Individual versus integration of multiple components of central blood pressure and aortic stiffness in predicting cardiovascular mortality in end-stage renal diseases

Aortic stiffness, measured by carotid-femoral pulse wave velocity (PWV), is a predictor of cardiovascular (CV) mortality in patients with end-stage renal disease (ESRD). Aortic stiffness increases aortic systolic and pulse pressures (cSBP, cPP) and augmentation index adjusted for a heart rate of 75 beats per minute (AIx@75). In this study, we examined if the integration of multiple components of central blood pressure and aortic stiffness (ICPS) into risk score categories could improve CV mortality prediction in ESRD. In a prospective cohort of 311 patients with ESRD on dialysis who underwent vascular assessment at baseline, 118 CV deaths occurred after a median follow-up of 3.1 years. The relationship between hemodynamic parameters and CV mortality was analyzed through Kaplan-Meier and Cox survival analysis. ICPS risk score from 0 to 5 points were calculated from points given to tertiles, and were regrouped into three risk categories (Average, High, Very-High). A strong association was found between the ICPS risk categories and CV mortality (High risk HR = 2.20, 95% CI: 1.05-4.62, P = 0.036); Very-High risk (HR = 4.44, 95% CI: 2.21-8.92, P < 0.001) as compared to the Average risk group. The Very-High risk category remained associated with CV mortality (HR = 3.55, 95% CI: 1.37-9.21, P = 0.009) after adjustment for traditional CV risk factors as compared to the Average risk group. While higher C-statistics value of ICPS categories (C: 0.627, 95% CI: 0.578-0.676, P = 0.001) was not statistically superior to PWV, cPP or AIx@75, the use of ICPS categories resulted in a continuous net reclassification index of 0.56 (95% CI: 0.07-0.99). In conclusion, integration of multiple components of central blood pressure and aortic stiffness may potentially be useful for better prediction of CV mortality in this cohort.

Subclinical Primary Aldosteronism and Cardiovascular Health: A Population-Based Cohort Study

BACKGROUND

Primary aldosteronism, characterized by overt renin-independent aldosterone production, is a common but underrecognized form of hypertension and cardiovascular disease. Growing evidence suggests that milder and subclinical forms of primary aldosteronism are highly prevalent, yet their contribution to cardiovascular disease is not well characterized.

METHODS

This prospective study included 1284 participants between the ages of 40 and 69 years from the randomly sampled population-based CARTaGENE cohort (Québec, Canada). Regression models were used to analyze associations of aldosterone, renin, and the aldosterone-to-renin ratio with the following measures of cardiovascular health: arterial stiffness, assessed by central blood pressure (BP) and pulse wave velocity; adverse cardiac remodeling, captured by cardiac magnetic resonance imaging, including indexed maximum left atrial volume, left ventricular mass index, left ventricular remodeling index, and left ventricular hypertrophy; and incident hypertension.

RESULTS

The mean (SD) age of participants was 54 (8) years and 51% were men. The mean (SD) systolic and diastolic BP were 123 (15) and 72 (10) mm Hg, respectively. At baseline, 736 participants (57%) had normal BP and 548 (43%) had hypertension. Higher aldosterone-to-renin ratio, indicative of renin-independent aldosteronism (ie, subclinical primary aldosteronism), was associated with increased arterial stiffness, including increased central BP and pulse wave velocity, along with adverse cardiac remodeling, including increased indexed maximum left atrial volume, left ventricular mass index, and left ventricular remodeling index (all P<0.05). Higher aldosterone-to-renin ratio was also associated with higher odds of left ventricular hypertrophy (odds ratio, 1.32 [95% CI, 1.002-1.73]) and higher odds of developing incident hypertension (odds ratio, 1.29 [95% CI, 1.03-1.62]). All the associations were consistent when assessing participants with normal BP in isolation and were independent of brachial BP.

CONCLUSIONS

Independent of brachial BP, a biochemical phenotype of subclinical primary aldosteronism is negatively associated with cardiovascular health, including greater arterial stiffness, adverse cardiac remodeling, and incident hypertension.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

Impact of Successive Office Blood Pressure Measurements During a Single Visit on Cardiovascular Risk Prediction: Analysis of CARTaGENE

BACKGROUND

Multiple office blood pressure (BP) readings correlate more closely with ambulatory BP than single readings. Whether they are associated with long-term outcomes and improve cardiovascular risk prediction is unknown. Our objective was to assess the long-term impact of multiple office BP readings.

METHODS

We used data from CARTaGENE, a population-based survey comprising individuals aged 40 to 70 years. Three BP readings (BP1, BP2, and BP3) at 2-minute intervals were obtained using a semiautomated device. They were averaged to generate BP1-2, BP2-3, and BP1-2-3 for systolic BP (SBP) and diastolic BP. Cardiovascular events (major adverse cardiovascular event [MACE]: cardiovascular death, stroke, and myocardial infarction) during a 10-year follow-up were recorded. Associations with MACE were obtained using adjusted Cox models. Predictive performance was assessed with 10-year atherosclerotic cardiovascular disease scores and their associated C statistics.

RESULTS

In the 17 966 eligible individuals, 2378 experienced a MACE during follow-up. Crude SBP values ranged from 122.5 to 126.5 mm Hg. SBP3 had the strongest association with MACE incidence (hazard ratio, 1.10 [1.05-1.15] per SD) and SBP1 the weakest (hazard ratio, 1.06 [1.01-1.10]). All models including SBP1 (SBP1, SBP1-2, and SBP1-2-3) were underperformed. At a given SBP value, the excess MACE risk conferred by SBP3 was 2× greater than SBP1. In atherosclerotic cardiovascular disease scores, SBP3 yielded the highest C statistic, significantly higher than most other SBP measures. In contrast to SBP, all diastolic BP readings yielded similar results.

CONCLUSIONS

Cardiovascular risk prediction is improved by successive office SBP values, especially when the first reading is discarded. These findings reinforce the necessity of using multiple office BP readings.

Antihypertensive treatment with hydrochlorothiazide-hydralazine combination aggravates medial vascular calcification in CKD rats with mineral bone disorder

Background

Arterial stiffness and medial vascular calcification, leading to isolated systolic blood pressure (BP), are major cardiovascular risk factors in patients with chronic kidney disease (CKD) and mineral bone disorders (MBD). The impact of BP on MBD-induced medial vascular calcification in CKD remains uncertain. We investigated whether BP reduction improves arterial stiffness and medial vascular calcification in a rat model of CKD-MBD.

Methods

CKD was induced in Wistar rats by subtotal nephrectomy. Then, MBD was generated by a Ca/P-rich diet with calcitriol supplementation to induce medial vascular calcification. Two antihypertensive treatments were evaluated: (1) the angiotensin AT1 receptor antagonist losartan, and (2) the combination of the thiazide diuretic hydrochlorothiazide and the direct vasodilator hydralazine (HCTZ/HY). After 5 weeks, mean BP (MBP), pulse pressure (PP), and pulse wave velocity (PWV) were determined. Vascular calcification was assessed in the thoracic aorta.

Results

While MBP was similar in CKD-MBD and control CKD rats, PP and PWV were increased in CKD-MBD rats. The heightened arterial stiffness in CKD-MBD rats was associated with diffused medial calcification along the thoracic aorta. Although both losartan and HCTZ/HY reduced MBP in CKD-MBD rats, losartan did not affect PP and PWV nor medial vascular calcification, whereas HCTZ/HY, unexpectedly, further increased arterial stiffness and medial vascular calcification.

