Clinical Challenges in a Patient With Dabigatran-Induced Fatal Hemorrhage

Spontaneous rectal sheath bleed while on DOAC anticoagulation

A man in his 80s was transferred from his nursing home residence with sudden onset right-sided abdominal pain. The nursing home staff reported that he was walking to the bathroom when he became diaphoretic, reported he was feeling unwell, then sat on the ground and was reluctant to move. Past medical history was significant for longstanding atrial fibrillation for which he was taking apixaban 2.5 mg twice daily. A CT scan of the abdomen and pelvis was performed which showed a 21×11 cm rectus sheath haematoma on the right extending into the lumbar region. Surgical review advised no invasive intervention. Two units of red cell concentrate were transfused and he was monitored for 5 days before being transferred back to the nursing home.

A Historical Perspective on the Reversal of Anticoagulants

There has been a landmark shift in the last several decades in the management and prevention of thromboembolic events. From the discovery of parenteral and oral agents requiring frequent monitoring as early as 1914, to the development of direct oral anticoagulants (DOACs) that do not require monitoring or dose adjustment in the late 20th century, great advances have been achieved. Despite the advent of these newer agents, bleeding continues to be a key complication, affecting 2 to 4% of DOAC-treated patients per year. Bleeding is associated with substantial morbidity and mortality. Although specific reversal agents for DOACs have lagged the release of these agents, idarucizumab and andexanet alfa are now available as antagonists. However, the efficacy of these reversal agents is uncertain, and complications, including thrombosis, have not been adequately explored. As such, guidelines continue to advise the use of nonspecific prohemostatic agents for patients requiring reversal of the anticoagulant effect of these drugs. As the indications for DOACs and the overall prevalence of their use expand, there is an unmet need for further studies to determine the efficacy of specific compared with nonspecific pro-hemostatic reversal agents. In this review, we will discuss the evidence behind specific and nonspecific reversal agents for both parenteral and oral anticoagulants.

Additive effect of dabigatran and high-dose aspirin in the development of haemorrhagic pleural effusion in a patient with tuberculous pleuritis

Tuberculous pleuritis can rarely cause haemorrhagic pleural effusion. Dabigatran etexilate can have an additive effect on increasing the risk of haemorrhage. Aspirin cannot cause major haemorrhage, but in the elderly it can cause gastrointestinal bleeding via ulceration of the gastrointestinal mucosa. We report here the case of a 77-year-old male who presented to the hospital with a 2-month history of progressive dyspnoea. He had been taking dabigatran etexilate (220 mg) and high-dose acetylsalicylic acid (aspirin; 300 mg) daily for chronic atrial fibrillation. A chest X-ray revealed a moderately sized right pleural effusion confirmed by a computed tomography scan, which also showed bronchiectasis of both lungs. Dabigatran was discontinued and aspirin was decreased to the minimal therapeutic dose of 100 mg before thoracentesis was performed. Lymphocyte-predominant (50%) haemorrhagic fluid of 500 ml was drained, positive for acid-fast bacilli smear and polymerase chain reaction of Mycobacterium tuberculosis. A chest tube was placed and an additional 1250 ml of haemorrhagic exudate drained out. We treated the patient with a routine regimen of antituberculous medication and the infection resolved without complications other than the bronchiectasis present before treatment. We think that the combination of dabigatran etexilate and high doses of aspirin increased the risk of pleural haemorrhage in this patient with tuberculous pleuritis.

Dabigatran must be used carefully: literature review and recommendations for management of adverse events

Atrial fibrillation increases the risk of stroke and death. The vitamin-K antagonist warfarin is recommended for patients with atrial fibrillation, but vitamin-K antagonists are cumbersome to use. Therefore, an effective, safe and convenient new anticoagulant is needed. Dabigatran acts by inhibiting free and fibrin-bound thrombin directly. It is an oral anticoagulant that was approved by the US Food and Drug Administration. The oral anticoagulant dabigatran has been used increasingly due to its good tolerance, predictable pharmacokinetics, effective anticoagulant effects, and absence of requirement of coagulation monitoring. However, an increasing prevalence of adverse events has been reported, some of them quite serious. Therefore, we searched and reviewed the literature on dabigatran with regard to adverse events, and proposed solutions to prevent and reduce the chance of adverse events occurring.

Signal detection for bleeding associated with the use of direct oral anticoagulants

PURPOSE

The potential link between serious or life-threatening bleeding and the use of direct oral anticoagulants (DOACs) was evaluated.

METHODS

Qualitative and quantitative reviews of case reports of bleeding events involving dabigatran, rivaroxaban, apixaban, edoxaban, and warfarin through March 31, 2017, were performed. A disproportionality analysis was conducted for each DOAC using an empirical Bayesian approach based on the relative reporting rate. Subanalyses were performed to assess (1) bleeding events (including mortality and life-threatening events) associated with DOACs among all adverse-event reports and (2) warfarin-related bleeding events. These analyses were conducted based on clinical definitions from the Medical Dictionary for Regulatory Activities.

RESULTS

During the Food and Drug Administration Adverse Event Reporting System (FAERS) review period, 35 adverse-event terms (in any system organ class) with a disproportionality score (EB₀₅) of >7.5 for DOACs were identified; this accounted for 40,109 adverse-event reports. Adverse events with the highest disproportionality scores included atrial thrombosis, increased factor X level, dysfunctional uterine bleeding, high-frequency ablation, pericardial hemorrhage, and internal hemorrhage. Adverse events with the highest EB₀₅ (>5) included internal hemorrhage, hemorrhage, and exsanguination; events with the greatest number of patient experiences included hemorrhage (6,881 events), internal hemorrhage (2,569 events), and hematoma (1,995 events). Warfarin-related events (including death or life-threatening events) were also assessed. A total of 8,729 adverse events were associated with warfarin use. The most common of these included hemorrhage (6,225 events), hematoma (2,199 events), and internal hemorrhage (270 events).

