduction as early as 3 months after RT. PWV and frequency domain measures of HRV after RT did not show statistically significant changes except the LF/HF ratio which had a significant increase at 6 months when compared with baseline. Systolic BPV total power showed a significant reduction by 3 months after RT.

CONCLUSIONS

Our data suggest that RT normalizes BRS in ESRD patients by 6 months which follows the improvement in the AI and central pulse pressure.

Determinants of progression of aortic stiffness in hemodialysis patients: a prospective longitudinal study

Aortic stiffness is associated with increased cardiovascular mortality in patients with chronic kidney disease. However, the rate of progression of arterial stiffness and the role of cardiovascular risk factors in the progression of arterial stiffness has never been established in a longitudinal study. In a prospective, longitudinal, observational study, carotid-femoral pulse wave velocity and carotid-radial pulse wave velocity were assessed in 109 hemodialysis patients at baseline and after a mean follow-up of 1.2 years. We examined the impact of age, atherosclerotic cardiovascular disease, diabetes mellitus, dialysis vintage, and pentosidine (a well-characterized, advanced glycation end products) on the rate of progression of aortic stiffness. The annual rate of changes in carotid-femoral pulse wave velocity and carotid-radial pulse wave velocity were 0.84 m/s per year (95% confidence interval, 0.50-1.12 m/s per year) and -0.66 m/s per year (95% confidence interval, -0.85 to -0.47 m/s per year), respectively. Older subjects, and patients with diabetes mellitus or atherosclerotic cardiovascular disease had higher aortic stiffness at baseline, however, the rate of progression of aortic stiffness was only determined by plasma pentosidine levels (P=0.001). The degree of baseline aortic stiffness was a significant determinant of the regression of brachial stiffness (P<0.001) suggesting that the regression of brachial stiffness occurs in response to central aortic stiffness. These findings suggest that traditional cardiovascular risk factors may play some role in the progression of aortic stiffness before development of advanced chronic kidney disease, and that the enhanced rate of progression of aortic stiffness in chronic kidney disease patients on dialysis are probably determined by more specific chronic kidney disease-related risk factors such as advanced-glycation end products.

Reduction in augmentation index after successful renal transplantation

BACKGROUND

Patients of end stage renal disease (ESRD) have an increased risk of cardiovascular events. Arterial stiffness is an established independent predictor of cardiovascular morbidity and mortality in ESRD patients. Carotid femoral pulse wave velocity (c-f PWV) and augmentation index (AI) are the indices which are used for the noninvasive assessment of arterial stiffness. Renal transplantation (RT) as a treatment modality in ESRD patients is associated with improvement in cardiovascular survival. Whether this improvement is due to attenuation of arterial stiffness has been inadequately investigated. The present study was conducted in ESRD patients before and 3 months after RT to assess the reversibility of the abnormalities of vascular compliance that are known to be associated with adverse outcome.

METHODS

Arterial stiffness indices (c-f PWV and AI) were measured using the principle of applanation tonometry with a SphygmoCor CvMS system (Atcor Medicals, Australia) in 23 ESRD patients (age: 35.9 ± 9.3 years) before and 3 months after successful RT.

RESULTS

After transplantation, augmentation index values reduced significantly as compared to their pre-transplant values (27.7 ± 11.3 % vs. 17.1 ± 9.0 %; P < 0.0001), while the carotid femoral pulse wave velocity values did not differ significantly (8.7 ± 2.0 vs. 8.6 ± 3.2 m/s). The augmentation index was correlated with the biochemical parameters of serum creatinine (Pearson r = 0.3628; P = 0.0128) and calcium phosphate product (Pearson r = 0.3868; P = 0.0079).

CONCLUSIONS

Restoration of renal function following successful RT is associated with differential effects on the two indices of arterial stiffness. The salient finding of our study is that 3 months after transplantation, functional changes in vasculature lead to a significant reduction in the augmentation index, while the pulse wave velocity may take longer to show an improvement.

Immunosuppressant regimen based on sirolimus decreases aortic stiffness in renal transplant recipients in comparison to cyclosporine

Whether or not a cyclosporine A (CsA)-free immunosuppressant regimen based on sirolimus (SRL) prevents aortic stiffening and improves central hemodynamics in renal recipients remains unknown. Forty-four patients (48 ± 2 years) enrolled in the CONCEPT trial were randomized at week 12 (W12) to continue CsA or switch to SRL, both associated with mycophenolate mofetil. Carotid systolic blood pressure (cSBP), pulse pressure (cPP), central pressure wave reflection (augmentation index, AIx) and carotid-to-femoral pulse-wave velocity (PWV: aortic stiffness) were blindly assessed at W12, W26 and W52 together with plasma endothelin-1 (ET-1), thiobarbituric acid-reactive substances (TBARS) and superoxide dismutase (SOD) and catalase erythrocyte activities. At W12, there was no difference between groups. At follow-up, PWV, cSBP, cPP and AIx were lower in the SRL group. The difference in PWV remained significant after adjustment for blood pressure and eGFR. In parallel, ET-1 decreased in the SRL group, while TBARS, SOD and catalase erythrocyte activities increased in both groups but to a lesser extent in the SRL group. Our results demonstrate that a CsA-free regimen based on SRL reduces aortic stiffness, plasma endothelin-1 and oxidative stress in renal recipients suggesting a protective effect on the arterial wall that may be translated into cardiovascular risk reduction.

Aortic stiffness is associated with vascular calcification and remodeling in a chronic kidney disease rat model

Increased aortic pulse-wave velocity (PWV) reflects increased arterial stiffness and is a strong predictor of cardiovascular risk in chronic kidney disease (CKD). We examined functional and structural correlations among PWV, aortic calcification, and vascular remodeling in a rodent model of CKD, the Lewis polycystic kidney (LPK) rat. Hemodynamic parameters and beat-to-beat aortic PWV were recorded in urethane-anesthetized animals [12-wk-old hypertensive female LPK rats ( n = 5)] before the onset of end-stage renal disease and their age- and sex-matched normotensive controls (Lewis, n = 6). Animals were euthanized, and the aorta was collected to measure calcium content by atomic absorption spectrophotometry. A separate cohort of animals ( n = 5/group) were anesthetized with pentobarbitone sodium and pressure perfused with formalin, and the aorta was collected for histomorphometry, which allowed calculation of aortic wall thickness, medial cross-sectional area (MCSA), elastic modulus (EM), and wall stress (WS), size and density of smooth muscle nuclei, and relative content of lamellae, interlamellae elastin, and collagen. Mean arterial pressure (MAP) and PWV were significantly greater in the LPK compared with Lewis (72 and 33%, respectively) animals. The LPK group had 6.8-fold greater aortic calcification, 38% greater aortic MCSA, 56% greater EM/WS, 13% greater aortic wall thickness, 21% smaller smooth muscle cell area, and 20% less elastin density with no difference in collagen fiber density. These findings demonstrate vascular remodeling and increased calcification with a functional increase in PWV and therefore aortic stiffness in hypertensive LPK rats.