Thrombosis in end-stage renal disease

Assessment of photobiomodulation in response to the microcirculation in arteriovenous fistula for hemodialysis patient

Background

Management of blood flow in arteriovenous fistula (AVF) is a critical clinical issue for hemodialysis (HD) patients.

Objectives

To determine the effect of microcirculation of AVF in HD patients with photobiomodulation (PBM).

Methods

Twenty HD patients were enrolled in this study. PBM was used to radiate the palm of HD patients at a total dose of 126 J, and the microcirculatory analysis in AVF was investigated.

Results

Among the patients <65 years old, there is an increase of 2.31% and 1.37% in the average velocity and flux in AVF, respectively. This increase is higher than those observed in patients aged >65 years old. Additionally, the cumulative effect of the 830 nm laser was observed for at least 10 min, resulting in continuous increases of 3.16% in velocity and 1.59% in flux for HD patients <65 years old. On the contrary, the average velocity and flux in AVF increased in patients who had undergone HD for <6 years.

Conclusions

In this study, the age and the duration of HD treatment are the two factors that influence microcirculation in HD patients with PBM. The results suggest that PBM could be used to improve the average velocity and flux in AVF, particularly for younger patients with shorter HD treatment durations.

Association of frailty and chronic limb-threatening ischemia in patients on maintenance hemodialysis: a prospective cohort study

Chronic limb-threatening ischemia (CLTI) is a prevalent yet unpredictable complication among patients undergoing hemodialysis, and frailty is linked to adverse outcomes in this population. This study examined the influence of clinical factors on vascular events in patients undergoing hemodialysis. This multicenter prospective cohort study included patients undergoing maintenance hemodialysis since January 2008. The initial cohort consisted of 1,136 patients, 828 of whom successfully underwent a frailty test. CLTI events were recorded at 3-month intervals until December 31, 2022. The mean patient age was 67 years, and 48% were female. Overall, 34% of participants were frail, 38% pre-frail, and 28% not frail. Frailty phenotype was associated with age, female sex, low educational level, diabetes mellitus, and history of stroke. During a median follow-up of 1461 days, 104 patients experienced CLTI events (not frail, 6.5%; pre-frail, 11%; frail, 20%; P < 0.001). Frail patients had a higher risk of CLTI than those who were non-frail (hazard ratio (HR) 3.94; 95% confidence interval (CI) 2.22-6.99; P < 0.001). After multivariable adjustment for age and comorbidities, frailty remained significantly associated with CLTI (HR 3.26; 95% CI 1.76-5.85; P < 0.001). Conclusively, these findings highlight the risk of CLTI in frail patients undergoing hemodialysis.

Severe Hyporesponsiveness to Erythropoiesis-Stimulating Agents in Patients on Chronic Hemodialysis-Reconsidering the Relationship with Thrombo-Inflammation and Oxidative Stress

BACKGROUND/OBJECTIVES

Besides a multitude of consequences patients on chronic renal replacement therapy have, anemia is one of the most prominent factors making a significant number of patients dependent on erythropoiesis-stimulating agent (ESA) therapy. The aim of this study was to examine the relationship between the levels of a broad spectrum of thrombo-inflammatory and oxidative stress-related biomarkers and the presence and level of ESA hyporesponsiveness in patients undergoing regular chronic hemodialysis.

METHODS

This cross-sectional study included 96 patients treated with chronic hemodialysis. Levels of several thrombo-inflammatory and oxidative stress-related biomarkers, as well as demographic, clinical, and laboratory analyses, were collected and analyzed based on the calculated value of the ESA-hyporesponsiveness index (EHRI).

RESULTS

In the analyzed sample, 58 patients received ESAs. Of all the investigated parameters, only body mass index (BMI), level of plasminogen activator inhibitor-1, and level of L-type fatty acid binding protein (L-FABP) were observed as significant predictors of EHRI. A significant diagnostic potential for ESA resistance has been observed in BMI and L-FABP between ESA-resistant and ESA-non-resistant groups of patients (p = 0.004, area under the curve 0.763 and p = 0.014, area under the curve 0.712, respectively) with the cut-off values of 25.46 kg/m2 and 5355.24 ng/mL, respectively. Having a BMI of 25.46 kg/m2 or less and an L-FABP level higher than 5355.24 ng/mL were observed as significant predictors of ESA resistance (odds ratio 9.857 and 6.125, respectively).

CONCLUSIONS

EHRI was positively predicted by low BMI and high levels of plasminogen activator inhibitor-1 and L-FABP. High levels of L-FABP and low BMI have been observed as strong predictors of ESA resistance.

Anticoagulation in Chronic Kidney Disease

The nuanced landscape of anticoagulation therapy in patients with chronic kidney disease (CKD) presents a formidable challenge, intricately balancing the dual hazards of hemorrhage and thrombosis. These patients find themselves in a precarious position, teetering on the edge of these risks due to compromised platelet functionality and systemic disturbances within their coagulation frameworks. The management of such patients necessitates a meticulous approach to dosing adjustments and vigilant monitoring to navigate the perilous waters of anticoagulant therapy. This is especially critical considering the altered pharmacokinetics in CKD, where the clearance of drugs is significantly impeded, heightening the risk of accumulation and adverse effects. In the evolving narrative of anticoagulation therapy, the introduction of direct oral anticoagulants (DOACs) has heralded a new era, offering a glimmer of hope for those navigating the complexities of CKD. These agents, with their promise of easier management and a reduced need for monitoring, have begun to reshape the contours of care, particularly for patients not yet on dialysis. However, this is not without its caveats. The application of DOACs in the context of advanced CKD remains a largely uncharted territory, necessitating a cautious exploration to unearth their true potential and limitations. Moreover, the advent of innovative strategies such as left atrial appendage occlusion (LAAO) underscores the dynamic nature of anticoagulation therapy, potentially offering a tailored solution for those at the intersection of CKD and elevated stroke risk. Yet the journey toward integrating such advancements into standard practice is laden with unanswered questions, demanding rigorous investigation to illuminate their efficacy and safety across the spectrum of kidney disease. In summary, the management of anticoagulation in CKD is a delicate dance, requiring a harmonious blend of precision, caution, and innovation. As we venture further into this complex domain, we must build upon our current understanding, embracing both emerging therapies and the need for ongoing research. Only then can we hope to offer our patients a path that navigates the narrow strait between bleeding and clotting, toward safer and more effective care.

Safety and efficacy of apixaban versus warfarin in peritoneal dialysis patients with non-valvular atrial fibrillation: protocol for a prospective, randomised, open-label, blinded endpoint trial (APIDP2)

INTRODUCTION

Several randomised controlled trials have demonstrated that novel oral anticoagulants are safer compared with vitamin K antagonists for the management of non-valvular atrial fibrillation (NVAF) to prevent thromboembolic events in the general population. There is a growing interest in the use of apixaban in patients with end-stage renal disease (ESRD) undergoing peritoneal dialysis (PD) but there is a lack of randomised data in this population.

METHODS AND ANALYSIS

APIDP2 is a prospective parallel, randomised, open-label, blinded endpoint trial involving patients with ESRD undergoing chronic PD who have NVAF. A total of 178 participants will be recruited from 20 French PD centres. Eligible patients will be randomly assigned to receive either apixaban at a reduced dose of 2.5 mg two times per day (dose determined with the previous pharmacokinetic study APIDP1) or dose-adjusted to international normalised ratio (INR) target (2-3) coumadin therapy. Anticoagulation to prevent thromboembolic events will be initiated or changed according to the randomisation for a duration of 1 year. The primary outcome is a major or clinically relevant non-major bleeding from randomisation up to month 12, assessed according to the International Society on Thrombosis and Haemostasis Score. Secondary outcomes encompass an efficacy composite criterion combining stroke or transient ischaemic attack (TIA), cardiovascular death and thrombosis including myocardial infarction cumulated at 12 months. Bleeding events will be also classified according to Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) and Thrombolysis In Myocardial Infarction (TIMI) criteria and pharmacodynamics outcomes will evaluate the time within the INR target range of 2-3 in the warfarin arm over 1 year, and anti-Xa apixaban activity in case of bleeding events and at 1 month, 6 months and 12 months of follow-up in the apixaban arm. To demonstrate that apixaban is safer than warfarin at 1 year, assuming two interim analyses after 60 and 118 patients, a bilateral alpha risk of 5% and a power of 80%, 178 patients are needed in this randomised trial (effect size found from the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) Study among patients with creatinine clearance 25-30 ml/min), that is, 89 patients per group.

ETHICS AND DISSEMINATION

The study has been approved by the ethics committee Comité de Protection des Personnes Sud Est III - Lyon - FRANCE, CT number 2023-507544-37-00. Written informed consent is required for each participant. Findings will be presented at scientific meetings and published in peer-reviewed journals.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT06045858; European Clinical Trial System, CT number 2023-507544-37-00.

