Prevalence and Mortality of Pulmonary Hypertension in ESRD: A Systematic Review and Meta-analysis

Therapeutic approaches for pulmonary hypertension in patients with chronic kidney disease

PURPOSE OF REVIEW

Pulmonary hypertension is a common comorbidity in patients with chronic kidney disease (CKD), but therapeutic options are limited. We discuss the epidemiology of pulmonary hypertension in patients with CKD and review therapies for pulmonary hypertension with a focus on emerging treatments for pulmonary arterial hypertension (PAH).

RECENT FINDINGS

The definition of pulmonary hypertension has been updated to a lower threshold of mean pulmonary artery pressures of more than 20 mmHg, potentially leading to more patients with CKD to qualify for the diagnosis of pulmonary hypertension. Endothelin receptor antagonists, a class of medications, which demonstrated efficacy in patients with PAH, have been shown to slow progression of CKD, but their efficacy in lowering pulmonary artery pressures and their effects on reducing cardiovascular mortality in this population remains unproven. Sotatercept, a novel activin signaling inhibitor, which was previously studied in dialysis patients has been shown to increase exercise capacity in patients with PAH. These studies may lead to new specific therapies for pulmonary hypertension in patients with CKD.

SUMMARY

Pulmonary hypertension is common in patients with CKD. Although our understanding of factors leading to pulmonary hypertension in this population have evolved, evidence supporting disease-specific therapy in CKD is limited arguing for larger, long-term studies.

Determinants of pulmonary hypertension in patients with end-stage kidney disease and arteriovenous access

BACKGROUND

Pulmonary Hypertension (PH) is a sequela of arteriovenous (AV) fistulas (AVF) or AV grafts (AVG) in patients with end-stage kidney disease (ESKD) due to the creation of shunt physiology and increased pulmonary blood flow. PH has been consistently associated with increased mortality but there is a paucity of data regarding management.

RESEARCH QUESTION

The objective of this study was to identify risk factors and outcomes in patients who develop PH after AVF or AVG creation for hemodialysis access.

METHODS

Using the United States Renal Data System, we identified all patients over age 18 initiated on dialysis from 2012-2019 who did not receive renal transplant. We identified a) the predictors of PH in patients with ESKD on hemodialysis; b) the independent mortality risk associated with development of PH.

RESULTS

We identified 478,896 patients initiated on dialysis from 2012-2019 of whom 27,787 (5.8 %) had a diagnosis of PH. The median age was 65 (IQR: 55-74) years and 59.1 % were male. Reduced ejection fraction, any congestive heart failure, obstructive sleep apnea, and female sex were the strongest predictors of PH diagnosis. Both AVG and AVF were also associated with an increased rate of PH diagnosis compared to catheter-based dialysis (p < 0.001). PH portended a poor prognosis and was associated with significantly increased mortality (p < 0.001).

CONCLUSIONS

Patients with AVF or AVG should be screened using echocardiography prior to creation and monitored with serial echocardiography for the development of PH, and if present, considered for revision of the AVA. This is also the first study to identify that AVG are a risk factor for PH in dialysis patients.

Frequency of Pulmonary Hypertension and Its Associated Risk Factors in End-Stage Renal Disease (ESRD) Patients on Maintenance Hemodialysis

Introduction Pulmonary hypertension (PH) is a recognized complication in patients with end-stage renal disease (ESRD undergoing maintenance hemodialysis (MHD). PH is commonly found in patients with chronic kidney disease (CKD) and ESRD. PH is associated with increased morbidity and mortality in patients with CKD. Methodology This cross-sectional study aimed to assess the prevalence of PH and its associated risk factors in MHD patients. A total of 220 ESRD patients on MHD patients at The Kidney Center, Karachi, Pakistan, aged 18-70 were included. Patients with chronic obstructive lung disease, valvular heart disease, and obstructive sleep apnea were excluded, as these conditions can be responsible for PH. PH was evaluated by echocardiography (ECHO), which was performed by a cardiologist. Results The mean age was 50.65 ± 14.4 years, with 131 (59.5%) males and 89 (40.5%) females. The average duration on hemodialysis was 5.3 ± 2.8 years. Hypertension (89.5%) and ischemic heart disease (24.1%) were prominent comorbidities. Hypertensive nephropathy (42.7%) was the leading cause of ESRD. Left ventricular hypertrophy was mild in most cases (85.5%), whereas regional wall motion abnormality (RWMA) was common (67.3%). The average pulmonary artery pressure was 35.2 ± 15.3 mmHg. Out of 220 patients, 109 patients (49.8%) of them had mild PH, nine patients (4.1%) had severe PH, and 72 patients (32.7%) had moderate PH. Associations between PH and various factors were examined. RWMA, left ventricular hypertrophy, and left ventricular ejection fraction were significantly associated with PH (p < 0.001). Serum calcium and albumin levels were also associated with PH severity (p < 0.05). Other demographic and laboratory parameters did not show a significant association. Conclusion This study highlights the prevalence of PH in MHD patients and identifies associated risk factors. Understanding these associations can aid in better managing PH in ESRD patients.

