The use of frozen plasma samples in thromboelastometry

Thromboelastometry is increasingly used in the clinical and scientific setting. The use of frozen plasma samples may be useful in overcoming certain limitations such as local and timely availability. Whole blood (WB) samples of 20 healthy volunteers were obtained, and plasma was generated. NATEM (n = 20), EXTEM (n = 20) and INTEM (n = 8) analyses were performed in WB, fresh plasma and frozen and thawed plasma. Dabigatran (500, 1000 ng/ml), rivaroxaban (100, 200 ng/ml) or alteplase (333 ng/ml) were added ex vivo to WB, and thromboelastometry was performed in WB and in frozen and thawed plasma samples. Clot formation time, mean clot firmness and the area under the curve were significantly altered in plasma compared to WB. In INTEM and EXTEM analysis, clotting time (CT) was comparable between WB (100%) and fresh (INTEM 114% and EXTEM 93%, ratio of the means) and frozen plasma samples (85 and 99%), whereas in NATEM analysis, the CT increased in fresh (193%) and frozen plasma samples (130%). Dabigatran dose-dependently increased the CT approximately 5- and 9-fold in WB and even more pronounced 10- and 26-fold in plasma. Accordingly, rivaroxaban dose-dependently increased the CT 2- and 2.7-fold in WB, and 3.5- and 4-fold in plasma samples. Hyperfibrinolysis was achieved by addition of alteplase in all WB samples and was reproducible in plasma samples. In conclusion, thromboelastometry, especially INTEM and EXTEM analyses, is possible using frozen and stored plasma samples with comparable results to the corresponding whole blood samples.

Point-of-care testing for emergency assessment of coagulation in patients treated with direct oral anticoagulants

Background

Point-of-care testing (POCT) of coagulation has been proven to be of great value in accelerating emergency treatment. Specific POCT for direct oral anticoagulants (DOAC) is not available, but the effects of DOAC on established POCT have been described. We aimed to determine the diagnostic accuracy of Hemochron® Signature coagulation POCT to qualitatively rule out relevant concentrations of apixaban, rivaroxaban, and dabigatran in real-life patients.

Methods

We enrolled 68 patients receiving apixaban, rivaroxaban, or dabigatran and obtained blood samples at six pre-specified time points. Coagulation testing was performed using prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), and activated clotting time (ACT+ and ACT-low range) POCT cards. For comparison, laboratory-based assays of diluted thrombin time (Hemoclot) and anti-Xa activity were conducted. DOAC concentrations were determined by liquid chromatography-tandem mass spectrometry.

Results

Four hundred and three samples were collected. POCT results of PT/INR and ACT+ correlated with both rivaroxaban and dabigatran concentrations. Insufficient correlation was found for apixaban. Rivaroxaban concentrations at <30 and <100 ng/mL were detected with >95% specificity at PT/INR POCT ≤1.0 and ≤1.1 and ACT+ POCT ≤120 and ≤130 s. Dabigatran concentrations at <30 and <50 ng/mL were detected with >95% specificity at PT/INR POCT ≤1.1 and ≤1.2 and ACT+ POCT ≤100 s.

Conclusions

Hemochron® Signature POCT can be a fast and reliable alternative for guiding emergency treatment during rivaroxaban and dabigatran therapy. It allows the rapid identification of a relevant fraction of patients that can be treated immediately without the need to await the results of much slower laboratory-based coagulation tests.

Trial registration

Unique identifier, NCT02371070. Retrospectively registered on 18 February 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1619-z) contains supplementary material, which is available to authorized users.

Coagulation Management in Jersey Calves: An ex vivo Study

OBJECTIVE

Jersey calves are frequently used as an experimental animal model for in vivo testing of cardiac assist devices or orthopedic implants. In this ex vivo study, we analyzed the coagulation system of the Jersey calves and the potential of human-based coagulation management to circumvent perioperative bleeding complications during surgery. Experimental Procedure: Blood from 7 Jersey calves was subjected to standard laboratory tests and thromboelastometry analysis. An ex vivo model of dilutional coagulopathy was used to study the effects of fibrinogen or prothrombin complex concentrate supplementation. Fibrinolysis was induced with tissue plasminogen activator to identify potential therapeutic strategies involving tranexamic acid or aprotinin. Furthermore, anticoagulation strategies were evaluated by incubating the blood samples with dabigatran or rivaroxaban.