Long-term outcomes following thrombolysis of arteriovenous grafts

BACKGROUND

Thrombolysis for arteriovenous grafts (AVG) yields high technical success rates, however, long-term outcomes are unclear. We conducted a multicenter retrospective cohort study to analyze 5-year patency rates following AVG thrombolysis.

METHODS

All patients who underwent AVG thrombolysis between 2005 and 2015 at three academic hospitals were included. Prospectively maintained institutional nephrology and radiology databases were used to record demographic, clinical, and AVG characteristics. The primary outcome was primary patency, defined as AVG access survival without re-intervention including angioplasty ± stent with/without re-thrombolysis. Secondary outcomes were assisted primary patency and cumulative patency, defined as AVG access survival until re-thrombosis requiring re-thrombolysis or abandonment, respectively. Technical success was defined as restoration of flow with <30% residual stenosis. Patients were followed until 2017. Patency rates were assessed using Kaplan-Meier survival analysis and Cox proportional hazards were calculated to determine associations between covariates and patency loss.

RESULTS

Seventy-four patients underwent AVG thrombolysis during the study period with a median follow-up period of 21.4 (IQR 8.3-42.8) months. The average age was 58.6 years with a high rate of comorbidities, including hypertension (82.4%) and diabetes (54.1%). Thrombolysis technical success was 96%. There were 147 re-interventions in 46 patients, of which 98 were re-thrombolysis (mean re-intervention rate of 1.27/patient/year). Primary patency at 1, 3, and 5 years were 43.2%, 20.2%, and 7.7%. Assisted primary patency at 1, 3, and 5 years were 47.5%, 20.2%, and 7.7%. Cumulative patency at 1, 3, and 5 years were 75.0%, 38.8%, and 22.6%. Cox proportional hazards analysis demonstrated no associations between demographic, clinical, and procedural characteristics and patency rates.

CONCLUSIONS

Despite a high technical success rate, thrombolysis for AVG dysfunction is associated with poor long-term patency. Future studies are needed to determine risk factors for re-thrombosis to identify patients who will benefit from AVG thrombolysis in the long-term.

Antiphospholipid Antibodies Associated with Native Arteriovenous Fistula Complications in Hemodialysis Patients: A Comprehensive Review of the Literature

Antiphospholipid antibody (aPL)-persistent positivity is frequent in hemodialysis (HD) patients. Native arteriovenous fistula (AVF) complications such as stenosis and thrombosis are among the most important causes of morbidity and mortality in hemodialysis patients. The association between aPL positivity and AVF thrombosis seems to now be well established. However, whether aPL positivity is associated with other AVF complications, such as maturation failure or stenosis, is not well known. Given the significant impact of AVF failure on patient's prognosis, it is of interest to further investigate this particular point in order to improve prevention, surveillance and treatment, and, ultimately, the patient's outcome. This literature review aims to report the recent literature on aPL-associated native AVF complications.

Dialysis in Pregnancy: An Update Review

Chronic kidney disease and end-stage kidney disease (ESKD) are important public health problems with increased rates of morbidity, mortality, and social costs. Pregnancy is rare in patients with ESKD, with reduced fertility rates in women undergoing dialysis. Although current advances have led to an increase in live births in pregnant dialysis patients, this modality still has an increased risk of multiple adverse events in pregnant women. Despite these existing risks, large-scale studies investigating the management of pregnant women on dialysis are lacking, resulting in the absence of consensus guidelines for this patient group. In this review, we aimed to present the effects of dialysis during pregnancy. We first discuss pregnancy outcomes in dialysis patients and the development of acute kidney injury during pregnancy. Then, we discuss our recommendations for the management of pregnant dialysis patients, including the maintenance of pre-dialysis blood urea nitrogen levels, the ideal frequency and duration of hemodialysis sessions, as well as the modality of renal replacement therapies, the difficulty of maintaining peritoneal dialysis in the third trimester of pregnancy, and optimization of prepregnancy modifiable risk factors. Finally, we present our recommendations for future studies investigating dialysis among pregnant patients.

Pulmonary embolism in an ESRD patient following minimal venotomy and milking for salvage of dysfunctional autogenous arteriovenous fistula

Pulmonary embolism can be a complication following an attempted salvage of a dysfuctional arteriovenous fistula (AVF). We report a case of bilateral pulmonary embolism in a patient with underlying pericardial effusion who, following minimal venotomy and milking of the AVF, developed sudden and significant respiratory distress, and later improved.

Effect of dialysis modalities on risk of hospitalization for gastrointestinal bleeding

Dialysis patients are at risk of both thromboembolic and bleeding events, while thromboembolism prevention and treatment may confer a risk of major bleeding. Gastrointestinal (GI) bleeding is a great concern which can result in high subsequent mortality rates. Our object was to clarify whether hemodialysis (HD) and peritoneal dialysis (PD) confer different incidence of GI bleeding, and further assist individualized decision-making on dialysis modalities. We conducted a population-based retrospective cohort study which included all incident dialysis patients above 18 years old derived from the National Health Insurance database from 1998 to 2013 in Taiwan. 6296 matched pairs of HD and PD patients were identified. A propensity score matching method was used to minimize the selection bias. The adjusted hazard ratio for GI bleeding was 1.13 times higher in the HD group than in the PD group, and data from the unmatched cohort and the stratified analysis led to similar results. Among subgroup analysis, we found that the use of anticoagulants will induce a much higher incidence of GI bleeding in HD patients as compared to in PD patients. We concluded that PD is associated with a lower GI bleeding risk than HD, and is especially preferred when anticoagulation is needed.

Asymptomatic pulmonary thromboembolism due to hemodialisys catheter thrombosis: case series and literature review

Right atrial thrombus is commonly associated to catheters. Catheter-related right atrial thrombus (CRAT) in hemodialysis patients frequently presents as pulmonary embolism. Although CRAT is sometimes asymptomatic, even in these cases it is associated with worse prognosis. The management strategy for CRAT is not well established, however, along with catheter removal, anticoagulation, thrombolysis, and surgical thrombectomy may be performed. Suspicion of asymptomatic pulmonary embolism associated to CRAT is important in order to perform proper treatment. The authors of this article report two cases of asymptomatic pulmonary thromboembolism due to CRAT in hemodialysis patients and perform a review of the literature.

HD, Sarma P, Srikanth L, V. SK. Thrombophilic risk factors and ABO blood group profile for arteriovenous access failure in end stage kidney disease patients: a single-center experience

INTRODUCTION

Thrombosis of fistula occurs most frequently in end-stage kidney disease (ESKD) patients receiving hemodialysis. However, the role of thrombophilia in arteriovenous fistula (AVF) failure has not been well established. Hence, this study was aimed at assessing the roles of hereditary and acquired thrombophilic factors in association with AVF failure among patients with ESKD undergoing hemodialysis.

METHODS

A cross-sectional study was conducted on 100 ESKD patients, of whom 50 patients with well-functioning AVFs with no fistula failures earlier were enrolled as Group 1, and 50 patients who have had AVF failure were enrolled as Group 2. The hereditary factors as factor V Leiden, factor XIII, prothrombin, and methylene tetrahydrofolate reductase and the acquired factors as lipoprotein (a), fibrinogen, homocysteine, and anticardiolipin antibodies IgG and IgM were studied.

RESULTS

Among the hereditary factors, no statistically significant difference was observed in relation to factor V Leiden and Prothrombin (p > 0.05). However, for factor XIII and methylene tetrahydrofolate reductase, a statistically significant difference was observed between patients with well-functioning AVFs and patients who have had AVF failure (p < 0.05). We found a statistically significant increase in all the acquired factors in patients who have had AVF failure in comparison with patients with well-functioning AVFs (p < 0.001). Association between ABO blood groups and thrombophilic factors showed significant association between factor V Leiden, anticardiolipin antibody IgG and IgM and ABO blood groups (p < 0.05), whereas none of the other thrombophilic factors showed significant association (p > 0.05).

CONCLUSION

Thus, our study suggests significant role of acquired factors in causing AVF failure.

Targeting ferroptosis in ischemia/reperfusion renal injury

Renal I/R injury is a severe medical condition contributing to acute kidney injury (AKI), leading to rapid kidney dysfunction and high mortality rates. It is generally observed during renal transplantation, shock, trauma, and urologic and cardiovascular surgery, for which there is no effective treatment. Cell death and damage are commonly linked to I/R. Cell death triggered by iron-dependent lipid peroxidation, such as ferroptosis, has been demonstrated to have a significant detrimental effect in renal IRI models, making it a new type of cell death currently being researched. Ferroptosis is a nonapoptotic type of cell death that occurs when free iron enters the cell and is a critical component of many biological processes. In ferroptosis-induced renal I/R injury, iron chelators such as Deferasirox, Deferiprone, and lipophilic antioxidants are currently suppressed lipid peroxidation Liproxstatin-1 (Lip-1), Ferrostatin-1 along with antioxidants like vitamin and quercetin. Ferroptosis has been considered a potential target for pharmaceutical intervention to alleviate renal IRI-associated cell damage. Thus, this review emphasized the role of ferroptosis and its inhibition in renal IRI. Also, Pharmacological modulation of ferroptosis mechanism in renal I/R injury has been conferred. Graphical abstract.