Paradoxical Worsening of Pulmonary Hypertension Following Closure of Arteriovenous Fistula: A Case Report and Literature Review

This case report presents the atypical instance of a 59-year-old female patient with end-stage renal disease (ESRD) who was initially referred to the pulmonary clinic for evaluation due to a low diffusing capacity of the lung for carbon monoxide (DLCO). Pulmonary hypertension (PH) was suspected, and a subsequent right heart catheterization (RHC) confirmed PH attributed to group 5 PH, leading to the decision to close the unused arteriovenous fistula (AVF) to manage PH. Unexpectedly, a follow-up RHC showed a worsening of PH with elevated pulmonary capillary wedge pressure (PCWP), revealing an additional component of post-capillary group 2 PH. This case emphasizes the significance of recognizing a low DLCO as a potential trigger for PH assessment, especially in patients with comorbidities like ESRD. Furthermore, it highlights the unusual yet critical occurrence of PH exacerbation following AVF closure.

Development and Validation of a Nomogram for Predicting All-Cause Mortality in Patients with Hemodialysis Having Pulmonary Hypertension

INTRODUCTION

Patients with end-stage renal disease receiving hemodialysis (HD) have a high morbidity and mortality rate associated with pulmonary hypertension (PH). A nomogram was developed to predict all-cause mortality in HD patients with PH. In this study, we aimed to validate the usefulness of this nomogram.

METHODS

A total of 274 HD patients with PH were hospitalized at the Affiliated Hospital of Xuzhou Medical University between January 2014 and June 2019 and followed up for 3 years. Echocardiography detected PH when the peak tricuspid regurgitation velocity (TRV) was more than 2.8 m/s. To evaluate the all-cause mortality for long-term HD patients with PH, Cox regression analysis was performed to determine the factors of mortality that were included in the prediction model. Next, the area under the receiver-operating characteristic curve (AUC-ROC) was used to assess the predictive power of the model. Calibration plots and decision curve analysis (DCA) were used to assess the accuracy of the prediction results and the clinical utility of the model.

RESULTS

The all-cause mortality rate was 29.20% throughout the follow-up period. The nomogram comprised six commonly available predictors: age, diabetes mellitus, cardiovascular disease, hemoglobin, left ventricular ejection fraction, and TRV. The 1-year, 2-year, and 3-year AUC-ROC values were 0.842, 0.800, and 0.781, respectively. The calibration curves revealed excellent agreement with the nomogram, while the DCA demonstrated favorable clinical practicability.

CONCLUSION

The first developed nomogram for predicting all-cause mortality in HD patients with PH could guide clinical decision-making and intervention planning.

Estimation of pulmonary artery systolic pressure in hemodialysis patients and its association with cardiorespiratory fitness and pulmonary function

PURPOSE

To evaluate the estimated pulmonary arterial systolic pressure (PASP) through transthoracic echocardiography in hemodialysis (HD) patients and associate it with cardiorespiratory fitness and pulmonary function.

METHODS

This study was a cross-sectional analysis of HD patients that performed evaluations of cardiac function, cardiorespiratory fitness, and pulmonary function, through transthoracic echocardiography, cardiopulmonary exercise test, spirometry, and manovacuometry, respectively. All patients underwent the evaluations on a non-dialysis day.

