Reversal of New, Factor-specific Oral Anticoagulants by rFVIIa, Prothrombin Complex Concentrate and Activated Prothrombin Complex Concentrate: A Review of Animal and Human Studies

Efficacy of human prothrombin complex concentrate in the treatment of warfarin overdose in patients receiving warfarin for mechanical heart valve replacement

Warfarin, a widely utilized anticoagulant, is paramount for preventing thromboembolic events in patients with mechanical heart valve replacements. However, its narrow therapeutic index can lead to over-anticoagulation and overdose, resulting in serious health risks. This study examines the efficacy of human prothrombin complex concentrate (PCC) in managing warfarin overdose, in comparison with traditional treatments. A retrospective analysis was conducted on 162 adults who presented with warfarin overdose (INR > 5.0) at a tertiary care hospital between 2016 and 2020. Participants were divided into 2 groups-those treated with PCC (n = 57) and those treated with conventional methods (n = 105), including vitamin K and fresh frozen plasma. The primary outcome was the rate of reaching the target (International Normalized Ratio) INR within 24 hours. Secondary outcomes included transfusion requirements, thromboembolic events, adverse reactions, 30-day mortality, and length of hospital stay. PCC demonstrated significant efficacy, with 89.5% of patients achieving the target INR within 24 hours, compared to 64.8% in the control group (P < .05). The PCC group also had reduced transfusion requirements and a shorter average hospital stay. There was no significant difference in thromboembolic events or adverse reactions between the 2 groups, and the reduced 30-day mortality in the PCC group was not statistically significant. Human prothrombin complex concentrate is associated with rapid reaching the target INR, decreased transfusion needs, and shortened hospitalization, making it a promising option for warfarin overdose management. While the results are encouraging, larger, multicenter, randomized controlled trials are necessary to further validate these findings and optimize PCC administration protocols.

Factor VIII Inhibitor Bypassing Activity (FEIBA) Reversal for Apixaban and Rivaroxaban in Patients With Acute Intracranial and Nonintracranial Hemorrhage

BACKGROUND

The clinical use of factor VIII inhibitor bypassing activity (FEIBA) for factor Xa (FXa) inhibitor reversal is derived from small studies with notable variation in patient eligibility for use, dosage regimens, concurrent supportive care, and outcome measures. Consequently, additional effectiveness and safety data are warranted to expand the literature evaluating FEIBA for FXa inhibitor reversal.

OBJECTIVE

This study sought to determine the incidence of observed effective hemostasis within 24 hours of post-FEIBA® administration as well as in-hospital and 30-day post-discharge incidences of thromboembolic event (TEE) and mortality between apixaban and rivaroxaban in the intracranial hemorrhage (ICH) and non-ICH populations.

METHODS

This case series evaluated patients between January 1, 2014 through July 1, 2019 who received at least one FEIBA® dose for apixaban or rivaroxaban reversal secondary to acute ICH or non-ICH. Patient demographics, FEIBA® dosages, adjunct treatments, effectiveness, and safety outcomes were retrospectively collected from electronic medical record review. Modified hemostasis outcomes, adapted from criteria previously published by Sarode et al., TEE, and mortality between apixaban and rivaroxaban in the ICH and non-ICH populations were evaluated.

RESULTS

Among the 104 patients evaluated, 62 received apixaban and 42 rivaroxaban. Thirty apixaban and 25 rivaroxaban users experienced ICH, whereas 32 apixaban and 17 rivaroxaban users experienced non-ICH. Among the combined ICH and non-ICH populations, effective hemostasis occurred in 89%, TEE in 8%, and mortality in 13%. No statistically significant differences were observed within ICH and non-ICH populations receiving apixaban or rivaroxaban regarding effective hemostasis, TEE, or mortality.

CONCLUSION AND RELEVANCE

The combined ICH and non-ICH overall rates of effective hemostasis, TEE, and mortality were comparable to preexisting studies of FEIBA for factor Xa inhibitor reversal. The limitations inherent to the study design warrant a randomized controlled trial with an active comparator to confirm these observations.

