The recommended dose of idarucizumab may not always be sufficient for sustained reversal of dabigatran

Prothrombotic Rebound After Discontinuation of Direct Oral Anticoagulants Therapy: A Systematic Review

Background/Objectives: The practice of holding anticoagulation is a relatively common approach, with the aim of either preventing excessive bleeding in preparation for surgical procedures or managing acute bleeding episodes. Methods: To assess the relationship between the discontinuation of direct oral anticoagulants (DOACs) therapy and the condition of hypercoagulability, a systematic review of the literature was conducted, following PRISMA guidelines, in PubMed/MEDLINE, Cochrane, and Google Scholar. These databases were searched for all publications that described a rebound phenomenon or hypercoagulability state after DOACs discontinuation. Results: A total of 1494 articles were selected from searched databases, and 29 were eligible. A final total of 16 case reports and 14 original research articles were subjected to analysis. Conclusions: The results of this study indicate that the cessation of DOAC therapy may be associated with an increased risk of thrombotic events. More studies are required to ascertain whether DOACs treatment cessation can be linked to rebound phenomena associated with thromboembolic events. This will provide the data needed to determine the incidence and risk of this phenomenon.

Is there a role for the laboratory monitoring in the management of specific antidotes of direct oral anticoagulants?

Given the growing number of patients receiving direct oral anticoagulant (DOAC), patients requiring rapid neutralization is also increasing in case of major bleedings or urgent surgery/procedures. Idarucizumab is commercialized as a specific antidote to dabigatran while andexanet alfa has gained the Food and Drug Administration and the European Medicines Agency approval as an oral anti-factor Xa inhibitors antidote. Other antidotes or hemostatic agents are still under preclinical or clinical development, the most advanced being ciraparantag. DOAC plasma levels measurement allows to appropriately select patient for antidote administration and may prevent unnecessary prescription of expensive molecules in some acute clinical settings. However, these tests might be inconclusive after some antidote administration, namely andexanet alfa and ciraparantag. The benefit of laboratory monitoring following DOAC reversal remains unclear. Here, we sought to provide an overview of the key studies evaluating the safety and efficacy of DOAC reversal using the most developed/commercialized specific antidotes, to discuss the potential role of the laboratory monitoring in the management of patients receiving DOAC specific antidotes and to highlight the areas that deserve further investigations in order to establish the exact role of laboratory monitoring in the appropriate management of DOAC specific antidotes.

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.

How the Hemostasis Laboratory Can Help Clinicians to Manage Patients on Oral Anticoagulants

Oral anticoagulants are widely used to treat or prevent cardiovascular diseases in millions of patients worldwide. They are the drugs of choice for stroke prevention and systemic embolism in patients with non-valvular atrial fibrillation and prosthetic heart valves, as well as for treatment/prevention of venous thromboembolism. Oral anticoagulants include vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs). The hemostasis laboratory plays a crucial role in the management of treated patients, spanning from dose adjustment based on laboratory testing that applies to VKAs to the measurement of drug concentrations in special situations that apply to DOACs. This article aims to overview how the hemostasis laboratory can help clinicians manage patients on oral anticoagulants. Special interest is devoted to the international normalized ratio, used to manage patients on VKAs and to the measurement of DOAC concentrations, for which the role of the laboratory is still not very well defined, and most interferences of DOACs with some of the most common hemostatic parameters are not widely appreciated.

[Update on point-of-care-based coagulation treatment : Systems, reagents, device-specific treatment algorithms]

Viscoelastic test (VET) procedures suitable for point-of-care (POC) testing are in widespread clinical use. Due to the expanded range of available devices and in particular due to the development of new test approaches and methods, the authors believe that an update of the current treatment algorithms is necessary. The aim of this article is to provide an overview of the currently available VET devices and the associated reagents. In addition, two treatment algorithms for the VET devices most commonly used in German-speaking countries are presented.

