When and how to use antidotes for the reversal of direct oral anticoagulants: guidance from the SSC of the ISTH

The Use of Idarucizumab for Dabigatran Reversal in Clinical Practice: A Case Series

PURPOSE

To describe the use of idarucizumab (Praxbind, Boehringer Ingelheim) in routine clinical practice at a large urban academic medical center.

SUMMARY

Seven total doses of idarucizumab were administered to six unique patients from October 31, 2015, to October 31, 2016. The reversal agent was used in conjunction with local bleeding control measures, blood product transfusions, and acid-suppressive therapy. In 86% of cases, idarucizumab administration resulted in a successful cessation of bleeding by clinical assessment. Two patients expired due to coexisting conditions. Idarucizumab was administered to patients with normal baseline coagulation tests in 43% of cases. No adverse reactions related to idarucizumab were reported.

CONCLUSIONS

Idarucizumab administration resulted in successful resolution of bleeding by clinical assessment. The therapy for acute bleeding with use of dabigatran (Pradaxa, Boehringer Ingelheim) remains supportive care, in addition to idarucizumab in cases of severe or uncontrolled bleeding. Development of institution-specific protocols and better guidance for using baseline coagulation tests are needed.

Neurosurgery in a patient at peak levels of rivaroxaban: taking into account all factors

We present a patient who underwent urgent neurosurgery for acute onset paraplegia due to a spontaneous subdural spinal hematoma less than 5 hours after she had taken rivaroxaban. The Key Clinical Question was whether early high-risk surgery on a patient taking direct oral anticoagulants is feasible. Prothrombin complex concentrate (PCC) and tranexamic acid were administered and perioperative hemostasis was good. There is scant data on neurosurgical procedures performed within 12 hours after the intake of a direct oral anticoagulant. With the hemostatic support of high-dose PCC, early surgery after administration of rivaroxaban seems feasible in case of an emergency indication, but should only be considered when delaying surgery is esteemed hazardous to the patient. More experience is needed to allow balancing risks and benefits of urgent vs delayed intervention and on the optimal hemostatic support in the absence of a specific antidote.

Major publications in the critical care pharmacotherapy literature: January-December 2016

PURPOSE

To summarize select critical care pharmacotherapy guidelines and studies published in 2016.

SUMMARY

The Critical Care Pharmacotherapy Literature Update (CCPLU) Group screened 31 journals monthly for relevant pharmacotherapy articles and selected 107 articles for review over the course of 2016. Of those included in the monthly CCPLU, three guidelines and seven primary literature studies are reviewed here. The guideline updates included are as follows: hospital-acquired pneumonia and ventilator-associated pneumonia management, sustained neuromuscular blocking agent use, and reversal of antithrombotics in intracranial hemorrhage (ICH). The primary literature summaries evaluate the following: dexmedetomidine for delirium prevention in post-cardiac surgery, dexmedetomidine for delirium management in mechanically ventilated patients, high-dose epoetin alfa after out-of-hospital cardiac arrest, ideal blood pressure targets in ICH, hydrocortisone in severe sepsis, procalcitonin-guided antibiotic de-escalation, and empiric micafungin therapy.

CONCLUSION

The review provides a synopsis of select pharmacotherapy publications in 2016 applicable to clinical practice.

Reversing factor Xa inhibitors - clinical utility of andexanet alfa

Approximately half of patients started on an oral anticoagulant in the USA now receive one of the newer direct oral anticoagulants (DOACs). Although there is an approved reversal agent for the direct thrombin inhibitor dabigatran, a specific reversal agent for the anti-factor Xa (FXa) DOACs has yet to be licensed. Unlike the strategy to reverse the only oral direct thrombin inhibitor with idarucizumab, which is a humanized monoclonal antibody fragment, a different approach is necessary to design a single agent that can reverse multiple anti-FXa medications. Andexanet alfa is a FXa decoy designed to reverse all anticoagulants that act through this part of the coagulation cascade including anti-FXa DOACs, such as apixaban, edoxaban and rivaroxaban, and indirect FXa inhibitors such as low-molecular-weight heparins. This narrative reviews the development of andexanet alfa and explores its basic science, pharmacokinetics/pharmacodynamics, animal models, and human studies.