CONCLUSION

The disproportionality analysis of the FAERS database suggests a quantitative signal between DOAC use and life-threatening or serious bleeding.

Current knowledge on assessing the effects of and managing bleeding and urgent procedures with direct oral anticoagulants

PURPOSE

Current knowledge on managing major bleeding events with available hemostatic agents, including their combined use with potential reversal agents, in patients taking direct oral anticoagulant (DOACs) is reviewed.

SUMMARY

Over the past five years, a new generation of oral agents, the DOACs, has emerged as commonly used anticoagulants for stroke prevention in non-valvular atrial fibrillation, and treatment or secondary prevention of venous thromboembolism. Management of a bleeding event in the setting of DOAC therapy should take into account the relative risks of bleeding and thrombosis, which will determine the degree of anticoagulant reversal required. In the setting of a major (critical) bleeding event associated with notable blood loss, management may include transfusions of blood products to sustain the function of organ systems, and the availability of specific reversal agents will provide additional options for bleeding management. Beyond withholding the DOAC and providing supportive management that addresses any factors contributing to the bleeding event, clinicians may desire to expedite the removal of any anticoagulation effects. In general, this is accomplished by either removing or neutralizing the anticoagulant or by independently establishing hemostasis.

CONCLUSION

With or without reversal agents, patients may require supportive management such as mechanical pressure, volume support, transfusions of blood products, and, depending on the situation, surgery to repair the bleeding source. Specific reversal agents are currently under development or have recently been approved for the urgent management of bleeding events or the facilitation of invasive procedures in patients receiving DOACs.

Direct oral anticoagulants compared with warfarin in patients with severe blunt trauma

METHODS

We queried our Trauma Quality Improvement Program registry for patients who presented between 6/1/2011 and 9/1/2015 with severe (injury severity score (ISS)>15) blunt traumatic injury during anticoagulant use. Patients were then grouped into those prescribed warfarin and patients prescribed any of the available novel Direct Oral Anticoagulants (DOAC) medications. We excluded severe (AIS≧4) head injuries.

RESULTS

There were no differences between DOAC and warfarin groups in terms of age, gender mean ISS, median hospital or intensive care unit lengths of stay, complication proportions, numbers of complications per patient, or the proportion of patients requiring transfusion. Finally, excluding patients who died, the observed proportion of discharge to skilled nursing facility was similar. In our sample of trauma patients, DOAC use was associated with significantly lower mortality (DOAC group 8.3% vs. warfarin group 29.5%, p<0.015). The ratio of units transfused per patient was also lower in the DOAC group (2.8±1.8 units/patient in the DOAC group vs. 6.7±6.4 units per patient in the warfarin group; p=0.001).

CONCLUSION

In conclusion, we report an association with decrease in mortality and a decrease in transfused blood products in severely injured trauma patients with likely minimal or no head injury taking novel DOACs over those anticoagulated with warfarin for outpatient anticoagulation.

Evaluation of the chromogenic anti-factor IIa assay to assess dabigatran exposure in geriatric patients with atrial fibrillation in an outpatient setting

Background

Dabigatran etexilate may be underutilized in geriatric patients because of inadequate clinical experience in individuals with severe renal impairment and post-marketing reports of bleeding events. Assessing the degree of anticoagulation may improve the risk:benefit ratio for dabigatran. The aim of this prospective study was to identify whether therapeutic drug monitoring of dabigatran anticoagulant activity using a chromogenic anti-factor IIa assay is a viable option for therapy individualization.

Methods

Plasma dabigatran concentration was assessed in nine patients with nonvalvular atrial fibrillation aged 75 years or older currently receiving dabigatran etexilate for prevention of stroke, using an anti-factor IIa chromogenic assay and HPLC-MS/MS. Trough concentrations were evaluated on two separate occasions to determine intrapatient variation.

Results

Blood was collected at 13.1 ± 2.3 h (mean ± SD) post dose from patients prescribed dabigatran etexilate 150 mg twice daily (5/9 patients) or dabigatran etexilate 75 mg twice daily (4/9 patients). Results from the anti-factor IIa chromogenic assay correlated with dabigatran concentrations as assessed by HPLC-MS/MS (r² = 0.81, n = 16). There was no correlation between dabigatran trough values taken at separate visits (r² = 0.002, n = 7). Furthermore, there was no correlation found between the drug concentrations and patients’ renal function determined by both creatinine and cystatin-C based equations. None of the patients enrolled in the study were in the proposed on-therapy trough range during at least one visit.

Conclusion

The chromogenic anti-factor IIa assay demonstrated similar performance in quantifying dabigatran plasma trough concentrations to HPLC-MS/MS. Single measurement of dabigatran concentration by either of two methods during routine visits may not be reliable in identifying patients at consistently low or high dabigatran concentrations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12959-016-0084-2) contains supplementary material, which is available to authorized users.

Emergent Bleeding in Patients Receiving Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) offer clinical advantages over warfarin, such as minimal medication and food interactions and fixed dosing without the need for routine monitoring of coagulation status. As with all anticoagulants, bleeding, either spontaneous or provoked, is the most common complication. The long-term use of these drugs is increasing, and there is a crucial need for emergency medicine service professionals to understand the optimal management of associated bleeding. This review aims to describe the indications and pharmacokinetics of available DOACs; to discuss the risk of bleeding; to provide a treatment algorithm to manage DOAC-associated emergency bleeding; and to discuss future directions in bleeding management, including the role of specific reversal agents, such as the recently approved idarucizumab for reversal of the direct thrombin inhibitor dabigatran. Because air medical personnel are increasingly likely to encounter patients receiving DOACs, it is important that they have an understanding of how to manage patients with emergent bleeding.