RESULTS

Baseline values for thromboelastometry and standard laboratory parameters, including prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin III, and D-dimers, were established. Fifty percent diluted blood showed a statistically significant impairment of hemostasis. The parameters significantly improved after the administration of fibrinogen or prothrombin complex concentrate. Tranexamic acid and aprotinin ameliorated tissue plasminogen activator-induced fibrinolysis. Both dabigatran and rivaroxaban significantly prolonged the coagulation parameters.

CONCLUSIONS

In this ex vivo study, coagulation factors, factor concentrate, antifibrinolytic reagents, and anticoagulants regularly used in the clinic positively impacted coagulation parameters in Jersey calf blood.

Measuring Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) can be quantified using methods that can be performed in any clinical or research laboratory using manual or automated instrument platforms. Dabigatran etexilate, the oral direct thrombin inhibitor, can be quantified by drug-calibrated clot or chromogenic-based assays using either thrombin or ecarin as substrates. Oral direct anti-Xa inhibitors, such as rivaroxaban, apixaban, and edoxaban, can be quantified with drug-calibrated anti-Xa kits or reagents as typically used for measuring heparins (unfractionated, low molecular weight, or pentasaccharides).

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

METHODS

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

RESULTS

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

CONCLUSION

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

[Vitamin K antagonist, direct oral anticoagulants: Where is the truth?]

Vitamin K antagonists (VKA) and direct oral anticoagulants (DOACs) are now in competition. The companies are trying to replace VKA by DOACs, totally or at least greatly VKA should VKA disappear in favor of DOACs? There are still many questions about DOACs. The purpose of this article is to make a well-considered decision in this area. The aim is not to denigrate one or the other but to share things between these two families of anticoagulants. Physicians using these drugs must have a full knowledge about compared efficacy and safety. We feel necessary to increase distance between effective results of the clinical trials and industrial communication around DOACs.

Safety and efficacy of contemporary catheter ablation for atrial fibrillation patients with a history of cardioembolic stroke in the era of direct oral anticoagulants

BACKGROUND

The safety and efficacy of the contemporary atrial fibrillation (AF) ablation in patients with a recent or previous history of cardioembolic stroke (CS) or transient ischemic attack (TIA) remain to be established.

METHODS

A total of 447 patients who underwent first-ever contact force (CF)-guided AF ablation with circumferential pulmonary vein isolation were included. Of these, 17 had CS or TIA within 6 months before ablation (Group 1), 30 more than 6 months before ablation (Group 2), and the other 400 without CS or TIA (Group 3). Procedural complications and recurrence of AF and atrial tachyarrhythmias were compared among the 3 groups.

RESULTS

The mean age was 71±7, 66±9, and 61±11 years in Groups 1, 2, and 3, respectively (p<0.05, Group 1 versus Group 3). The oral anticoagulants were warfarin (n=108, 24.1%), dabigatran (n=101, 22.6%), rivaroxaban (n=147, 32.9%), apixaban (n=87, 19.5%), and edoxaban (n=4, 0.9%), and did not differ among the 3 groups. Median follow-up period was 14 [IQR 12-22], 13 [12-14], and 12 [10-16] months, respectively. One episode of cardiac tamponade, 2 episodes of arteriovenous fistula, and some minor complications occurred in Group 3, but no complications occurred in Groups 1 and 2 in the periprocedural period. Although one episode of CS occurred 11 days after the procedure in Group 3, there were no periprocedural CS, TIA, or major bleedings in Groups 1 and 2. AF recurrence-free rate after the procedure was 76.5%, 86.7%, and 79.1% in Groups 1, 2, and 3, respectively, and there was no difference in Kaplan-Meier curves among the 3 groups.

CONCLUSION

The safety and efficacy of CF-guided AF ablation in the era of direct oral anticoagulants in patients with a recent or previous history of CS or TIA are similar to those in patients without it.

Bleeding with Direct Oral Anticoagulants vs Warfarin: Clinical Experience

The risk of bleeding in the setting of anticoagulant therapy continues to be re-evaluated following the introduction of a new generation of direct oral anticoagulants (DOACs). Interruption of DOAC therapy and supportive care may be sufficient for the management of patients who present with mild or moderate bleeding, but in those with life-threatening bleeding, a specific reversal agent is desirable. We review the phase 3 clinical studies of dabigatran, rivaroxaban, apixaban, and edoxaban in patients with nonvalvular atrial fibrillation, in the context of bleeding risk and management.