Comparison of different laboratory tests in the evaluation of hemorrhagic risk of patients using rivaroxaban in the critical care setting: diagnostic accuracy study

Background

Rivaroxaban is a direct oral anticoagulant designed to dispense with the necessity of laboratory monitoring. However, monitoring rivaroxaban levels is necessary in certain clinical conditions, especially in the critical care setting.

Methods

This is a diagnostic accuracy study evaluating sensitivity and specificity of prothrombin time (PT), activated partial thromboplastin time (aPTT), and Dilute Russell viper venom time (dRVVT), to evaluate the hemorrhagic risk in patients taking rivaroxaban. The study used a convenience sample of 40 clinically stable patients using rivaroxaban to treat deep vein thrombosis or atrial fibrillation admitted in a private hospital in Brazil, compared to a group of 60 healthy controls. The samples from patients were collected two hours after the use of the medication (peak) and two hours before the next dose (trough).

Results

The correlation with the plasmatic concentration measured by anti-FXa assay was higher for PT and dRVVTS. The PT and aPTT tests presented higher specificity, while dRVVT was 100% sensible.

Conclusions

There was a strong correlation between the tests and the plasma concentration of the drug. Additionally, our results demonstrated the potential use of dRVVT as a screening test in the emergency room and the need of a second test to improve specificity.

Accuracy and consistency of anti-Xa activity measurement for determination of rivaroxaban plasma levels

Essentials Accurate determination of anticoagulant plasma concentration is important in clinical practice. We studied the accuracy and consistency of anti-Xa assays for rivaroxaban in a multicentre study. In a range between 50 and 200 μg L-1 , anti-Xa activity correlated well with plasma concentrations. The clinical value might be limited by overestimation and intra- and inter-individual variation.

SUMMARY

Background Determining the plasma level of direct oral anticoagulants reliably is important in the work-up of complex clinical situations. Objectives To study the accuracy and consistency of anti-Xa assays for rivaroxaban plasma concentration in a prospective, multicenter evaluation study employing different reagents and analytical platforms. Methods Rivaroxaban 20 mg was administered once daily to 20 healthy volunteers and blood samples were taken at peak and trough levels (clinicaltrials.gov NCT01710267). Anti-Xa activity was determined in 10 major laboratories using different reagents and analyzers; corresponding rivaroxaban plasma concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Findings Overall Pearson's correlation coefficient of anti-Xa levels and HPLC-MS results was 0.99 for Biophen® Heparin (95% CI, 0.99, 0.99), Biophen® DiXaI (95% CI, 0.99, 0.99) and STA® anti-Xa liquid (95% CI, 0.99, 1.00). Correlation was lower in rivaroxaban concentrations below 50 μg L-1 and above 200 μg L-1 . The overall bias of the Bland-Altman difference plot was 14.7 μg L-1 for Biophen Heparin, 17.9 μg L-1 for Biophen DiXal and 19.0 μg L-1 for STA anti-Xa liquid. Agreement between laboratories was high at peak level but limited at trough level. Conclusions Anti-Xa activity correlated well with rivaroxaban plasma concentrations, especially in a range between 50 and 200 μg L-1 . However, anti-Xa assays systematically overestimated rivaroxaban concentration as compared with HPLC-MS, particularly at higher concentrations. This overestimation, coupled with an apparent interindividual variation, might affect the interpretation of results in some situations.

Clinical implications, benefits and pitfalls of using and reversing non-vitamin K antagonist oral anticoagulants

INTRODUCTION

The use of non-Vitamin K antagonist oral anticoagulant (NOAC) drugs is increasingly common in clinical practice. As compared to vitamin K antagonists they are more straightforward to initiate, require no hematological monitoring and offer potentially more stable therapeutic indices. Concern has been raised with regard to their safety profiles particularly in the context of acute reversal in major bleeding. Further issues pertain to patient concordance. Areas covered: This review article aims to provide an overview of the current evidence relating to NOAC safety as well as the management of NOAC-related major bleeding with particular emphasis on reversal agents in use and in development following a selective literature review. Second, the effects of medication concordance and dosing regimens on NOAC efficacy will be considered. Expert commentary: The short half-lives and low overall bleeding risk of NOACs is likely to mean that specific reversal agents in development are infrequently required and costly with associated practicality issues with their use in clinical emergencies. Concern regarding patient concordance can be practicably addressed with appropriate medication, dosing regimen and patient selection and continuous education with active, informed patient involvement in the decision-making process.