Predictive Value of HAS-BLED Score Regarding Bleeding Events and Graft Survival following Renal Transplantation

Objective: Due to the high prevalence and incidence of cardio- and cerebrovascular diseases among dialysis-dependent patients with end-stage renal disease (ERSD) scheduled for kidney transplantation (KT), the use of antiplatelet therapy (APT) and/or anticoagulant drugs in this patient population is common. However, these patients share a high risk of complications, either due to thromboembolic or bleeding events, which makes adequate peri- and post-transplant anticoagulation management challenging. Predictive clinical models, such as the HAS-BLED score developed for predicting major bleeding events in patients under anticoagulation therapy, could be helpful tools for the optimization of antithrombotic management and could reduce peri- and postoperative morbidity and mortality. Methods: Data from 204 patients undergoing kidney transplantation (KT) between 2011 and 2018 at the University Hospital Leipzig were retrospectively analyzed. Patients were stratified and categorized postoperatively into the prophylaxis group (group A)—patients without pretransplant anticoagulation/antiplatelet therapy and receiving postoperative heparin in prophylactic doses—and into the (sub)therapeutic group (group B)—patients with postoperative continued use of pretransplant antithrombotic medication used (sub)therapeutically. The primary outcome was the incidence of postoperative bleeding events, which was evaluated for a possible association with the use of antithrombotic therapy. Secondary analyses were conducted for the associations of other potential risk factors, specifically the HAS-BLED score, with allograft outcome. Univariate and multivariate logistic regression as well as a Cox proportional hazard model were used to identify risk factors for long-term allograft function, outcome and survival. The calibration and prognostic accuracy of the risk models were evaluated using the Hosmer−Lemshow test (HLT) and the area under the receiver operating characteristic curve (AUC) model. Results: In total, 94 of 204 (47%) patients received (sub)therapeutic antithrombotic therapy after transplantation and 108 (53%) patients received prophylactic antithrombotic therapy. A total of 61 (29%) patients showed signs of postoperative bleeding. The incidence (p < 0.01) and timepoint of bleeding (p < 0.01) varied significantly between the different antithrombotic treatment groups. After applying multivariate analyses, pre-existing cardiovascular disease (CVD) (OR 2.89 (95% CI: 1.02−8.21); p = 0.04), procedure-specific complications (blood loss (OR 1.03 (95% CI: 1.0−1.05); p = 0.014), Clavien−Dindo classification > grade II (OR 1.03 (95% CI: 1.0−1.05); p = 0.018)), HAS-BLED score (OR 1.49 (95% CI: 1.08−2.07); p = 0.018), vit K antagonists (VKA) (OR 5.89 (95% CI: 1.10−31.28); p = 0.037), the combination of APT and therapeutic heparin (OR 5.44 (95% CI: 1.33−22.31); p = 0.018) as well as postoperative therapeutic heparin (OR 3.37 (95% CI: 1.37−8.26); p < 0.01) were independently associated with an increased risk for bleeding. The intraoperative use of heparin, prior antiplatelet therapy and APT in combination with prophylactic heparin was not associated with increased bleeding risk. Higher recipient body mass index (BMI) (OR 0.32 per 10 kg/m2 increase in BMI (95% CI: 0.12−0.91); p = 0.023) as well as living donor KT (OR 0.43 (95% CI: 0.18−0.94); p = 0.036) were associated with a decreased risk for bleeding. Regarding bleeding events and graft failure, the HAS-BLED risk model demonstrated good calibration (bleeding and graft failure: HLT: chi-square: 4.572, p = 0.802, versus chi-square: 6.52, p = 0.18, respectively) and moderate predictive performance (bleeding AUC: 0.72 (0.63−0.79); graft failure: AUC: 0.7 (0.6−0.78)). Conclusions: In our current study, we could demonstrate the HAS-BLED risk score as a helpful tool with acceptable predictive accuracy regarding bleeding events and graft failure following KT. The intensified monitoring and precise stratification/assessment of bleeding risk factors may be helpful in identifying patients at higher risks of bleeding, improved individualized anticoagulation decisions and choices of antithrombotic therapy in order to optimize outcome after kidney transplantation.

Creating patient-specific vein models to characterize wall shear stress in hemodialysis population

End-Stage Renal Disease (ESRD) patients require arteriovenous fistulas (AVF) that allow a mature vein to withstand hemodialysis. Unfortunately, venous thrombosis and stenosis in the cephalic vein arch after AVF placement is common and heavily influenced by hemodynamics. To better assess forces and flow behavior in the cephalic arch, we have built patient-specific millifluidic models that allow us to explore the complex interplay between patient-specific vein geometry and fluctuating hemodynamics. These 3D models were created from patient-specific intravascular ultrasound and venogram images obtained three- and twelve-months post AVF creation and fabricated into soft elastomer-based millifluidic devices. Geometric validation of fabricated phantom millifluidic device shows successful replication of original computational 3D model. Millifluidic devices were perfused with a blood-mimicking fluid containing fluorescent tracer beads under steady-state physiologic cephalic vein flow conditions (20 mL/min). Particle image velocimetry was employed to calculate wall shear stress (WSS) across the cephalic arches. Experimental WSS profile evaluation reveals that the physiologic cephalic arch model yields WSS values within physiologic range [76–760 mPa]. Moreover, upon comparing WSS profiles across all models, it is noticeable that WSS values increase as vein diameter decreases, which further supports employed experimental and analysis strategy. The presented millifluidic devices show promise for experimental WSS characterization under pathologic flow conditions to contrast from calculated physiologic hemodynamics and better understand WSS influence on thrombosis and stenosis in hemodialysis patients.

Acute ischemic events after COVID-19 infection in patients undergoing maintenance hemodialysis

INTRODUCTION

Patients undergoing maintenance hemodialysis have unique risk factors that render them prone to ischemia. To what extent coronavirus infectious disease 2019 (COVID-19) increases this risk is unknown.

METHODS

This retrospective cohort study included incident patients undergoing maintenance hemodialysis from one city in Turkey. A comparison was made between those who developed COVID-19 and those who did not for clinical variables. Independent predictors of acute ischemic complications in the total cohort were assessed using the logistic regression analysis.

FINDINGS

By the start of the pandemic in Turkey, 33 of 154 (21.4%) patients developed COVID-19. During the 15 months of median follow-up after the start of the pandemic, 16 (10.4%) patients developed acute ischemic complications. These included acute myocardial infarction (n = 10), acute ischemic stroke (n = 4), acute peripheral artery thrombosis (n = 1), and pulmonary thromboembolism (n = 1). Overall, acute ischemic events occurred more commonly in those who experienced COVID-19 (24.2% vs. 6.6%, p = 0.007). Ischemia-free survival was significantly shorter in the COVID-19 group (p = 0.001). In the eight patients with COVID-19, ischemic complications emerged at a median 185 (range 21-306) days after the diagnosis of COVID-19. While age, dialysis vintage, and experience of COVID-19 were found as factors significantly associated with the development of acute ischemic events in univariate analysis, the association between COVID-19 and acute ischemia remained significant in the multivariate regression model (odds ratio 3.99, 95% CI [1.3, 12.13], p = 0.016). During the pandemic, 23 (14.9%) patients died. Overall survival was significantly shorter among those who developed acute ischemic event (p < 0.001). The hazard ratio of acute ischemic event for death was 6.76 (95% CI [2.92, 15.66], p < 0.001).

DISCUSSION

A considerable number of patients undergoing maintenance hemodialysis developed acute ischemic complications weeks to months after the resolution of COVID-19. Hemodialysis patients appear to require specific interventions in order to prevent subsequent acute ischemic events after the resolution of COVID-19.

Biomarkers in the clinical management of patients with atrial fibrillation and heart failure

Atrial fibrillation (AF) and heart failure (HF) are two cardiovascular diseases with an increasing prevalence worldwide. These conditions share common pathophysiologiesand frequently co-exit. In fact, the occurrence of either condition can 'cause' the development of the other, creating a new patient group that demands different management strategies to that if they occur in isolation. Regardless of the temproral association of the two conditions, their presence is linked with adverse cardiovascular outcomes, increased rate of hospitalizations, and increased economic burden on healthcare systems. The use of low-cost, easily accessible and applicable biomarkers may hasten the correct diagnosis and the effective treatment of AF and HF. Both AF and HF effect multiple physiological pathways and thus a great number of biomarkers can be measured that potentially give the clinician important diagnostic and prognostic information. These will then guide patient centred therapeutic management. The current biomarkers that offer potential for guiding therapy, focus on the physiological pathways of miRNA, myocardial stretch and injury, oxidative stress, inflammation, fibrosis, coagulation and renal impairment. Each of these has different utility in current clinincal practice.

