Use of prothrombin complex concentrates for urgent reversal of dabigatran in the Emergency Department

Clinical guideline on reversal of direct oral anticoagulants in patients with life threatening bleeding

BACKGROUND

Anticoagulation is essential for the treatment and prevention of thromboembolic events. Current guidelines recommend direct oral anticoagulants (DOACs) over vitamin K antagonists in DOAC-eligible patients. The major complication of anticoagulation is serious or life-threatening haemorrhage, which may necessitate prompt haemostatic intervention. Reversal of DOACs may also be required for patients in need of urgent invasive procedures. This guideline from the European Society of Anaesthesiology and Intensive Care (ESAIC) aims to provide evidence-based recommendations and suggestions on how to manage patients on DOACs undergoing urgent or emergency procedures including the treatment of DOAC-induced bleeding.

DESIGN

A systematic literature search was performed, examining four drug comparators (dabigatran, rivaroxaban, apixaban, edoxaban) and clinical scenarios ranging from planned to emergency surgery with the outcomes of mortality, haematoma growth and thromboembolic complications. The GRADE (Grading of Recommendations, Assessment, Development and Evaluation) methodology was used to assess the methodological quality of the included studies. Consensus on the wording of the recommendations was achieved by a Delphi process.

RESULTS

So far, no results from prospective randomised trials comparing two active comparators (e.g. a direct reversal agent and an unspecific haemostatic agent such as prothrombin complex concentrate: PCC) have been published yet and the majority of publications were uncontrolled and observational studies. Thus, the certainty of evidence was assessed to be either low or very low (GRADE C). Thirty-five recommendations and clinical practice statements were developed. During the Delphi process, strong consensus (>90% agreement) was achieved in 97.1% of recommendations and consensus (75 to 90% agreement) in 2.9%.

DISCUSSION

DOAC-specific coagulation monitoring may help in patients at risk for elevated DOAC levels, whereas global coagulation tests are not recommended to exclude clinically relevant DOAC levels. In urgent clinical situations, haemostatic treatment using either the direct reversal or nonspecific haemostatic agents should be started without waiting for DOAC level monitoring. DOAC levels above 50 ng ml-1 may be considered clinically relevant necessitating haemostatic treatment before urgent or emergency procedures. Before cardiac surgery under activated factor Xa (FXa) inhibitors, the use of andexanet alfa is not recommended because of inhibition of unfractionated heparin, which is needed for extracorporeal circulation. In the situation of DOAC overdose without bleeding, no haemostatic intervention is suggested, instead measures to eliminate the DOACs should be taken. Due to the lack of published results from comparative prospective, randomised studies, the superiority of reversal treatment strategy vs. a nonspecific haemostatic treatment is unclear for most urgent and emergency procedures and bleeding. Due to the paucity of clinical data, no recommendations for the use of recombinant activated factor VII as a nonspecific haemostatic agent can be given.

CONCLUSION

In the clinical scenarios of DOAC intake before urgent procedures and DOAC-induced bleeding, practitioners should evaluate the risk of bleeding of the procedure and the severity of the DOAC-induced bleeding before initiating treatment. Optimal reversal strategy remains to be determined in future trials for most clinical settings.

Antidote vs. unspecific hemostatic agents for the management of direct oral anticoagulant-related bleeding in trauma

PURPOSE OF REVIEW

The advent of direct oral anticoagulants (DOACs) marks a significant milestone in anticoagulant treatment. However, DOACs can exacerbate bleeding, which is challenging for the treating clinician, especially when combined with traumatic injury.

RECENT FINDINGS

In major bleeding associated with DOACs, rapid reversal of the anticoagulant effects is crucial. Recent observational and nonrandomized interventional trials have demonstrated the effectiveness of the specific antidotes andexanet alfa and idarucizumab as well as the unspecific prothrombin complex concentrates (PCCs) to counteract the anticoagulant effects of DOACs. The European Society of Anaesthesiology and Intensive Care guideline for severe perioperative bleeding and the European trauma guideline propose divergent recommendations for the use of andexanet alfa and PCC to obtain hemostasis in Factor Xa inhibitor-related bleeding. The conflicting recommendations are due to limited evidence from clinical studies and the potential increased risk of thromboembolic complications after the administration of andexanet. Regarding dabigatran-associated major bleeding, both guidelines recommend the specific reversal agent idarucizumab as first-line therapy.