The Reversal of Bleeding Caused by New Oral Anticoagulants (NOACs): A Systematic Review and Meta-Analysis

New oral anticoagulants (NOACs; ie, direct thrombin inhibitor [DTI] and factor Xa [FXa] inhibitors) were used as alternatives to warfarin. Specific antidotes (idarucizumab for dabigatran and andexanet alfa for FXa inhibitors) and hemostatic reversal agents were used for lowering bleeding, but their efficacies were still uncertain. The objectives of this study were to estimate and compare the efficacy of NOAC antidotes on bleeding reversal and death. Studies were identified from MEDLINE and Scopus databases until May 2018. Case reports/series and cohorts were selected if they assessed reversal or death rates. Data were independently extracted by 2 reviewers. Individual patient data and aggregated data of outcomes were extracted from case reports/series and cohorts. Binary regression was used to estimate outcome rates, risk ratio (RR) along with 95% confidence interval (CI). Interventions were NOACs and reversal agents (ie, DTI-specific, DTI-standard, FXa-specific, and FXa-standard). Among 220 patients of 93 case reports/series, reversal rates were 95.9%, 77.6%, and 71.5% for DTI-specific, FXa-standard, and DTI-standard. Pooled RRs for DTI-specific and FXa-standard versus DTI-standard, respectively, were 1.34 (CI: 1.13-1.60) and 1.09 (CI: 0.84-1.40). Death rate was 0.18 (CI: 0.06-0.57) times lower in DTI-specific versus DTI-standard. For pooling 10 subcohorts, pooled RRs were 1.08 (CI: 1.00-1.16), 1.29 (CI: 1.20-1.39), and 1.13 (CI: 1.01-1.25) for DTI-specific, FXa-specific, and FXa-standard versus DTI-standard. In conclusion, specific reversal agents might be useful for reversal of bleeding and lowering the risk of death than standard reversal agents. Our findings were based on case reports/series and selected cohorts, further comparative studies are thus needed.

Indications and Methods of Anticoagulation Reversal

The use of anticoagulation in the prevention of strokes due to atrial fibrillation or the treatment of venous thromboembolic disease has been on the rise. With the advent and proliferation of direct oral anticoagulation medications, the management of anticoagulation reversal has become increasingly complex, especially when urgent or emergent reversal is required. This review details the commonly used parenteral and oral anticoagulants, the treatment strategies necessary for their reversal, and therapies still in development.

[State of the art: Direct oral anticoagulants and transfusion]

Direct oral anticoagulants (DOAC) are indicated for stroke prevention in atrial fibrillation and for the prevention and treatment of venous thromboembolism. As any anticoagulant, they are associated with a bleeding risk. Management of DOAC-induced bleeding is challenging. Idarucizumab, antidote for dabigatran, is currently available and is part of the therapeutic strategy, whereas antidotes for anti-Xa agents are under development. Activated or non-activated prothrombin concentrates are proposed, although their efficacy to reverse DOAC is uncertain. We propose an update on DOAC-associated bleeding management, integrating the availability of idarucizumab and the critical place of DOAC concentration measurements.

Management of Severe Bleeding in Patients Treated with Direct Oral Anticoagulants

Background

The use of prothrombin complex concentrates and the role of plasma concentration of anticoagulants in the management of bleeding in patients treated with direct oral anticoagulants are still debated. Our aim was to describe management strategies and outcomes of severe bleeding events in patients treated with direct oral anticoagulants.

Methods

We performed a prospective cohort study of 732 patients treated with dabigatran, rivaroxaban, or apixaban hospitalized for severe bleeding, included prospectively in the registry from June 2013 to November 2015.

