Thromboembolism and anticoagulant management in hemodialysis patients: A practical guide to clinical management

Anticoagulant therapy in renal insufficiency theme: Anticoagulation in complex situations

Many patients with impaired renal function have concurrent indications for anticoagulant therapy, including atrial fibrillation and venous thromboembolism. For mild chronic kidney disease, data from clinical trials and existing guidelines can be applied to clinical management. The benefits and harms of anticoagulation therapy in patients with more advanced renal impairment are nuanced, as both thrombotic and bleeding risk are increased. Until recently, data regarding anticoagulants in severe renal impairment were primarily observational, but emerging evidence includes a few small clinical trials and the emergence of novel agents hypothesized to have improved efficacy and safety in this population. In this review, we summarize existing data on anticoagulation in patients with chronic kidney disease. We suggest a framework for anticoagulation decision-making in the burgeoning worldwide population of patients with chronic kidney disease.

Nonvalvular atrial fibrillation in patients undergoing chronic hemodialysis. Should dialysis patients with atrial fibrillation receive oral anticoagulation?

Chronic kidney disease (CKD) is an independent risk factor for presenting atrial fibrillation (AF), which conditions an increased risk already present in CKD of suffering a thromboembolic event. And this risk is even higher in the hemodialysis (HD) population. On the other hand, in CKD patients and even more so in HD patients, the probability of suffering serious bleeding is also higher. Therefore, there is no consensus on whether or not to anticoagulate this population. Taking as a model what is advised for the general population, the most common attitude among nephrologists has been to opt for anticoagulation, even though there is no randomized studies to support it. Classically, anticoagulation has been done with vitamin K antagonists, at high cost for our patients: severe bleeding events, vascular calcification, and progression of nephropathy, among other complications. With the emergence of direct-acting anticoagulants, a hopeful outlook was opened in the field of anticoagulation, as they were postulated as more effective and safer drugs than antivitamin K. However, in clinical practice, this has not been the case. In this paper we review various aspects of AF and its anticoagulant treatment in the HD population.

Kidney transplantation in valvular heart disease and pulmonary hypertension: Consensus in waiting

Kidney transplantation induces a lesser anesthetic, surgical, and physiological alterations than other solid organ transplantation. Concomitant valvular pathologies expose these patients to poor postoperative outcome. There is a critical gap in knowledge and lack of coherence in the guidelines related to the management in patients with end-stage renal disease with valvular heart disease. The individualized diagnostic and management plan should be based on the assessment of perioperative outcomes. Similarly, pulmonary hypertension in end-stage renal disease poses a unique challenge, it can manifest in isolation or may be associated with other cardiac lesions, namely left-sided valvular heart disease and left ventricular systolic and diastolic dysfunction. Quantification and stratification according to etiology are needed in pulmonary hypertension to ensure an adequate management plan to minimize the adverse perioperative outcomes. Lack of randomized controlled trials has imposed hindrance in proposing a unified approach to clinical decision-making in these scenarios. In this review, we have described the magnitude of the problems, pathophysiologic interactions, impact on clinical outcomes and have also proposed a management algorithm for both the scenarios.

The effect of self-selected soothing music on fistula puncture-related pain in hemodialysis patients

OBJECTIVE

This study was intended to examine the effect of selective soothing music on fistula puncture-related pain in hemodialysis patients.

MATERIALS AND METHODS

This is a randomized clinical trial in which 114 participants were selected from two hemodialysis units by means of a non-random, convenience sampling method. The participants were then allocated in three groups of music (N = 38), headphone (N = 38), and control (N = 38). The fistula puncture-related pain was measured 1 min after venipuncture procedure in all three groups. The music group listened to their self-selected and preferred music 6 min before needle insertion into a fistula until the end of procedure. The headphone group wore a headphone alone without listening to music 6 min before needle insertion into a fistula until the end of procedure. The control group did not receive any intervention from the research team during needle insertion into a fistula. The pain intensity was measured immediately after the intervention in all three groups.