Conclusion

In the rat model of CKD-MBD, antihypertensive treatment with losartan did not affect arterial stiffness or medial vascular calcification. However, HCTZ/HY treatment aggravated arterial stiffness and vascular calcification despite a similar reduction of MBP, suggesting a blood pressure-independent mechanism for vascular calcification.

Pembrolizumab-Induced Anti-GBM Glomerulonephritis: A Case Report

Immune checkpoint inhibitors are known to have a wide range of autoimmune toxicities, such as acute interstitial nephritis. Immunotherapy induced glomerulonephritis has been described, but anti-glomerular basement membrane disease (anti-GBM) is rarely reported. We present a case report of a 60-year-old woman with squamous cell carcinoma of the cervix who was treated with pembrolizumab, an anti-programmed cell death protein 1, and who developed severe acute kidney injury 4 months after therapy initiation. The immune workup showed a positive serum anti-GBM antibody (24 U/mL). The kidney biopsy showed crescentic glomerulonephritis with linear immunoglobulin G2 glomerular basement membrane staining, compatible with anti-GBM glomerulonephritis. The patient was treated with plasmapheresis, IV steroids, and cyclophosphamide, but she developed kidney failure, necessitating dialysis. Few case reports, such as the present case, provide a possible link between anti-GBM glomerulonephritis and immune checkpoint inhibitors, warranting early clinical suspicion and investigation in patients who are treated with these agents and subsequently develop acute kidney injury.

Screening for Primary Aldosteronism Among Hypertensive Adults with Obstructive Sleep Apnea: A Retrospective Population-Based Study

BACKGROUND

Hypertension plus obstructive sleep apnea (OSA) is recommended in some guidelines as an indication to screen for primary aldosteronism (PA), yet prior data has brought the validity of this recommendation into question. Given this context, it remains unknown whether this screening recommendation is being implemented into clinical practice.

METHODS

We conducted a population-based retrospective cohort study of all adult Ontario (Canada) residents with hypertension plus OSA from 2009 to 2020 with follow-up through 2021 utilizing provincial health administrative data. We measured the proportion of individuals who underwent PA screening via the aldosterone-to-renin ratio by year. We further examined screening rates among patients with hypertension plus OSA by the presence of concurrent hypokalemia and resistant hypertension. Clinical predictors associated with screening were assessed via Cox regression modeling.

RESULTS

The study cohort included 53,130 adults with both hypertension and OSA, of which only 634 (1.2%) underwent PA screening. Among patients with hypertension, OSA, and hypokalemia, the proportion of eligible patients screened increased to 2.8%. Among patients ≥65 years with hypertension, OSA, and prescription of ≥4 antihypertensive medications, the proportion of eligible patients screened was 1.8%. Older age was associated with a decreased likelihood of screening while hypokalemia and subspecialty care with internal medicine, cardiology, endocrinology, or nephrology were associated with an increased likelihood of screening. No associations with screening were identified with sex, rural residence, cardiovascular disease, diabetes, or respirology subspecialty care.

CONCLUSIONS

The population-level uptake of the guideline recommendation to screen all patients with hypertension plus OSA for PA is exceedingly low.

CENtral blood pressure Targeting: a pragmatic RAndomized triaL in advanced Chronic Kidney Disease (CENTRAL-CKD): A Clinical Research Protocol

Background

Emerging data favor central blood pressure (BP) over brachial cuff BP to predict cardiovascular and kidney events, as central BP more closely relates to the true aortic BP. Considering that patients with advanced chronic kidney disease (CKD) are at high cardiovascular risk and can have unreliable brachial cuff BP measurements (due to high arterial stiffness), this population could benefit the most from hypertension management using central BP measurements.

Objective

To assess the feasibility and efficacy of targeting central BP as opposed to brachial BP in patients with CKD G4-5.

Design

Pragmatic multicentre double-blinded randomized controlled pilot trial.

Setting

Seven large academic advanced kidney care clinics across Canada.

Patients

A total of 116 adults with CKD G4-5 (estimated glomerular filtration rate [eGFR] < 30 mL/min) and brachial cuff systolic BP between 120 and 160 mm Hg. The key exclusion criteria are 1) ≥ 5 BP drugs, 2) recent acute kidney injury, myocardial infarction, stroke, heart failure or injurious fall, 3) previous kidney replacement therapy.

Methods

Double-blind randomization to a central or a brachial cuff systolic BP target (both < 130 mm Hg) as measured by a validated central BP device. The study duration is 12 months with follow-up visits every 2 to 4 months, based on local practice. All other aspects of CKD management are at the discretion of the attending nephrologist.

Outcomes

Primary Feasibility: Feasibility of a large-scale trial based on predefined components. Primary Efficacy: Carotid-femoral pulse wave velocity at 12 months. Others: Efficacy (eGFR decline, albuminuria, BP drugs, and quality of life); Events (major adverse cardiovascular events, CKD progression, hospitalization, mortality); Safety (low BP events and acute kidney injury).

Limitations

May be challenging to distinguish whether central BP is truly different from brachial BP to the point of significantly influencing treatment decisions. Therapeutic inertia may be a barrier to successfully completing a randomized trial in a population of CKD G4-5. These 2 aspects will be evaluated in the feasibility assessment of the trial.

Conclusion

This is the first trial to evaluate the feasibility and efficacy of using central BP to manage hypertension in advanced CKD, paving the way to a future large-scale trial.

Trial registration

clinicaltrials.gov (NCT05163158).

Cerebral blood flow pulsatility and cerebral artery stiffness acutely decrease during hemodialysis

End-stage kidney disease (ESKD) is associated with increased arterial stiffness and cognitive impairment. Cognitive decline is accelerated in ESKD patients on hemodialysis and may result from repeatedly inappropriate cerebral blood flow (CBF). The aim of this study was to examine the acute effect of hemodialysis on pulsatile components of CBF and their relation to acute changes in arterial stiffness. In eight participants (age: 63 ± 18 years, men: 5), CBF was estimated using middle cerebral artery blood velocity (MCAv) assessed with transcranial Doppler ultrasound before, during, and after a single hemodialysis session. Brachial and central blood pressure, along with estimated aortic stiffness (eAoPWV) were measured using an oscillometric device. Arterial stiffness from heart to MCA was measured as the pulse arrival time (PAT) between electrocardiogram (ECG) and transcranial Doppler ultrasound waveforms (cerebral PAT). During hemodialysis, there was a significant reduction in mean MCAv (-3.2 cm/s, p < 0.001), and systolic MCAv (-13.0 cm/s, p < 0.001). While baseline eAoPWV (9.25 ± 0.80 m/s) did not significantly change during hemodialysis, cerebral PAT increased significantly (+0.027 , p < 0.001) and was associated with reduced pulsatile components of MCAv. This study shows that hemodialysis acutely reduces stiffness of arteries perfusing the brain along with pulsatile components of blood velocity.