Results

Bleeding was gastrointestinal or intracranial in 37% (212 of 732) and 24% (141 of 732) of the cases, respectively. Creatinine clearance was lower than 60 ml/min in 61% (449 of 732) of the cases. The plasma concentration of direct oral anticoagulants was determined in 62% (452 of 732) of the cases and was lower than 50 ng/ml or higher than 400 ng/ml in 9.2% (41 of 452) and in 6.6% (30 of 452) of the cases, respectively. Activated or nonactivated prothrombin complex concentrates were administered in 38% of the cases (281 of 732). Mortality by day 30 was 14% (95% CI, 11 to 16).

Conclusions

Management of severe bleeding in patients treated with direct oral anticoagulants appears to be complex. The use of prothrombin complex concentrates differs depending on bleeding sites and direct oral anticoagulant plasma concentrations. Mortality differs according to bleeding sites and was similar to previous estimates.

Viscoelastic testing inside and beyond the operating room

Hemorrhage is a major contributor to morbidity and mortality during the perioperative period. Current methods of diagnosing coagulopathy have various limitations including long laboratory runtimes, lack of information on specific abnormalities of the coagulation cascade, lack of in vivo applicability, and lack of ability to guide the transfusion of blood products. Viscoelastic testing offers a promising solution to many of these problems. The two most-studied systems, thromboelastography (TEG) and rotational thromboelastometry (ROTEM), offer similar graphical and numerical representations of the initiation, formation, and lysis of clot. In systematic reviews on the clinical efficacy of viscoelastic tests, the majority of trials analyzed were in cardiac surgery patients. Reviews of the literature suggest that transfusions of packed red blood cells (pRBC), plasma, and platelets are all decreased in patients whose transfusions were guided by viscoelastic tests rather than by clinical judgement or conventional laboratory tests. Mortality appears to be lower in the viscoelastic testing groups, despite no difference in surgical re-intervention rates and massive transfusion rates. Cost-effectiveness studies also seem to favor viscoelastic testing. Viscoelastic testing has also been investigated in small studies in other clinical contexts, such as sepsis, obstetric hemorrhage, inherited bleeding disorders, perioperative thromboembolism risk assessment, and management of anticoagulation for patients on mechanical circulatory support systems or direct oral anticoagulants (DOACs). While the results are intriguing, no systematic, larger trials have taken place to date. Viscoelastic testing remains a relatively novel method to assess coagulation status, and evidence for its use appears favorable in reducing blood product transfusions, especially in cardiac surgery patients.

Spontaneous, Life-Threatening Hemorrhagic Cardiac Tamponade Secondary to Rivaroxaban

Bleeding is the most feared complication of anticoagulants. Rivaroxaban is a newer oral anticoagulant with a favorable regimen due to lack of frequent blood monitoring and fewer drug interactions. We report a case of spontaneous pericardial hemorrhage associated with rivaroxaban. Within 10 days of starting rivaroxaban for atrial fibrillation, the patient developed a life-threatening cardiac tamponade leading to shock and multiorgan failure. After urgent pericardiocentesis/drainage, the patient recovered. This case highlights the necessity of larger clinical trials and consensus guideline on monitoring the effects of novel oral anticoagulants and development of an antidote for reversal in cases of major bleeding events.

Nonvitamin K antagonist oral anticoagulant activity: challenges in measurement and reversal

Background

Four nonvitamin K antagonist oral anticoagulants (NOACs) are approved for the prevention of stroke in patients with nonvalvular atrial fibrillation and for the treatment of venous thromboembolism. These include the direct thrombin inhibitor dabigatran and the direct factor Xa inhibitors rivaroxaban, apixaban, and edoxaban. Bleeding is a complication for all anticoagulants and concerns regarding bleeding risk and the suitability of effective reversal strategies may be a barrier to their prescription. Despite the reduced risk of bleeding compared with vitamin K antagonists, questions persist regarding the management of bleeding related to NOAC use.