Coagulopathy and haemorrhagic progression in traumatic brain injury: advances in mechanisms, diagnosis, and management

Normal haemostasis depends on an intricate balance between mechanisms of bleeding and mechanisms of thrombosis, and this balance can be altered after traumatic brain injury (TBI). Impaired haemostasis could exacerbate the primary insult with risk of initiation or aggravation of bleeding; anticoagulant use at the time of injury can also contribute to bleeding risk after TBI. Many patients with TBI have abnormalities on conventional coagulation tests at admission to the emergency department, and the presence of coagulopathy is associated with increased morbidity and mortality. Further blood testing often reveals a range of changes affecting platelet numbers and function, procoagulant or anticoagulant factors, fibrinolysis, and interactions between the coagulation system and the vascular endothelium, brain tissue, inflammatory mechanisms, and blood flow dynamics. However, the degree to which these coagulation abnormalities affect TBI outcomes and whether they are modifiable risk factors are not known. Although the main challenge for management is to address the risk of hypocoagulopathy with prolonged bleeding and progression of haemorrhagic lesions, the risk of hypercoagulopathy with an increased prothrombotic tendency also warrants consideration.

Clinical pearls: Laboratory assessments of direct oral anticoagulants (DOACS)

Direct oral anticoagulants (DOACS) are being used for stroke prevention in patients with atrial fibrillation as well as for prophylaxis and treatment of venous thromboembolism. Clinicians who treat, or may encounter, patients with DOAC exposure, should be aware of the limitations of coagulation testing in this setting, and seek counsel from their laboratory to understand the effects of DOACS on coagulation results. Generally, assays that employ clot based principles, or methods that require thrombin or Factor Xa activation or substrates may be affected by the presence of DOACS. The clinical laboratory should have an algorithmic testing plan for adequately assessing the presence of all DOACS and readily provide this information to clinicians. We describe Clinical Pearls for DOAC assessment using common and esoteric coagulation testing.

Recent advances in the treatment of venous thromboembolism in the era of the direct oral anticoagulants

The direct oral anticoagulants (DOACs) have now supplanted vitamin K antagonists (VKAs) for the treatment of venous thromboembolism (VTE). The DOACs include dabigatran, which inhibits thrombin, and rivaroxaban, apixaban, and edoxaban, which inhibit factor Xa. The DOACs are as effective for the prevention of recurrence as conventional VTE treatment, consisting of a parenteral anticoagulant followed by a VKA, and are associated with less bleeding. Because of these properties and the convenience of fixed dosing without the need for routine coagulation monitoring, guidelines now recommend DOACs over VKAs for VTE treatment in patients without active cancer. This paper examines the increasing role of the DOACs for VTE treatment.

International clinical practice guidelines including guidance for direct oral anticoagulants in the treatment and prophylaxis of venous thromboembolism in patients with cancer

Venous thromboembolism (VTE) is the second leading cause of death in patients with cancer. These patients are at an increased risk of developing VTE and are more likely to have a recurrence of VTE and bleeding while taking anticoagulants. Management of VTE in patients with cancer is a major therapeutic challenge and remains suboptimal worldwide. In 2013, the International Initiative on Thrombosis and Cancer (ITAC-CME), established to reduce the global burden of VTE in patients with cancer, published international guidelines for the treatment and prophylaxis of VTE and central venous catheter-associated thrombosis. The rapid global adoption of direct oral anticoagulants for management of VTE in patients with cancer is an emerging treatment trend that needs to be addressed based on the current level of evidence. In this Review, we provide an update of the ITAC-CME consensus recommendations based on a systematic review of the literature ranked according to the Grading of Recommendations Assessment, Development, and Evaluation scale. These guidelines aim to address in-hospital and outpatient cancer-associated VTE in specific subgroups of patients with cancer.