SUMMARY

Current guidelines recommend specific antidots and PCCs in DOAC-related major bleeding. Prospective randomized trials comparing specific vs. nonspecific hemostatic agents in the perioperative setting are needed to evaluate the effectiveness and safety of the hemostatic agents.

Contemporary Perioperative Management of Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) have rapidly emerged as popular alternatives to warfarin in the setting of nonvalvular atrial fibrillation, prevention and treatment of venous thromboembolism, and secondary prevention of arterial thrombosis. It is now estimated that more patients in the United States take DOACs than warfarin for approved indications. Studies to date have shown that these drugs are similarly efficacious with perhaps a lower bleeding risk than warfarin. The purpose of this review is to provide insight into the currently available DOACs and discuss the management and reversal strategies for patients in the perioperative period.

Reversing anticoagulation in the hemorrhaging patient

PURPOSE OF REVIEW

Anticoagulants in general, but especially the relatively new direct oral anticoagulants and platelet inhibitors, pose a great challenge for physicians in the hemorrhaging patient. The aim of the present review is to provide an overview on recent studies dealing with the reversal of anticoagulation in the hemorrhaging patient and to describe our therapeutic emergency strategy for those patients.

RECENT FINDINGS

A specific antidote for dabigatran is already on the market and antidotes for the direct and indirect factor Xa inhibitors are in development. Moreover, bleeding under platelet inhibitors remains critical with very little evidence on effective reversal strategies.

SUMMARY

To reverse anticoagulation in the hemorrhaging patient, specific antidotes should be the first option if available, followed by four-factor prothrombin complex concentrate (PCC), activated PCC and recombinant activated factor seven as the emergency strategy. Fibrinogen concentrate, antifibrinolytics and oral charcoal, respectively, can be considered as an additional measure. Massive blood loss and thrombocytopenia should be treated independently according to the respective, local guidelines for (massive) transfusion of blood and blood products.

The impact of prothrombin complex concentrates when treating DOAC-associated bleeding: a review

Background

Bleeding complications are a risk associated with all anticoagulants. Currently, the treatment options for the management of direct oral anticoagulant (DOAC)-associated bleeding are limited. Prothrombin complex concentrates (PCCs) have been proposed as a potential therapeutic option, and evidence regarding their use is increasing.

Review

Many studies supporting PCC have used preclinical models and healthy volunteers; however, more recently, observational studies have further improved insight into current DOAC reversal strategies. Multiple clinical practice guidelines now specifically suggest use of PCCs for this indication. Specific reversal agents for Factor Xa inhibitors may become available in the near future, but data on their efficacy are still emerging.

Conclusions

Ultimately, a multimodal approach may be the optimal strategy to restore haemostasis in patients presenting with DOAC-associated coagulopathy.

Electronic supplementary material

The online version of this article (10.1186/s12245-018-0215-6) contains supplementary material, which is available to authorized users.

Direct Oral Anticoagulants in Emergency Trauma Admissions

BACKGROUND

Direct (non-vitamin-K-dependent) oral anticoagulants (DOAC) are given as an alternative to vitamin K antagonists (VKA) to prevent stroke and embolic disease in patients with atrial fibrillation that is not due to pathology of the heart valves. Fatal hemorrhage is rarer when DOACs are given (nonvalvular atrial fibrillation: odds ratio [OR] 0.68; 95% confidence interval [95% CI: 0.48; 0.96], and venous thromboembolism: OR 0.54; [0.22; 1.32]). 48% of emergency trauma patients need an emergency operation or early surgery. Clotting disturbances elevate the mortality of such patients to 43%, compared to 17% in patients without a clotting disturbance. This underscores the impor tance of the proper, targeted treatment of trauma patients who are aking DOAC.

METHODS

This review is based on articles retrieved by a selective search in PubMed and on a summary of expert opinion and the recommendations of the relevant medical specialty societies.