The role of anticoagulation clinics needs to be reassessed to include follow up of patients on direct oral anticoagulants

A survey was carried out to assess the state of organization of care (including clinical and laboratory) delivered to patients on vitamin K antagonists (VKA) or direct oral anticoagulants (DOAC) followed by clinics affiliated with the Italian Federation of Thrombosis Centers (FCSA), traditionally engaged to assist anticoagulated outpatients within the country. Participants were asked to answer questions concerning (i) proportion of patients on VKA-vs-DOAC and (ii) whether dedicated testing for DOAC is available. The proportion of patients on VKA-vs-DOAC was 60 % vs 40 %. This proportion is in sharp contrast with the real-life distribution where DOAC outweigh VKA prescriptions. Furthermore, the proportion of anticoagulation clinics that provide DOAC testing (even in special situations) is relatively small (i.e., 31 % of the respondents). Furthermore, 25 % of those that declared to follow DOAC patients do not provide any testing at all. The answers to the above questions cause concerns as (i) most patients on DOAC within the country are probably on self-management, or they are managed by general practitioners or specialists outside thrombosis centers. (ii) Most patients on DOAC have no access to testing even in special situations where it would be needed. We feel that there is a (false) perception that the care needed for DOAC treatment can be much less than that required for VKA, as DOAC require prescription and not regular follow-up. A call for action should be urgently made to reassess the role of anticoagulation clinics, which should pay the same attention to patients on DOAC as those on VKA.

The myths behind DOAC measurement: Analyses of prescribing information from different regulatory bodies and a call for harmonization

For more than a decade, US laboratories have failed to implement solutions to help their clinicians in managing complex situations or patients on direct oral anticoagulants (DOACs). The problem may find different origins, among which is the position of the Food and Drug Administration, which categorized these drugs as monitoring- and measurement-free, whereas other regulatory bodies like the European Medicines Agency or the Therapeutic Goods Administration in Australia were more conservative on the principle that the absence of proof (of monitoring/measurement benefits) is not proof of an absence (of monitoring/measurement needs). Pivotal clinical studies that led to the approval of DOACs were presented as devoid of such testing, although some companies considered monitoring as a solution to improve their benefit/risk ratio. In this JTH In Clinics issue, we report more than a decade of development that has permitted the activation of smart laboratory solutions to qualify or quantify DOACs and discuss myths and misconceptions around technical and regulatory requirements that support the current reluctance of implementing these technologies in most US laboratories. Use of DOACs is ever expanding, with DOAC prescriptions now exceeding those of other anticoagulants, including vitamin K antagonists, in some geographies. As this use increases, the likely need to measure DOAC exposure will also increase. Measurement of DOACs does not represent any technical difficulty. That these laboratory tests are not available in some locations suggests disparities in patient care, and we suggest it is time to address such inequalities.

Retrospective analysis of the effectiveness of a reduced dose of idarucizumab in dabigatran reversal

BACKGROUND

The recommended dose of idarucizumab, the specific reversal agent for dabigatran etexilate, is 5g. However, published data showed biochemical reversal after an initial 2.5g dose.

OBJECTIVES

This study aims to retrospectively compare the clinical effectiveness of 2.5g and 5g doses of idarucizumab used in dabigatran reversal in three hospitals in Auckland, New Zealand.

METHODS

All patients receiving idarucizumab for dabigatran reversal between 1st April 2016 and 31st December 2018 were included. The primary outcome was the likelihood of receiving a second dose of idarucizumab during the same admission. Secondary outcomes included normalisation of coagulation profiles; and 30-day thrombotic, bleeding and mortality rates.

RESULTS

Of 329 patients included, 206 received an upfront 2.5g dose and 123 received a 5g dose. The median age was 78 years and median creatinine clearance was 50mL/min. Most patients (62.6%) required idarucizumab for an urgent procedure, while 37.4% presented with bleeding. A 2.5g dose was not associated with an increased rate of receiving a second dose (OR 0.686, 95% CI 0.225-2.090). A similar proportion of patients in each group achieved a normal APTT (73.8% vs 80.0%, p=0.464) and dTCT (95.9% vs 91.4%, p=0.379) following idarucizumab infusion. There was no increase in the rate of death (OR 0.602, 95% CI 0.292-1.239), thrombosis (OR 0.386, 95% CI 0.107-1.396) or bleeding (OR 0.96, 95% CI 0.27-3.33) in the 2.5g dose group compared to the 5g dose group.

CONCLUSIONS

An initial 2.5g dose of idarucizumab appears effective for dabigatran reversal in the real-world setting.

Strategies for the prevention and treatment of bleeding in patients treated with dabigatran: an update

INTRODUCTION

Although dabigatran is safer than vitamin K antagonists, bleeding still occurs. Bleeding is an important cause of short-term morbidity and rarely mortality and can also have long-term consequences that are often under-appreciated. After bleeding, patients often do not restart treatment or are poorly adherent, which is associated with increased thromboembolism and mortality. Consequently, we need strategies to prevent and treat bleeding in patients with atrial fibrillation treated with dabigatran.