Monitoring of anticoagulant therapy in cancer patients with thrombosis and the usefulness of blood activation markers

Thrombotic diseases caused by cancer progression have been reported as one of the major causes of cancer associated morbidity and mortality along with cancer invasiveness and infectious complications. Moreover, anticoagulant therapy with heparin and heparin-like drugs, or vitamin K antagonists, or the Direct Oral Anticoagulants, is seeing an extended application in cancer patients and offers prolonged life expectancy to oncology patients for whom blood activation and thrombotic events have a variable incidence, depending on cancer type. Laboratory tools are highly useful for identifying patients at thrombotic risk through the measurement of blood activation markers and selecting those appropriate for anticoagulant therapy. Among the pathological markers, DDimer or Extracellular Vesicles have the highest diagnostic value in these pathological conditions. Global assays are useful for dosage adjustment, such as assessing either an induced anticoagulant effect or the measurement of drug activity. Various assays are also developed such as platelet aggregometry techniques for evaluating drug induced- aggregates or methods allowing measurement of the drug activity to its targeted coagulation factors such as: heparin to thrombin or Factor Xa; DOACs to Thrombin or Factor Xa (Dabigatran to thrombin and DiXaIs, Rivaroxaban, Apixaban, and Edoxaban, to Factor Xa). Such explorative techniques help to find the right dosage adjustment to protect patients from developing thrombosis without exposing them bleeding. It also permits exploration of unexpected drug behavior in treated patients, to check the right adherence to therapy in long-term anticoagulant protocols, and prevention of bleeding in patients with impaired renal or hepatic function. Complementary use of blood activation markers brings additional information on the curative effects of the anticoagulant therapy, and allows identification of pro-thrombotic activity in the clinically silent state. These issues are concisely addressed below.

Perioperative management of patients on direct oral anticoagulants

Direct oral anticoagulants (DOACs) have been licensed worldwide for several years for various indications. Each year, 10-15% of patients on oral anticoagulants will undergo an invasive procedure and expert groups have issued several guidelines on perioperative management in such situations. The perioperative guidelines have undergone numerous updates as clinical experience of emergency management has increased and perioperative studies including measurement of residual anticoagulant levels have been published. The high inter-patient variability of DOAC plasma levels has challenged the traditional recommendation that perioperative DOAC interruption should be based only on the elimination half-life of DOACs, especially before invasive procedures carrying a high risk of bleeding. Furthermore, recent publications have highlighted the potential danger of heparin bridging use when DOACs are stopped before an invasive procedure. As antidotes are progressively becoming available to manage severe bleeding or urgent procedures in patients on DOACs, accurate laboratory tests have become the standard to guide their administration and their actions need to be well understood by clinicians. This review aims to provide a systematic approach to managing patients on DOACs, based on recent updates of various perioperative guidance, and highlighting the advantages and limits of recommendations based on pharmacokinetic properties and laboratory tests.

Real-life experience with the specific reversal agent idarucizumab for the management of emergency situations in dabigatran-treated patients: a series of 11 cases

Non-vitamin K antagonist oral anticoagulants (NOACs) have a favorable benefit-risk profile compared with vitamin K antagonists. However, the lack of specific reversal agents has made the management of some patients receiving long-term treatment with NOACs problematic in emergency situations such as major bleeding events or urgent procedures. Idarucizumab, a fully humanized Fab antibody fragment that binds specifically and with high affinity to dabigatran, was recently approved for use in adult patients treated with dabigatran when rapid reversal of its anticoagulant effect is required. Clinical experience with idarucizumab is currently limited. We report 11 real-life clinical cases in which idarucizumab was used after multidisciplinary consultation in a variety of emergency situations including severe postoperative bleeding, emergency high-bleeding-risk surgery (hip/spine surgery and neurosurgery), invasive diagnostic testing (lumbar puncture), intracranial bleeding (pre-pontine subarachnoid hemorrhage and lobar intracerebral hemorrhage) and thrombolysis with recombinant tissue plasminogen activator for acute ischemic stroke. This case series illustrates the role of idarucizumab in improving patient safety in rare emergency situations requiring rapid reversal of the anticoagulant effect of dabigatran, while highlighting the importance of information and education about the availability and appropriate use of this recently approved specific reversal agent.