Indoleamine 2,3-dioxygenase-1, a Novel Therapeutic Target for Post-Vascular Injury Thrombosis in CKD

BACKGROUND

CKD, characterized by retained uremic solutes, is a strong and independent risk factor for thrombosis after vascular procedures . Urem ic solutes such as indoxyl sulfate (IS) and kynurenine (Kyn) mediate prothrombotic effect through tissue factor (TF). IS and Kyn biogenesis depends on multiple enzymes, with therapeutic implications unexplored. We examined the role of indoleamine 2,3-dioxygenase-1 (IDO-1), a rate-limiting enzyme of kynurenine biogenesis, in CKD-associated thrombosis after vascular injury.

METHODS

IDO-1 expression in mice and human vessels was examined. IDO-1-/- mice, IDO-1 inhibitors, an adenine-induced CKD, and carotid artery injury models were used.

RESULTS

Both global IDO-1-/- CKD mice and IDO-1 inhibitor in wild-type CKD mice showed reduced blood Kyn levels, TF expression in their arteries, and thrombogenicity compared with respective controls. Several advanced IDO-1 inhibitors downregulated TF expression in primary human aortic vascular smooth muscle cells specifically in response to uremic serum. Further mechanistic probing of arteries from an IS-specific mouse model, and CKD mice, showed upregulation of IDO-1 protein, which was due to inhibition of its polyubiquitination and degradation by IS in vascular smooth muscle cells. In two cohorts of patients with advanced CKD, blood IDO-1 activity was significantly higher in sera of study participants who subsequently developed thrombosis after endovascular interventions or vascular surgery.

CONCLUSION

Leveraging genetic and pharmacologic manipulation in experimental models and data from human studies implicate IS as an inducer of IDO-1 and a perpetuator of the thrombotic milieu and supports IDO-1 as an antithrombotic target in CKD.

Association of whole blood viscosity with thrombus presence in patients undergoing transoesophageal echocardiography

Whole blood viscosity (WBV) is considered as a reasonable proxy measure of blood flow, and it has been investigated in different cohort settings, including in patients with deep venous thrombosis, arterial thrombosis, acute stent thrombosis, and left ventricular apical thrombus formation following acute coronary syndrome. To determine the association between WBV and the presence of thrombus in the left atrium (LA) or left atrial appendage (LAA) in individuals who had transoesophageal echocardiography (TEE). The clinical data from 262 consecutive patients who had TEE at our facility were included in this retrospective cohort study. WBV was determined at both a high shear rate (HSR) and low shear rate (LSR) using hematocrit and total protein levels. In 22 cases (8.3%), the thrombus was detected. According to multivariable analyses, WBV at HSR and LSR were independently linked with thrombus detection in TEE. In a receiver operating characteristic (ROC) analysis, the area under curve (AUC) values of WBV at HSR and LSR were 0.77 and 0.76, respectively. To predict the presence of thrombus in TEE; the ideal value of WBV at HSR was > 16.6 with 81% sensitivity and 69% specificity and the ideal value of WBV at LSR was > 51.4 with 81% sensitivity and 70% specificity. This was the first study to indicate that significantly higher levels of WBV at both the HSR and LSR were linked to the presence of thrombus in the LA and LAA in cases who underwent TEE.

Comparison of long-term clinical outcomes among zotarolimus-, everolimus-, and biolimus-eluting stents in acute myocardial infarction patients with renal impairment

BACKGROUND

It is important to determine the best drug-eluting stent (DES) for acute myocardial infarction (AMI) in patients with renal impairment. In this studythe outcomes of everolimus-eluting stents (EESs), zotarolimus-eluting stents (ZESs) and biolimus-eluting stents (BESs) were evaluated.

METHODS

From the Korea Acute Myocardial Infarction-National Institutes of Health registry, a total of 1,470 AMI patients with renal impairment undergoing percutaneous coronary intervention (PCI) were enrolled (816 with EES, 345 with ZES, and 309 with BES). Renal impairment was defined as creatinine clearance < 60 mL/min/1.73 m² estimated by the Cockcroft-Gault method. Major adverse cardiac and cerebrovascular events were determined as the composite of all-cause death, non-fatal myocardial infarction (MI), cerebrovascular accident, any revascularization, rehospitalization and stent thrombosis. All clinical outcomes were analyzed.

RESULTS

The baseline characteristics of the patients revealed no significant difference between the three groups, except for Killip classification > 2, beta-blockers, lesion type, vascular approach, staged PCI, left main coronary artery (LMCA) complex lesions, LMCA PCI, and the number and length of implanted stents. In the Kaplan-Meier analysis, similar clinical outcomes were derived from the unadjusted data between the three DES groups. However, after the inverse probability of treatment weighting, a statistically significant difference was found in non-fatal MI, which implied a higher incidence of non-fatal MI in the ZES group than in the other two DES groups.

CONCLUSIONS

In AMI patients with renal impairment, there was no significant difference between the three stent groups in terms of long-term clinical outcomes, except for non-fatal MI.

Direct oral anticoagulants for the treatment of pulmonary embolism in patients with renal impairment

Pulmonary embolism (PE) is associated with adverse outcomes and substantial morbidity and mortality. Patients with PE often have renal impairment because of shared risk factors and close links between the renal and cardiovascular systems. Furthermore, patients with PE and renal impairment are at increased risk of recurrent thrombosis. Therefore, anticoagulation is crucial to treat the acute event, prevent recurrent venous thromboembolism (VTE), and optimize patient outcomes. However, when treated with an anticoagulant, patients with renal impairment also have an elevated risk of bleeding. Direct oral anticoagulants (DOACs) are the first-choice treatment for acute VTE in eligible patients. However, as all DOACs have a degree of renal excretion, the management of anticoagulation therapy can be more complicated in patients with renal impairment. This review provides an overview of the clinical challenges of managing anticoagulation in patients with PE and renal impairment and explores the optimal practice management of this special patient group.

Hereditary thrombophilia and thrombosis of tunneled hemodialysis catheters: A single center study

Introduction: Vascular access thrombosis increases the risk of mortality and morbidity in end-stage renal disease (ESRD) patients on hemodialysis (HD). This study aimed to evaluate hereditary thrombophilia factors in HD patients and its association with tunneled cuffed catheters’ thrombosis.

Methods: In this cross-sectional study, 60 consecutive patients with ESRD on HD with tunneled cuffed catheters were selected. Inherited thrombophilia factors (Anti-thrombin III, Protein C, Protein S, and Factor V Leiden) were measured and the patients were followed for 3 months to evaluate the incidence of catheter-related thrombosis. The association between these factors and catheter thrombosis was assessed.

Results: The mean age of patients was 60.30 ± 8.69 years. Forty-seven patients (78.30%) were female and thirteen patients (21.70%) were male. The most common cause of ESRD was diabetes mellitus (41.67%). The most catheter site was the right internal jugular vein (55%). There were 22 (36.67%) and 8 (13.33%) cases of thrombosis and mortality, respectively. The association between hereditary thrombophilia factors and catheter thrombosis was not statistically significant (P > 0.05).

Conclusion: In this small group of our patients, the frequency of hereditary thrombophilia was not significantly different between those with and without thrombosis of tunneled HD catheter.

Terminal Phase Components of the Clotting Cascade in Patients with End-Stage Renal Disease Undergoing Hemodiafiltration or Hemodialysis Treatment

Hemostasis disorder in patients with end-stage renal disease (ESRD) is frequently associated with bleeding diathesis but it may also manifest in thrombotic complications. Analysis of individual coagulation and fibrinolytic factors may shed light on the background of this paradox situation. Here we explored components essential for fibrin formation/stabilization in ESRD patients being on maintenance hemodiafiltration (HDF) or hemodialysis (HD). Pre-dialysis fibrinogen, factor XIII (FXIII) antigen concentrations and FXIII activity were elevated, while α₂-plasmin inhibitor (α₂PI) activity decreased. The inflammatory status, as characterized by C-reactive protein (CRP) was a key determinant of fibrinogen concentration, but not of FXIII and α₂PI levels. During a 4-h course of HDF or HD, fibrinogen concentration and FXIII levels gradually elevated. When compensated for the change in plasma water, i.e., normalized for plasma albumin concentration, only FXIII elevation remained significant. There was no difference between HDF and HD treatments. Individual HDF treatment did not influence α₂PI activity, however after normalization it decreased significantly. HD treatment had a different effect, α₂PI activities became elevated but the elevation disappeared after normalization. Elevated fibrinogen and FXIII levels in ESRD patients might contribute to the increased thrombosis risk, while decreased α₂PI activity might be associated with elevated fibrinolytic potential.