RESULTS

Peak DOAC levels are reached 2-4 hours after the drug is taken. In patients with normal renal and hepatic function, no drug accumulation, and no drug interactions, the plasma level of DOAC 24 hours after administration is generally too low to cause any clinically relevant risk of bleeding. The risk of drug accumulation is higher in patients with renal dysfunction (creatinine clearance [CrCl] of 30 mL/min or less). Dabigatran levels can be estimated from the thrombin time, ecarin clotting time, and diluted thrombin time, while levels of factor Xa inhibitors can be estimated by means of calibrated chromogenic anti-factor Xa activity tests. Routine clotting studies do not reliably reflect the anticoagulant activity of DOAC. Surgery should be postponed, if possible, until at least 24-48 hours after the last dose of DOAC. For patients with mild, non-life threatening hemorrhage, it suffices to discontinue DOAC; for patients with severe hemorrhage, there are special treatment algorithms that should be followed.

CONCLUSION

DOACs in the setting of hemorrhage are a clinical challenge in the traumatological emergency room because of the inadequate validity of the relevant laboratory tests. An emergency antidote is now available only for dabigatran.

Reversing the anticoagulation effects of dabigatran

The standard of care for oral anticoagulation therapy has primarily been warfarin, which is limited by its indirect mechanism-of-action, variable kinetics, tolerability, and routine monitoring concerns. The direct-acting oral anticoagulants (DOACs) have predictable pharmacokinetics and pharmacodynamics, and improved safety and efficacy compared to warfarin for the prevention of stroke in patients with nonvalvular atrial fibrillation and prevention or management of venous thromboembolism. Consequential bleeding is a concern with all anticoagulants. Vitamin K is not a rapid reversal agent for warfarin; rather it facilitates synthesis of new vitamin K-dependent clotting factors, which can take longer than 24 h. Other nonspecific agents, including recombinant activated factor VII, three- and four-factor prothrombin complex concentrates (PCC), and activated PCC or Factor Eight Inhibitor Bypassing Activity (FEIBA®), are options based on clinical need. Specific agents to quickly reverse the effects of DOACs have been under development, and idarucizumab, a monoclonal antibody fragment that rapidly binds dabigatran, has been approved for clinical use in cases of dabigatran-related life-threatening bleeding, or if a dabigatran-treated patient needs emergency surgery or an invasive procedure. Idarucizumab specifically and rapidly reverses dabigatran-induced anticoagulation as measured by established coagulation assays. However, this does not guarantee complete hemostasis, especially if a patient has underlying comorbidities such as renal or liver disease, or has experienced recent trauma that requires urgent surgery. In these cases, concomitant supportive therapy and/or administration of concentrated clotting factors may be considered. Emerging data from ongoing trials and clinical experience will further inform providers regarding optimal approaches for anticoagulation reversal.

Reversal of dabigatran-associated major bleeding with activated prothrombin concentrate: A prospective cohort study

The reversal of dabigatran-associated major bleeding can now be achieved with the antidote idarucizumab. We evaluated activated prothrombin complex concentrate (aPCC) as an alternative for this purpose. Patients treated with dabigatran and suffering a major bleed were treated as per existing hospital protocol with aPCC. They were subsequently recruited for a 30-day follow-up. Effectiveness was evaluated by the treating physician, using an Assessment Guide. Safety outcomes were arterial or venous thromboembolism or death. A comparison was also made with historic cases with dabigatran-associated major bleeds treated with supportive care, by matching 1:2 for type of bleed, age and sex. We aimed at 32 evaluable cases but the study was prematurely discontinued after 14 cases due to the availability of the approved antidote. The effectiveness of aPCC was assessed as Good in 9 (64%), moderate in 5 (36%) and poor in none. There were no thromboembolic events and one death. In the secondary adjudication of effectiveness, using the same criteria and by the same adjudicators as previously done for the historic cases, the outcome was graded for the current cases versus the historic cases as Good, Moderate, or Poor in 10 (71%) versus 16 (57%), 3 (21%) versus 4 (14%), and 1 (7%) versus 8 (29%), respectively. Although supportive care is sufficient to manage many patients with dabigatran-associated bleeding, aPCC might provide an additional benefit to control life-threatening bleeding in selected cases and does not appear to cause an excess of thromboembolic events.

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.

Management of bleeding in patients treated with direct oral anticoagulants

BACKGROUND

Recently, a new generation of direct-acting oral anticoagulants (DOACs) with a greater specificity towards activated coagulation factors was introduced based on encouraging results for efficacy and safety in clinical studies. An initial limitation of these new drugs was the absence of an adequate strategy to reverse the effect if a bleeding event occurs or an urgent invasive procedure has to be carried out.