Main text

To date, although a number of assays are responsive to NOACs, no single routine laboratory test has been identified to accurately measure the clinical anticoagulation state of patients on NOACs or established as a reliable predictor of bleeding risk. In addition, the establishment of a reliable human bleeding model to test novel inhibitors of the coagulation cascade has proved challenging. Although routine monitoring of anticoagulant levels is not necessary in patients taking NOACs, anticoagulant reversal and a means of measuring reversal may be required for patients who present with bleeding or require urgent surgery. Prothrombin complex concentrates are pooled plasma products containing varying amounts of inactive vitamin K-dependent clotting factors in addition to vitamin K-dependent proteins and can replenish factors in the intrinsic and extrinsic coagulation cascade, reversing an anticoagulant effect. Only one agent, idarucizumab, has been approved for rapid reversal of dabigatran-induced anticoagulation and one more agent, andexanet alfa, has been submitted for approval to reverse the anticoagulatory effects of direct and indirect factor Xa inhibitors.

Conclusions

This review discusses the laboratory tests available for assessing anticoagulation, human models of bleeding, and the use of current strategies—including prothrombin complex concentrates for reversal of anticoagulation by NOACs—to manage bleeding in patients.

[Direct oral anticoagulant associated bleeding]

Direct oral anticoagulants (DOAC) are recommended for stroke prevention in atrial fibrillation and for the treatment of venous thromboembolism. However, they are associated with hemorrhagic complications. Management of DOAC-induced bleeding remains challenging. Activated or non-activated prothrombin concentrates are proposed, although their efficacy to reverse DOAC is uncertain. Therapeutic options also include antidotes: idarucizumab, antidote for dabigatran, has been approved for use whereas andexanet alpha, antidote for anti-Xa agents, and aripazine, antidote for all DOAC, are under development. Other options include hemodialysis for the treatment of dabigatran-associated bleeding and administration of oral charcoal if recent DOAC ingestion. DOAC plasma concentration measurement is necessary to guide DOAC reversal. We propose an update on DOAC-associated bleeding, integrating the availability of dabigatran antidote and the critical place of DOAC concentration measurements.

Drug Treatment of Venous Thromboembolism in the Elderly

Half of all patients with acute venous thromboembolism are aged over 70 years; they then face the added hazard of an age-related increase in the incidence of major bleeding. This makes it even more important to weigh the balance of benefit and risk when considering anticoagulant treatment and treatment duration. Traditional treatment with a heparin (usually low molecular weight) followed by a vitamin K antagonist such as warfarin is effective but is often complicated, especially in the elderly. The direct-acting oral anticoagulants (DOACs), i.e. the thrombin inhibitor dabigatran and the factor Xa inhibitors rivaroxaban, apixaban and edoxaban, are given in fixed doses, do not need laboratory monitoring, have fewer drug-drug interactions and are therefore much easier to take. Randomised trials, their meta-analyses and 'real-world' data indicate the DOACs are no less effective than warfarin (are non-inferior) and probably cause less major bleeding (especially intracranial). It seems the relative safety of DOACs extends to age above 65 or 70 years, although bleeding becomes more likely regardless of the chosen anticoagulant. Renal impairment, comorbidities (especially cancer) and interventions are special hazards. Ways to minimise bleeding include patient selection and follow-up, education about venous thromboembolism, anticoagulants, drug interactions, regular checks on adherence and avoiding needlessly prolonged treatment. The relatively short circulating half-lives of DOACs mean that time, local measures and supportive care are the main response to major bleeding. They also simplify the management of invasive interventions. An antidote for dabigatran, idarucizumab, was recently approved by regulators, and a general antidote for factor Xa inhibitors is in advanced development.

The European guideline on management of major bleeding and coagulopathy following trauma: fourth edition

BACKGROUND

Severe trauma continues to represent a global public health issue and mortality and morbidity in trauma patients remains substantial. A number of initiatives have aimed to provide guidance on the management of trauma patients. This document focuses on the management of major bleeding and coagulopathy following trauma and encourages adaptation of the guiding principles to each local situation and implementation within each institution.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004 and included representatives of six relevant European professional societies. The group used a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were reconsidered and revised based on new scientific evidence and observed shifts in clinical practice; new recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated. This guideline represents the fourth edition of a document first published in 2007 and updated in 2010 and 2013.