AREAS COVERED

We review a) relevant dabigatran pharmacology, b) the burden and consequences of bleeding, c) how to identify patients at high risk of bleeding; and d) existing and novel approaches to prevent and treat bleeding in dabigatran-treated patients.

EXPERT OPINION

Concerns about the risk of bleeding associated with anticoagulant therapy and emerging evidence of increased risk of thromboembolism and mortality after bleeding highlight the need for improved approaches to prevention and treatment of bleeding. Future research priorities should focus on improving our ability to prevent bleeding by identifying modifiable risk factors and the development of safer agents. The current front runners include drugs that selectively target the contact pathway of coagulation (e.g. factor XI). Targeting upstream drivers of thrombosis (e.g. inflammation) could help to further reduce the risk of thromboembolism.

Antithrombotic and Antiplatelet Drug Toxicity

Anticoagulant and antiplatelet drugs target a specific portion of the coagulation cascade or the platelet activation and aggregation pathway. The primary toxicity associated with these agents is hemorrhage. Understanding the pharmacology of these drugs allows the treating clinician to choose the correct antidotal therapy. Reversal agents exist for some of these drugs; however, not all have proven patient-centered outcomes. The anticoagulants covered in this review are vitamin K antagonists, heparins, fondaparinux, hirudin derivatives, argatroban, oral factor Xa antagonists, and dabigatran. The antiplatelet agents reviewed are aspirin, adenosine diphosphate antagonists, dipyridamole, and glycoprotein IIb/IIIa antagonists. Additional notable toxicities are also reviewed.

Impact of Idarucizumab and Andexanet Alfa on DOAC Plasma Concentration and ClotPro® Clotting Time: An Ex Vivo Spiking Study in A Cohort of Trauma Patients

Specific antagonists have been developed for the reversal of direct oral anticoagulants (DOAC). We investigated the impact of these reversal agents on the plasma concentration and visco-elastic test results of dabigatran and factor Xa inhibitors. After baseline measurements of dabigatran, the plasma concentration, and the visco-elastic ClotPro^® ecarin clotting time (ECA-CT), we added the reversal agent Idarucizumab in vitro and these two analyses were repeated. Likewise, the baseline plasma concentration of apixaban, edoxaban, and rivaroxaban as well as ClotPro^® Russell’s viper venom test clotting time (RVV-CT) were measured and reanalyzed following Andexanet alfa spiking. We analyzed fifty blood samples from 37 patients and 10 healthy volunteers. Idarucizumab decreased the measured dabigatran plasma concentration from 323.9 ± 185.4 ng/mL to 5.9 ± 2.3 ng/mL and ECA-CT from 706.2 ± 344.6 s to 70.6 ± 20.2 s, (all, p < 0.001). Andexanet alfa decreased the apixaban concentration from 165.1 ± 65.5 ng/mL to 9.8 ± 8.1 ng/mL, edoxaban from 152.4 ± 79.0 ng/mL to 36.4 ± 19.2 ng/mL, and rivaroxaban from 153.2 ± 111.8 ng/mL to 18.1 ± 9.1 ng/mL (all p < 0.001). Andexanet alfa shortened the RVV-CT of patients with apixaban from 239.2 ± 71.7 s to 151.1 ± 30.2 s, edoxaban from 288.2 ± 65.0 s to 122.7 ± 37.1 s, and rivaroxaban from 225.9 ± 49.3 s to 103.7 ± 12.1 s (all p < 0.001). In vitro spiking of dabigatran-containing blood with Idarucizumab substantially reduced the plasma concentration and ecarin-test clotting time. Andexanet alfa lowered the concentration of the investigated factor Xa-inhibitors but did not normalize the RVV-CT. In healthy volunteers’ blood, Idarucizumab spiking had no impact on ECA-CT. Andexanet alfa spiking of non-anticoagulated blood prolonged RVV-CT (p = 0.001), potentially as a consequence of a competitive antagonism with human factor Xa.

Direct oral anticoagulant reversal: An update

ABSTRACT

The rise in direct oral anticoagulant (DOAC) use means nurses must understand the reversal of these agents in case of bleeding. Depending on bleed severity, as well as other criteria, pharmacologic reversal can be considered in place of supportive care alone. Knowledge of literature surrounding DOAC reversal is crucial.