RESULTS

Thirty-five HD patients were evaluated and separated according to the presence of probable pulmonary hypertension (PH) (estimated PASP ≥ 35 mmHg) or not (estimated PASP < 35 mmHg). Those HD patients with probable PH had the worst cardiorespiratory fitness, evaluated by the peak oxygen consumption (VO_2peak) (17.11 ± 4.40 versus 12.90 ± 2.73 mL/kg/min; p = 0.011), and pulmonary function, evaluated by absolute and predicted of forced vital capacity (FVC) (85.52 ± 12.29 versus 71.38 ± 11.63%; p = 0.005) and absolute and predicted of forced expiratory volume in the first second (FEV₁) (83.37 ± 14.98 versus 69.21 ± 13.48%; p = 0.017). The secondary analysis showed that estimated PASP was correlated with VO_2peak (r = - 0.508; p = 0.002), FVC (r = - 0.450; p = 0.007), and FEV₁ (r = - 0.361; p = 0.033). Moreover, the adjusted odds ratio by HD vintage, dry weight and gender showed that increments in VO_2peak (OR 1.62; CI 95% 1.04-2.54; p = 0.034), FVC (OR 39.67; CI 95% 1.74-902.80; p = 0.021), and FEV₁ (OR 39.54; CI 95% 1.89-826.99; p = 0.018) were associated with 1-fold and 39-fold higher chance, respectively, for not having PH. However, all these associations were lost when age was included in the analysis.

CONCLUSIONS

The HD patients with probable PH had the worst cardiorespiratory fitness and pulmonary function. Exploratory analyses showed that greater cardiopulmonary fitness was associated with better cardiac function. Moreover, increments in cardiorespiratory fitness and pulmonary function may increase the chance of not having PH.

Impact of Pulmonary Hypertension on Renal Functions in Obstructive Sleep Apnea Syndrome

OBJECTIVES

Pulmonary hypertension (PH) is common in obstructive sleep apnea syndrome (OSAS). This study aimed to evaluate the effect of PH on kidney functions in patients with OSAS.

METHODS

The data of patients who were diagnosed as having OSAS after referral to the sleep center in the Gaziantep University Medical Faculty between January 2005 and June 2017 were evaluated. The estimated glomerular filtration rate was calculated with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Renal functions of the subjects who had data after 5 years were included for long-term analysis.

RESULTS

A total of 2152 patients with OSAS (n = 1540), PH (n = 49), OSAS and PH coexistence (n = 359), and the control group (n = 204) were included in the study. Pulmonary arterial pressure (PAP) was 44.51 ± 23.73 in the PH group; it was 37.1 ± 13.14 in the group with OSAS + PH (P = 0.001) Urea and uric acid were found to be higher in the association of OSAS + PH. CKD-EPI was lower in the presence of PH or OSAS + PH than in the presence of OSAS. PH was present in 16.06% of males and 25.10% of females (P = 0.000), and PAP was detected as 35.80 ± 13.23 and 40.96 ± 16.65, respectively (P = 0.001). PH was present in 15.99% of males and 25.84% of females with OSAS (P = 0.000). The PAP of males with OSAS was 36.03 ± 13.46, and the PAP of females was 38.68 ± 12.55 (P = 0062). Urea, creatinine, and uric acid were higher and CKD-EPI was lower in male subjects in the presence of OSAS and PH, whereas the same scenario also was present in the presence of PH alone in female subjects. Long-term comparisons (n = 343) revealed significant decreases in the CKD-EPI in those with OSAS and OSAS + PH and these decrease were more pronounced in the presence of OSAS and PH. The regression analysis revealed that female patients had lower CKD-EPI in the presence of PH, although the presence of PH had no effect on CKD-EPI in males.

CONCLUSIONS

PH is a risk factor for the deterioration of renal function in OSAS and more prominent in the long term.