RESULTS

This study showed a significant difference between the music and control groups, and the music and headphone groups in terms of the mean pain score after the intervention. However, the analysis did not indicate any significant difference between the headphone and control groups with regard to the mean pain score after the intervention.

CONCLUSION

It is concluded that music can be used effectively for pain related to needle insertion into a fistula in hemodialysis patients. Future research should investigate the comparative effects of pharmacological and non-pharmacological interventions on fistula puncture-related pain.

Thrombosis and anticoagulation in the setting of renal or liver disease

Thrombosis and bleeding are among the most common causes of morbidity and mortality in patients with renal disease or liver disease. The pathophysiology underlying the increased risk for venous thromboembolism and bleeding in these 2 populations is distinct, as are considerations for anticoagulation. Anticoagulation in patients with kidney or liver disease increases the risk of bleeding; this risk is correlated with the degree of impairment of anticoagulant elimination by the kidneys and/or liver. Despite being in the same pharmacologic category, anticoagulant agents may have varied degrees of renal and liver metabolism. Therefore, specific anticoagulants may require dose reductions or be contraindicated in renal impairment and liver disease, whereas other drugs in the same class may not be subject to such restrictions. To minimize the risk of bleeding, while ensuring an adequate therapeutic effect, both appropriate anticoagulant drug choices and dose reductions are necessary. Renal and hepatic function may fluctuate, further complicating anticoagulation in these high-risk patient groups.

Periprocedural Risk of Stroke Is Elevated in Patients with End-Stage Renal Disease on Hemodialysis

OBJECTIVE

To describe the most common clinical factors and stroke etiologies in a case series of patients with end-stage renal disease on hemodialysis (ESRD/HD) with transient ischemic attack (TIA) or ischemic stroke (IS).

BACKGROUND

Prior studies have shown that patients on HD are at an elevated risk of stroke, but these studies have focused on the overall stroke risk. This case series sought to determine the percentage of acute ischemic events that occur during or immediately after HD.

METHODS

ICD-9 codes were used to identify IS and TIA patients with ESRD/HD admitted to the stroke service from August 22, 2011, to June 21, 2014. Charts were reviewed to determine the age, sex, and race/ethnicity of the cohort. TIA/IS diagnosis was confirmed by a vascular neurologist. Clinical factors were assessed, including: onset during or shortly after HD, defined as occurring within 12 h of HD; the presence of a lesion on diffusion-weighted MRI; hypotension, hyponatremia, or hypoglycemia at symptom onset; the stroke etiology; the presence of focal neurologic deficits; whether the patient was in the window period for intravenous tissue plasminogen activator (IVtPA) upon presentation, and whether the patient received IVtPA.

RESULTS

We identified 34 ESRD/HD patients with a diagnosis of TIA/stroke in the specified time period. A majority of patients (70.6%) were African American. Patient age ranged from 32 to 84 years, with a median age of 67 years. Twenty-seven patients (79.4%) had confirmed ischemic infarcts on diffusion-weighted MRI. Seven patients (20.6%) were diagnosed with TIA. In 13 patients (38.2%), symptom onset occurred during or shortly after HD. Of these 13 patients, 8 (61.5%) had symptom onset during HD. Three patients (8.8%) had documented hypotension near the time of symptom onset, and 2 (5.9%) were hyponatremic on presentation to the emergency department. The distribution of stroke etiologies was as follows: 4 (11.8%) watershed distribution, 1 (2.9%) large artery atherosclerosis, 2 (20.6%) small vessel disease, 10 (29.4%) cardioembolic, and 9 (26.5%) cryptogenic. In 28 patients (82.4%), focal neurologic deficits were observed on presentation. Nine patients (26.5%) arrived within the window period for IVtPA, and 4 (11.8%) were eligible and received IVtPA.