RESULTS

The guideline now recommends that patients be transferred directly to an appropriate trauma treatment centre and encourages use of a restricted volume replacement strategy during initial resuscitation. Best-practice use of blood products during further resuscitation continues to evolve and should be guided by a goal-directed strategy. The identification and management of patients pre-treated with anticoagulant agents continues to pose a real challenge, despite accumulating experience and awareness. The present guideline should be viewed as an educational aid to improve and standardise the care of the bleeding trauma patients across Europe and beyond. This document may also serve as a basis for local implementation. Furthermore, local quality and safety management systems need to be established to specifically assess key measures of bleeding control and outcome.

CONCLUSIONS

A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. The implementation of locally adapted treatment algorithms should strive to achieve measureable improvements in patient outcome.

Successful hemostasis and reversal of highly elevated PT/INR after dabigatran etexilate use in a patient with acute kidney injury

Dabigatran etexilate is a novel oral anticoagulant indicated for anticoagulation in the management of atrial fibrillation and venous thromboembolism. Before its approval by the US Food and Drug Administration, warfarin, a vitamin K antagonist, was one of few oral anticoagulant options. The burden of therapeutic drug monitoring, dietary restrictions, and various drug interactions associated with warfarin have countered its extensive history of efficacy. Although dabigatran etexilate may alleviate some concerns encountered with warfarin therapy, there remains a paucity of evidence surrounding emergent reversal strategies in severe hemorrhage. We report here a 71-year-old man who presented to the emergency department with gastrointestinal hemorrhage precipitated by acute kidney injury while on dabigatran etexilate, with laboratory derangements highly uncharacteristic of dabigatran therapy (international normalized ratio, > 10, and activated partial thromboplastin time, 93 seconds). After admission to the intensive care unit and 7 U of fresh frozen plasma, the patient remained hemodynamically unstable due to blood loss. Other observations were made that are poorly characterized in medical literature related to dabigatran: refractory hemorrhagic shock after 7 U of fresh frozen plasma, rapid correction of coagulation parameters (international normalized ratio, 1.7, and activated partial thromboplastin time, 44 seconds) achieved 4 hours after 26 U/kg of 4-factor prothrombin complex concentrate (Kcentra; CSL Behring, King of Prussia, PA), and with subsequent achievement of hemostasis. The patient was discharged to home 7 days later without sequelae.

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.

[Management of direct oral anticoagulants for invasive procedures]

Three new Direct Oral Anticoagulants (DOACs), rivaroxaban, apixaban and dabigatran etexilate are available on the French market. Management of DOAC-induced bleeding risk remains challenging. For elective procedures with high hemorrhagic risk, a last DOAC intake five days before procedure ensures complete elimination in all patients. Heparin bridging therapy should be proposed only to patients at high thrombotic risk. For elective procedures with low hemorrhagic risk, the DOAC intake of the night before procedure should be omitted. For urgent procedures with high bleeding risk, DOAC plasmatic concentration can be helpful: concentration lower than 30 ng/mL should enable performing the procedure; a high concentration is associated with a higher bleeding risk, especially if higher than 400 ng/mL. In case of massive bleeding, no antidote is approved yet; activated prothrombin concentrates or non-activated 4-factors prothrombin concentrates could be considered.

Multimodal assessment of non-specific hemostatic agents for apixaban reversal

BACKGROUND

Non-specific hemostatic agents, namely activated prothrombin complex concentrate (aPCC), PCC and recombinant activated factor (F) VII (rFVIIa), can be used, off-label, to reverse the effects of FXa inhibitors in the rare cases of severe hemorrhages, as no approved specific antidote is available. We have evaluated the ability of aPCC, PCC and rFVIIa to reverse apixaban.

METHODS

Healthy volunteer whole blood was spiked with therapeutic or supra-therapeutic apixaban concentrations and two doses of aPCC, PCC or rFVIIa. Tests performed included a turbidimetry assay for fibrin polymerization kinetics analysis, scanning electron microscopy for fibrin network structure observation, thrombin generation assay (TGA), thromboelastometry, prothrombin time and activated partial thromboplastin time.