Oxidized-LDL Deteriorated the Renal Residual Function and Parenchyma in CKD Rat through Upregulating Epithelial Mesenchymal Transition and Extracellular Matrix-Mediated Tubulointerstitial Fibrosis-Pharmacomodulation of Rosuvastatin

This study tested the hypothesis that intrarenal arterial transfusion of oxidized low-density lipoprotein (ox-LDL) jeopardized the residual renal function and kidney architecture in rat chronic kidney disease ((CKD), i.e., induced by 5/6 nephrectomy) that was reversed by rosuvastatin. Cell culture was categorized into A1 (NRK-52E cells), A2 (NRK-52E + TGF-β), A3 (NRK-52E + TGF-β + ox-LDL) and A4 (NRK-52E + TGF-β + ox-LD). The result of in vitro study showed that cell viability (at 24, 48 and 72 h), NRK-52E ox-LDL-uptake, protein expressions of epithelial−mesenchymal−transition (EMT) markers (i.e., p-Smad2/snail/α-SMA/FSP1) and cell migratory and wound healing capacities were significantly progressively increased from A1 to A4 (all p < 0.001). SD rats were categorized into group 1 (sham-operated control), group 2 (CKD), group 3 (CKD + ox-LDL/0.2 mg/rat at day 14 after CKD induction) and group 4 (CKD + ox-LDL-treated as group 3+ rosuvastatin/10 mg/kg/day by days 20 to 42 after CKD induction) and kidneys were harvested at day 42. The circulatory levels of BUN and creatinine, ratio of urine-protein to urine-creatinine and the protein expressions of the above-mentioned EMT, apoptotic (cleaved-caspase3/cleaved-PARP/mitochondrial-Bax) and oxidative-stress (NOX-1/NOX-2/oxidized-protein) markers were lowest in group 1, highest in group 3 and significantly higher in group 4 than in group 2 (all p < 0.0001). Histopathological findings demonstrated that the kidney injury score, fibrotic area and kidney injury molecule-1 (KIM-1) displayed an identical pattern, whereas the cellular expression of podocyte components (ZO-1/synaptopodin) exhibited an opposite pattern of EMT markers (all p < 0.0001). In conclusion, ox-LDL damaged the residual renal function and kidney ultrastructure in CKD mainly through augmenting oxidative stress, EMT and fibrosis that was remarkably reversed by rosuvastatin.

The problem of pulmonary arterial hypertension in end-stage renal disease: can peritoneal dialysis be the solution

BACKGROUND

Pulmonary arterial hypertension (PAH) in the setting of end-stage renal disease (ESRD) has important prognostic and therapeutic consequences. We estimated the prevalence of PAH among patients with ESRD treated with automated peritoneal dialysis (APD), investigated the effect of different variables and compared pulmonary artery pressure and cardiac function at the beginning and end of the study.

METHODS

This is a 5-year study in which 31 ESRD patients on APD were recruited after fulfilling inclusion criteria. Blood samples were collected from all patients for the biochemical and hematological data at the beginning of the study and every month and at the study termination. Total body water (TBW) and extracellular water (ECW) were calculated using Watson's and Bird's calculation methods. All patients were followed-up at 3-month interval for cardiac evaluation. Logistic regression analysis was used to assess the relation between different variables and PAH.

RESULTS

The mean age of the study population (n = 31) was 51.23 ± 15.24 years. PAH was found in 24.2% of the patients. Mean systolic pulmonary artery pressure (sPAP) and mean pulmonary artery pressure (mPAP) were significantly higher in the APD patients at study initiation than at the end of the study (40.75 + 10.61 vs 23.55 + 9.20 and 29.66 + 11.35 vs 18.24 + 6.75 mmHg respectively, p = 0.001). The median ejection fraction was significantly lower in patients with PAH at zero point than at study termination [31% (27-34) vs 50% (46-52), p = 0.002]. Hypervolemia decreased significantly at the end of study (p <  0.001) and correlated positively with the PAP (r = 0.371 and r = 0.369), p = 0.002). sPAP correlated with left ventricular mass index, hemoglobin level, and duration on APD.

CONCLUSIONS

Long term APD (> 1 years) seemed to decrease pulmonary arterial pressure, right atrial pressure and improve left ventricular ejection fraction (LVEF). Risk factors for PAH in ESRD were hypervolemia, abnormal ECHO findings and low hemoglobin levels. Clinical and echocardiographic abnormalities and complications are not uncommon among ESRD patients with PAH. Identification of those patients on transthoracic echocardiography may warrant further attention to treatment with APD.