Assessment of novel oral anticoagulant use within a community teaching hospital

Background: Novel oral anticoagulants (NOACs) are considered to be at least as effective and safe as warfarin with several advantages such as predictable pharmacokinetics, allowing for standardized dosing without monitoring, a lack of food interactions and fewer drug interactions; however, their misuse could potentially result in patient harm. Objective: To evaluate the appropriate use of the NOACs within a community teaching hospital. Setting: A community teaching hospital in the United States. Method: A retrospective chart review of patients that were prescribed dabigatran, rivaroxaban, or apixaban at our institution from October 2012 through November 2014 was conducted. Main outcome measure: The primary objective was to determine the percentage of patients that were appropriately prescribed NOACs. Secondary objectives were to determine the number of patients who were inappropriately transitioned from warfarin or parenteral anticoagulants to a NOAC or vice versa, the number of incidents when a NOAC was held or discontinued inappropriately before a procedure and the number of bleeding or thrombotic events while taking a NOAC. Results: Of the 113 patients receiving therapy with an NOAC, appropriate prescribing was observed in 79.7%. Dabigatran, rivaroxaban, and apixaban were appropriately prescribed in 73.8%, 88.3%, and 85.8% of patients respectively. Lack of renal dose-adjustment in patients with reduced renal function was the most common reason for inappropriate use (8.8%). Ten out of 38 patients (26%) were inappropriately transitioned from/to other anticoagulants. Two out of six patients underwent a procedure without holding NOACs as recommended prior to surgery. Of all patients receiving NOACs, a total of 3 bleeding incidents were observed, one with each NOAC. Conclusion: The NOACs were appropriately prescribed for the majority of patients within our institution. Future efforts however should focus on ensuring appropriate dose adjustments for renal impairment, procedures for transitioning between NOACs and parenteral anticoagulants, and adequate withholding times for NOACs prior to surgery in order to optimize the management of NOACs usage within our institution.

New Target-Specific Oral Anticoagulants and Intracranial Bleeding: Management and Outcome in a Single-Center Case Series

INTRODUCTION

New target-specific anticoagulants such as the direct thrombin inhibitor dabigatran and the factor Xa inhibitor rivaroxaban are used in an increasing number of patients. Several studies comparing these new oral anticoagulants with vitamin K antagonists revealed a lower risk of severe bleeding complications and reduced thromboembolic events. However, the lack of antidotes is a challenging issue in the treatment of traumatic or spontaneous intracranial hemorrhage.

METHODS

A retrospective analysis of patients with intracranial bleeding under new oral anticoagulants was performed; these patients were admitted to our department between January 2011 and November 2014. Treatment, reversal management of blood coagulopathy, and outcome of the patients were analyzed.

RESULTS

Seventeen patients were included. The median age was 80.4 years. Seven patients were treated with dabigatran and 10 with rivaroxaban. Eight patients had traumatic intracranial bleeding and 9 patients had spontaneous intracranial hemorrhage. Complex perioperative hematologic treatment followed. In 9 cases, the clinical outcome was devastating with severe neurologic deficits (n = 2), comatose status (n = 4), or death (n = 3). Patients with the indication for acute surgical treatment had a high risk for a critical clinical outcome.

CONCLUSIONS

Only a few case reports have analyzed the clinical course and the outcome after intracranial bleeding under new target-specific oral anticoagulants. Here, one of the first larger series is presented. Because of the lack of reversibility of the anticoagulative effects and the overall risks with geriatric patients, surgical treatment should be delayed as long as possible and comorbidities have to be considered.

Hemodialysis for the treatment of dabigatran-associated bleeding: a case report and systematic review

BACKGROUND

Dabigatran, a direct thrombin inhibitor, is effective for the treatment of venous thromboembolism and the prevention of stroke and systemic embolism resulting from atrial fibrillation. The most effective way of reversing the anticoagulant effect of dabigatran in patients who have bleeding complications is unknown.

OBJECTIVES

To document the clinical outcomes of patients undergoing renal replacement therapy (RRT) for dabigatran-associated bleeding.

METHODS

We searched MEDLINE and EMBASE up to May 2015. Articles were selected if the patients presented with dabigatran-associated bleeding, underwent RRT for dabigatran removal, and reported an effect on bleeding.

RESULTS

The search yielded 22 studies representing 35 unique patient cases. The median patient age was 74.1 years (range, 56-94 years). Thirteen patients (37.1%) were female, and 32 (91.4%) patients received dabigatran for atrial fibrillation. Twenty-three patients (65.7%) underwent intermittent hemodialysis, 10 patients (28.6%) underwent continuous RRT (CRRT), and two patients underwent both intermittent hemodialysis and CRRT. Following RRT, there were significant reductions in dabigatran concentrations (P = 0.001). Rebound of the dabigatran concentration was reported in 12 (57.1%) patients following cessation of RRT. Hemostasis was reportedly achieved in 24 patients (70.6%), and 10 patients (29.4%) died because of bleeding.

CONCLUSIONS

In patients with dabigatran-associated bleeding, RRT appears to be effective in reducing dabigatran concentrations, and in case reports this has been associated with a reduction in the duration and/or severity of bleeding. However, a rebound in concentrations may be seen following withdrawal of RRT, suggesting that a prolonged course of RRT may be more effective.