Dabigatran activates inflammation resolution by promoting fibrinogen-like protein 2 shedding and RvD5n-3 DPA production

Rationale: The interaction between coagulation and inflammation resolution remains elusive. We recently highlighted a link between fibrinogen-like protein 2 (Fgl2) and a specialized pro-resolving mediator (SPM)-n-3 docosapentaenoic acid-derived resolvin D5 (RvD5_{n-3 DPA}) in sepsis. This study aimed to investigate the functions of commonly used anticoagulants warfarin, dabigatran and heparin in regulating inflammation resolution.

Methods: Peripheral blood was collected from clinical sepsis patients and healthy control for the determination of indicated indexes. Mouse sepsis models of zymosan-induced peritonitis and cecal ligation and puncture (CLP) were employed for the measurement of inflammation- and coagulation-related indexes. Western-blotting, ELISA and flow cytometry were applied to assess proteins. UPLC-MS/MS was used to evaluate lipid metabolites.

Results: Here we report that the transmembrane Fgl2 (mFgl2) was positively associated with coagulation, while soluble Fgl2 (sFgl2) level correlated with the enhanced number of peripheral blood mononuclear cells in the sepsis patients. The anticoagulants dabigatran and warfarin attenuated zymosan-induced peritonitis, which was not shared by heparin, while only dabigatran significantly improved sepsis survival in the CLP sepsis mouse model. Although these anticoagulants consistently inhibited pro-inflammatory mediators including prostaglandin E₂ and leukotriene B₄, only dabigatran increased sFgl2 at both the initiation and resolution phases of inflammation. Mechanistically, dabigatran elicited the shedding of sFgl2 via prothrombin-related metalloproteases, thereby enhanced the subsequent biosynthesis of RvD5_{n-3 DPA}via STAT6-ALOX15 axis. Blocking metalloproteases or ALOX15 significantly impaired dabigatran-enhanced macrophage efferocytosis in vitro, as well as delayed the dabigatran-accelerated inflammation resolution in vivo.

Conclusions: Our findings identify the dual anti-inflammatory and pro-resolving actions of dabigatran, through promoting sFgl2-triggered RvD5_{n-3 DPA} production, which has important implications for promoting tissue homeostasis of sepsis.

Pitfalls in the assessment of disseminated intravascular coagulation in patients on dabigatran

Dabigatran is an orally administrated anticoagulant that directly inhibits thrombin. However, the drug can affect routine coagulation tests such as prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT), as well as haemostasis assays, (e.g., clot-based coagulation factor assays). There are limited data on the effect of dabigatran on some fibrinogen measurements and on D-dimer assays, both important components in the laboratory assessment of disseminated intravascular coagulation (DIC). The objectives of this study were: (1) to determine the effects of various concentrations of dabigatran on fibrinogen and D-Dimer assays; and (2) to compare the von Clauss method of fibrinogen measurement using two reagents with differing thrombin concentrations (35 UNIH/mL and 100 UNIH/mL) and PT-derived fibrinogen measurement in the presence of the drug. Aliquots of pooled normal plasma were spiked with different concentrations of dabigatran to reflect in vivo on-therapy levels as well as levels observed in cases of massive accumulation of the drug. Of the routine coagulation assays, in ascending order of sensitivity to dabigatran were PT, APTT and TT. The von Clauss method of measuring fibrinogen using a reagent with low thrombin concentration was affected even at drug levels corresponding to in vivo trough concentrations, whereas the reagent with higher thrombin concentration was only affected at drug levels that were above observed peak concentrations in patients taking 150 mg of the drug twice daily. PT-derived fibrinogen was affected at approximately in vivo peak drug concentrations. The D-dimer assay was affected only at drug concentrations well above peak drug levels. Attempts at in vitro neutralisation of the drug with DOAC-Stop resulted in 'correction' of some of these measurements depending on drug concentration. Like the routine coagulation assays, there is a dabigatran concentration dependent effect on the accuracy of fibrinogen and D-dimer assays. Falsely low fibrinogen results due to dabigatran may confound the assessment of DIC and diagnostic laboratories need to evaluate the performance of their own reagents.

[TEG-guided treatment of a dabigatran overdose in a patient with acute kidney failure]

This article presents the case of a multimorbid male patient with an accidental dabigatran overdose caused by kidney failure in the context of an acute intestinal disorder. After effective initial antagonizing of the dabigatran effect using idarucizumab a dabigatran rebound was detected caused by a single hemodialysis leading to a severe intrapulmonary hemorrhage. As dabigatran plasma level testing was not available and conventional coagulation analysis was out of interpretable range due to the impact of dabigatran, continuous thrombelastography (TEG) was used to detect the effect of dabigatran and monitor the treatment results. The most significant parameter used in the kaolin activated clotting time was the R‑time parameter, which was massively prolonged by the interrupted coagulation cascade.