Wnt/β-catenin pathway inhibitors, bone metabolism and vascular health in kidney transplant patients

BACKGROUND AND OBJECTIVES

Sclerostin, dickkopf-related protein 1 (DKK1), fibroblast growth factor-23 (FGF23) and α-klotho have been shown to play an important role in bone and vascular disease of chronic kidney disease. We aimed to evaluate the evolution of these bone markers in newly kidney transplanted patients, and whether they are associated with bone metabolism and vascular stiffness.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

This is a longitudinal single-center observational cohort study. Circulating levels of Wnt/β-catenin pathway inhibitors (sclerostin, DKK1, FGF23 and α-klotho), arterial stiffness (carotid-femoral pulse-wave velocity (PWV), carotid-radial PWV, PWV ratio, augmented index) and bone parameters were assessed before (M0), and at 3 (M3) and 6 months (M6) after transplantation. Generalized estimating equations were conducted for comparative analyses between the three time points. We used a marginal structural model for repeated measures for the impact of changes in bone markers on the evolution of arterial stiffness. Multivariate linear regression analyses were performed for the associations between Wnt/β-catenin pathway inhibitors and mineral metabolism parameters.

RESULTS

We included 79 patients (70% male; median age of 53 (44-60) years old). The levels of sclerostin (2.06 ± 1.18 ng/mL at M0 to 0.88 ± 0.29 ng/mL at M6, p ≤ 0.001), DKK1 (364.0 ± 266.7 pg/mL at M0 to 246.7 ± 149.1 pg/mL at M6, p ≤ 0.001), FGF23 (5595 ± 9603 RU/mL at M0 to 137 ± 215 RU/mL at M6, p ≤ 0.001) and α-klotho (457.6 ± 148.6 pg/mL at M0 to 109.8 ± 120.7 pg/mL at M6, p < 0.05) decreased significantly after kidney transplant. Sclerostin and FGF23 were positively associated with carotid-femoral (standardized β = 0.432, p = 0.037 and standardized β = 0.592, p = 0.005) and carotid-radial PWV (standardized β = 0.259, p = 0.029 and standardized β = 0.242, p = 0.006) throughout the 6 months of follow-up. The nature of the associations between bone markers and bone metabolism parameters varies after kidney transplant.

CONCLUSIONS

The circulating levels of Wnt/β-catenin pathway inhibitors and α-klotho significantly decrease after kidney transplantation, while sclerostin and FGF23 levels might be associated with improvement of vascular stiffness and blood pressure.

Enhancing central blood pressure accuracy through statistical modeling: A proof-of-concept study

Background

Non-invasive estimation of central blood pressure (BP) may have better prognostic value than brachial BP. The accuracy of central BP is limited in certain populations, such as in females and the elderly. This study aims to examine whether statistical modeling of central BP for clinical and hemodynamic parameters results in enhanced accuracy.

Methods

This study is a cross-sectional analysis of 500 patients who underwent cardiac catheterization. Non-invasive brachial cuff and central BP were measured simultaneously to invasive aortic systolic BP (AoSBP). Central BP was calibrated for brachial systolic (SBP) and diastolic BP (Type I calibration; C1SBP) or brachial mean and diastolic BP (Type II calibration; C2SBP). Differences between central SBP and the corresponding AoSBP were assessed with linear regression models using clinical and hemodynamic parameters. These parameters were then added to C1SBP and C2SBP in adjusted models to predict AoSBP. Accuracy and precision were computed in the overall population and per age or sex strata.

Results

C1SBP underestimated AoSBP by 11.2 mmHg (±13.5) and C2SBP overestimated it by 6.2 mmHg (±14.8). Estimated SBP amplification and heart rate were the greatest predictors of C1- and C2-AoSBP accuracies, respectively. Statistical modeling improved both accuracy (0.0 mmHg) and precision (±11.4) but more importantly, eliminated the differences of accuracy seen in different sex and age groups.

Conclusion

Statistical modeling greatly enhances the accuracy of central BP measurements and abolishes sex- and age-based differences. Such factors could easily be implemented in central BP devices to improve their accuracy.

Prediction of Cardiovascular Events by Pulse Waveform Parameters: Analysis of CARTaGENE

Background Waveform parameters provide approximate data about aortic wave reflection. However, their association with cardiovascular events remains controversial and their role in cardiovascular prediction is unknown. Methods and Results We analyzed participants aged between 40 and 69 from the population-based CARTaGENE cohort. Baseline pulse wave analysis (central pulse pressure, augmentation index) and wave separation analysis (forward pressure, backward pressure, reflection magnitude) parameters were derived from radial artery tonometry. Associations between each parameter and major adverse atherosclerotic events (MACE; cardiovascular death, stroke, myocardial infarction) were obtained using adjusted Cox models. The incremental predictive value of each parameter compared with the 10-year atherosclerotic cardiovascular disease score alone was assessed using hazard ratios, c-index differences, continuous net reclassification indexes, and integrated discrimination indexes. From 17 561 eligible patients, 2315 patients had a MACE during a median follow-up of 10.1 years. Central pulse pressure, forward pressure, and backward pressure, but not augmentation index and reflection magnitude, were significantly associated with MACE after full adjustment. All parameters except forward pressure statistically improved MACE prediction compared with the atherosclerotic cardiovascular disease score alone. The greatest prediction improvement was seen with augmentation index and reflection magnitude but remained small in magnitude. These 2 parameters enhanced predictive performance more strongly in patients with low baseline atherosclerotic cardiovascular disease scores. Up to 5.7% of individuals were reclassified into a different risk stratum by adding waveform parameters to atherosclerotic cardiovascular disease scores. Conclusions Some waveform parameters are independently associated with MACEs in a population-based cohort. Augmentation index and reflection magnitude slightly improve risk prediction, especially in patients at low cardiovascular risk.

Accuracy Difference of Noninvasive Blood Pressure Measurements by Sex and Height

IMPORTANCE

Women are at higher risk of cardiovascular events than men with similar blood pressure (BP). Whether this discrepancy in risk is associated with the accuracy of brachial cuff BP measurements is unknown.

OBJECTIVES

To examine the difference in brachial cuff BP accuracy in men and women compared with invasively measured aortic BP and to evaluate whether noninvasive central BP estimation varies with sex.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study enrolled 500 participants without severe aortic stenosis or atrial fibrillation from January 1 to December 31, 2019, who were undergoing nonurgent coronary angiography at a tertiary care academic hospital.

EXPOSURES

Simultaneous measurements of invasive aortic BP and noninvasive BP.

MAIN OUTCOMES AND MEASURES

Sex differences in accuracy were determined by calculating the mean difference between the noninvasive measurements (brachial and noninvasive central BP) and the invasive aortic BP (reference). Linear regression and mediation analyses were performed to identify mediators between sex and brachial cuff accuracy.

RESULTS

This study included 500 participants (145 female [29%] and 355 male [71%]; 471 [94%] White; mean [SD] age, 66 [10] years). Baseline characteristics were similar for both sexes apart from body habitus. Despite similar brachial cuff systolic BP (SBP) (mean [SD], 124.5 [17.7] mm Hg in women vs 124.4 [16.4] in men; P = .97), invasive aortic SBP was higher in women (mean [SD], 130.9 [21.7] in women vs 124.7 [20.1] mm Hg in men; P < .001). The brachial cuff was relatively accurate compared with invasive aortic SBP estimation in men (mean [SD] difference, -0.3 [11.7] mm Hg) but not in women (mean [SD] difference, -6.5 [12.1] mm Hg). Noninvasive central SBP (calibrated for mean and diastolic BP) was more accurate in women (mean [SD] difference, 0.6 [15.3] mm Hg) than in men (mean [SD] difference, 8.3 [14.2] mm Hg). This association of sex with accuracy was mostly mediated by height (3.4 mm Hg; 95% CI, 1.1-5.6 mm Hg; 55% mediation).