Novel Oral Anticoagulants: Efficacy, Laboratory Measurement, and Approaches to Emergent Reversal

Warfarin, the most commonly used of the vitamin K antagonists, has been a mainstay of oral anticoagulation for decades. However, its usage is limited by morbidity and mortality secondary to bleeding as well as a cumbersome therapeutic monitoring process. In the past several years, a number of competing novel oral anticoagulants (NOACs) have been developed, each of which aspires to match or exceed warfarin's effectiveness while mitigating bleeding risk and eliminating therapeutic monitoring requirements. At present, 1 oral direct thrombin inhibitor and 2 direct factor Xa inhibitors are approved by the US Food and Drug Administration. Here, we compare the clinical efficacy and safety profiles of these new drugs. In addition, we discuss various laboratory assays that may be useful to measure these drugs in certain clinical circumstances. Finally, we discuss emerging strategies to reverse these agents in an emergency. The purpose of this article is to provide a framework for practicing pathologists to advise clinicians on NOAC laboratory measurement and management of NOAC-associated bleeding.

A sanguineous pleuro pericardial effusion in a patient recently treated with Dabigatran

Dabigatran, a direct thrombin inhibitor, is one of the new oral anticoagulants. As more patients receive treatment with Dabigatran, and as the clinical indications for Dabigatran use expand, reporting serious adverse effects is fundamental to future safety assessment. Although patients taking Dabigatran had fewer life-threatening bleeds when compared to Coumadin, those events continue to be reported. We describe, in the same patient, a sanguineous pleuro pericardial effusion that was diagnosed incidentally on a pre-ablation cardiac CT angiography. The diagnosis was made approximately two months after initiating Dabigatran treatment for non-valvular atrial fibrillation in a 63-year-old patient.

Clinical experience of life-threatening dabigatran-related bleeding at a large, tertiary care, academic medical center: a case series

INTRODUCTION

Dabigatran, an oral direct thrombin inhibitor, is FDA approved for the prevention of stroke in patients with nonvalvular atrial fibrillation. No agent exists for the reversal of dabigatran-related major bleeding. Prothrombin complex concentrate (PCC) has been studied in reversal but was not shown to affect the surrogate markers of bleeding such as the thrombin time, ecarin clotting time, or activated partial thromboplastin time (aPTT). Recombinant factor VIIa (rFVIIa) may provide benefit in patients with life-threatening or major bleeding; however, it has not been studied in dabigatran-related bleeding. PCC and rFVIIa are agents utilized at our institution for major bleeding in patients receiving anticoagulant therapy. Due to the high cost and thrombogenic risk of both rVIIa and PCC and lack of a clear reversal strategy, we reviewed the management of all reported cases of dabigatran-related bleeding.

METHODS

This was a retrospective chart review of patients admitted to UMass Memorial Medical Center with a bleeding event and also receiving dabigatran therapy.

RESULTS

Eleven patients on dabigatran admitted for bleeding were identified. Seven were admitted for an intracranial hemorrhage (ICH) and four for a gastrointestinal hemorrhage (GIH). The baseline characteristics are as follows: mean age was 74.55 years (range, 63-89), and seven were male. Admission mean hemoglobin was 11.88 g/dl (range, 6.1-18), mean international normalized ratio (INR) was 2.2 (range, 1.1-7.1), and mean aPTT was 42.21 s (range, 36-81.4). Interventions received included fresh frozen plasma (n = 6), platelets (n = 3), packed red blood cells (n = 4), rFVIIa (n = 2), intravenous fluids (n = 10), surgical intervention (n = 3), and dialysis (n = 2). No patients received PCC. Four patients survived in the ICH group, and four patients survived in the GIH group.

CONCLUSION

Reversal strategies for dabigatran-related bleeding events at our institution are highly variable. Intracranial hemorrhage in patients on dabigatran was associated with 43 % mortality. Patients with severe dabigatran-related bleeding may benefit from a standardized approach to treatment.

Comparison of intermittent and continuous extracorporeal treatments for the enhanced elimination of dabigatran

CONTEXT

Severe bleeding associated with dabigatran frequently requires intensive care management. An antidote is currently unavailable and data reporting the effect of dialysis on elimination of dabigatran are encouraging, but limited. Objective. To report the effect of intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT) at enhancing elimination of dabigatran.

MATERIALS AND METHODS

Patients were identified by existing collaborative networks. Pre-filter dabigatran plasma concentrations were measured in all patients, and in dialysate of three patients.

RESULTS

Seven patients received dialysis, five with active bleeding and two requiring emergent surgery. Five received IHD and two received CRRT. The plasma elimination half-life of dabigatran was 1.5-4.9 h during IHD, and 14.0-27.5 h during CRRT. Mean dabigatran plasma clearance during IHD was 85-169 mL/min in three patients. Time to obtain a subtherapeutic dabigatran concentration depended on the initial concentration, being 8-18 h for IHD in three patients while 4 h was insufficient in a supratherapeutic case. A 38% rebound in dabigatran levels occurred after one case during IHD, and thrombin time increased after IHD in another, but not after 144 h CRRT or 17 h IHD in two others; data were incomplete in three cases. The amount removed during IHD was proportional to the pre-IHD concentration and clearance, but was consistently low at 3.3-17.4 mg in three patients where this was determined. Moderate bleeding occurred while obtaining vascular access in one patient. Two patients died from intracerebral bleeding, and the influence of treatments could not be determined in these cases.

DISCUSSION AND CONCLUSIONS

IHD enhanced elimination of dabigatran more efficiently than CRRT, but their net effect remains poorly defined. Dialysis decisions, including modality and duration, must be individualized based on a risk-benefit assessment.

Risk of bleeding with dabigatran in atrial fibrillation

IMPORTANCE

It remains unclear whether dabigatran etexilate mesylate is associated with higher risk of bleeding than warfarin sodium in real-world clinical practice.