MAIN TEXT

Specific reversing agents for DOACs have become available, however, and are now evaluated in clinical studies. For the anti-factor Xa agents (rivaroxaban, apixaban, and edoxaban) a number of studies have shown that the administration of prothrombin complex concentrate resulted in a correction of the prolonged prothrombin time and restored depressed thrombin generation after rivaroxaban treatment in a controlled trial in healthy human subjects. In view of the relatively wide availability of prothrombin complex concentrates, this would be an interesting option if the results can be confirmed in patients on oral factor Xa inhibitors who present with bleeding complications. More specific reversal can be achieved with andexanet, a new agent currently in development that competitively binds to the anti-factor Xa agents. For the direct thrombin inhibitor dabigatran, the administration of prothrombin complex concentrates showed variable results in various volunteer trials and efficacy at relatively high doses in animal studies. Recently, a Fab fragment of a monoclonal antibody (idarucizumab) was shown to be an effective reversal agent for dabigatran in human studies.

CONCLUSION

For the new generation of DOACs, several reversal strategies and specific antidotes are under evaluation, although most interventions need further evaluation in clinical trials.

Novel oral anticoagulants in plastic surgery

Novel oral anticoagulants (NOACs) have emerged as a good alternative to warfarin in the prevention of stroke for patients with atrial fibrillation. NOAC use is increasing rapidly; therefore, greater understanding of their use in the perioperative period is important for optimal care. Studies and reviews that reported on the use of NOACs were identified, with particular focus on the perioperative period. PubMed was searched for relevant articles published between January 2000 and August 2015. The inevitable rise in the use of NOACs such as rivaroxaban (Xarelto™), apixaban (Eliquis™), edoxaban (Lixiana™) and dabigatran (Pradaxa™) may present a simplified approach to perioperative anticoagulant management due to fewer drug interactions, rapidity of onset of action and relatively short half-lives. Coagulation status, however, cannot reliably be monitored and no antidotes are currently available. When planning for discontinuation of NOACs, special consideration of renal function is required. Advice regarding the management of bleeding complications is provided for consideration in emergency surgery. In extreme circumstances, haemodialysis may be considered for bleeding with the use of dabigatran. NOACs will increasingly affect operative planning in plastic surgery. In order to reduce the incidence of complications associated with anticoagulation, the management of NOACs in the perioperative period requires knowledge of the time of last dose, renal function and the bleeding risk of the planned procedure. Consideration of these factors will allow appropriate interpretation of the current guidelines.

Management of new oral anticoagulants related life threatening or major bleedings in real life: a brief report

Although new oral anticoagulants (NOAs) have been marketed in many countries, concern exists about the management of bleedings related to these drugs due to the lack of specific antidotes. The aim of our study was to report on real life management of NOAs-related life-threatening or major bleedings. We report data from consecutive cases of NOAs related major bleedings admitted to 4 hospitals since NOAs became marketed in Italy. We treated 8 patients, 4 males, with mean age 84 ± 7 years, 7 of whom were on dabigatran and one on rivaroxaban. The indication for NOA was atrial fibrillation. All bleedings were spontaneous and involving the gastro-intestinal tract. At the time of bleeding all patients had a drop in hemoglobin levels over 20 g/L. Creatinine clearance was ≤30 mL/min in 4 patients. All patients received general supportive measures, 4 of 8 patients were transfused with packed red cells and one patient received platelet transfusion. Three patients were treated with tranexamic acid and one patient on dabigatran received 4-factor prothrombin complex concentrate (PCC) with bleeding cessation, although coagulation parameters were not corrected. The median time for normalization of coagulation parameters was 3 days (range 1-6 days). All patients were discharged alive and NOAs were discontinued. In NOAs related major gastro-intestinal bleeding general supportive measures seem to be effective for the majority of patients. Despite promoting bleeding cessation, 4-factor PCC does not reverse abnormal coagulation parameters.

Prothrombin Complex Concentrate Is Effective in Treating the Anticoagulant Effects of Dabigatran in a Porcine Polytrauma Model

Background

In the event of trauma, emergency reversal of anticoagulation therapy may be required. However, no specific reversal agents are routinely available for the direct oral anticoagulants such as dabigatran. The authors investigated four-factor prothrombin complex concentrate (PCC) for treating dabigatran-induced anticoagulation in a porcine polytrauma model.