CONCLUSIONS AND RELEVANCE

In this cross-sectional study, women had higher true aortic SBP than men with similar brachial cuff SBP, an association that was mostly mediated by a shorter stature. This difference in BP measurement may lead to unrecognized undertreatment of women and could partly explain why women are at greater risk for cardiovascular diseases for a given brachial cuff BP than men. These findings may justify the need to study sex-specific BP targets or integration of sex-specific parameters in BP estimation algorithms.

Assessment of Stiffness of Large to Small Arteries in Multistage Renal Disease Model: A Numerical Study

Arterial stiffness (AS), as assessed via pulse wave velocity (PWV), is a major biomarker for cardiovascular risk assessment in patients with chronic kidney disease (CKD). However, the mechanisms responsible for the changes in PWV in the presence of kidney disease are not yet fully elucidated. In the present study, we aimed to investigate the direct effects attributable to biomechanical changes in the arterial tree caused by staged renal removal, independent of any biochemical or compensatory effects. Particularly, we simulated arterial pressure and flow using a previously validated one-dimensional (1-D) model of the cardiovascular system with different kidney configurations: two kidneys (2KDN), one single kidney (1KDN), no kidneys (0KDN), and a transplanted kidney (TX) attached to the external iliac artery. We evaluated the respective variations in blood pressure (BP), as well as AS of large-, medium-, and small-sized arteries via carotid-femoral PWV (cfPWV), carotid-radial PWV (crPWV), and radial-digital PWV (rdPWV), respectively. Our results showed that BP was increased in 1KDN and 0KDN, and that systolic BP values were restored in the TX configuration. Furthermore, a rise was reported in all PWVs for all tested configurations. The relative difference in stiffness from 2KDN to 0KDN was higher in the case of crPWV (15%) in comparison with the increase observed for cfPWV (11%). In TX, we observed a restoration of the PWVs to values close to 1KDN. Globally, it was demonstrated that alterations of the outflow boundaries to the renal arteries with staged kidney removal led to changes in BP and central and peripheral PWV in line with previously reported clinical data. Our findings suggest that the PWV variations observed in clinical practice with different stages of kidney disease may be partially attributed to biomechanical alterations of the arterial tree and their effect on BP.

Increased Excess Pressure After Creation of an Arteriovenous Fistula in End-Stage Renal Disease

BACKGROUND

Reservoir-wave analysis (RWA) separates the arterial waveform into reservoir and excess pressure (XSP) components, where XSP is analogous to flow and related to left ventricular workload. RWA provides more detailed information about the arterial tree than traditional blood pressure (BP) parameters. In end-stage renal disease (ESRD), we have previously shown that XSP is associated with increased mortality and is higher in patients with arteriovenous fistula (AVF). In this study, we examined whether XSP increases after creation of an AVF in ESRD.

METHODS

Before and after a mean of 3.9 ± 1.2 months following creation of AVF, carotid pressure waves were recorded using arterial tonometry. XSP and its integral (XSPI) were derived using RWA through pressure wave analysis alone. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (CF-PWV).

RESURLTS

In 38 patients (63% male, age 59 ± 15 years), after AVF creation, brachial diastolic BP decreased (79 ± 10 vs. 72 ± 12 mm Hg, P = 0.002), but the reduction in systolic BP, was not statistically significant (133 ± 20 vs. 127 ± 26 mm Hg, P = 0.137). However, carotid XSP (14 [12-19] to 17 [12-22] mm Hg, P = 0.031) and XSPI increased significantly (275 [212-335] to 334 [241-439] kPa∙s, P = 0.015), despite a reduction in CF-PWV (13 ± 3.6 vs. 12 ± 3.5 m/s, P = 0.025).

CONCLUSIONS

Creation of an AVF resulted in increased XSP in this population, despite improvement in diastolic BP and aortic stiffness. These findings underline the complex hemodynamic impact of AVF on the cardiovascular system.

Screening Rates for Primary Aldosteronism Among Individuals With Hypertension Plus Hypokalemia: A Population-Based Retrospective Cohort Study

Primary aldosteronism is a common, yet highly underdiagnosed, cause of hypertension that leads to disproportionately high rates of cardiovascular disease. Hypertension plus hypokalemia is a guideline-recommended indication to screen for primary aldosteronism, yet the uptake of this recommendation at the population level remains unknown. We performed a population-based retrospective cohort study of adults ≥18 years old in Ontario, Canada, with hypertension plus hypokalemia (potassium <3.5 mEq/L) from 2009 to 2015 with follow-up through 2017. We measured the proportion of individuals who underwent primary aldosteronism screening via the aldosterone-to-renin ratio based upon hypokalemia frequency and severity along with concurrent antihypertensive medication use. We assessed clinical predictors associated with screening via Cox regression. The cohort included 26 533 adults of which only 422 (1.6%) underwent primary aldosteronism screening. When assessed by number of instances of hypokalemia over a 2-year time window, the proportion of eligible patients who were screened increased only modestly from 1.0% (158/15 983) with one instance to 4.8% (71/1494) with ≥5 instances. Among individuals with severe hypokalemia (potassium <3.0 mEq/L), only 3.9% (58/1422) were screened. Among older adults prescribed ≥4 antihypertensive medications, only 1.0% were screened. Subspecialty care with endocrinology (hazard ratio [HR], 1.52 [95% CI, 1.10-2.09]), nephrology (HR, 1.43 [95% CI, 1.07-1.91]), and cardiology (HR, 1.39 [95% CI, 1.14-1.70]) were associated with an increased likelihood of screening, whereas age (HR, 0.95 [95% CI, 0.94-0.96]) and diabetes (HR, 0.66 [95% CI, 0.50-0.89]) were inversely associated with screening. In conclusion, population-level uptake of guideline recommendations for primary aldosteronism screening is exceedingly low. Increased education and awareness are critical to bridge this gap.

Modulation of Arterial Stiffness Gradient by Acute Administration of Nitroglycerin

Background: Physiologically, the aorta is less stiff than peripheral conductive arteries, creating an arterial stiffness gradient, protecting microcirculation from high pulsatile pressure. However, the pharmacological manipulation of arterial stiffness gradient has not been thoroughly investigated. We hypothesized that acute administration of nitroglycerin (NTG) may alter the arterial stiffness gradient through a more significant effect on the regional stiffness of medium-sized muscular arteries, as measured by pulse wave velocity (PWV). The aim of this study was to examine the differential impact of NTG on regional stiffness, and arterial stiffness gradient as measured by the aortic-brachial PWV ratio (AB-PWV ratio) and aortic-femoral PWV ratio (AF-PWV ratio).

Methods: In 93 subjects (age: 61 years, men: 67%, chronic kidney disease [CKD]: 41%), aortic, brachial, and femoral stiffnesses were determined by cf-PWV, carotid-radial (cr-PWV), and femoral-dorsalis pedis artery (fp-PWV) PWVs, respectively. The measurements were repeated 5 min after the sublingual administration of NTG (0.4 mg). The AB-PWV and AF-PWV ratios were obtained by dividing cf-PWV by cr-PWV or fp-PWV, respectively. The central pulse wave profile was determined by radial artery tonometry through the generalized transfer function.