CONCLUSIONS

Of all patients with ESRD on HD admitted to the stroke service over the study period, over one third (38.3%) had the onset of their ischemic event during or shortly after HD, and nearly one quarter (23.5%) had the onset during HD. While clinicians may be tempted to attribute neurologic changes after HD to metabolic etiologies, they should also be aware that HD represents a period of elevated risk for acute ischemia.

Effect of impaired renal function on the maintenance dose of warfarin in Japanese patients

BACKGROUND

Chronic kidney disease (CKD) alters dose-effect relationship not only of drugs eliminated by the kidney but also of some drugs metabolized by the liver and not renally excreted. It is not known whether impaired renal function alters dose-effect relationship of warfarin in Asian patients. It is also unknown whether the maintenance dose of warfarin can be predicted more accurately by incorporating renal function in Asians.

METHODS

This was a cross-sectional study of patients receiving constant doses of warfarin who had PT-INR within 1.5-3.0 for 3 months or longer.

RESULTS

In a total of 137 participants, the estimated creatinine clearance (eCrCl) was 62.5±25.5 [ml/min] and the warfarin dose was 3.21±1.46 [mg/day] (both mean±standard deviation). There was a significant correlation between warfarin dose and eCrCl (p<0.0001, r(2)=0.23). In a stepwise linear regression with the maintenance dose of warfarin as the dependent variable, eCrCl as well as age, body weight, intra-individual average prothrombin time/international normalized ratio (PT-INR), and genotype of VKORC1 -1639 G>A polymorphism were chosen as independent variables. The coefficient of determination (r(2)) of this formula was 0.47. A regression equation with all the same explanatory variables except for eCrCl had an r(2) of 0.41.

CONCLUSIONS

The maintenance warfarin dose was positively correlated with kidney function as represented by eCrCl in Japanese patients. Incorporating eCrCl improved accuracy of predicting warfarin maintenance dose in this population.

Anticoagulant and antiplatelet therapy in patients with chronic kidney disease: risks versus benefits review

PURPOSE OF REVIEW

Atrial fibrillation and cardiovascular death are increased in end-stage renal disease (ESRD) patients compared to the general population. The effect of anticoagulant and antiplatelet medications for these indications in ESRD is unclear. However, both classes of medications have been used for the preservation of vascular access. This review explores the risks and benefits of anticoagulant and antiplatelet medications in ESRD.

RECENT FINDINGS

ESRD patients with atrial fibrillation have a two and three-fold greater risk of death and stroke, respectively, than ESRD patients without atrial fibrillation. Warfarin does not appear to decrease this risk, and increases the risk of bleeding and vascular calcification. Warfarin also does not appear to be effective for vascular access preservation. In a few large observational studies, antiplatelet agents did not decrease the risk of cardiovascular death, but confounding by indication is likely. Antiplatelet agents do appear to prolong unassisted arteriovenous graft patency, but the effect is modest.

SUMMARY

The role of anticoagulant and antiplatelet agents for atrial fibrillation and cardiovascular disease in ESRD remains unclear. Well designed randomized controlled trials to determine the role of anticoagulation in ESRD patients with atrial fibrillation, and anticoagulant and antiplatelet medications in the preservation of central venous catheter function are required.

Major bleeding events and risk stratification of antithrombotic agents in hemodialysis: results from the DOPPS

Benefits and risks of antithrombotic agents remain unclear in the hemodialysis population. To help clarify this we determined variation in antithrombotic agent use, rates of major bleeding events, and factors predictive of stroke and bleeding in 48,144 patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases I-IV. Antithrombotic agents including oral anticoagulants (OACs), aspirin (ASA), and anti-platelet agents (APAs) were recorded along with comorbidities at study entry, and clinical events including hospitalization due to bleeding were then collected every 4 months. There was wide variation in OAC (0.3-18%), APA (3-25%), and ASA use (8-36%), and major bleeding rates (0.05-0.22 events/year) among countries. All-cause mortality, cardiovascular mortality, and bleeding events requiring hospitalization were elevated in patients prescribed OACs across adjusted models. The CHADS2 score predicted the risk of stroke in atrial fibrillation patients. Gastrointestinal bleeding in the past 12 months was highly predictive of major bleeding events; for patients with previous gastrointestinal bleeding, the rate of bleeding exceeded the rate of stroke by at least twofold across all categories of CHADS2 score, including patients at high stroke risk. Appropriate risk stratification and a cautious approach should be considered before OAC use in the dialysis population.