Italian intersociety consensus on DOAC use in internal medicine

The direct oral anticoagulants (DOACs) are drugs used in clinical practice since 2009 for the prevention of stroke or systemic embolism in non-valvular atrial fibrillation, and for the treatment and secondary prevention of venous thromboembolism. The four DOACs, including the three factor Xa inhibitors (rivaroxaban, apixaban and edoxaban) and one direct thrombin inhibitor (dabigatran) provide oral anticoagulation therapy alternatives to Vitamin K antagonists (VKAs). Despite their clear advantages, the DOACs require on the part of the internist a thorough knowledge of their pharmacokinetic and pharmacodynamic characteristics to ensure their correct use, laboratory monitoring and the appropriate management of adverse events. This document represents a consensus paper on the use of DOACs by representatives of three Italian scientific societies: the Italian Society of Internal Medicine (SIMI), the Federation of the Associations of Hospital Managers (FADOI), and the Society for the Study of Haemostasis and Thrombosis (SISET). This document formulates expert opinion guidance for pragmatic managing, monitoring and reversing the anticoagulant effect of DOACs in both chronic and emergency settings. This practical guidance may help the internist to create adequate protocols for patients hospitalized ion internal medicine wards, where patients are often elderly subjects affected by poly-morbidities and renal insufficiency, and, thus, require particular attention to drug-drug interactions and peri-procedural protocols.

Reversal of direct oral anticoagulants

An understanding of how to counteract the anticoagulant effect of direct oral anticoagulants is essential in the event of haemorrhage, emergency surgery and overdose. This review summarizes strategies for the reversal of direct oral anticoagulants, including the use of novel agents.

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.

Real-world use of idarucizumab for dabigatran reversal in three cases of serious bleeding

Bleeding is a rare complication of direct oral anticoagulant potentially associated with high mortality rates. Biological monitoring is necessary for more than 24 h after idarucizumab antidote therapy in case of bleeding with dabigatran therapy.

The Nonvitamin K Antagonist Oral Anticoagulants and Atrial Fibrillation: Challenges and Considerations

The nonvitamin K antagonist oral anticoagulants (NOACs) dabigatran, rivaroxaban, apixaban, and edoxaban are used for the reduction of the risk of stroke or systemic embolism (SEE) in patients with nonvalvular atrial fibrillation (NVAF). The purpose of this review is to highlight the safety and efficacy results of the pivotal NOAC clinical trials for use in NVAF, discuss some of the unique management challenges in the use of NOACs in special populations, summarize data on emerging and novel indications, and address potential future directions.

METHODS

A literature search was conducted and to identify relevant clinical trials and studies regarding the use of NOACs for the prevention of stroke or SEE in patients with atrial fibrillation.

RESULTS

Relative to warfarin, NOACs are as effective or superior in the prevention of stroke or SEE, and are associated with similar or lower rates of major bleeding and significantly decreased rates of intracranial bleeding, but may be associated with a slightly increased risk of gastrointestinal bleeding in patients with AF. The NOACs are not indicated for use and have not been widely tested in AF patients with other cardiovascular conditions. Additional ongoing and planned clinical trials will provide additional information regarding the use of NOACs in these patients. In situations requiring rapid reversal of anticoagulation, the availability of specific antidotes will improve safety and facilitate NOAC use.

CONCLUSIONS

Use of NOACs in clinical practice requires consideration of patient characteristics as well as potentially required procedures.