Molecular Mechanisms Underlying the Cardiovascular Toxicity of Specific Uremic Solutes

Mounting evidence strongly suggests a causal link between chronic kidney disease (CKD) and cardiovascular disease (CVD). Compared with non-CKD patients, patients with CKD suffer disproportionately from CVD and derive suboptimal benefits from interventions targeting conventional CVD risk factors. Uremic toxins (UTs), whose plasma levels rapidly rise as CKD progresses, represent a unique risk factor in CKD, which has protean manifestations on CVD. Among the known UTs, tryptophan metabolites and trimethylamine N-oxide are well-established cardiovascular toxins. Their molecular mechanisms of effect warrant special consideration to draw translational value. This review surveys current knowledge on the effects of specific UTs on different pathways and cell functions that influence the integrity of cardiovascular health, with implication for CVD progression. The effect of UTs on cardiovascular health is an example of a paradigm in which a cascade of molecular and metabolic events induced by pathology in one organ in turn induces dysfunction in another organ. Deciphering the molecular mechanisms underlying such cross-organ pathologies will help uncover therapeutic targets to improve the management of CVD in patients with CKD.

Pre-clinical model of severe glutathione peroxidase-3 deficiency and chronic kidney disease results in coronary artery thrombosis and depressed left ventricular function

Background

Chronic kidney disease (CKD) patients have deficient levels of glutathione peroxidase-3 (GPx3). We hypothesized that GPx3 deficiency may lead to cardiovascular disease in the presence of chronic kidney disease due to an accumulation of reactive oxygen species and decreased microvascular perfusion of the myocardium. Methods. To isolate the exclusive effect of GPx3 deficiency in kidney disease-induced cardiac disease, we studied the GPx3 knockout mouse strain (GPx3-/-) in the setting of surgery-induced CKD. Results. Ribonucleic acid (RNA) microarray screening of non-stimulated GPx3-/- heart tissue show increased expression of genes associated with cardiomyopathy including myh7, plac9, serpine1 and cd74 compared with wild-type (WT) controls. GPx3-/- mice underwent surgically induced renal mass reduction to generate a model of CKD. GPx3-/- + CKD mice underwent echocardiography 4 weeks after injury. Fractional shortening (FS) was decreased to 32.9 ± 5.8% in GPx3-/- + CKD compared to 62.0% ± 10.3 in WT + CKD (P < 0.001). Platelet aggregates were increased in the myocardium of GPx3-/- + CKD. Asymmetric dimethylarginine (ADMA) levels were increased in both GPx3-/- + CKD and WT+ CKD. ADMA stimulated spontaneous platelet aggregation more quickly in washed platelets from GPx3-/-. In vitro platelet aggregation was enhanced in samples from GPx3-/- + CKD. Platelet aggregation in GPx3-/- + CKD samples was mitigated after in vivo administration of ebselen, a glutathione peroxidase mimetic. FS improved in GPx3-/- + CKD mice after ebselen treatment.

Conclusion

These results suggest GPx3 deficiency is a substantive contributing factor to the development of kidney disease-induced cardiac disease.

Evaluation of Different Dialyzers and the Impact of Predialysis Albumin Priming in Intermittent Hemodialysis With Reduced Anticoagulation

Introduction

Systemic anticoagulation is widely used in routine clinical hemodialysis, but can be contraindicated in specific settings. Anticoagulant-free treatment regimens are prone to failure even in chronic intermittent hemodialysis. We quantified fiber blocking in settings of reduced anticoagulation to assess performance of different dialyzers and the potential benefit of albumin priming.

Methods

This crossover study included 10 patients performing 4 hours of hemodialysis at midweek in 7 different settings: that is, using Solacea 19H and FX800, both with regular and half dose of anticoagulation, Evodial 1.3 without systemic anticoagulation, and FX800 (half dose) and Evodial (no anticoagulation) when primed with a human albumin solution. Dialyzer fiber blocking was visualized in the dialyzer outlet potting using a 3-dimensional computed tomography (CT) scanning technique on micrometer resolution.

Results

No sessions had to be prematurely interrupted because of circuit clotting. The relative number of open fibers post dialysis was not influenced by the reduction of anticoagulation in the Solacea making this dialyzer superior in fiber patency in this setting above both the FX800 with reduced anticoagulation and the Evodial with no anticoagulation. Furthermore, no differences in relative number of open fibers were found in the FX800 and Evodial dialyzers with versus without albumin priming.

Conclusion

In situations in which reduced anticoagulation is indicated, the asymmetric triacetate ATA Solacea dialyzer outperforms a dialyzer with a conventional polysulfone membrane (FX800) or with the heparin-coated polyacrylonitrile membrane (Evodial). The use of human albumin to prime the dialysis circuit did not improve dialyzer patency.

Emerging Factors Implicated in Fibrotic Organ-Associated Thrombosis: The Case of Two Organs

Thrombosis is at the heart of cardiovascular complications observed in specific diseases. A heightened thrombosis risk above that in general population in diseases such as myelofibrosis and chronic kidney disease implicates disease-specific mediators of thrombosis. This relative lack of information regarding the mechanisms of thrombosis in specific organ pathologies hitherto has remained limited. Evolving literature implicates some soluble factors in the blood of patients with discrete disorders, inflicting fundamental changes in the components of thrombosis. In this era of precision medicine, integrating these disease-specific factors in a comprehensive thrombotic risk assessment of patients is imperative in guiding therapeutic decisions. A complex network of mechanisms regulates each organ pathology and resultant thrombotic phenotypes. This review surveys different effectors of thrombogenicity associated with two pathologically fibrotic organs used as model systems, the bone marrow and kidney, as well as focuses attention to a common inducer of fibrosis and thrombosis, lysyl oxidase.

Correlation between oxidative stress and hematological profile abnormalities in diabetic nephropathy

AIMS

Diabetes patients with renal impairment commonly have a degree of hematological abnormalities than those non-diabetics with chronic kidney disease. The present study aimed to clarify the association between oxidative stress and hematological abnormalities with the progression of diabetic nephropathy.

METHODS

A total of 20 healthy subjects and 100 patients were enrolled in the study. Eligible renal dysfunction patients were classified according to biochemical markers into five groups (20 patients); diabetic patients, pre-renal failure patients, diabetic pre-renal failure patients, renal failure patients, and diabetic renal failure patients.

RESULTS

Erythrocytes and platelets count, hemoglobin and hematocrit levels revealed a significant decrease in all renal dysfunction groups, while leukocytes count, red cell distribution width, platelet distribution width, and mean platelet volume showed significant increases in diabetic and renal dysfunction groups as compared to the healthy control. Nitric oxide level increased significantly, while reduced glutathione showed a marked decrease in diabetic and all renal dysfunction groups compared to the healthy control.

CONCLUSION

Nitric oxide and reduced glutathione were associated with the inflammatory status in diabetic renal dysfunction patients which reflected by elevation in leukocytes and neutrophils count, red cell distribution width as well as the reduction in values of erythrocytes, platelets count, hemoglobin and hematocrit. Therefore, hematological indices can play a role in predict the progression of diabetic nephropathy.

Venous Thromboembolism in Special Populations: Preexisting Cardiopulmonary Disease, Cirrhosis, End-Stage Renal Disease, and Asplenia

Venous thromboembolism (VTE) is a common cause of morbidity and mortality. Presence of preexisting conditions, such as cardiopulmonary diseases, cirrhosis, renal dysfunction, and asplenia, commonly occurs in VTE patients. Moreover, these conditions often are risk factors for developing VTE. These preexisting conditions make VTE diagnosis and treatment challenging and worsen outcomes. Current guidelines do not include detailed features in the diagnosis and management of patients with preexisting conditions. This review discusses presence of VTE in patients with preexisting cardiopulmonary diseases, cirrhosis, renal dysfunction, and asplenia.

N-Acetylcysteine and Sulodexide Reduce the Prothrombotic Effect of Uremic Serum on the Venous Endothelial Cells

BACKGROUND/AIMS

Thromboembolic episodes are a frequent problem in end stage renal failure patients. The pathomechanism of the disorder is complex, including bioincompatibility of renal replacement therapy, endothelial dysfunction, increased blood level of procoagulant factors and uremic toxins. We studied changes in the functional properties of venous endothelial cells (VEC) in the presence of uremic serum and evaluated their possible modulation by N-acetylcysteine (NAC) or sulodexide (SUL).

METHODS

Serum samples from 12 uremic patients treated with hemodialysis were studied ex vivo on in vitro cultured VEC. In separate experiments, NAC 1 mmol/L or SUL 0.5 LRU/mL were added to uremic serum samples. Both changes in the gene expression and secretory activity of VEC were studied.