Methods

Dabigatran etexilate was given orally for 3 days and intravenously on day 4 to 32 pigs. Animals were randomized 1:1:1:1 to PCC (25, 50, or 100 U/kg) or saline. Study medication was administered 12 min after bilateral femur fractures and blunt liver injury. The primary endpoint was blood loss at 300 min.

Results

The mean plasma concentration of dabigatran was 487 ± 161 ng/ml after intravenous administration. Blood loss was 3,855 ± 258 ml in controls and 3,588 ± 241 ml in the PCC25 group. In the PCC50 and PCC100 groups, blood loss was significantly lower: 1,749 ± 47 ml and 1,692 ± 97 ml, respectively. PCC50 and PCC100 effectively reduced dabigatran’s effects on coagulation parameters, whereas control and (to a lesser extent) PCC25 animals developed severe coagulopathy. Sustained increases in endogenous thrombin potential occurred with PCC50 and PCC100.

Conclusion

Four-factor PCC (50 or 100 U/kg) is effective in reducing blood loss in dabigatran-anticoagulated pigs, but higher doses may induce a procoagulant state.

Emergency admissions for major haemorrhage associated with direct oral anticoagulants

INTRODUCTION

To describe the population admitted in an emergency department of a teaching hospital for severe bleeding associated with direct oral anticoagulants (DOAC).

METHOD

During a three-year period (2012-2014) patients older than 16 years were prospectively identified by haemorrhagic symptoms from computerised requests. At least one of the following criteria defined major haemorrhage: haemorrhagic shock, unstable haemodynamic, need for transfusion or haemostatic procedure, or a life threatening location.

RESULTS

Fifty four patients, 23 receiving dabigatran, 30 rivaroxaban and one apixaban were included, 2 in 2012, 35 in 2013 and 17 in 2014. Median age was 84 years (range 63-99) with a sex ratio of 1.16. Haemorrhagic complications were gastrointestinal (n=27), intracranial (n=12) or miscellaneous (n=15). Indication of DOAC was stroke prevention in atrial fibrillation in 49 cases and deep vein thrombosis in 5 cases. Hospitalization was required for 45 patients (83%) with a mean length of stay of 8.5 days. Sixteen patients needed intensive care. Reversal therapy was prescribed in 11 patients. At 1 month, overall mortality was 24%, reaching 41.7% for intracranial haemorrhage. Among surviving patients, DOAC was stopped in 10 cases, continued in 17 patients and switched for other antithrombotic in 17 patients.

CONCLUSION

Our study contributes to the post marketing surveillance of major haemorrhagic complications associated with DOAC. It takes part to the knowledge about the course of this severe event in emergencies. Careful awareness in risk benefit assessment, especially in elderly, is needed.

Perioperative Management of Dabigatran: A Prospective Cohort Study

BACKGROUND

The perioperative management of dabigatran in clinical practice is heterogeneous. We performed this study to evaluate the safety of perioperative management of dabigatran using a specified protocol.

METHODS AND RESULTS

Patients treated with dabigatran and planned for an invasive procedure were eligible for inclusion. The timing of the last dose of dabigatran before the procedure was based on the creatinine clearance and procedure-related bleeding risk. Resumption of dabigatran was prespecified according to the complexity of the surgery and consequences of a bleeding complication. Patients were followed up for 30 days for major bleeding (primary outcome), minor bleeding, arterial thromboembolism, and death. We included 541 cases: 324 procedures (60%) with standard risk of bleeding and 217 procedures (40%) with increased risk of bleeding. The last dose of dabigatran was at 24, 48, or 96 hours before surgery according to the protocol in 46%, 37%, and 6%, respectively, of the patients. Resumption was timed according to protocol in 77% with 75 mg as the first dose on the day of procedure in 40% of the patients. Ten patients (1.8%; 95% confidence interval, 0.7-3.0) had major bleeding, and 28 patients (5.2%; 95% confidence interval, 3.3-7.0) had minor bleeding events. The only thromboembolic complication was transient ischemic attack in 1 patient (0.2%; 95% confidence interval, 0-0.5), and there were 4 deaths unrelated to bleeding or thrombosis. Bridging was not used preoperatively but was administered in 9 patients (1.7%) postoperatively.