Management of Bleeding With Non-Vitamin K Antagonist Oral Anticoagulants in the Era of Specific Reversal Agents

Vitamin K antagonists are commonly used by clinicians to provide anticoagulation to patients who have or are at risk of having thrombotic events. In addition to familiarity with the dosing and monitoring of vitamin K antagonists, clinicians are accustomed to using vitamin K if there is a need to reverse the anticoagulant effect of vitamin K antagonists. There are now 4 new non-vitamin K antagonist oral anticoagulants (NOACs) that are attractive alternatives to vitamin K antagonists. Despite similar or lower rates of serious bleeding with NOACs in comparison with warfarin, there is a pressing need for strategies to manage bleeding when it does occur with NOACs and to reverse the pharmacological effect of these agents if needed. Important steps in minimizing bleeding risks with NOACs include dose adjustment of the agents in the setting of renal dysfunction and avoidance of the concomitant use of other antithrombotic agents if feasible. Laboratory measurement of the anticoagulant effect of NOACs is best accomplished with specialized assays, although some of the more widely available coagulation tests can provide information that is potentially useful to clinicians. Nonspecific hemostatic agents such as prothrombin complex concentrates and recombinant factor VIIa can be used to reverse the effect of NOACs. More specific reversing agents include the approved humanized monoclonal antibody fragment idarucizumab for reversing the effects of dabigatran, the investigational factor Xa decoy andexanet alfa, and the synthetic small molecule ciraparantag. Both andexanet and ciraparantag have been reported to reverse the effects of the anti-Xa NOACs (rivaroxaban, apixaban, and edoxaban), and a number of other anticoagulant agents in common clinical use, as well.

Discontinuation and Management of Direct-Acting Anticoagulants for Emergency Procedures

Patients taking direct oral anticoagulants (DOACs) who then need an emergency invasive procedure require specialized management strategies. Appropriate patient evaluation includes assessment of the current anticoagulation state, including timing of the last dose. DOACs require particular coagulation assays to measure anticoagulation levels accurately, although standard coagulation screening tests may provide qualitative guidance. Specialty societies have endorsed general recommendations for patient management to promote hemostasis in anticoagulated patients requiring surgery or other invasive procedures. These include general stopping rules (such as ≥24 hours for low-risk procedures and ≥48 hours for high-risk surgery with normal renal function) for elective procedures. Bridging therapy when oral anticoagulant treatment is interrupted has recently been questioned, depending on the clinical scenario. Novel agents for the reversal of DOAC-induced anticoagulation have recently been developed. Idarucizumab, a humanized monoclonal antibody fragment that selectively binds dabigatran, was recently approved for clinical use in patients with life-threatening or uncontrolled bleeding, and for patients requiring emergency interventions. Idarucizumab can streamline the pre- and periprocedural anticoagulation management of dabigatran-treated patients, as it provides fast, complete, and sustainable reversibility. Andexanet alfa is an inactive, decoy factor Xa (FXa) molecule that binds FXa inhibitors, and ciraparantag is a synthetic molecule designed to bind fractionated and unfractionated heparins, and each of the currently approved DOACs. As clinical development of the additional anti-FXa-specific anticoagulant reversal agents proceeds, the respective role of each in the management of emergency bleeding events and invasive procedures will be better defined, and it is hoped they will make important contributions to patient care.

DOACs - advances and limitations in real world

The group of new oral anticoagulants or NOACs, now termed direct oral anticoagulants or DOACs, with their favourable results from large scale phase III clinical trials, represent a major advancement and expanded armamentarium in antithrombotic therapy. Dabigatran, rivaroxaban, apixaban and edoxaban are now in clinical routine use for prevention and treatment of arterial and venous thrombotic diseases as addressed in their clinical trials. Usage of the DOACs is expected to increase as clinicians gain more experience and reassurance with data from the real world studies which are generally consistent with that from clinical trials. Development of specific antidotes in management of bleeding complications and development of coagulation assays for their plasma levels will further boost the confidence in the DOACs. Nonetheless, there are still limitations associated with the DOACs. Many patients in need of anticoagulant therapy for indications not studied in the clinical trials will not be eligible for treatment with a DOAC. Conditions where more data is required include DOACs use in the paediatric age group, patients with atrial fibrillation and valvular heart disease, thrombosis associated with the anti-phospholipid syndrome and cancer associated thrombosis. The affordability and access to these drugs may pose an issue for many patients under healthcare systems not providing for these medications. With four new anticoagulants coming onboard very quickly, the focus has shifted to the practical approach and management in real life as many clinicians are not yet familiar with the DOACs. Clinicians need to be educated on how to manage this new class for drugs, from choosing the appropriate drug to prevention and managing bleeding complications as a lack of knowledge and understanding in these drugs will lead to inappropriate use and compromise on patient safety.