Management of special conditions in patients on vitamin K antagonists

Physicians are occasionally faced with difficult situations in the management of vitamin K antagonists (VKA) due to the lack of sound data available in controlled studies on certain conditions. In this review we would like to address some special but frequent conditions that can be encountered in daily clinical practice. These include the use of VKA in hemodialysis, thromboembolism in patients with liver cirrhosis and the thromboembolic risk in patients who bleed in the course of treatment with VKA. Moreover, two other conditions were examined: what the best way of expressing prothrombin time would be in patients with liver disease and how to behave when a patient treated with VKA shows a subtherapeutic INR. These topics were discussed by a panel of experts during a workshop recently held in Milan by the Italian Federation of Centres for the Diagnosis of Thrombosis and the Surveillance of Antithrombotic Therapies (FCSA). The main aim of the workshop was to provide helpful and practical advice to physicians in the daily management of VKA.

Atrial fibrillation in hemodialysis patients: clinical features and associations with anticoagulant therapy

Using data from the international Dialysis Outcomes and Practice Patterns Study (DOPPS), we determined incidence, prevalence, and outcomes among hemodialysis patients with atrial fibrillation. Cox proportional hazards models, to identify associations with newly diagnosed atrial fibrillation and clinical outcomes, were stratified by country and study phase and adjusted for descriptive characteristics and comorbidities. Of 17,513 randomly sampled patients, 2188 had preexisting atrial fibrillation, with wide variation in prevalence across countries. Advanced age, non-black race, higher facility mean dialysate calcium, prosthetic heart valves, and valvular heart disease were associated with higher risk of new atrial fibrillation. Atrial fibrillation at study enrollment was positively associated with all-cause mortality and stroke. The CHADS2 score identified approximately equal-size groups of hemodialysis patients with atrial fibrillation with low (less than 2) and higher risk (more than 4) for subsequent strokes on a per 100 patient-year basis. Among patients with atrial fibrillation, warfarin use was associated with a significantly higher stroke risk, particularly in those over 75 years of age. Our study shows that atrial fibrillation is common and associated with elevated risk of adverse clinical outcomes, and this risk is even higher among elderly patients prescribed warfarin. The effectiveness and safety of warfarin in hemodialysis patients require additional investigation.

Oral anticoagulant therapy in hemodialysis patients: do the benefits outweigh the risks?

Managing oral anticoagulation may be difficult in hemodialysis patients because the antithrombotic effect can be counterbalanced by an increased risk of hemorrhagic complications. There is insufficient evidence to recommend the routine use of warfarin for thrombosis prophylaxis of the vascular access in all patients. If a decision for anticoagulation is made, dosing warfarin to a "therapeutic" level is suggested, although the most appropriate target INR range remains unclear. Many hemodialysis patients with atrial fibrillation have multiple risk factors for stroke and generally benefit from warfarin, with careful and frequent laboratory monitoring. Treatment with standard dose warfarin is also recommended in patients with venous thromboembolism provided that patients do not have contraindications to anticoagulation. For those with such contraindications, placement of an inferior vena cava filter is suggested. These recommendations are limited by the almost complete lack of data in dialysis patients. Sound randomized evidence of efficacy and harm for anticoagulation in these patients will likely never be available. Knowledge of the risk of bleeding and thrombosis in anticoagulated and nonanticoagulated dialysis patients could be provided by feasible, well-designed cohort studies.