RESULTS

aPCC generated a dense clot constituting thin and branched fibers similar to those of a control without apixaban, increased fibrin polymerization velocity and improved quantitative (endogenous thrombin potential and peak height) as well as latency (clotting and lag times) parameters. Adding PCC also improved the fibrin and increased quantitative parameters, but fibrin polymerization kinetics and latency parameters were not corrected. Finally, rFVIIa improved latency parameters but failed to restore the fibrin network structure, fibrin polymerization velocity and quantitative parameters.

CONCLUSION

aPCC was more effective than PCC or rFVIIa in reversing in vitro the effects of apixaban. aPCC rapidly triggered the development of an apparently normal fibrin network and corrected latency and quantitative parameters, whereas PCC or rFVIIa had only a partial effect.

Global assays and the management of oral anticoagulation

Coagulation tests range from global or overall tests to assays specific to individual clotting factors and their inhibitors. Whether a particular test is influenced by an oral anticoagulant depends on the principle of the test and the type of oral anticoagulant. Knowledge on coagulation tests applicable in monitoring status and reversal of oral anticoagulation is a prerequisite when studying potential reversal agents or when managing anticoagulation in a clinical setting. Specialty tests based on the measurement of residual activated factor X (Xa) or thrombin activity, e.g., are highly effective for determining the concentration of the new generation direct factor Xa- and thrombin inhibitors, but these tests are unsuitable for the assessment of anticoagulation reversal by non-specific prohemostatic agents like prothrombin complex concentrate (PCC) and recombinant factor VIIa (FVIIa). Global coagulation assays, in this respect, seem more appropriate. This review evaluates the current status on the applicability of the global coagulation assays PT, APTT, thrombin generation and thromboelastography in the management of oral anticoagulation by vitamin K antagonists and the direct factor Xa and thrombin inhibitors. Although all global tests are influenced by both types of anticoagulants, not all tests are useful for monitoring anticoagulation and reversal thereof. Many (pre)analytical conditions are of influence on the assay readout, including the oral anticoagulant itself, the concentration of assay reagents and the presence of other elements like platelets and blood cells. Assay standardization, therefore, remains an issue of importance.

Emergency neurosurgical care in patients treated with apixaban: report of 2 cases

A debate has emerged regarding the safety profile of direct anticoagulants, which are increasingly prescribed for the prevention of thromboembolic events. Despite favorable safety data derived from controlled clinical trials, the absence of specific antidotes for the management of hemorrhagic complications represents a major challenge for emergency physicians. Here, we present the first report on patients treated with the direct factor Xa inhibitor apixaban and conditions requiring urgent neurosurgical intervention (intracerebral hemorrhage, n = 1; subdural hematoma, n = 1). Prothrombin complex concentrates were administered before surgery, and both patients had a favorable postsurgical course without bleeding or thromboembolic complications. Further studies are needed, but this approach seems to be suitable for the emergency management of apixaban-associated intracranial hemorrhage.

Reversing targeted oral anticoagulants

Dabigatran, rivaroxaban, and apixaban are orally active anticoagulants that are approved in many countries. Dabigatran inhibits thrombin, whereas rivaroxaban and apixaban are factor Xa inhibitors. In clinical trials, these novel oral anticoagulants were at least as effective as warfarin for preventing stroke in patients with atrial fibrillation, but with a lower rate of serious bleeding. However, the lack of true antidotes for these agents has caused concern when patients suffer life-threatening bleeding or trauma or require emergent invasive procedures. True antidotes are under development for all of these agents. In the meantime, activated and nonactivated prothrombin complex concentrates have been used as reversal agents. Factor VIIa may also be effective for reversal of the factor Xa inhibitors. Reversal of novel oral anticoagulants by these hemostatic agents has not been studied in bleeding human patients, so their true efficacy and appropriate dosing are not known.