CONCLUSION

Our protocol for perioperative management of dabigatran appears to be effective and feasible.

Updates in the perioperative and emergency management of non-vitamin K antagonist oral anticoagulants

Perioperative management of patients treated with the non-vitamin K antagonist oral anticoagulants is an ongoing challenge. Due to the lack of good clinical studies involving adequate monitoring and reversal therapies, management requires knowledge and understanding of pharmacokinetics, renal function, drug interactions, and evaluation of the surgical bleeding risk. Consideration of the benefit of reversal of anticoagulation is important and, for some low risk bleeding procedures, it may be in the patient's interest to continue anticoagulation. In case of major intra-operative bleeding in patients likely to have therapeutic or supra-therapeutic levels of anticoagulation, specific reversal agents/antidotes would be of value but are currently lacking. As a consequence, a multimodal approach should be taken which includes the administration of 25 to 50 U/kg 4-factor prothrombin complex concentrates or 30 to 50 U/kg activated prothrombin complex concentrate (FEIBA®) in some life-threatening situations. Finally, further studies are needed to clarify the ideal therapeutic intervention.

Use of 4-factor prothrombin complex concentrate in the treatment of a gastrointestinal hemorrhage complicated by dabigatran

Target-specific oral anticoagulants (TSOACs) provide patients and healthcare providers with an alternative to vitamin K antagonists (VKA). The TSOACs are of similar or superior efficacy to warfarin, but unlike VKAs, there are no approved ‘antidotes’ for rapid reversal of life-threatening bleeding on therapy. We report here the case of an 83-year-old gentleman, who presented to the emergency department with severe gastrointestinal hemorrhage and coagulopathy (hemoglobin: 5.3 g/dL and INR: 2.2) while on the direct thrombin inhibitor dabigatran. His coagulopathy reversed rapidly after administration of 4-factor prothrombin complex concentrate (4 F-PCC), and after initial administration of 2 units of packed red blood cells, no further product transfusions were required. He was discharged 4 days later without further complications.

[Perioperative management of direct oral anticoagulant in emergency surgery and bleeding. Haemostasis monitoring and treatment]

There is an almost unanimous consensus on the management of the direct new oral anticoagulants, dabigatran, rivaroxaban, and apixaban in elective surgery. However, this general consensus does not exist in relation with the direct new oral anticoagulants use in emergency surgery, especially in the bleeding patient. For this reason, a literature review was performed using the MEDLINE-PubMed. An analysis was made of the journal articles, reviews, systematic reviews, and practices guidelines published between 2000 and 2014 using the terms "monitoring" and "reversal". From this review, it was shown that the routine tests of blood coagulation, such as the prothrombin time and activated partial thromboplastin time, have a limited efficacy in the perioperative control of blood coagulation in these patients. There is currently no antidote to reverse the effects of these drugs, although the possibility of using concentrated prothrombin complex and recombinant activated factor vii has been suggested for the urgent reversal of the anticoagulant effect.

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.

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.

New oral pharmacotherapeutic agents for venous thromboprophylaxis after total hip arthroplasty

Patients undergoing total hip arthroplasty (THA) are at high risk for developing venous thromboembolism and, therefore, require short term prophylaxis with antithrombotic agents. Recently, target specific oral anticoagulants (TSOA) including the direct thrombin inhibitor, dabigatran, and the factor Xa inhibitors rivaroxaban, apixaban, and edoxaban have been approved for THA thrombopropylaxis in various countries. The TSOAs provide a rapid acting, oral alternative to parenteral agents including low-molecular weight heparins (LMWH) and fondaparinux; and compared to warfarin, they do not require routine laboratory monitoring and possess much fewer drug-drug interactions. Based on phase III clinical studies, TSOAs have established themselves as an effective and safe option for thromboprophylaxis after THA compared to LMWH, particularly enoxaparin, but require additional evaluation in specific populations such as the renally impaired or elderly. The ability to monitor and reverse these TSOAs in the case of bleeding complications or suspected sub- or supra-therapeutic anticoagulation is of importance, but remains investigational. This review will focus on the drug-specific characteristics, efficacy, safety, and economic impact of the TSOAs for thromboprophylaxis following THA, as well as the aspects of therapeutic monitoring and anticoagulation reversal in the event of bleeding complications or a need for urgent reversal.

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.