RESULTS

Uremic serum increased the expression of the following genes: IL6 +97%, p < 0.002; VEGF +28%, p < 0.002; vWF +47%, p < 0.002; PECAM +76%, p < 0.002; ICAM-1 +275%, p < 0.002; t-PA +96%, p < 0.002. Changes in gene expression were reflected by the increased secretory activity of VEC treated with the uremic serum. Exposure of VEC to uremic serum supplemented with NAC or SUL resulted in weaker stimulation of the studied genes' expression. Also, secretion of the studied solutes, with the exception of ICAM-1, was reduced in the presence of NAC: IL6 -34%, p < 0.01; VEGF -40%, p < 0.005; vWF -25%, p < 0.001; t-PA -47%, p < 0.01, and MMP9 -37%, p < 0.001. SUL reduced the uremic serum-induced secretion of all solutes: IL6 -24%, p < 0.05; ICAM-1 -43%, p < 0.01; VEGF -38%, p < 0.01; vWF -23%, p < 0.01; t-PA -49%, p < 0.01, and MMP9 -25%, p < 0.05.

CONCLUSIONS

Uremic serum induces prothrombotic changes in VEC, which may cause a predisposition to thrombotic disorders in patients with renal failure. NAC and SUL reduce the effects of the uremic serum in VEC, which suggests their potential therapeutic application in uremic patients.

Unique aspects of peripheral artery disease in patients with chronic kidney disease

Peripheral artery disease (PAD) represents a major health care burden. Despite the advent of screening and interventional procedures, the long-term clinical outcomes remain suboptimal, especially in patients with chronic kidney disease (CKD). While CKD and PAD share common predisposing factors, emerging studies indicate that their co-existence is not merely an association; instead, CKD represents a strong, independent risk factor for PAD. These findings implicate CKD-specific mediators of PAD that remain incompletely understood. Moreover, there is a need to understand the mechanisms underlying poor outcomes after interventions for PAD in CKD. This review discusses unique clinical aspects of PAD in patients with CKD, including high prevalence and worse outcomes after vascular interventions and the influence of renal allograft transplantation. In doing so, it also highlights underappreciated aspects of PAD in patients with CKD, such as disparities in revascularization and higher peri-procedural mortality. While previous reviews have discussed general mechanisms of PAD pathogenesis, focusing on PAD in CKD, this review underscores a need to probe for CKD-specific pathogenic pathways that may unravel novel biomarkers and therapeutic targets in PAD and ultimately improve the risk stratification and management of patients with CKD and PAD.

Increased risk of deep vein thrombosis in end-stage renal disease patients

Background

Previous studies have shown that chronic kidney disease increases the risk of deep vein thrombosis (DVT). DVT is the risk of pulmonary embolism among persons with end-stage renal disease (ESRD). Information on the incidence of DVT in ESRD is limited, and no studies have been conducted in the Asian population. The aim of our study was to investigate the incidence of DVT in Asian ESRD patients by comparing with the non-ESRD patients and to identify the associated risk factors.

Methods

This study retrieved patients who were diagnosed with ESRD (ICD-9-CM codes 585 or 586) between January 1, 2004, and December 31, 2010, from the National Health Insurance Research Database in Taiwan. All ESRD patients had received a catastrophic illness card from the Ministry of Health and Welfare in Taiwan, with the major illness identified as ESRD. Patients who had DVT before the index date or who had incomplete records were excluded from the analysis. A total of 4865 ESRD patients were enrolled. There are 3564 ESRD patients included after exclusion of patients with previous DVT and patients with incomplete records. The control subjects were randomly selected as the patients without ESRD by matching study subjects according to age (±3 years), gender, and the year of admission at a 2:1 ratio from the same dataset.

Results

The incidence rate of DVT was substantially higher in the ESRD group than in the without-ESRD group (20.9 vs. 1.46 per 10^4 person-years). The adjusted hazard ratio (aHR 13.92; 95% CI 9.25–20.95) of DVT for the ESRD patients was 13.92 times that for the non-ESRD patients. ESRD patients older than 50 years had a higher risk of DVT (aHR 1.65; 95% CI 1.13–2.40; P = 0.01). Hyperlipidemia was significantly associated with an increased risk of DVT (aHR 1.73; 95% CI 1.08–2.78; P = 0.02). ESRD patients with three or more comorbidities were substantially more likely to have DVT (aHR 1.45; 95% CI 1.03–2.03; P = 0.03).

Conclusions

ESRD patients had a higher risk of DVT than non-ESRD patients. Among the ESRD patients, being older than 50 years and having dyslipidemia increased the risk of DVT.

Increased Thrombogenicity in Chronic Renal Failure in a Rat Model Induced by 5/6 Ablation/Infarction

PURPOSE

Abnormalities in hemostasis and coagulation have been suggested in chronic renal failure (CRF). In this study, we compared processes of thrombus formation between rats with CRF and those with normal kidney function.

MATERIALS AND METHODS

CRF was induced by 5/6 ablation/infarction of the kidneys in Sprague-Dawley rats, and surviving rats after 4 weeks were used. Ferric chloride (FeCl₃)-induced thrombosis in the carotid artery was induced to assess thrombus formation. Whole blood clot formation was evaluated using rotational thromboelastometry (ROTEM). Platelet aggregation was assessed with impedance platelet aggregometry.

RESULTS

FeCl₃-induced thrombus formation was initiated faster in the CRF group than in the control group (13.2±1.1 sec vs. 17.8±1.0 sec, p=0.027). On histological examination, the maximal diameters of thrombi were larger in the CRF group than in the control group (394.2±201.1 μm vs. 114.0±145.1 μm, p=0.039). In extrinsic pathway ROTEM, the CRF group showed faster clot initiation (clotting time, 59.0±7.3 sec vs. 72.8±5.0 sec, p=0.032) and increased clot growth kinetics (α angle, 84.8±0.2° vs. 82.0±0.6°, p=0.008), compared to the control group. Maximal platelet aggregation rate was higher in the CRF group than in the control group (58.2±0.2% vs. 44.6±1.2%, p=0.006).

CONCLUSION

Our study demonstrated that thrombogenicity is increased in rats with CRF. An activated extrinsic coagulation pathway may play an important role in increasing thrombogenicity in CRF.

Uremic Solute-Aryl Hydrocarbon Receptor-Tissue Factor Axis Associates with Thrombosis after Vascular Injury in Humans

Individuals with CKD are particularly predisposed to thrombosis after vascular injury. Using mouse models, we recently described indoxyl sulfate, a tryptophan metabolite retained in CKD and an activator of tissue factor (TF) through aryl hydrocarbon receptor (AHR) signaling, as an inducer of thrombosis across the CKD spectrum. However, the translation of findings from animal models to humans is often challenging. Here, we investigated the uremic solute-AHR-TF thrombosis axis in two human cohorts, using a targeted metabolomics approach to probe a set of tryptophan products and high-throughput assays to measure AHR and TF activity. Analysis of baseline serum samples was performed from 473 participants with advanced CKD from the Dialysis Access Consortium Clopidogrel Prevention of Early AV Fistula Thrombosis trial. Participants with subsequent arteriovenous thrombosis had significantly higher levels of indoxyl sulfate and kynurenine, another uremic solute, and greater activity of AHR and TF, than those without thrombosis. Pattern recognition analysis using the components of the thrombosis axis facilitated clustering of the thrombotic and nonthrombotic groups. We further validated these findings using 377 baseline samples from participants in the Thrombolysis in Myocardial Infarction II trial, many of whom had CKD stage 2-3. Mechanistic probing revealed that kynurenine enhances thrombosis after vascular injury in an animal model and regulates thrombosis in an AHR-dependent manner. This human validation of the solute-AHR-TF axis supports further studies probing its utility in risk stratification of patients with CKD and exploring its role in other diseases with heightened risk of thrombosis.

Targeting STUB1-tissue factor axis normalizes hyperthrombotic uremic phenotype without increasing bleeding risk

Chronic kidney disease (CKD/uremia) remains vexing because it increases the risk of atherothrombosis and is also associated with bleeding complications on standard antithrombotic/antiplatelet therapies. Although the associations of indolic uremic solutes and vascular wall proteins [such as tissue factor (TF) and aryl hydrocarbon receptor (AHR)] are being defined, the specific mechanisms that drive the thrombotic and bleeding risks are not fully understood. We now present an indolic solute-specific animal model, which focuses on solute-protein interactions and shows that indolic solutes mediate the hyperthrombotic phenotype across all CKD stages in an AHR- and TF-dependent manner. We further demonstrate that AHR regulates TF through STIP1 homology and U-box-containing protein 1 (STUB1). As a ubiquitin ligase, STUB1 dynamically interacts with and degrades TF through ubiquitination in the uremic milieu. TF regulation by STUB1 is supported in humans by an inverse relationship of STUB1 and TF expression and reduced STUB1-TF interaction in uremic vessels. Genetic or pharmacological manipulation of STUB1 in vascular smooth muscle cells inhibited thrombosis in flow loops. STUB1 perturbations reverted the uremic hyperthrombotic phenotype without prolonging the bleeding time, in contrast to heparin, the standard-of-care antithrombotic in CKD patients. Our work refines the thrombosis axis (STUB1 is a mediator of indolic solute-AHR-TF axis) and expands the understanding of the interconnected relationships driving the fragile thrombotic state in CKD. It also establishes a means of minimizing the uremic hyperthrombotic phenotype without altering the hemostatic balance, a long-sought-after combination in CKD patients.