Results: At baseline, cf-PWV, cr-PWV, and fp-PWV were 12.12 ± 3.36, 9.51 ± 1.81, and 9.71 ± 1.89 m/s, respectively. After the administration of NTG, there was a significant reduction in cr-PWV of 0.86 ± 1.27 m/s (p < 0.001) and fp-PWV of 1.12 ± 1.74 m/s (p < 0.001), without any significant changes in cf-PWV (p = 0.928), leading to a significant increase in the AB-PWV ratio (1.30 ± 0.39 vs. 1.42 ± 0.46; p = 0.001) and AF-PWV ratio (1.38 ± 0.47 vs. 1.56 ± 0.53; p = 0.001). There was a significant correlation between changes in the AF-PWV ratio and changes in the timing of wave reflection (r = 0.289; p = 0.042) and the amplitude of the heart rate-adjusted augmented pressure (r = − 0.467; p < 0.001).

Conclusion: This study shows that acute administration of NTG reduces PWV of muscular arteries (brachial and femoral) without modifying aortic PWV. This results in an unfavorable profile of AB-PWV and AF-PWV ratios, which could lead to higher pulse pressure transmission into the microcirculation.

Twenty-Four-Hour Central (Aortic) Systolic Blood Pressure: Reference Values and Dipping Patterns in Untreated Individuals

Supplemental Digital Content is available in the text.

Central (aortic) systolic blood pressure (cSBP) is the pressure seen by the heart, the brain, and the kidneys. If properly measured, cSBP is closer associated with hypertension-mediated organ damage and prognosis, as compared with brachial SBP (bSBP). We investigated 24-hour profiles of bSBP and cSBP, measured simultaneously using Mobilograph devices, in 2423 untreated adults (1275 women; age, 18–94 years), free from overt cardiovascular disease, aiming to develop reference values and to analyze daytime-nighttime variability. Central SBP was assessed, using brachial waveforms, calibrated with mean arterial pressure (MAP)/diastolic BP (cSBP_MAP/DBPcal), or bSBP/diastolic blood pressure (cSBP_SBP/DBPcal), and a validated transfer function, resulting in 144 509 valid brachial and 130 804 valid central measurements. Averaged 24-hour, daytime, and nighttime brachial BP across all individuals was 124/79, 126/81, and 116/72 mm Hg, respectively. Averaged 24-hour, daytime, and nighttime values for cSBP_MAP/DBPcal were 128, 128, and 125 mm Hg and 115, 117, and 107 mm Hg for cSBP_SBP/DBPcal, respectively. We pragmatically propose as upper normal limit for 24-hour cSBP_MAP/DBPcal 135 mm Hg and for 24-hour cSBP_SBP/DBPcal 120 mm Hg. bSBP dipping (nighttime-daytime/daytime SBP) was −10.6 % in young participants and decreased with increasing age. Central SBP_SBP/DBPcal dipping was less pronounced (−8.7% in young participants). In contrast, cSBP_MAP/DBPcal dipping was completely absent in the youngest age group and less pronounced in all other participants. These data may serve for comparison in various diseases and have potential implications for refining hypertension diagnosis and management. The different dipping behavior of bSBP versus cSBP requires further investigation.

Changes in arterial stiffness indices during a single haemodialysis session in end-stage renal disease population: a systematic review and meta-analysis protocol

INTRODUCTION

Patients with end-stage renal disease are at higher risk of cardiovascular morbidity and mortality, a risk mediated in part by increased aortic stiffness. Arterial stiffness is assessed at different anatomical locations (central elastic or peripheral muscular arteries) using a variety of mechanical biomarkers. However, little is known on the robustness of each of these mechanical biomarkers following a haemodynamic stress caused by a single haemodialysis (HD) session.

METHODS AND ANALYSIS

A systematic review has been designed and reported in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. A targeted search strategy applicable in key databases (PubMed, Embase, the Cochrane Library, Web of Science and grey literature) is constructed to search articles and reviews from inception to 16 October 2020. Only articles of studies conducted with adults under chronic HD for kidney failure, with repeated measures of arterial stiffness metrics (pulse wave velocity, Augmentation Index, arterial distensibility or stiffness) following a before-and-after design surrounding a HD session will be selected. The screening process, data extraction and assessment of risk bias will be done by two independent pairs of reviewers. Meta-analysis will enable adjustments for potential confounders and subgroup analyses will be performed to discriminate changes in arterial stiffness metrics from elastic, muscular or global arterial territories.

ETHICS AND DISSEMINATION

This study does not require ethical approval. Findings will be submitted for publication to relevant peer-reviewed journals and will be presented at profession-specific conferences.

PROSPERO REGISTRATION NUMBER

CRD42020213946.

Health literacy level in a various nephrology population from Québec: predialysis clinic, in-centre hemodialysis and home dialysis; a transversal monocentric observational study

Background

Health literacy refers to the ability of individuals to gain access to, use, and understand health information and services in order to maintain a good health. It is especially important in nephrology due to the complexity of chronic kidney disease (CKD). The present study sought to define health literacy levels in patients followed in predialysis clinic, in-center dialysis (ICHD), peritoneal dialysis (PD) and home hemodialysis (HHD).

Methods

This transversal monocentric observational study analysed 363 patients between October 2016 and April 2017. The Brief Health Literacy Screen (BHLS) and the Health Literacy Questionnaire (HLQ) were used to measure health literacy. Multivariate linear regressions were used to compare the mean scores on the BHLS and HLQ, across the four groups.

Results

Patients on PD had a significantly higher BHLS’score than patients on ICHD (p = 0.04). HLQ’s scores differed across the groups: patients on HHD (p = 0.01) and PD (p = 0.002) were more likely to feel understood by their healthcare providers. Compared to ICHD, patients on HHD were more likely to have sufficient information to manage their health (p = 0.02), and patients in the predialysis clinic were more likely to report high abilities for health information appraisal (p < 0.001).

Conclusion

In a monocentric study, there is a significant proportion of CKD patients, especially in predialysis clinic and in-centre hemodialysis, with limited health literacy. Patients on home dialysis (HHD and PD) had a higher level of health literacy compared to the other groups.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02464-1.

Effects of living kidney donation on arterial stiffness: a systematic review protocol

INTRODUCTION

Kidney donors have been reported to have accelerated progression of aortic stiffness and decreased glomerular filtration compared with healthy non-donors. This is a concern because increased aortic stiffness is an independent predictor of overall cardiovascular disease and all-cause mortality in the general population. To confirm if arterial stiffness increases after donation, we will systematically review all studies that evaluated indices of arterial stiffness in healthy individuals who underwent unilateral nephrectomy for kidney donation compared with age-matched healthy non-nephrectomised controls.

METHODS/ANALYSIS

We will comprehensively search for studies published between 1 January 1960 and 15 March 2021 in MEDLINE, EMBASE, Cochrane Central, OVID and EBM reviews. All prospective (cohort, case-control, case series and before-and-after studies) and retrospective non-randomised studies reporting indices of arterial stiffness in nephrectomised and non-nephrectomised healthy participants will be included. Primary outcome will be the difference in the functional metrics of arterial stiffness between donors and non-donors. Secondary outcomes will be the differences in systolic/diastolic blood pressures, serum creatinine, glomerular filtration, carotid artery intima-media thickness and vascular calcification. Study screening, selection and data extraction will be performed by two independent reviewers. Risk of bias will be independently assessed with the ROBINS-I tool and confidence in evidence by the Grading of Recommendations Assessment, Development and Evaluation recommendations. Qualitative and quantitative data syntheses as well as clinical and statistical heterogeneity (Forest plots, I2 and Cochran's Q statistics) will be evaluated. If clinical and statistical heterogeneity are acceptable, inverse variance-weighted effects will be analysed by random effect models.