Idarucizumab, a Specific Reversal Agent for Dabigatran: Mode of Action, Pharmacokinetics and Pharmacodynamics, and Safety and Efficacy in Phase 1 Subjects

The direct oral anticoagulants (DOACs) provide a number of clinical advantages over vitamin K antagonists for the treatment of thromboembolism, including improved efficacy and safety, as well as no need for regular monitoring of anticoagulant effect. However, as with all anticoagulants, bleeding complications may occur, and anticoagulant reversal may be required in specific clinical situations, such as in patients experiencing spontaneous or traumatic bleeds, or in anticoagulated patients requiring emergency surgery or other invasive procedures. Therefore, several reversal agents for the DOACs are in development. This includes the specific reversal agent idarucizumab, which has been approved by the U.S. Food and Drug Administration and the European Medicines Agency for use in patients treated with dabigatran when urgent reversal of its anticoagulant effects is needed. Idarucizumab is a humanized monoclonal antibody fragment that binds with high affinity to free and thrombin-bound dabigatran, resulting in an almost irreversibly bound idarucizumab-dabigatran complex and thereby neutralizing dabigatran's anticoagulant activity. The reversal of the anticoagulant effects of dabigatran by idarucizumab has been demonstrated in animal bleeding models, in healthy volunteers with a range of ages and renal function, and in anticoagulated patients. In the phase 1 trials, at doses of 2 g or greater, idarucizumab resulted in immediate and complete reversal of the dabigatran anticoagulant effects and was well tolerated. In the absence of dabigatran, idarucizumab showed no effect on coagulation parameters or thrombin formation. These findings provide initial evidence that idarucizumab could provide a safe and effective means of reversing anticoagulant activity in patients treated with dabigatran in need of emergency surgery or in emergency bleeding situations.

Idarucizumab and Factor Xa Reversal Agents: Role in Hospital Guidelines and Protocols

As expected with all antithrombotic agents, there is a risk of bleeding complications in patients receiving direct oral anticoagulants (DOACs) because of the DOAC itself, acute trauma, invasive procedures, or underlying comorbidities. For many bleeding events, a prudent course of action will be to withdraw the DOAC, then "wait and support" the patient, with the expectation that the bleeding event should resolve with time. Likewise, DOAC therapy may be interrupted ahead of a planned procedure, the stopping time being dependent on the agent involved and the patient's renal function. However, urgent reversal of anticoagulation is required in patients with serious or life-threatening bleeding or in those requiring urgent surgery or procedures. Novel specific reversal agents, either under development or recently approved, will need to be incorporated into local anticoagulation reversal protocols. For dabigatran-treated patients, idarucizumab recently has been approved for clinical use in cases of life-threatening or uncontrolled bleeding or when patients require emergency surgery or urgent procedures, both associated with a high risk of bleeding. As clinical experience with individual specific reversal agents grows, their roles in managing major bleeding events in DOAC-treated patients will become better defined. Future research, as well as ongoing use of idarucizumab, should help establish when it is appropriate to re-dose with idarucizumab, co-administer with prothrombin complex concentrates, or re-initiate DOAC after idarucizumab use. Ongoing trials should help identify the appropriate doses and expected durations of effect for andexanet alfa and ciraparantag, which are likely to vary depending on the individual oral anticoagulants.

Safety of Direct Oral Anticoagulants: Insights from Postmarketing Studies

Direct oral anticoagulants (DOACs) have been marketed in the United States since 2010. While numerous large-scale prospective phase 3 outcomes studies have documented the effectiveness of DOACs for the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation, the primary safety concern with all of these drugs-as it is with the more established oral anticoagulant warfarin-is the risk of major bleeding. Postmarketing surveillance studies (PMSS) provide the opportunity to evaluate the safety of these recently approved drugs across a spectrum of patients that may be broader than those included in randomized controlled trials. This review will summarize the safety findings of numerous recently performed, large-scale PMSS evaluations, and consider the currently available evidence regarding the risks for bleeding in patients treated with DOACs, in order to give providers and patients additional evidence regarding the safety of DOACs.

[Use of non-vitamin K antagonist oral anticoagulants in Primary Care: ACTUA study]

OBJECTIVES

Approximately 40% of patients with non-valvular auricular fibrillation (NVAF) who receive vitamin K antagonists (VKA) in Primary Care in Spain have poor anticoagulation control. The objective of the study Actuación en antiCoagulación, Tratamiento y Uso de anticoagulantes orales de acción directa (ACOD) en Atención primaria (ACTUA) (Action in Coagulation, Treatment and Use of direct oral anticoagulants [DOACs]) in Primary Care) was to analyse the current situation regarding the use of VKA and non-vitamin K antagonist oral anticoagulants (NOACs) in patients with NVAF in Primary Care in Spain and the possible issues arising from it.

PATIENTS AND METHODS

An online survey was created covering various aspects of the use of oral anticoagulants in NAFV. A two-round modified Delphi approach was used. Results were compiled as a set of practical guidelines.