New Oral Anticoagulants and Their Reversal Agents

OPINION STATEMENT

Direct oral anticoagulants (DOAC) are an attractive therapeutic option for anticoagulant treatment in the setting of venous thromboembolism or non-valvular atrial fibrillation. These drugs overall appear to have a lower risk of life-threatening hemorrhage than the vitamin K antagonists. In addition, they demonstrate more predictable and stable pharmacokinetics. Measurement of the degree of anticoagulation is desirable in patients with DOAC-associated hemorrhage, but commonly available coagulation assays show poor sensitivity for degree of DOAC effect. DOAC-specific tests are time consuming and not widely available. All coagulation tests should be interpreted considering the timing of last intake and renal function. When life-threatening bleeding occurs, hemostasis should be restored as rapidly as possible. Non-specific prohemostatic drugs may have a role in DOAC reversal, and specific antidotes are at different stages of development. In this review, we provide a summary of DOAC characteristics and an overview of the different therapeutic options available for DOAC reversal.

Practical Considerations for the Nonvitamin K Antagonist Oral Anticoagulants

OBJECTIVES

Dabigatran, rivaroxaban, apixaban, and edoxaban are nonvitamin K antagonist oral anticoagulants (NOACs) approved for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF). Phase-3 clinical trials demonstrated NOACs were as effective as warfarin in the prevention of stroke or systemic embolism and associated with decreased incidences of intracranial bleeding. Additionally, NOACs provide quicker onset of action, simpler dosing, more predictable pharmacokinetic profiles, and decreased food and drug interactions compared with warfarin. Despite the advantages of NOACs, the lack of knowledge may limit their use in clinical practice.

METHODS

A search was performed on the terms 'atrial fibrillation' and 'dabigatran', 'apixaban', 'edoxaban', or 'rivaroxaban' to identify relevant papers; large randomized clinical trials, meta-analyses, and treatment guideline recommendations were given preference. Searches to identify registries, treatment guidelines, and meta-analyses relevant to patient subgroups were also employed.

RESULTS

Dosing recommendations, initiation of treatment, and applications in patients who undergo NVAF procedures, have mechanical heart valves, or experience other cardiovascular conditions such as myocardial infarction, previous stroke, and valvular heart disease are summarized. The NOAC-specific reversal approaches are also discussed.

CONCLUSIONS

Several important factors should be considered regarding the adequate use of NOACs, especially in patients with renal impairment or cardiovascular conditions other than NVAF.

Idarucizumab: A Review as a Reversal Agent for Dabigatran

Idarucizumab (Praxbind(®)), a humanized monoclonal antibody, is a specific reversal agent for the direct oral thrombin inhibitor dabigatran, available as its prodrug dabigatran etexilate (Pradaxa(®)). Idarucizumab is approved in several countries (including the USA, the EU, Canada and Australia) for use in adult patients on dabigatran when the reversal of its anticoagulant effects is required for emergency surgery/procedures or in the event of life-threatening or uncontrolled bleeding. In the ongoing pivotal RE-VERSE AD trial in these populations (n = 90), intravenous idarucizumab 5 g reversed dabigatran-induced prolongation of dilute thrombin time (dTT) and ecarin clotting time (ECT) within minutes. The median maximum percentage reversal was 100 % for both assays (primary endpoint). Idarucizumab normalized dTT and ECT in 88-98 % of patients who had elevated levels at baseline. After idarucizumab administration, bleeding stopped in 97 % of evaluable patients in the bleeding cohort within 24 h (median time to cessation of bleeding was 11.4 h), and the rate of normal intraoperative haemostasis was 92 % in the surgical cohort. Idarucizumab was generally well tolerated. In conclusion, idarucizumab is a unique and specific treatment option for the reversal of the anticoagulant effects of dabigatran in adult patients requiring emergency procedures or in the event of life-threatening or uncontrolled bleeding.