ETHICS AND DISSEMINATION

No ethical approval is necessary. Our results will be disseminated through peer-review publication and presentations to guide stakeholders on the evaluation and follow-up care of kidney donors.

PROSPERO REGISTRATION NUMBER

CRD42020185551.

Radial-digital pulse wave velocity: a noninvasive method for assessing stiffness of small conduit arteries

Pulse wave velocity (PWV) is used to evaluate regional stiffness of large and medium-sized arteries. Here, we examine the feasibility and reliability of radial-digital PWV (RD-PWV) as a measure of regional stiffness of small conduit arteries and its response to changes in hydrostatic pressure. In 29 healthy subjects, we used Complior Analyse piezoelectric probes to record arterial pulse wave at the radial artery and the tip of the index. We determined transit time by second-derivative and intersecting tangents using the device-embedded algorithms and in-house MATLAB-based analyses of only reliable waves and by numerical simulation using a one-dimensional (1-D) arterial tree model coupled with a heart model. Second-derivative RD-PWV was 4.68 ± 1.18, 4.69 ± 1.21, and 4.32 ± 1.19 m/s for device-embedded, MATLAB-based, and numerical simulation analyses, respectively. Intersecting-tangent RD-PWV was 4.73 ± 1.20, 4.45 ± 1.08, and 4.50 ± 0.84 m/s for device-embedded, MATLAB-based, and numerical simulation analyses, respectively. Intersession coefficients of variation were 7.0% ± 4.9% and 3.2% ± 1.9% (P = 0.04) for device-embedded and MATLAB-based second-derivative algorithms, respectively. In 15 subjects, we examined the response of RD-PWV to changes in local hydrostatic pressure by vertical displacement of the hand. For an increase of 10 mmHg in local hydrostatic pressure, RD-PWV increased by 0.28 m/s (95% confidence interval: 0.16-0.40; P < 0.001). This study shows that RD-PWV can be used for the noninvasive assessment of regional stiffness of small conduit arteries. This finding allows for an integrated approach for assessing arterial stiffness gradient from the aorta to medium-sized arteries and now to small conduit arteries.NEW & NOTEWORTHY The interaction between the stiffness of various arterial segments is important in understanding the behavior of pressure and flow waves along the arterial tree. In this article, we provide a novel and noninvasive method of assessing the regional stiffness of small conduit arteries using the same piezoelectric sensors used for determination of pulse wave velocity over large- and medium-sized arteries. This development allows for an integrated approach for studying arterial stiffness gradient.

Prediction of Cardiovascular Events by Type I Central Systolic Blood Pressure: A Prospective Study

Supplemental Digital Content is available in the text.

Compared with brachial blood pressure (BP), central systolic BP (SBP) can provide a better indication of the hemodynamic strain inflicted on target organs, but it is unclear whether this translates into improved cardiovascular risk stratification. We aimed to assess which of central or brachial BP best predicts cardiovascular risk and to identify the central SBP threshold associated with increased risk of future cardiovascular events. This study included 13 461 participants of CARTaGENE with available central BP and follow-up data from administrative databases but without cardiovascular disease or antihypertensive medication. Central BP was estimated by radial artery tonometry, calibrated for brachial SBP and diastolic BP (type I), and a generalized transfer function (SphygmoCor). The outcome was major adverse cardiovascular events. Cox proportional-hazards models, differences in areas under the curves, net reclassification indices, and integrated discrimination indices were calculated. Youden index was used to identify SBP thresholds. Over a median follow-up of 8.75 years, 1327 major adverse cardiovascular events occurred. The differences in areas under the curves, net reclassification indices, and integrated discrimination indices were of 0.2% ([95% CI, 0.1–0.3] P<0.01), 0.11 ([95% CI, 0.03–0.20] P=0.01), and 0.0004 ([95% CI, −0.0001 to 0.0014] P=0.3), all likely not clinically significant. Central and brachial SBPs of 112 mm Hg (95% CI, 111.2–114.1) and 121 mm Hg (95% CI, 120.2–121.9) were identified as optimal BP thresholds. In conclusion, central BP measured with a type I device is statistically but likely not clinically superior to brachial BP in a general population without prior cardiovascular disease. Based on the risk of major adverse cardiovascular events, the optimal type I central SBP appears to be 112 mm Hg.

Association of Glomerular Hyperfiltration and Cardiovascular Risk in Middle-Aged Healthy Individuals

IMPORTANCE

Glomerular hyperfiltration is associated with increased risk of cardiovascular disease in high-risk conditions, but its significance in low-risk individuals is uncertain.

OBJECTIVE

To determine whether glomerular hyperfiltration is associated with increased cardiovascular risk in healthy individuals.

DESIGN, SETTING, AND PARTICIPANTS

This was a prospective population-based cohort study, for which enrollment took place from August 2009 to October 2010, with follow-up available through March 31, 2016. Analysis of the data took place in October 2019. The cohort was composed of 9515 healthy individuals, defined as individuals without hypertension, diabetes, cardiovascular disease, estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m2, or statin and/or aspirin use, identified among 20 004 patients aged 40 to 69 years with health information accessed through the CARTaGENE research platform.

EXPOSURES

Individuals with glomerular hyperfiltration (eGFR >95th percentile after stratification for sex and age) were compared with individuals with normal filtration rate (eGFR 25th-75th percentiles).

MAIN OUTCOMES AND MEASURES

Adverse cardiovascular events were defined as a composite of cardiovascular mortality, myocardial infarction, unstable angina, heart failure, stroke, and transient ischemic attack. Risk of adverse cardiovascular events was assessed using Cox and fractional polynomial regressions and propensity score matching.

RESULTS

From the 20 004 CARTaGENE participants, 9515 healthy participants (4050 [42.6%] male; median [interquartile range] age, 50.4 [45.9-55.6] years) were identified. Among these, 473 had glomerular hyperfiltration (median [interquartile range] eGFR, 112 [107-115] mL/min/1.73 m2) and 4761 had a normal filtration rate (median [interquartile range] eGFR, 92 [87-97] mL/min/1.73 m2). Compared with the normal filtration rate, glomerular hyperfiltration was associated with an increased cardiovascular risk (hazard ratio, 1.88; 95% CI, 1.30-2.74; P = .001). Findings were similar with propensity score matching. The fractional polynomial regression showed that only the highest eGFR percentiles were associated with increased cardiovascular risk. The cardiovascular risk of individuals with glomerular hyperfiltration was similar to that of the 597 participants with an eGFR between 45 and 60 mL/min/1.73 m2 (hazard ratio, 0.90; 95% CI, 0.56-1.42; P = .64).

CONCLUSIONS AND RELEVANCE

These findings suggest that glomerular hyperfiltration is independently associated with increased cardiovascular risk in middle-aged healthy individuals. This risk profile appears to be similar to stage 3a chronic kidney disease.

Determinants of Increased Central Excess Pressure in Dialysis: Role of Dialysis Modality and Arteriovenous Fistula

BACKGROUND

Arterial reservoir-wave analysis (RWA)-a new model of arterial hemodynamics-separates arterial wave into reservoir pressure (RP) and excess pressure (XSP). The XSP integral (XSPI) has been associated with increased risk of clinical outcomes. The objectives of the present study were to examine the determinants of XSPI in a mixed cohort of hemodialysis (HD) and peritoneal dialysis (PD) patients, to examine whether dialysis modality and the presence of an arteriovenous fistula (AVF) are associated with increased XSPI.