OBJECTIVE

To compare the risk of bleeding associated with dabigatran and warfarin using Medicare data.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective cohort study, we used pharmacy and medical claims in 2010 to 2011 from a 5% random sample of Medicare beneficiaries. We identified participants as those newly diagnosed as having atrial fibrillation from October 1, 2010, through October 31, 2011, and who initiated dabigatran or warfarin treatment within 60 days of initial diagnosis. We followed up patients until discontinued use or switch of anticoagulants, death, or December 31, 2011.

EXPOSURES

Dabigatran users (n = 1302) and warfarin users (n = 8102).

MAIN OUTCOMES AND MEASURES

We identified any bleeding events and categorized them as major and minor bleeding by anatomical site. Major bleeding events included intracranial hemorrhage, hemoperitoneum, and inpatient or emergency department stays for hematuria, gastrointestinal, or other hemorrhage. We used a propensity score weighting mechanism to balance patient characteristics between 2 groups and Cox proportional hazards regression models to evaluate the risk of bleeding. We further examined the risk of bleeding for 4 subgroups of high-risk patients: those 75 years or older, African Americans, those with chronic kidney disease, and those with more than 7 concomitant comorbidities.

RESULTS

Dabigatran was associated with a higher risk of bleeding relative to warfarin, with hazard ratios of 1.30 (95% CI, 1.20-1.41) for any bleeding event, 1.58 (95% CI, 1.36-1.83) for major bleeding, and 1.85 (95% CI, 1.64-2.07) for gastrointestinal bleeding. The risk of intracranial hemorrhage was higher among warfarin users, with a hazard ratio of 0.32 (95% CI, 0.20-0.50) for dabigatran compared with warfarin. Dabigatran was consistently associated with an increased risk of major bleeding and gastrointestinal hemorrhage for all subgroups analyzed. The risk of major bleeding among dabigatran users was especially high for African Americans and patients with chronic kidney disease.

CONCLUSIONS AND RELEVANCE

Dabigatran was associated with a higher incidence of major bleeding (regardless of the anatomical site), a higher risk of gastrointestinal bleeding, but a lower risk of intracranial hemorrhage. Thus, dabigatran should be prescribed with caution, especially among high-risk patients.

Strategies for urgent reversal of target-specific oral anticoagulants

The direct thrombin inhibitor dabigatran and factor Xa inhibitors rivaroxaban and apixaban are US Food and Drug Administration (FDA)-approved target-specific oral anticoagulants (TSOACs) that have emerged onto the market for use in some indications similar to those for warfarin; in addition, edoxaban is seeking FDA approval. Similar indications include reducing the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation for all 3 agents, for the prevention of deep vein thrombosis that may lead to pulmonary embolism in patients undergoing hip or knee surgery for rivaroxaban and apixaban, and for the treatment and prevention of deep vein thrombosis and pulmonary embolism. As anticoagulants, they are all associated with a risk of bleeding, and, unfortunately, there are no approved antidotes for reversal of these agents. A number of small studies in human subjects and in human/animal models exposed to TSOACs have evaluated the use of activated charcoal, hemodialysis for dabigatran, or clotting factor concentrates for their ability to neutralize the anticoagulant effects or reduce drug concentrations of TSOACs. Clotting factor concentrates that have been used include prothrombin complex concentrates and recombinant factor VII. This review examines studies and case reports evaluating these strategies for expedited or emergent reversal of TSOACs.

What is the role of hemodialysis for dabigatran-associated major bleeding?

A 70-year-old male with a history of atrial fibrillation who is being anticoagulated with dabigatran etexilate presents to the emergency room with melena. He reports taking his most recent dose of dabigatran more than 2 hours ago. On examination, he is hypotensive and tachycardic, and he continues to have melanotic stools. Laboratory testing reveals a calculated creatinine clearance of 15 mL/min, a prothrombin time of 16.5 seconds (reference range: 11.8-15.2 seconds), an international normalized ratio of 1.2 (reference range: 0.9-1.2), and an activated partial thromboplastin time of 50 seconds (reference range: 22.2-33.0 seconds). You are asked by the emergency medicine physician whether hemodialysis should be considered to decrease the patient's plasma dabigatran level.

Use of hemodialysis for the treatment of intracerebral hemorrhage in patients on dabigatran with normal renal function

Dabigatran is a direct thrombin inhibitor which is approved by the Food and Drug Administration (FDA) for prevention of embolic stroke in patients with atrial fibrillation. Dabigatran has been shown to be non- inferior to warfarin in preventing stroke in patients with atrial fibrillation [1, 6]. The rate of major bleeding in patients taking dabigatran is also similar to that seen in patients on warfarin [1]. Unlike warfarin, there is currently no antidote available for reversal of anticoagulant effects of dabigatran [2, 3]. Dabigatran is excreted renally and accumulates in patients with acute kidney injury (AKI). Hemodialysis has been reported to increase clearance of dabigatran in patients with acute kidney injury and life-threatening bleeding [4, 5]. We present two cases of dabigatran-associated intracranial hemorrhage where hemodialysis was used to accelerate clearance of dabigatran from the blood in patients with normal renal function.

New oral anticoagulant-induced bleeding: clinical presentation and management

Bleeding is a significant complication of anticoagulant therapy. With the emergence of new oral anticoagulants (NOACs; ie, direct factor IIa or Xa inhibitors), this risk is further compounded by the lack of validated reversal strategies for these agents. Emerging postmarketing evidence suggests that the bleeding risks are in line with results observed in head-to-head clinical trials of NOACs versus traditional anticoagulants. Several guidelines have recommended the use of hemostatic agents for NOAC reversal in patients with life-threatening bleeding. Ultimately, adequately powered studies will be crucial for full assessment of the effectiveness and safety of any proposed reversal strategies.