Assessing and Reversing the Effect of Direct Oral Anticoagulants on Coagulation

This article presents a focused review of the available tests to assess the effect of direct oral anticoagulants on coagulation and the use of reversal agents in the perioperative setting for practicing anesthesiologists.

Direct-Acting Oral Anticoagulants and Their Reversal Agents-An Update

Background: Over the last ten years, a new class of drugs, known as the direct-acting oral anticoagulants (DOACs), have emerged at the forefront of anticoagulation therapy. Like the older generation anticoagulants, DOACs require specific reversal agents in cases of life-threatening bleeding or the need for high-risk surgery. Methods: Published literature was searched, and information extracted to provide an update on DOACS and their reversal agents. Results: The DOACs include the direct thrombin inhibitor—dabigatran, and the factor Xa inhibitors—rivaroxaban, apixaban, edoxaban, and betrixaban. These DOACs all have a rapid onset of action and each has a predictable therapeutic response requiring no monitoring, unlike the older anticoagulants, such as warfarin. Two reversal agents have been approved within the last five years: idarucizumab for the reversal of dabigatran, and andexanet alfa for the reversal of rivaroxaban and apixaban. Additionally, ciraparantag, a potential “universal” reversal agent, is currently under clinical development. Conclusions: A new generation of anticoagulants, the DOACs, and their reversal agents, are gaining prominence in clinical practice, having demonstrated superior efficacy and safety profiles. They are poised to replace traditional anticoagulants including warfarin.

Idarucizumab in major trauma patients: a single centre real life experience

INTRODUCTION

Trauma care providers are facing an increasing number of elderly patients on direct oral anticoagulants prior to injury. For dabigatran etexilate (DAB), the specific antagonist idarucizumab (IDA) has been approved since 2015 as a reversal agent. However, only limited data regarding the use of IDA in trauma patients are available.

METHODS

We performed a retrospective analysis of trauma patients under DAB for whom IDA administration was deemed necessary to reverse DAB's antithrombotic effect.

RESULTS

A total of 15 (9 male) patients were treated with IDA during the study period. The mean age was 81 ± 10 years. Intracranial haemorrhage (n = 7) and long bone fractures (n = 5) were the most common types of injury. Three patients were diagnosed as polytrauma. In all but one patient, atrial fibrillation was the indication for DAB intake. The median dose of IDA was 2.5 g (IQR 2.5-5). IDA administration decreased DAB plasma levels from 112.4 (IQR 73.4-123.4) to 5 (IQR 4-12) ng/mL (p = 0.031), thrombin time from 114.8 ± 48.3 to 16.2 ± 0.5 s (p < 0.0001) and activated partial thromboplastin time form 45.4 ± 11.3 to 34.2 ± 7.0 s (p = 0.0025). No thromboembolic events or side effects attributed to IDA were observed. All patients survived until hospital discharge.

CONCLUSIONS

In trauma patients under DAB prior to injury, IDA decreased DAB plasma levels and normalized coagulation parameters. IDA appears to be safe, and no serious side effects were observed in this small cohort of patients.

Lessons learnt from local real-life experience with idarucizumab for the reversal of dabigatran

BACKGROUND

Idarucizumab is a specific antidote for the direct thrombin inhibitor oral anticoagulant dabigatran etexilate. It has been used with increasing frequency in Australia since it was granted Therapeutic Goods Administration approval in October 2016.

AIMS

To assess idarucizumab usage, effect on coagulation parameters and clinical outcomes in patients who received idarucizumab in Western Sydney Local Health District (WSLHD).

METHODS

A retrospective audit was conducted of all patients who received idarucizumab in WSLHD between September 2015 and December 2017.

RESULTS

Of the 23 patients who received idarucizumab, 17 (74%) had bleeding, and 6 (26%) required urgent surgery/procedure. Thrombin time (TT) or activated partial thromboplastin time (APTT, when TT not available) remained prolonged at 24 h post-idarucizumab infusion in 10 of 20 (50%) patients. Renal impairment at admission was associated with prolonged TT/APTT at 24 h (P = 0.02). Of the six (26%) patients who died during hospital admission, five had raised TT/APTT at 24 h (P = 0.05). Two deaths were due to continued bleeding despite idarucizumab. Only 17% of patients received prohaemostatic treatments, and none received plasma derivatives. Despite assay availability, dabigatran drug level was only measured in eight patients.