Intensive ultrafiltration strategy restores kidney transplant candidacy for patients with echocardiographic evidence of pulmonary hypertension

INTRODUCTION

Pulmonary hypertension (PH) is prevalent in those with end-stage kidney disease (ESKD) and poses a barrier to kidney transplant due to its association with poor outcomes. Studies examining these adverse outcomes are limited and often utilize echocardiographic measurements of pulmonary artery systolic pressure (PASP) instead of the gold standard right heart catheterization (RHC). We hypothesized that in ESKD patients deemed ineligible for kidney transplant because of an echocardiographic diagnosis of PH the predominant cause of PH is hypervolemia and is potentially reversible.

METHODS

We conducted a prospective study of 16 patients with ESKD who were denied transplant candidacy. Prior echocardiograms and RHCs were reviewed for confirmation of PH. Patients were admitted for daily sessions of ultrafiltration for volume removal and repeat RHCs were performed following intervention. RHC parameters and body weight were compared before and after intervention. Statistical analysis was performed using PRISM GraphPad software. A p-value <.05 was considered statistically significant.

RESULTS

Following intervention, the mean pulmonary artery pressure (mPAP) and pulmonary arterial wedge pressure decreased from 45.0 ± 3.06 to 29.1 ± 7.77 mmHg (p < .0001) and 22.2 ± 5.06 to 13.1 ± 7.25 mmHg (p = .003), respectively. The pulmonary vascular resistance decreased from 4.73 ± 1.99 to 4.28 ± 2.07 WU (p = .30). Eleven patients from the initial cohort underwent successful kidney transplantation post-intervention with 100% survival at 1-year.

CONCLUSIONS

In ESKD patients, diagnoses of PH made by echocardiography may be largely due to hypervolemia and may be optimized using an intensive ultrafiltration strategy to restore transplant candidacy.

Prognostic effect of pulmonary hypertension in patients with chronic kidney disease: Univariate and multivariate analyses of factors associated with survival

Background

Prognostic effect of pulmonary hypertension (PH) in patients with chronic kidney disease (CKD) is not fully clear yet, this study was designed to elucidate baseline characteristics of CKD patients with different severities of PH, the association between kidney indicators and PH severity, and survival factors in CKD patients with PH.

Methods

We extracted clinical data from electronic medical records of all patients diagnosed with PH in CKD from Jan 2016 to Dec 2020, and those with comorbid conditions causing PH were excluded. CKD stages were defined by estimated glomerular filtration rate thresholds. PH was defined as a systolic pulmonary artery pressure (sPAP) >35 mmHg estimated using echocardiograms. Demographics, clinical data, and test results were analyzed, and all-cause mortality data were obtained.

Results

A total of 137 patients were included in the study. The mean age of the participants was 60 (42.5, 67) years, the mean sPAP was 58 (51, 69.5) mmHg, and 40.9% of the patients were women. Moderate PH group had more patients undergoing dialysis and higher frequency of coronary heart disease. Moderate-severe PH group had higher parathyroid hormone levels and lower low-density lipoprotein levels. Severe PH group had better kidney function parameters and lower serum phosphorus levels. PH severity had no direct relationship with CKD stages. In the univariate analysis, age and PH severity influenced survival. Multivariate analysis also showed independent prognostic effects for age and sPAP. Kaplan-Meyer curve intuitively displayed the survival differences among CKD patients with different PH severity. Predictor values of nomogram identified from survival analyses enabled calculation of death probabilities for CKD with PH patients. Nomogram was validated by ROC analysis.

Conclusions

PH begins with early-stage CKD, and PH severity is not related to CKD progression. A higher pulmonary artery pressure and an older age are associated with an increased risk of death.

Risk Factors of Pulmonary Hypertension in Patients on Hemodialysis: A Single Center Study

Introduction

Pulmonary hypertension (PH) is an underestimated cardiovascular consequence and a mortality predictor in patients on hemodialysis (HD). Thus, we studied its prevalence, risk factors, association with inflammation/oxidative stress, and cardiac changes in HD patients.

Methods

This was a single-center cross-sectional observational study conducted at a tertiary care hospital. Patients aged >18 years on hemodialysis for at least three months were included and divided into those with and without PH; patients with secondary causes for PH were excluded. Clinical characteristics, HD-related factors, lab parameters (C-reactive protein and malondialdehyde with thiol assay were used as markers of inflammation and oxidative stress, respectively), and echocardiography details were compared. PH was defined as a mean pulmonary artery pressure of >25 mmHg at rest, and it was further divided as mild (25–40 mmHg), moderate (40–60 mmHg), and severe (>60 mmHg).