RESULTS

Forty-four experts responded to the survey. Consensus was reached in 62% (37/60) of the items. Experts concluded that a considerable number of patients with NVAF who receive VKA do not have a well-controlled INR and that a substantial group of patients who could benefit from being treated with NOACs do not receive them. The use of NOACs increases the probability of having good anticoagulation control and decreases the risk of severe and intracranial haemorrhage. Current limitations to the use of NOACs include administrative barriers, insufficient knowledge about the benefits and risks of NOACs, limited experience of doctors in using them, and their price. Renal insufficiency influences the choice of a particular anticoagulant.

CONCLUSIONS

The ACTUA study highlights the existing controversies about the use of oral anticoagulants for the treatment of NVAF in Primary Care in Spain, and provides consensus recommendations that may help to improve the use of these medications.

Sensitivity of routine coagulation assays to direct oral anticoagulants: patient samples versus commercial drug-specific calibrators

Most studies on the sensitivities of coagulation assays to direct oral anticoagulants (DOACs) are based on normal plasma spiked with anticoagulant in the laboratory. Recent studies have shown that reagent sensitivity varies significantly depending on whether spiked or patient samples are used. The aim of this study was to compare the sensitivities of routine coagulation assays in patient samples and commercial drug specific calibrators using commonly used activated partial thromboplastin time (APTT) and prothrombin time (PT) reagents (i.e., Actin FS and Neoplastine CI Plus for APTT and PT, respectively) in Australian laboratories. Samples collected at Pathology North Hunter (PN-H) for dabigatran (n=39), rivaroxaban, (n=56) or apixaban levels (n=22) between February 2013 and November 2015 were analysed and compared to two different commercial drug specific calibrators from different manufacturers for each DOAC. Our results show that dabigatran (Hyphen and Technoclone) and rivaroxaban (Stago) calibrators tend to overestimate the APTT but are similar to patient samples for PT. A cut-off DOAC level of 50 ng/mL based on results from patient samples within the laboratory can be used as the lower limit which will result in prolongation of APTT for dabigatran (sensitivity 96%, n=25) and PT for rivaroxaban (sensitivity 97%, n=29), respectively. Individual laboratories should be familiar with the sensitivity of their coagulation reagents to different DOACs including differences between patient samples versus different commercial drug specific calibrators.

Major bleeding complications in patients treated with direct oral anticoagulants: One-year observational study in a Paris Hospital

Direct oral anticoagulants (DAOC) are indicated for the treatment of venous thromboembolism and the prevention of stroke or systemic embolism in patients with non-valvular atrial fibrillation. Given their advantages and friendly use for patient, the prescription of long term DOAC therapy has rapidly increased both as first line treatment while initiating anticoagulation and as a substitute to vitamins K antagonist (VKA) in poorly controlled patients. However, DOAC therapy can also be associated with significant bleeding complications, and in the absence of specific antidote at disposal, treatment of serious hemorrhagic complications under DOAC remains complex. We report and discuss herein five cases of major hemorrhagic complications under DOAC, which were reported to the pharmacological surveillance department over one year at Saint-Louis University Hospital (Paris, France). We further discuss the need for careful assessment of the risk/benefit ratio at time of starting DOAC therapy in daily clinical practice.

Management of venous thromboembolism: an update

Venous thromboembolism (VTE), which constitutes pulmonary embolism and deep vein thrombosis, is a common disorder associated with significant morbidity and mortality. Landmark trials have shown that direct oral anticoagulants (DOACs) are as effective as conventional anticoagulation with vitamin K antagonists (VKA) in prevention of VTE recurrence and associated with less bleeding. This has paved the way for the recently published guidelines to change their recommendations in favor of DOACs in acute and long-term treatment of VTE in patients without cancer. The recommended treatment of VTE in cancer patients remains low-molecular-weight heparin. The initial management of pulmonary embolism (PE) should be directed based on established risk stratification scores. Thrombolysis is an available option for patients with hemodynamically significant PE. Recent data suggests that low-risk patients with acute PE can safely be treated as outpatients if home circumstances are adequate. There is lack of support for use of inferior vena cava filters in patients on anticoagulation. This review describes the acute, long-term, and extended treatment of VTE and recent evidence on the management of sub-segmental PE.