CONCLUSION

Idarucizumab helped achieve haemostasis in 15 bleeding patients and allowed 6 patients to undergo urgent surgery. Half the patients had prolonged TT/APTT at 24 h post-idarucizumab, which was more likely to occur in patients with impaired renal function.

Novel reversal agents and laboratory evaluation for direct-acting oral anticoagulants (DOAC): An update

Novel oral anticoagulants (NOACs) are no longer "novel" but their reversal agents definitely are. Although NOACs enjoy high clinical efficacy, monitoring and reversal of their effect is a challenge which this review attempts to surmount. Ideally, for NOAC activity measurement, specific anti-Factor IIa levels and anti -Factor Xa levels should be monitored (chromogenic assays), but such tests are not readily available. Modifications of the existing coagulation tests catering to this unmet need for quantification of DOAC activity have been reviewed. The available United States Food and Drug Administration (FDA) approved reversal agents, idarucizumab for dabigatrin and andexanet alfa for anti-Xa direct acting oral anticoagulants have given promising results but are prohibitively priced. Medline, Embase, and Scopus databases were thoroughly searched for clinical trials on laboratory investigations and specific as well as non-specific reversal-agents for DOACs.

Testing and monitoring direct oral anticoagulants

Direct oral anticoagulants (DOACs) have significantly improved the care of patients requiring anticoagulation. With similar or better efficacy and safety outcomes and easier use in the outpatient setting compared with the standard-of-care vitamin K antagonists and low molecular weight heparin, DOACs are now endorsed as first-line treatment of indications including prevention of stroke and systemic embolism in nonvalvular atrial fibrillation and treatment of venous thromboembolism. DOACs are easy-to-use oral agents that offer simple dosing and short half-lives, with no need to test levels because of the wide therapeutic window and limited drug-drug interactions. After almost a decade of DOAC use, the question of testing DOAC levels in certain clinical situations has become the focus of debate. Although guidance for using routine coagulation tests is available, these tests are inadequate for optimal care. DOAC-specific tests have been developed but have limited availability in Europe and less availability in the United States. None are licensed. DOAC testing may be useful in the setting of critical clinical situations such as life-threatening bleeding or need for emergent surgery, especially with the availability of DOAC reversal agents. Patients with characteristics that fall outside the normal range may benefit from the guidance that DOAC testing could offer. Obstacles to adopting DOAC testing have been raised, such as test reliability and staffing costs; however, these problems are rapidly being resolved. Further investigation of the role of DOAC testing is needed to explore its full potential and role in clinical practice.

Pharmacological reversal of the direct oral anticoagulants-A comprehensive review of the literature

The direct oral anticoagulants (DOACs) are used for stroke prevention in atrial fibrillation (SPAF) and the prevention and treatment of venous thromboembolic disease (VTE). Although DOAC-associated bleeding events are less frequent as compared to vitamin K antagonists, there is significant concern surrounding physicians' ability to evaluate and manage DOAC-associated bleeding when it does occur. Idarucizumab is a specific reversal agent for dabigatran and is the agent of choice for dabigatran reversal in the setting of major bleeding or urgent surgery/procedures. There are no commercially available specific reversal agents for the direct Xa inhibitors. Although they have not been rigorously studied in DOAC-treated patients requiring urgent anticoagulant reversal, limited evidence from in vitro studies, animal bleeding models, human volunteer studies (in vivo and in vitro) and case series suggest that coagulation factor replacement with prothrombin complex concentrate (PCC) and activated PCC (FEIBA) may contribute to hemostasis. However, the safety and efficacy of these agents and the optimal dosing strategies remain uncertain.

Position Paper on laboratory testing for patients on direct oral anticoagulants. A Consensus Document from the SISET, FCSA, SIBioC and SIPMeL

Although direct oral anticoagulants (DOAC) do not require dose-adjustment on the basis of laboratory test results, the measurement of their anticoagulant effect is useful in special situations. This position paper issued by the Italian Scientific Societies that are mainly involved in the management of patients on DOAC is aimed at providing guidance to care-givers on which tests should be used and the situations in which testing is useful. The guidance is based on the data from the literature so far available and/or on consensus among experts.