Direct-Acting Oral Anticoagulants: Practical Considerations for Emergency Medicine Physicians

Nonvalvular atrial fibrillation- (NVAF-) related stroke and venous thromboembolism (VTE) are cardiovascular diseases associated with significant morbidity and economic burden. The historical standard treatment of VTE has been the administration of parenteral heparinoid until oral warfarin therapy attains a therapeutic international normalized ratio. Warfarin has been the most common medication for stroke prevention in NVAF. Warfarin use is complicated by a narrow therapeutic window, unpredictable dose response, numerous food and drug interactions, and requirements for frequent monitoring. To overcome these disadvantages, direct-acting oral anticoagulants (DOACs)—dabigatran, rivaroxaban, apixaban, and edoxaban—have been developed for the prevention of stroke or systemic embolic events (SEE) in patients with NVAF and for the treatment of VTE. Advantages of DOACs include predictable pharmacokinetics, few drug-drug interactions, and low monitoring requirements. In clinical studies, DOACs are noninferior to warfarin for the prevention of NVAF-related stroke and the treatment and prevention of VTE as well as postoperative knee and hip surgery VTE prophylaxis, with decreased bleeding risks. This review addresses the practical considerations for the emergency physician in DOAC use, including dosing recommendations, laboratory monitoring, anticoagulation reversal, and cost-effectiveness. The challenges of DOACs, such as the lack of specific laboratory measurements and antidotes, are also discussed.

Direct Oral Anticoagulants in Dental Patients Including the Frail Elderly Population

Direct oral anticoagulants (DOACs) have led to a paradigm shift in the field of anticoagulation, providing safe and convenient anticoagulation without the need for regular blood testing. Currently, there are three major DOACs available-Factor Xa inhibitors (apixaban and rivaroxaban) and direct thrombin inhibitors (dabigatran)-that are available for use in atrial fibrillation and venous thromboembolism. While these agents have been shown to be as effective as warfarin, with a similar or better bleeding profile, there remains some concern of the use of these drugs in vulnerable populations, such as the frail elderly patients; particularly since reversal agents and drug monitoring are not routinely available. We aim to provide a review of the use of DOACs and the impact of DOACs on dental treatment in the elderly population.

Choosing Non-Vitamin K Antagonist Oral Anticoagulants: Practical Considerations We Need to Know

BACKGROUND

Warfarin is a well-established agent for use in the prevention of stroke or systemic embolic event (SEE) in patients with nonvalvular atrial fibrillation (NVAF) and for the treatment of venous thromboembolism (VTE). However, management of patients requiring oral anticoagulation with warfarin can be complicated by the need for frequent monitoring, drug-drug and drug-food interactions, and a variable response based on genetic polymorphisms. The non-vitamin K antagonist oral anticoagulants (NOACs) were developed as alternatives to warfarin; they do not require routine monitoring and have predictable pharmacokinetics, fewer drug-drug interactions, and limited drug-food interactions. Four NOACs-dabigatran, rivaroxaban, apixaban, and edoxaban-have received approval from the US Food and Drug Administration for the prevention of stroke or SEE in NVAF and for the treatment of VTE. Selecting the most appropriate agent for each patient should be done in consideration of patient preferences and characteristics, including renal function, bleeding risk, and the need for other medications.

METHODS

A search was performed on the terms atrial fibrillation and venous thromboembolism with individual terms dabigatran, apixaban, edoxaban, or rivaroxaban to identify relevant manuscripts; large randomized clinical trials, metaanalyses, and treatment guideline recommendations were given preference. Searches to identify registries, treatment guidelines, and metaanalyses relevant to specific subgroups were also used.

RESULTS

NOACs are effective in reducing the risk of stroke or SEE in patients with NVAF and are associated with fewer incidents of intracranial bleeding vs warfarin.

CONCLUSION

NOACs provide a convenient and safe alternative to warfarin and may result in improved therapeutic outcomes for patients with NVAF or VTE. The use of NOACs in other indications and patient populations is under investigation, and clinical trials investigating their use in acute coronary syndrome, medically ill patients, percutaneous coronary intervention, cardioversion, catheter ablation, coronary arterial disease, and heart failure have been announced.