Results

Of 52 patients, 28 patients had PH (mild 24, moderate 4, and none had severe PH) with prevalence of 54%. No difference was found in clinical characteristics, dialysis-related factors, biochemical parameters including inflammation (C-reactive protein; p=0.76), or oxidative stress (thiol; p=0.36 and MDA; p=0.46) between the groups. When compared to individuals without PH, HD patients with PH exhibited significantly more mitral regurgitation (p=0.002).

Conclusion

Hemodialysis patients have a high prevalence of PH. PH was significantly associated with the presence of mitral regurgitation on echocardiography. Our study did not find differences in traditional risk factors, HD-related factors, and inflammation/oxidative markers between the groups with and without PH.

Pulmonary Hypertension in Chronic Kidney Disease

There is a high prevalence of pulmonary hypertension in chronic kidney disease (CKD), with rates increasing as glomerular filtration rate declines. Pulmonary hypertension is associated with a higher risk of cardiovascular events and mortality in non-dialysis-dependent CKD stages 3 to 5, dialysis-dependent CKD, as well as kidney transplant recipients. The pathophysiology of pulmonary hypertension in CKD is multifactorial and includes higher pulmonary capillary wedge pressure caused by ischemic heart disease and cardiomyopathy, higher cardiac output caused by anemia and arteriovenous access used for hemodialysis, as well as potentially higher pulmonary vascular resistance. Treatment should focus on the underlying cause.

KDOQI US Commentary on the 2020 KDIGO Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation

Evaluation of patients for kidney transplant candidacy is a comprehensive process that involves a detailed assessment of medical and surgical issues, psychosocial factors, and patients' physical and cognitive abilities with an aim of balancing the benefits of transplantation and potential risks of surgery and long-term immunosuppression. There is considerable variability among transplant centers in their approach to evaluation and decision-making regarding transplant candidacy. The 2020 KDIGO (Kidney Disease: Improving Guidelines Outcome) clinical practice guideline on the evaluation and management of candidates for kidney transplantation provides practice recommendations that can serve as a useful reference guide to transplant professionals. The guideline, covering a broad range of topics, was developed by an international group of experts from transplant and nephrology through a review of literature published until May 2019. A work group of US transplant nephrologists convened by NKF-KDOQI (National Kidney Foundation-Kidney Disease Quality Initiative) chose key topics for this commentary with a goal of presenting a broad discussion to the US transplant community. Each section of this article has a summary of the key KDIGO guideline recommendations, followed by a brief commentary on the recommendations, their clinical utility, and potential implementation challenges. The KDOQI work group agrees broadly with the KDIGO recommendations but also recognizes and highlights the decision-making challenges that arise from lack of high-quality evidence and the need to balance equity with utility of organ transplantation.

Intravenous iron therapy and the cardiovascular system: risks and benefits

Anaemia is a common complication of chronic kidney disease (CKD). In this setting, iron deficiency is frequent because of the combination of increased iron needs to sustain erythropoiesis with increased iron losses. Over the years, evidence has accumulated on the involvement of iron in influencing pulmonary vascular resistance, endothelial function, atherosclerosis progression and infection risk. For decades, iron therapy has been the mainstay of therapy for renal anaemia together with erythropoiesis-stimulating agents (ESAs). Despite its long-standing use, grey areas still surround the use of iron therapy in CKD. In particular, the right balance between either iron repletion with adequate therapy and the avoidance of iron overload and its possible negative effects is still a matter of debate. This is particularly true in patients having functional iron deficiency. The recent Proactive IV Iron Therapy in Haemodialysis Patients trial supports the use of intravenous (IV) iron therapy until a ferritin upper limit of 700 ng/mL is reached in haemodialysis patients on ESA therapy, with short dialysis vintage and minimal signs of inflammation. IV iron therapy has also been proven to be effective in the setting of heart failure (HF), where it improves exercise capacity and quality of life and possibly reduces the risk of HF hospitalizations and cardiovascular deaths. In this review we discuss the risks of functional iron deficiency and the possible benefits and risks of iron therapy for the cardiovascular system in the light of old and new evidence.