Reversal of dabigatran-induced bleeding by coagulation factor concentrates in a rat-tail bleeding model and lack of effect on assays of coagulation

BACKGROUND

Dabigatran is a potent oral anticoagulant. Like any anticoagulant, there is an increased risk of bleeding associated with its use, and reversal may be needed in cases of severe bleeding.

METHODS

In this study, six coagulation factor concentrates (CFCs) were tested for their ability to reduce bleeding induced by oral dabigatran etexilate (30 mg/kg) in a rat-tail bleeding model (n = 5 to 8 per group): three-factor (Profilnine [Grifols Biologicals Inc., Los Angeles, CA] and Bebulin [Baxter BioScience, Westlake Village, CA]) and four-factor prothrombin complex concentrates (Beriplex [CSL Behring, Marburg, Germany] and Octaplex [Octapharma AG, Lachen, Switzerland]), activated prothrombin complex concentrate (Factor Eight Inhibitor Bypassing Activity; Baxter AG, Vienna, Austria), and recombinant factor VIIa (NovoSeven; NovoNordisk, Bagsværd, Denmark). The effect of CFCs on prolongation of coagulation assays was measured. Thrombin generation after administration of each CFC was compared in vitro using human plasma (n = 5) spiked with dabigatran in concentrations corresponding to median peak (200 ng/ml) and supratherapeutic values (600 and 1,000 ng/ml).

RESULTS

Dabigatran resulted in an approximately three-fold increase in bleeding time, consistent with supratherapeutic dabigatran plasma levels. Beriplex (35 and 50 IU/kg), Octaplex (40 IU/kg), Profilnine (50 IU/kg), Bebulin (60 IU/kg), Factor Eight Inhibitor Bypassing Activity (100 U/kg), and NovoSeven (500 μg/kg) significantly decreased this prolonged bleeding time over 30 min (P < 0.001). The coagulation assays were prolonged three- to eight-fold over baseline (P = 0.01). None of the CFCs produced a consistent change in these assays that was predictive of reduced bleeding. Thrombin generation reversal was dependent on the concentration of dabigatran and each CFC; normalization occurred at the lower concentration of dabigatran with most CFCs, but not at higher concentrations.

CONCLUSIONS

In this animal model, bleeding induced by high doses of dabigatran can be reduced by CFCs. However, routine coagulation assays do not predict this effect.

Concerns about the use of new oral anticoagulants for stroke prevention in elderly patients with atrial fibrillation

The prevalence of atrial fibrillation (AF) and the embolic risk increase with age. Elderly AF patients are undertreated with vitamin K antagonists (VKA). The new oral anticoagulants (NOAC) dabigatran, rivaroxaban and apixaban have been shown to be non-inferior to VKA for stroke prevention in AF. We summarize the knowledge about primary and secondary stroke prevention by NOAC in AF patients >75 years of age. A literature search was carried out using the terms 'dabigatran', 'rivaroxaban', 'apixaban', 'elderly', 'octogenarians', 'atrial fibrillation' and 'anticoagulation' from 1998 to 2013. Randomized clinical trials, longitudinal studies, case series and case reports were included. Whereas studies investigating the use of VKA for stroke prevention in the 1990s were carried out by industry-independent institutions, all NOAC-investigating trials were sponsored by the manufacturers of the respective drugs. Frail elderly people were not represented in NOAC-investigating trials because of various exclusion criteria, and only one-third of patients were aged >75 years. A subgroup analysis from the dabigatran-investigating trial indicated that elderly patients might have a higher risk for extracranial bleeding complications with NOAC than with VKA. Further concerns about the use of NOAC in the elderly are the high prevalence of renal insufficiency in AF patients >75 years of age, the largely unknown risk of drug-drug and drug-food interactions, the lack of easily available laboratory monitoring tests of anticoagulant activity and the lack of an antidote. There is a need for independent studies comparing the efficacy and risk of side effects of NOAC with that of VKA in elderly AF patients.

New oral anticoagulants: clinical indications, monitoring and treatment of acute bleeding complications

New oral anticoagulants like the direct thrombin inhibitor, dabigatran (Pradaxa®), and factor Xa-inhibitors, rivaroxaban (Xarelto®) and apixaban (Eliquis®) are available for prophylaxis and treatment of thromboembolic disease. They are emerging alternatives to warfarin and provide equal or better clinical outcome together with reduced need for routine monitoring. Methods for measuring drug concentrations are available, although a correlation between plasma drug concentrations and the risk of bleeding has not been firmly established. Standard laboratory measures like prothrombin time and activated partial thromboplastin time are not sensitive enough to detect thrombin or factor Xa inhibition provided by new oral anticoagulants. Thus, these standard tests may only be used as a crude estimation of the actual anticoagulation status. Further challenges regarding patients receiving new oral anticoagulants who presents with major bleeding or need for emergency surgery pose a unique problem. No established agents are clinically available to reverse the anticoagulant effect, although preclinical data report prothrombin complex concentrate as more efficient than fresh frozen plasma or other prohaemostatic agents. This review summaries current knowledge on approved new oral anticoagulants and discusses clinical aspects of monitoring, with particular focus on the management of the bleeding patient.