Association between uremic toxin-anthranilic acid and fibrinolytic system activity in predialysis patients at different stages of chronic kidney disease

PURPOSE

Chronic kidney disease (CKD) is an estimated risk factor for increased mortality and morbidity due to fibrinolytic system disturbances. Progressive loss of renal function leads to retention of uremic toxins. Anthranilic acid (AA) is a tryptophan-derived uremic toxin with multidirectional properties that can affect the hemostatic system. The goal of this study was to examine the association between AA and the parameters of fibrinolysis at different stages of CKD.

METHODS

Patients with CKD were divided into two groups: mild-to-moderate (n = 20) and severe-to-end-stage CKD (n = 28). Seventeen healthy volunteers served as an additional control group. Parameters of fibrinolysis, inflammation, and monocytes activation were determined by ELISA immune-enzymatic kits. AA levels were evaluated using high-performance liquid chromatography.

RESULTS

AA concentration and parameters of fibrinolysis: urokinase-type plasminogen activator (uPA), its soluble receptor (suPAR), tissue plasminogen activator (tPA), tissue plasminogen activator inhibitor-1 (PAI-1) and plasmin-antiplasmin complex (PAP) were significantly elevated in the CKD groups compared with the controls. The markers of inflammation, monocyte activation, and impaired kidney function were also increased in those with CKD. AA was positively correlated with the uPA/suPAR system in the early stages of CKD, whereas during severe-to-end-stage CKD, inverse relationships were observed between AA, tPA and PAI-1. Additionally, AA was an independent variable associated with tPA in patients with CKD overall and with uPA levels in the mild-to-moderate CKD group.

CONCLUSIONS

Obtained results suggest for the first time the association between AA and the fibrinolytic system in CKD patients. The distinct relationship between AA and individual parameters of fibrinolysis appears to be dependent on CKD stage.

Risk of pulmonary embolism in patients with end-stage renal disease receiving long-term dialysis

BACKGROUND

This study compared the pulmonary embolism (PE) risks between Asian dialysis patients and a comparison cohort without clinical kidney disease.

METHODS

From the National Health Insurance claims data of Taiwan, we identified 106 231 newly diagnosed end-stage renal disease patients undergoing dialysis in 1998-2010 and randomly selected 106 231 comparison subjects, frequency matched by age, sex and the index year. We further selected 7430 peritoneal dialysis (PD) patients and 7340 propensity score-matched hemodialysis (HD) patients. Incidence rates and hazard ratios (HRs) of PE and odds ratio (OR) of subsequent 30-day deaths from PE were evaluated among study cohorts by the end of 2011.

RESULTS

The overall incident PE was nearly 3-fold greater in dialysis patients than in the comparison cohort (0.92 versus 0.33 per 1000 person-years), with an adjusted HR of 2.02 [95% confidence interval (CI) = 1.63-2.50]. The PE incidence was greater in the propensity score-matched HD patients, than in PD patients with an adjusted HR of 2.30 (95% CI = 1.23-4.29). There was a greater PE risk for central venous catheter users than non-users among HD patients (1.83 versus 0.75 per 1000 person-years). The 30-day mortality from PE was higher in dialysis patients than in the comparison cohort (16.5 versus 9.77%) with an adjusted OR of 2.56 (95% CI = 1.32-4.95).

CONCLUSIONS

Dialysis patients are at a nearly 2-fold increased hazard of developing PE and are at greater risk of fatality from PE compared with those without clinical kidney disease. This study also shows a higher PE risk in HD patients than in PD patients.

The comparative safety of abciximab versus eptifibatide in patients on dialysis undergoing percutaneous coronary intervention: Insights from the Blue Cross Blue Shield of Michigan Cardiovascular Consortium (BMC2)

OBJECTIVES

We sought to evaluate the patterns of use and outcomes associated with eptifibatide and abciximab administration among dialysis patients who underwent percutaneous coronary intervention (PCI).

BACKGROUND

Contraindicated medications are frequently administered to dialysis patients undergoing PCI often resulting in adverse outcomes. Eptifibatide is a glycoprotein IIb/IIIa inhibitor that is often used during PCI and is contraindicated in dialysis.

METHODS

We included dialysis patients who underwent PCI from January 2010 to September 2015 at 47 hospitals in Michigan. We compared outcomes between patients who received eptifibatide compared with abciximab. Both groups required concurrent treatment with unfractionated heparin only. In-hospital outcomes included repeat PCI, bleeding, major bleeding, need for transfusion, and death. Optimal full matching was used to adjust for non-random drug administration.

RESULTS

Of 177 963 patients who underwent PCI, 4303 (2.4%) were on dialysis. Among those, 384 (8.9%) received eptifibatide and 100 (2.3%) received abciximab. Prior to matching, patients who received eptifibatide had higher pre-procedural hemoglobin levels (11.3 g/dL vs. 10.7 g/dL; P < 0.001) and less frequently had a history of myocardial infarction (36.5% vs. 52.0%; P = 0.005). After matching, there were no significant differences in in-hospital outcomes between eptifibatide and abciximab including transfusion (aOR: 1.15; 95%CI: 0.55-2.40; P = 0.70), bleeding (1.47; 0.64-3.40; P = 0.36), major bleeding (4.68; 0.42-52.3; P = 0.21), repeat PCI (0.38; 0.03-4.23; P = 0.43), and death (1.53; 0.2-9.05; P = 0.64).

CONCLUSIONS

Despite being contraindicated in dialysis, eptifibatide was used approximately 3.5 times more frequently than abciximab among dialysis patients undergoing PCI but was associated with similar in-hospital outcomes.

Subacute pulmonary embolism in a hemodialysis patient, successfully treated with surgical thrombectomy

A 53-year-old woman was admitted to our hospital with a 1-month history of gradually progressive resting dyspnea and lumbar backache. For the preceding 6 years, she had received regular hemodialysis for end-stage renal disease caused by autosomal dominant polycystic kidney disease and had taken tamoxifen for 3 years as post-operative chemotherapy for breast cancer. Before admission, the patient's symptoms had been attributed to volume overload, based on right thoracic fluid and leg edema. However, despite volume correction by dialysis therapy, her symptoms had not improved. The patient was transferred to our hospital, where she was diagnosed with subacute pulmonary embolism (PE). Emergent pulmonary thrombectomy was performed using cardio-pulmonary bypass. The patient was discharged from our hospital on post-operative day 23. Recent reports have shown that hemodialysis patients have a relatively higher risk of PE compared with the general population. Our case had additional risk factors for PE: female sex, decreased protein C level, tamoxifen use, and autosomal dominant polycystic kidney disease. These factors may have had a synergistic effect on the onset of PE.

Antithrombotic medications in dialysis patients: a double-edged sword

In the clinical context of end-stage renal disease (ESRD), thrombosis and bleeding risks are simultaneously increased and may have devastating consequences. While anticoagulant and antiplatelet drugs are indispensable for the prevention of thromboembolic events, the significantly higher bleeding risk makes their handling extremely complicated. In ESRD, they are frequently administered for a wide array of conditions. For example, atrial fibrillation is quite common in ESRD and warrants the use of anticoagulants like warfarin. Unfractionated heparin and low molecular weight heparins are typically used for clotting prevention in the hemodialysis extracorporeal circuit. The antithrombotics use dilemma has worsened because ESRD patients have been excluded from major clinical trials that defined standard indications, contraindications and optimal management of these medications. That limits our knowledge and results in that the process of decision-making depends on weaker data. Besides the substantial bleeding risk, warfarin may also increase cardiovascular risk because it is implicated in the pathogenesis of vascular calcifications in ESRD. The present article attempts to offer a comprehensive overview of practical considerations for the use of the most common antithrombotic medications in ESRD linking them, at the same time, to the best available evidence from randomized controlled trials and observational studies.