Warfarin use associates with increased risk for stroke in hemodialysis patients with atrial fibrillation

Use of warfarin, clopidogrel, or aspirin associates with mortality among patients with ESRD, but the risk-benefit ratio may depend on underlying comorbidities. Here, we investigated the association between these medications and new stroke, mortality, and hospitalization in a retrospective cohort analysis of 1671 incident hemodialysis patients with preexisting atrial fibrillation. We followed patient outcomes from the time of initiation of dialysis for an average of 1.6 yr. Compared with nonuse, warfarin use associated with a significantly increased risk for new stroke (hazard ratio 1.93; 95% confidence interval 1.29 to 2.90); clopidogrel or aspirin use did not associate with increased risk for new stroke. Analysis using international normalized ratio (INR) suggested a dose-response relationship between the degree of anticoagulation and new stroke in patients on warfarin (P = 0.02 for trend). Warfarin users who received no INR monitoring in the first 90 d of dialysis had the highest risk for stroke compared with nonusers (hazard ratio 2.79; 95% confidence interval 1.65 to 4.70). Warfarin use did not associate with statistically significant increases in all-cause mortality or hospitalization. In conclusion, warfarin use among patients with both ESRD and atrial fibrillation associates with an increased risk for stroke. The risk is greatest in warfarin users who do not receive in-facility INR monitoring.

Continuous renal replacement therapies in patients with acute neurological injury

Acute neurological injury may occur in patients with end-stage kidney disease on dialysis. Less frequently, acute kidney injury requiring renal dialytic support develops following acute neurological injury. Surrounding any site of neurological injury there is a penumbra of damage which is potentially reversible. To maximize full potential neurological recovery in patients requiring renal dialytic support, it is important that treatments do not themselves cause further cerebral ischemia. Standard intermittent hemodialysis is associated with cerebral swelling even in healthy outpatients and often with episodes of intradialytic hypotension. Continuous modes of renal replacement therapy have been shown to cause fewer surges in intracranial pressure and greater stability of cerebral perfusion pressure than standard intermittent techniques. In patients with acute neurological injury, renal replacement therapy should be carefully adapted to minimize cardiovascular instability and reduce the rate of change of serum osmolality.

Atrial fibrillation in end-stage renal disease

End-stage renal disease (ESRD) is associated with increased cardiovascular morbidity and mortality. Recent studies indicate that atrial fibrillation (AF) is prevalent among ESRD patients while it adversely affects the clinical outcome. Despite these considerations, AF management in this population is problematic. Notably, most ESRD patients with AF are deprived of the benefits of anticoagulation therapy because of the fear of hemorrhagic complications. This article provides a concise and critical overview of the complex pathophysiology, epidemiology, and discusses the clinical issues regarding the emerging association between ESRD and AF.

Atrial fibrillation in haemodialysis patients: Do the guidelines for anticoagulation apply?

AIM

Atrial fibrillation (AF) is common in haemodialysis patients, but the risks and benefits of anticoagulation in this group are not well characterized. We investigated the prevalence of AF, its associated risk factors, and the incidence of stroke and haemorrhage in a cohort of haemodialysis patients.

METHODS

We retrospectively reviewed 155 patients undergoing maintenance haemodialysis on 1 April 2003 (age 56.9 +/- 13.5 years; men 62.6%; mean duration of haemodialysis 39.3 +/- 37.5 months). Patients with paroxysmal or permanent AF were identified, and baseline clinical and echocardiographic data were obtained. The incidence of cerebrovascular accidents, major haemorrhage and all-cause mortality was assessed during the 26 month average follow-up period.