An evaluation of oral dabigatran etexilate pharmacokinetics and pharmacodynamics in hemodialysis

Dabigatran etexilate represents a possible improved alternative to warfarin for anticoagulation in hemodialysis patients with atrial fibrillation (AF). The objective was to determine dabigatran plasma concentrations and anticoagulant effects following administration of a single 110 mg oral dose of dabigatran etexilate to 10 adult patients immediately prior to starting hemodialysis. Mass spectrometry and the Hemoclot® assay were used, respectively, to determine free (unconjugated) dabigatran concentrations and thrombin time (TT) in plasma samples collected intermittently over 48 hours. The median time (tmax ) to reach the maximum plasma-free dabigatran concentration (Cmax ) was 2 hours (range 1-3 hours). The mean free dabigatran Cmax was 95.5 ± 33.4 ng/mL. The mean elimination half-lives on and off hemodialysis were, respectively, 2.6 ± 1.3 and 30.2 ± 7.8 hours. Hemodialysis effectively removed dabigatran with an extraction ratio of 0.63 ± 0.07. The maximal TT ratio was 2.1 and the TT ratio demonstrated a strong linear dependence on free dabigatran concentration (r(2)  = 0.741). A 110 mg oral dabigatran dose prior to hemodialysis was rapidly absorbed and achieved therapeutic concentrations. Hemodialysis effectively removed dabigatran from the plasma and may be an effective means of accelerating the elimination of dabigatran in circumstances of excessive anticoagulation.

Management of dabigatran-associated intracerebral and intraventricular hemorrhage: a case report

BACKGROUND

Dabigatran is an oral, reversibly bound, direct thrombin inhibitor currently approved in the United States for prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation. In the phase III trial leading to approval of the agent, the incidence of life-threatening bleeding was 1.80%/year in the dabigatran 150 mg twice daily arm. Because there is no direct antidote or reversal agent for this drug, the need to manage life-threatening hemorrhages with procoagulant products will arise.

OBJECTIVE

To describe a case of dabigatran-associated intracerebral and intraventricular hemorrhage and subsequent management with activated prothrombin complex concentrate.

CASE REPORT

An 85-year-old man currently taking dabigatran 150 mg twice daily presented to the Emergency Department for incoordination, expressive aphasia, and weakness. A computed tomography image of his head demonstrated an intracranial hemorrhage. The last dose of dabigatran was approximately 14 h prior to arrival, and conventional coagulation assays (thrombin time and activated partial thromboplastin time) confirmed the presence of dabigatran in the patient's serum. The patient received 27.5 units/kg of activated prothrombin complex concentrate (FEIBA®; Baxter Healthcare Corporation, Deerfield, IL) after an initial intravenous fluid bolus. His activated partial thromboplastin time was not completely normalized by the use of FEIBA; however, the patient's neurological examination slightly improved and remained stable throughout his hospital course despite some intraventricular expansion of the hematoma. After discharge to physical rehabilitation, the patient developed an ischemic cerebrovascular accident and was discharged home on hospice.

CONCLUSION

Due to lack of an available antidote, activated prothrombin complex concentrate was utilized as a nonspecific procoagulant to stabilize an intracerebral hemorrhage in a patient on dabigatran.

Hip arthroplasty fatality related to dabigatran induced gastrointestinal haemorrhage

We report a fatality due to massive gastrointestinal haemorrhage in a patient receiving prophylactic dabigatran etexilate following a total hip replacement. A 79-year-old woman was commenced on dabigatran for venous thromboembolic prophylaxis following a total hip replacement. She presented again four days after surgery with haematemesis and hypotension but her coagulopathy could not be corrected, leading to her death. This case highlights the lack of reversal agent for dabigatran etexilate that resulted in this fatal complication.

Positive outcome after intentional overdose of dabigatran

INTRODUCTION

Dabigatran (Pradaxa™), an orally active direct thrombin inhibitor, was approved by the United States Food and Drug Administration for the prevention of stroke in patients with atrial fibrillation in October 2010. Life-threatening consequences from dabigatran therapy include hemorrhage and bleeding complications, but they typically occur after renal impairment. We describe the first case report of intentional, acute overdose with dabigatran.

CASE REPORT

A 57-year-old woman with a medical history of depression and atrial fibrillation presented to the emergency department after ingesting 11.25 g of dabigatran in a suicide attempt. Despite an ecchymosis indicative of prior trauma, there was no evidence of acute bleeding. After receiving gastric lavage and activated charcoal therapy in the emergency department, she was admitted to the ICU. On presentation, dabigatran blood levels measured 970 ng/mL and thrombin clot times measured above the testable limits (>120 s) until 52 h post-arrival. The remainder of her clinical course was uncomplicated, and the patient was transferred to an inpatient psychiatric unit for depression follow-up.

DISCUSSION

This case shows the clinical course of a patient with an acute, massive dabigatran overdose with no significant clinical consequences. Currently, there is no ideal method to monitor anticoagulation levels; there is no pharmacologic reversal method, and hemodialysis is an undesirable treatment option.

Evaluation of dabigatran exposures reported to poison control centers

BACKGROUND

Dabigatran is a novel oral anticoagulant for which a well-defined range of toxicity and proven antidote has not been established.

OBJECTIVE

The primary objective of this study was to characterize dabigatran exposures reported to poison centers by dose ingested, clinical effects, treatments used, and managment sites to gain a better understanding of patient outcomes.

METHODS

A retrospective database review was conducted for dabigatran exposures reported to the National Poison Data System for the American Association of Poison Control Centers (AAPCC) over the period October 2010 to December 2012.

RESULTS

There were 802 human dabigatran exposures involving adults predominantly (91% of cases). Exposure chronicity was acute in 43%, acute-on-chronic in 46%, and chronic in 11%, with the most common reason for an exposure call being an unintentional therapeutic error (70.6%). The most common management sites were on-site in 72% of cases and within a health care facility for 26%. Bleeding events and coagulopathies were the most commonly observed clinical effects. Treatments administered included activated charcoal, blood and coagulation products, hemodialysis, and supportive measures. Confirmed outcomes included death in 13 patients (1.6%), major effects in 23 (2.9%), and moderate effects in 50 (6.2%). More severe outcomes were significantly associated with adverse drug reactions, patients ≥65 years of age, those treated with blood and coagulation products and/or dialysis, and renal dysfunction (P < .05). Children experienced few moderate effects and no major effects or deaths.