METHOD

In a cross-sectional study, 290 subjects (232 HD and 130 with AVF) underwent carotid artery tonometry (calibrated with brachial diastolic and mean blood pressure). The XSPI was calculated through RWA using pressure-only algorithms. Logistic regression was used for determinants of XSPI above median. Through forward conditional linear regression, we examined whether treatment by HD or the presence of AVF is associated with higher XSPI.

RESULTS

Patients with XSPI above median were older, had a higher prevalence of diabetes and cardiovascular disease, had a higher body mass index, and were more likely to be on HD. After adjustment for confounders, HD was associated with a higher risk of higher XSPI (odds ratio = 2.39, 95% confidence interval: 1.16-4.98). In a forward conditional linear regression analysis, HD was associated with higher XSPI (standardized coefficient: 0.126, P = 0.012), but on incorporation of AVF into the model, AVF was associated with higher XSPI (standardized coefficient: 0.130, P = 0.008) and HD was excluded as a predictor.

CONCLUSION

This study suggests that higher XSPI in HD patients is related to the presence of AVF.

Pharmacologic Therapies for Aortic Stiffness in End-Stage Renal Disease: A Systematic Review and Meta-Analysis

Background:

Increased carotid-femoral pulse wave velocity (cf-PWV), a surrogate of increased aortic stiffness, is a risk factor for cardiovascular events and all-cause mortality in end-stage renal disease (ESRD). To minimize the deleterious effects of an increased aortic stiffness in ESRD patients, several interventions have been developed and cf-PWV has been used to monitor responses.

Objective:

The aim of this study was to determine the effects of pharmacologic interventions that target aortic stiffness on cf-PWV and systolic blood pressure (SBP) in adults with ESRD.

Study design:

This study implements a systematic review and meta-analysis.

Data sources:

MEDLINE, EMBASE, Cochrane Central, Health Technology Assessment, and EBM databases were searched.

Study eligibility, participants, and interventions:

Randomized and non-randomized studies involving adults (>18 years) with ESRD of any duration, receiving or not renal replacement therapy (hemodialysis, peritoneal dialysis) and exposed to a pharmacologic intervention whose effects were assessed by cf-PWV.

Methods:

Study screening, selection, data extraction, and quality assessments were performed by 2 independent reviewers. Narrative synthesis and quantitative data analysis summarized the review.

Results:

We included 1027 ESRD participants from 13 randomized and 5 non-randomized studies. Most pharmacologic interventions targeted bone mineral metabolism disorder or hypertension. Treatment with vitamin D analogues or cinacalcet did not decrease cf-PWV or SBP over placebo or matched controls (P > .05). Calcium-channel blockers (CCB) decreased cf-PWV and SBP compared with placebo or standard care (P < .05). Renin-angiotensin system inhibitors did not show any advantage over placebo in decreasing cf-PWV (P > .05).

Limitations:

Quality of evidence ranged from very low to moderate. Overall evidence was limited by the low number of studies, small sample sizes, and methodological inconsistencies.

Conclusions:

Pharmacologic interventions targeting aortic stiffness in ESRD have mixed effects on reducing cf-PWV, with some strategies suggesting potential benefit. The quality of evidence, however, is insufficient to draw definitive conclusions on their use to slow progression of aortic stiffness in ESRD. Further well-designed studies are needed to confirm these associations and their impact on cardiovascular outcomes in ESRD.

Registered in PROSPERO (CRD42016033463)

Sodium and urea excretion as determinants of urine output in autosomal dominant polycystic kidney disease patients on V2 receptor antagonists: impact of dietary intervention

PURPOSE

Tolvaptan, a vasopressin V2 receptor antagonist, slows the decline in renal function in autosomal dominant polycystic kidney disease (ADPKD). However, it increases urine output such that patient adherence could be compromised. In a cohort of patients with ADPKD on tolvaptan, we aimed to identify the contribution of sodium and urea excretion rate to daily urine output, and to evaluate the effectiveness of dietary counseling on sodium and urea excretion rates.

METHODS

Retrospective analysis of 30 ADPKD patients who underwent a single session of personalized dietary counseling to reduce sodium and protein intake before initiation of tolvaptan. Creatinine and 24-h urine were obtained regularly on treatment. Generalized estimation equations were used.

RESULTS

Mean age and median eGFR were 44 ± 11 years and 52 (43-74) ml/min/1.73 m². Tolvaptan increased diuresis from 2.5 to 5.2 l/day. After adjusting for the dose of tolvaptan, an increase in sodium and urea excretion rate by 50 mmol/day was associated with an estimated additional urine volume of 0.6 l/day (95% CI 0.4-0.8 l/day; P < 0.001) and 0.25 l/day (95% CI 0.11-0.39 l/day; P < 0.001), respectively. Dietary counseling resulted in a transient reduction of sodium excretion by 19 mmol/day during the first 4 months (P = 0.016) but resulted in a more sustained reduction in urea excretion by 69 mmol/day (P = 0.008).

CONCLUSION

Both sodium and urea excretion rates contribute significantly to daily urine volume in patients treated with tolvaptan, and a single session of dietary counseling was transiently effective in reducing sodium intake but achieved a more sustained reduction in protein intake. Dietary counseling should be considered in the management of ADPKD patients treated by tolvaptan.

Prognostic Value of Carotid and Radial Artery Reservoir-Wave Parameters in End-Stage Renal Disease

Background Reservoir-wave approach is an alternative model of arterial hemodynamics based on the assumption that measured arterial pressure is composed of volume-related (reservoir pressure) and wave-related components (excess pressure). However, the clinical utility of reservoir-wave approach remains debatable. Methods and Results In a single-center cohort of 260 dialysis patients, we examined whether carotid and radial reservoir-wave parameters were associated with all-cause and cardiovascular mortality. Central pulse pressure and augmentation index at 75 beats per minute were determined by radial arterial tonometry through generalized transfer function. Carotid and radial reservoir-wave analysis were performed to determine reservoir pressure and excess pressure integral. After a median follow-up of 32 months, 171 (66%) deaths and 88 (34%) cardiovascular deaths occurred. In Cox regression analysis, carotid excess pressure integral was associated with a hazard ratio of 1.33 (95% CI , 1.14-1.54; P<0.001 per 1 SD) for all-cause and 1.45 (95% CI : 1.18-1.75; P<0.001 per 1 SD) for cardiovascular mortality. After adjustments for age, heart rate, sex, clinical characteristics and carotid-femoral pulse wave velocity, carotid excess pressure integral was consistently associated with increased risk of all-cause (hazard ratio per 1 SD, 1.30; 95% CI : 1.08-1.54; P=0.004) and cardiovascular mortality (hazard ratio per 1 SD, 1.31; 95% CI : 1.04-1.63; P=0.019). Conversely, there were no significant associations between radial reservoir-wave parameters, central pulse pressure, augmentation index at 75 beats per minute, pressure forward, pressure backward and reflection magnitude, and all-cause or cardiovascular mortality after adjustment for comorbidities. Conclusions These observations support the clinical value of reservoir-wave approach parameters of large central elastic vessels in end-stage renal disease.

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.