RESULTS

AF was present in 25.8% of patients, paroxysmal in 18.1%, and permanent in 7.7%. Patients with AF were more likely to be older (64.2 +/- 9.4 vs 54.4 +/- 13.8 years; P < 0.005), have underlying ischaemic heart disease or congestive heart failure, and have a lower serum albumin (P < 0.05 for all). Only 12.5% of AF patients were anticoagulated, although 47.5% had contraindications to warfarin. Cerebrovascular events occurred in 5.2% of all patients (30.4 episodes/1000 patient-years), and major haemorrhage in 20.0% (106.4 episodes/1000 patient-years). All-cause mortality was 29.7%. The endpoints for the AF group did not significantly differ from the non-AF group.

CONCLUSION

AF is common in haemodialysis patients. The incidence of major haemorrhage was over three times that of cerebrovascular accidents. Guideline recommendations for anticoagulation in AF in the general population may not be appropriate for the haemodialysis population.

Warfarin anticoagulation in hemodialysis patients: a systematic review of bleeding rates

BACKGROUND

Despite common use of warfarin, the bleeding risk associated with this treatment in hemodialysis (HD) patients is unknown.

STUDY DESIGN

Systematic review.

SELECTION CRITERIA FOR STUDIES

Inclusion criteria were case series, cohort studies, and randomized controlled trials in dialysis patients that examined the bleeding risk associated with warfarin use compared with no warfarin or subcutaneous heparin. Studies with fewer than 10 subjects, case reports, abstracts lacking complete data sets, review articles, and editorials were excluded.

PREDICTOR

Warfarin use compared with no warfarin or subcutaneous heparin.

OUTCOMES

Data for bleeding were reported as rates: number of bleeding episodes per number of patient-years of warfarin exposure or follow-up.

RESULTS

Of 79 articles and abstracts, 5 met inclusion criteria and 3 more could be added after investigators provided additional information. All studies were of HD patients, and 7 of 8 evaluated the use of warfarin for the prevention of HD access thrombosis. Intensity of anticoagulation varied. Meta-analysis was not possible because of study heterogeneity. Studies of full-intensity anticoagulation and the 1 randomized controlled trial of low-intensity anticoagulation showed major bleeding episode rates ranging from 0.1 to 0.54 events/patient-year of warfarin exposure. These rates are approximately twice as high as those of HD patients receiving either no warfarin or subcutaneous heparin.

LIMITATIONS

This review is based largely on data from observational studies in which bleeding rates may be confounded by comorbidity. Relatively small sample sizes may provide imprecise estimates of rates.

CONCLUSION

Low- and full-intensity anticoagulation use in HD patients is associated with a significant bleeding risk, which has to be balanced against any potential benefit of therapy. This has to be considered carefully when prescribing warfarin to HD patients.

HEMATOLOGY: ISSUES IN THE DIALYSIS PATIENT: The Safety of Heparins in End-Stage Renal Disease

In patients on chronic dialysis, unfractionated heparin (UFH) is the most commonly used agent for anticoagulation of the hemodialysis extracorporeal circuit, for hemodialysis catheter "locking" between dialysis treatments, and for nondialysis indications such as venous thromboembolic disease, peripheral vascular disease, and acute coronary artery disease. Potentially serious complications of UFH, such as hemorrhage, osteoporosis, and thrombocytopenia, have led to consideration of other options for anticoagulation, including low molecular weight heparin (LMWH) and direct thrombin inhibitors (DTIs). LMWH can be used for anticoagulation of the hemodialysis circuit, but whether this has significant benefit compared to UFH remains to be proven. Because of the somewhat unpredictable risk of severe bleeding complications when LMWH is used for other indications in dialysis patients, UFH rather than LMWH is preferred for treatment of thromboembolic disease in these patients. DTIs have been used for anticoagulation in dialysis patients with heparin-induced thrombocytopenia (HIT), with argatroban being the preferred agent if heparin-free hemodialysis cannot be performed. UFH still remains the preferred anticoagulant in the vast majority of dialysis patients requiring systemic anticoagulation and for anticoagulation of the extracorporeal hemodialysis circuit.