CONCLUSIONS

Severe outcomes from dabigatran exposures were not common, occurring in approximately 5% of cases.

Pathology consultation on monitoring direct thrombin inhibitors and overcoming their effects in bleeding patients

OBJECTIVES

Direct thrombin inhibitors (DTIs), a relatively new class of anticoagulants, present several challenges regarding monitoring of their anticoagulant effects and overcoming bleeding associated with their use. The aim of this article is to (1) briefly present the pharmacologic properties of currently available DTIs, (2) discuss approaches to laboratory assessment of these drugs, and (3) review management of bleeding associated with their use.

METHODS

Published literature on DTIs, including clinical trials, case reports, and experimental animal models, was reviewed. The primary authors also reviewed their first-hand experiences with DTI anticoagulation.

RESULTS

Based on the literature review and the practical experiences of the authors, suggestions for the monitoring of DTIs and algorithmic approaches for the management of DTI-associated bleeding were developed.

CONCLUSIONS

Routine coagulation assays (eg, the prothrombin time) show a relatively poor correlation with the degree of anticoagulation and DTI drug concentrations. Newer assays, such as the ecarin clotting time and dilute thrombin time, may be more useful in assessing DTI anticoagulation, but these assays are not yet widely available. Low-grade DTI-associated bleeds are best managed with cessation of the drug and supportive care, while higher-grade and/or life-threatening bleeds may best be reversed by active drug removal (eg, via the administration of activated charcoal or hemodialysis). At present there is little evidence to suggest that transfusion products such as factor concentrates or thawed plasma are of any particular benefit in DTI reversal; however, these products may play a supportive role in the management of bleeding.

Anticoagulant therapy with the oral direct factor Xa inhibitors rivaroxaban, apixaban and edoxaban and the thrombin inhibitor dabigatran etexilate in patients with hepatic impairment

The direct factor Xa (FXa) inhibitors rivaroxaban, apixaban and edoxaban, and the thrombin inhibitor dabigatran etexilate (dabigatran) have gained approval for use in several indications, most notably for the prevention and treatment of venous thromboembolism (VTE) and for the prevention of stroke in patients with atrial fibrillation. Hepatic impairment can affect the disposition of these anticoagulants considerably not only because of the hepatic metabolism of the direct FXa inhibitors but also because moderate to severely impaired hepatic function will affect coagulation. This review describes the key pharmacological properties of novel oral anticoagulants with special attention to patients with impaired hepatic function. In subjects with moderately impaired liver function (i.e. Child-Pugh classification B), the area under the plasma concentration-time curve (AUC) of rivaroxaban (10 mg single dose) is increased by 2.27-fold, which is paralleled by an increase in FXa inhibition. The AUC of apixaban (5 mg single dose) is increased by 1.09-fold, whereas the AUC of edoxaban (15 mg single dose) is decreased by 4.8 % and the AUC of dabigatran (150 mg single dose) is decreased by 5.6 %. Specific labelling restrictions for rivaroxaban, apixaban and dabigatran regarding impaired hepatic function are based on both the Child-Pugh classification and liver-related exclusion criteria applied in pivotal clinical trials. Rivaroxaban is contraindicated in patients with hepatic disease associated with coagulopathy and clinically relevant bleeding risk, including cirrhotic patients classified as Child-Pugh B and C. Apixaban can be used with caution in patients with mild (Child-Pugh A) or moderate (Child-Pugh B) hepatic impairment or in patients with alanine aminotransferase and aspartate aminotransferase levels >2× upper limit of normal (ULN). Apixaban is not recommended in patients with severe hepatic impairment and is contraindicated in those with hepatic disease associated with coagulopathy and clinically relevant bleeding risk. Dabigatran is not recommended in patients with elevated liver enzymes (>2× ULN). Dabigatran is contraindicated in patients with hepatic impairment or liver disease expected to have any impact on survival. Currently, edoxaban is not available in the US or European markets. However, the Japanese label did not restrict use in hepatic dysfunction but advises care in patients with severe hepatic impairment.

Extracorporeal therapy for dabigatran removal in the treatment of acute bleeding: a single center experience

BACKGROUND AND OBJECTIVES

Dabigatran is an oral direct thrombin inhibitor that is Food and Drug Administration-approved for prevention of stroke in patients with atrial fibrillation. No antidote is available for reversal of dabigatran's anticoagulant effect. Despite limited clinical data, hemodialysis has been suggested as a strategy to remove dabigatran during acute bleeding. This work presents five cases, in which extracorporeal therapy was performed for dabigatran removal in acutely bleeding patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The series is comprised of five consecutive cases of patients receiving dabigatran 150 mg per os two times daily who were admitted with life-threatening bleeding between March of 2012 and January of 2013. Dabigatran plasma concentrations ranged from 149 to 1200 ng/ml. Treatment included administration of blood products to all patients and then, high-flux intermittent hemodialysis alone or followed by continuous renal replacement therapy.

RESULTS

Dabigatran concentrations decreased by 52%-77% during intermittent hemodialysis but rebounded up to 87% within 2 hours after completion of dialysis. Initiation of continuous renal replacement therapy after intermittent hemodialysis attenuated the rebound effect in one patient and contributed to a reduction in dabigatran concentrations of 81% over 30 hours.

CONCLUSIONS

Extracorporeal therapy lowered dabigatran concentrations, suggesting that it removed the drug and may effectively accelerate total clearance, especially in patients with impaired kidney function. The use of prolonged intermittent hemodialysis or intermittent hemodialysis followed by continuous renal replacement therapy is recommended for the management of life-threatening bleeding in patients receiving dabigatran. The advantage of extracorporeal therapy should be weighed against the risk of bleeding with catheter insertion.