High calcium, phosphate and calcitriol supplementation leads to an osteocyte-like phenotype in calcified vessels and bone mineralisation defect in uremic rats

A link between vascular calcification and bone anomalies has been suggested in chronic kidney disease (CKD) patients with low bone turnover disease. We investigated the vascular expression of osteocyte markers in relation to bone microarchitecture and mineralization defects in a model of low bone turnover CKD rats with vascular calcification. CKD with vascular calcification was induced by 5/6 nephrectomy followed by high calcium and phosphate diet, and vitamin D supplementation (Ca/P/VitD). CKD + Ca/P/VitD group (n = 12) was compared to CKD + normal diet (n = 12), control + normal diet (n = 8) and control + Ca/P/VitD supplementation (n = 8). At week 6, tibia, femurs and the thoracic aorta were analysed by Micro-Ct, histomorphometry and for expression of osteocyte markers. High Ca/P/VitD treatment induced vascular calcification only in CKD rats, suppressed serum parathyroid hormone levels and led to higher sclerostin, DKK1 and FGF23 serum levels. Expression of sclerostin, DKK1 and DMP1 but not FGF23 were increased in calcified vessels from CKD + Ca/P/VitD rats. Despite low parathyroid hormone levels, tibia bone cortical thickness was significantly lower in CKD + Ca/P/VitD rats as compared to control rats fed a normal diet, which is likely the result of radial growth impairment. Finally, Ca/P/VitD treatment in CKD rats induced a bone mineralization defect, which is likely explained by the high calcitriol dose. In conclusion, Ca/P/VitD supplementation in CKD rats induces expression of osteocyte markers in vessels and bone mineralisation anomalies. Further studies should evaluate the mechanisms of high dose calcitriol-induced bone mineralisation defects in CKD.

Blood Pressure Measurement in Severely Obese Patients: Validation of the Forearm Approach in Different Arm Positions

BACKGROUND

Blood pressure measurement in severe obesity may be technically challenging as the cuff of the device may not fit adequately around the upper arm. The aim of the study was to assess the agreement between intra-arterial blood pressure values (gold standard) compared with forearm blood pressure measurements in severely obese patients in different arm positions.

METHODS

Thirty-three severely obese patients and 21 controls participated in the study. Pairs of intra-arterial blood pressures were compared with simultaneous forearm blood pressure measurement using an oscillometric device in 4 positions: (i) supine, (ii) semi-fowler with the forearm resting at heart level, (iii) semi-fowler with the arm downward, and (iv) semi-fowler with the arm raised overhead. Degree of agreement between measurements was assessed.

RESULTS

Overall, correlations of systolic and diastolic blood pressure measurements between the gold standard and forearm blood pressure were 0.95 (n = 722; P < 0.001) and 0.89 (n = 482; P < 0.001), respectively. Systolic blood pressure measured using the forearm approach in the supine and the semi-fowler positions with arm downward showed the best agreement when compared with the gold standard (-4 ± 11 (P < 0.001) and 2 ± 14 mm Hg (P = 0.19), respectively). In the control group, better agreement was found between the supine and semi-fowler positions with the arm resting at heart level (1 ± 9 mm Hg (P = 0.29) and -3 ± 10 mm Hg (P = 0.01), respectively).

CONCLUSIONS

Forearm systolic blood pressure consistently agreed with the gold standard in the supine position. This method can be of use in clinical settings when upper-arm measurement is challenging in severe obesity.

An Adjustable Dalteparin Sodium Dose Regimen for the Prevention of Clotting in the Extracorporeal Circuit in Hemodialysis: A Clinical Trial of Safety and Efficacy (the PARROT Study)

Background:

Dalteparin sodium, a low-molecular-weight heparin, is indicated for prevention of clotting in the extracorporeal circuit during hemodialysis (HD). Product labeling recommends a fixed single-bolus dose of 5000 international units (IU) for HD sessions lasting up to 4 hours, but adjustable dosing may be beneficial in clinical practice.

Objective:

The aim of the PARROT study was to investigate the safety and efficacy of an adjustable dose of dalteparin in patients with end-stage renal disease requiring 3 to 4 HD sessions per week.

Design:

A 7-week, open-label, multicenter study with a single treatment arm, conducted between October 2013 and March 2016.

Setting:

Ten sites in Canada.

Patients:

A total of 152 patients with end-stage renal disease requiring 3 to 4 HD sessions per week.

Measurements:

The primary outcome was the proportion of HD sessions completed without premature termination due to inadequate anticoagulation.

Methods:

All participants initially received a dose of 5000 IU dalteparin, which could be adjusted at subsequent HD sessions when clinically indicated, by increment or decrement of 500 or 1000 IU, with no specified dose limits.

Results:

Patients were followed for 256 patient-months. Nearly all (99.9%; 95% confidence interval [CI]: 99.7-100) evaluable HD sessions were completed without premature clotting. Dose was adjusted for more than half (52.3%) of participants, mostly owing to clotting or access compression time >10 minutes. Median dalteparin dose was 5000 IU (range: 500-13 000 IU). There were no major bleeds, and minor bleeding was reported in 2.3% of all HD sessions. There was no evidence of bioaccumulation.

Limitations:

This short-term study, with a single treatment arm, was designed to optimize dalteparin dose using a flexible dosing schedule; it was not designed to specifically evaluate dalteparin dose minimization, provide a direct comparison of dalteparin versus unfractionated heparin, or provide information on long-term safety for flexible dalteparin dosing. Patients were excluded if they were at high risk of bleeding, including those on anticoagulants and those on antiplatelet agents other than aspirin <100 mg/d.

Conclusions:

Overall, an adjustable dalteparin sodium dose regimen allowed safe completion of HD, with clinical benefits over fixed dosing.

Trial Registration:

ClinicalTrials.gov NCT01879618, registered June 13, 2013.

FGF23-klotho axis, bone fractures, and arterial stiffness in dialysis: a case-control study

We performed a case-control study on 130 age- and sex-matched hemodialysis patients. In multivariate analysis, we observed that FGF23 levels were associated with fracture incidence and that soluble α-klotho levels were associated with the aortic-brachial arterial stiffness ratio.

INTRODUCTION

New bone markers such as sclerostin, Dickkopf-related protein 1 (DKK1), fibroblast growth factor-23 (FGF23), and α-klotho have been identified as potential key players in bone and vascular abnormalities of chronic kidney disease. Therefore, we aimed to assess whether these markers are associated with fractures, bone metabolism, and vascular stiffness in dialysis patients.

METHODS

In a prospective hemodialysis cohort, where plasma samples and vascular assessment were performed at baseline, we matched patients who experienced a fracture during follow-up with sex- and age-matched non-fractured patients on a 1:4 ratio. Sclerostin, DKK1, α-klotho, FGF23, and markers of bone formation (alkaline phosphatase and procollagen type 1-N terminal propeptide [P1NP]) and bone resorption (tartrate-resistant acid phosphatase 5b [TRAP5b]) were measured in baseline plasma samples. Aortic-brachial pulse wave velocity ratio, a blood pressure independent measure of arterial stiffness, was used to assess vascular stiffness at baseline.

RESULTS

We included 130 hemodialysis patients (26 fractured, 104 non-fractured) with a median follow-up of 42 months and a median age of 72 years. In multivariate Cox regression models, high FGF23 levels were associated with increased fracture incidence (adjusted HR = 2.97; 95% CI 1.18, 7.43). α-Klotho levels were associated with bone formation but not resorption markers. In both univariate and multivariable adjusted models, α-klotho levels were inversely associated with the aortic-brachial pulse wave velocity ratio (β = - 0.070; 95% CI - 0.133, - 0.006).

CONCLUSIONS

These results suggest a role for FGF23/klotho axis on bone and vascular metabolism in dialysis populations.