Impact of Indoxyl Sulfate on Progenitor Cell-Related Neovascularization of Peripheral Arterial Disease and Post-Angioplasty Thrombosis of Dialysis Vascular Access

Patients with chronic kidney disease (CKD) have an increased risk of vascular disease, which is associated with considerable health care costs. Vascular disease in CKD differs clinically and pathobiologically from that in patients with normal renal function. Besides the traditional risk factors, retention of uremic toxins contributes to the pathogenesis of vascular disease in patients with CKD. Indoxyl sulfate is a protein-bound uremic toxin and is inefficiently removed by conventional dialysis. Accumulating evidence suggests that indoxyl sulfate is a vascular toxin involved in atherosclerosis, arteriosclerosis, vascular calcification and vascular repair. Clinically, indoxyl sulfate is associated with total and cardiovascular mortality in patients with CKD. Recent studies have indicated that in addition to coronary and cerebral arteries, indoxyl sulfate plays a role in peripheral artery disease (PAD) and dialysis graft thrombosis. Emerging evidence suggests that indoxyl sulfate is implicated via novel mechanisms, including progenitor cell-related neovascularization and tissue factor-related hypercoagulability. These findings raise the possibility that strategies targeting serum indoxyl sulfate may have the potential to improve the outcomes of PAD and dialysis vascular access in patients with CKD.

Coagulation, thrombophilia and patency of arteriovenous fistula in children undergoing haemodialysis compared with healthy volunteers: a prospective analysis

This study aimed to assess whether markers of coagulation, fibrinolysis or thrombophilia are increased in children on haemodialysis compared with controls and whether measurement of any of these factors could help to identify patients at an increased risk of arteriovenous fistula (AVF) occlusion. Blood samples were taken from 55 children immediately before a session of haemodialysis and from 20 healthy volunteers. Thrombin-antithrombin (TAT), D-dimer, plasmin-antiplasmin (PAP) and anticardiolipin immunoglobulin G (ACA-Ig G) were measured by ELISA. Factor V Leiden mutation (G1691A) was determined by gene polymorphism [restriction fragment length polymorphism (RFLP)]. Determination of the patency of the AVF was prospectively followed up for a minimum of 4 years or until the AVF was nonfunctioning. Fifty-five patients were studied with a median follow-up of 659 days (range 30-1670 days). A significant increase was found in the levels of D-dimer, PAP and ACA-Ig G in haemodialysis patients with thrombosed and nonthrombosed native AVFs vs.

CONTROLS

There was a significant difference between both chronic haemodialysis patients with thrombosed and nonthrombosed native AVF with regard to ACA-IgG levels. At 1 year follow-up, primary patency was 61.4% (27 patients). In multivariate analysis, D-dimer was inversely associated with secondary patency.Thrombophilia may predispose children with end stage renal disease to access failure. The promising finding is that in children on haemodialysis, D-dimer levels were increased and inversely correlated with secondary patency. Further evaluation is required into the possible role of D-dimer as a biomarker of AVF occlusion.

Unexpected Normal Colloid Osmotic Pressure in Clinical States with Low Serum Albumin

BACKGROUND

In clinical states associated with systemic oxidative stress (OS) and inflammation such as chronic kidney disease (CKD), oxidative modifications of serum albumin impair its quantification, resulting in apparent hypoalbuminemia. As the maintenance of oncotic pressure/colloid osmotic pressure (COP) is a major function of albumin, this study examined the impact of albumin oxidation on COP, both in-vivo and in-vitro.

METHODS

Patients with proteinuria and patients on chronic hemodialysis (HD) with systemic inflammation and OS were enrolled. Blood samples were collected from 134 subjects: 32 healthy controls (HC), proteinuric patients with high (n = 17) and low (n = 31) systemic inflammation and from 54 patients on chronic hemodialysis (HD) with the highest levels of OS and inflammation.

RESULTS

In-vitro oxidized albumin showed significantly higher COP values than non-oxidized albumin at identical albumin levels. In vivo, in hypoalbuminemic HD patients with the highest OS and inflammation, COP values were also higher than expected for the low albumin levels. The contribution to COP by other prevalent plasma proteins, such as fibrinogen and immunoglobulins was negligible. We imply that the calculation of COP based on albumin levels should be revisited in face of OS and inflammation. Hence, in hypoalbuminemic proteinuric patients with systemic OS and inflammation the assumption of low COP should be verified by its measurements.

Risk of Retinal Vein Occlusion Following End-Stage Renal Disease

The aim of the study was to investigate the risk of retinal vein occlusion (RVO) following end-stage renal disease (ESRD). The study was designed as a retrospective, nationwide, matched cohort study. The subjects were ESRD patients identified by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), code 585. The study cohort included 92,774 ESRD patients registered between January 2000 and December 2009 at the Taiwan National Health Insurance Research Database. An age- and sex-matched control group comprised 92,774 patients (case:control = 1:1) selected from the Taiwan Longitudinal Health Insurance Database 2000. Information for each patient was collected from the index date until December 2011. The incidence and risk of RVO were compared between the ESRD and control groups. The adjusted hazard ratio (HR) for RVO after adjustment for potential confounders was obtained by Cox proportional hazard regression analysis. Kaplan-Meier analysis was used to calculate the RVO cumulative incidence rate. The main outcome measure was the incidence of RVO following ESRD. In total, 904 ESRD patients (0.97%) and 410 controls (0.44%) had RVO (P < 0.0001) during the follow-up period, leading to a significantly elevated risk of RVO in the ESRD patients compared with controls (incidence rate ratio = 3.05, 95% confidence interval = 2.72-3.43). After adjustment for potential confounders including diabetes mellitus, hypertension, hyperlipidemia, congestive heart failure, and coronary artery disease, ESRD patients were 3.05 times more likely to develop RVO in the full cohort (adjusted hazard ratio = 3.05, 95% confidence interval = 2.64-3.51). In addition, hypertension patients showed high incidence rate of RVO in the ESRD group compared with controls (incidence rate ratio = 1.71, 95% confidence interval = 1.44-2.03) and maintained significant risk of RVO after adjustment for other confounders in the cohort (adjusted hazard ratio = 1.39, 95% confidence interval = 1.20-1.60). ESRD increases the risk of RVO. For ESRD patients, we recommend education regarding RVO in addition to blood pressure control to prevent subsequent RVO.

Candidate Gene Analysis of Mortality in Dialysis Patients

Background

Dialysis patients have high cardiovascular mortality risk. This study aimed to investigate the association between SNPs of genes involved in vascular processes and mortality in dialysis patients.

Methods

Forty two SNPs in 25 genes involved in endothelial function, vascular remodeling, cell proliferation, inflammation, coagulation and calcium/phosphate metabolism were genotyped in 1330 incident dialysis patients. The effect of SNPs on 5-years cardiovascular and non-cardiovascular mortality was investigated.

Results

The mortality rate was 114/1000 person-years and 49.4% of total mortality was cardiovascular. After correction for multiple testing, VEGF rs699947 was associated with all-cause mortality (HR1.48, 95% CI 1.14–1.92). The other SNPs were not associated with mortality.

Conclusions

This study provides further evidence that a SNP in the VEGF gene may contribute to the comorbid conditions of dialysis patients. Future studies should unravel the underlying mechanisms responsible for the increase in mortality in these patients.

Periprocedural management of aspirin during colonoscopy: a survey of practice patterns in the United States

BACKGROUND

The risk of postpolypectomy bleeding for patients taking aspirin is low, and gastroenterology society guidelines state that aspirin is likely safe to continue; however, many practices recommend aspirin discontinuation.

OBJECTIVE

To characterize practice patterns of periprocedural aspirin use with colonoscopy in the United States.

DESIGN

Survey study.

SETTING

Endoscopy units in the United States.

INTERVENTIONS

We reviewed colonoscopy preparation instruction sheets available online to characterize recommendations regarding periprocedural aspirin use. The endoscopy units that recommended discontinuation of aspirin before colonoscopy were contacted to determine their reasons for doing so. We also determined which endoscopy units were recognized by the American Society for Gastrointestinal Endoscopy (ASGE) quality recognition program.

MAIN OUTCOME MEASUREMENTS

Endoscopy unit recommendations regarding aspirin use before colonoscopy.

RESULTS

We reviewed colonoscopy preparation instructions from 317 endoscopy units, of which 138 (43.5%) recommended continuing aspirin, 103 (32.5%) recommended stopping aspirin, and 76 (24%) requested patients to contact a physician. The most common reasons for recommending aspirin discontinuation were concern about bleeding after polypectomy (62%), perceived minimal downside to stopping aspirin (38%), inertia to changing old policies (20%), and concern about medicolegal implications of postpolypectomy bleeding (15%). There was no significant association between endoscopy unit recommendations about periprocedural aspirin use and ASGE quality certification (P = .17) or type of endoscopy facility (ambulatory surgical center vs hospital affiliated) (P = .55).

LIMITATION

Non-response bias.

CONCLUSION

Less than half of the endoscopy units surveyed in the United States routinely continue aspirin before screening colonoscopies despite evidence that benefits outweigh the risks. It is important for gastroenterology and cardiology societies to make a firm statement, educate their members, and give them confidence and support to continue aspirin periprocedurally.