Safety ad efficacy of direct oral anticoagulants for extended treatment of venous thromboembolism

Currently available anticoagulants have limitations for long-term treatment of venous thromboembolism (VTE). We have evaluated the efficacy and safety of direct oral anticoagulants (DOACs) for extended treatment of VTE. Four randomized controlled trials (RCTs) comparing DOACs (apixaban, rivaroxaban, and dabigatran) with placebo or warfarin for extended treatment of VTE were published. Primary efficacy outcome was recurrent VTE or VTE-related death, and primary safety outcome was major bleeding. DOACs significantly lower the risk of recurrent VTE or VTE-related death compared to placebo/warfarin, as well as all-cause mortality. Risk of major bleeding is not different with DOACs compared to placebo/warfarin. However, DOACs are associated with a significantly higher rate of the composite of major and clinically relevant bleeding compared to placebo. In conclusion, DOACs are effective and safe for the extended treatment of VTE, and may reduce the risk of all-cause mortality.

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.

Management of direct oral anticoagulants in patients undergoing elective surgeries and invasive procedures: Updated guidelines from the French Working Group on Perioperative Hemostasis (GIHP) - September 2015

Since 2011, data on patients exposed to direct oral anticoagulants (DOAs) while undergoing invasive procedures have accumulated. At the same time, an increased hemorrhagic risk during perioperative bridging anticoagulation without thrombotic risk reduction has been demonstrated. This has led the GIHP to update their guidelines published in 2011. For scheduled procedures at low bleeding risk, it is suggested that patients interrupt DOAs the night before irrespective of type of drug and to resume therapy six hours or more after the end of the invasive procedure. For invasive procedures at high bleeding risk, it is suggested to interrupt rivaroxaban, apixaban and edoxaban three days before. Dabigatran should be interrupted according to the renal function, four days and five days if creatinine clearance is higher than 50mL/min and between 30 and 50mL/min, respectively. For invasive procedures at very high bleeding risk such as intracranial neurosurgery or neuraxial anesthesia, longer interruption times are suggested. Finally, bridging with parenteral anticoagulation and measurement of DOA concentrations can no longer routinely be used.

Reversal agents for direct oral anticoagulants: A focused review

For several decades the vitamin K antagonist oral anticoagulants were the only outpatient therapy that existed to reduce the risk of stroke and thromboembolism. When the new direct oral anticoagulants were approved for use and addressed many of the issues associated with oral vitamin K antagonists, a new concern arose-the lack of rapid ability to reverse these agents. Physicians and patients were concerned that in cases of life-threatening bleeding or need for emergent surgery, an antidote to reverse the anticoagulation effect of these agents did not exist. Contemporary research has aimed to produce reversal agents that can be administered to safely neutralize the anticoagulant effect. In this focused review we describe the clinical development as well as mechanisms of action of three agents (idarucizumab, andexanet alpha, and ciraparantag). We review the pharmacokinetics, animal and human study data of these reversal agents and outline the evidence supporting their use. Although questions of safety and appropriate use remain, these reversal agents offer a significant step forward in the widespread use of direct oral anticoagulants and overall management of the anticoagulant effect.

Medication Error When Switching from Warfarin to Rivaroxaban Leading to Spontaneous Large Ecchymosis of the Abdominal and Chest Wall

Non-vitamin K oral anticoagulant (NOAC) therapy may be inappropriate if prescription was incorrect, the patient’s physiological parameters change, or interacting concomitant medications are erroneously added. The aim of this report was to illustrate inappropriate NOAC prescription in a 78-year-old woman with non-valvular atrial fibrillation and borderline renal dysfunction who was switched from warfarin to rivaroxaban and subsequently developed bruising with hemorrhagic shock and acute on chronic renal failure. Administration of 4-factor prothrombin complex concentrate effectively reversed coagulopathy and stopped bleeding. Retrospective determination of circulating plasma levels of rivaroxaban and warfarin confirmed that excessive anticoagulation was likely due to warfarin that the patient probably continued to take although rivaroxaban was initiated. Pharmacodynamic interaction between rivaroxaban and warfarin may not only be additive but synergistic. In patients at high risk of complications, judicious prescribing and dosing of NOACs, and regular monitoring of concomitant medications and renal function are highly recommended.

Pharmacologic Therapies in Anticoagulation

Anticoagulants are beneficial for prevention and treatment of venous thromboembolism and stroke prevention in atrial fibrillation. The development of target-specific oral anticoagulants is changing the landscape of anticoagulation therapy and created growing interest on this subject. Understanding the pharmacology of different anticoagulants is the first step to adequately treat patients with best available therapy while avoiding serious bleeding complications. This article reviews the pharmacology of the main anticoagulant classes (vitamin K antagonists, direct oral anticoagulants, and heparins) and their clinical indications based on evidence-based data currently available in the literature.

Efficacy and Safety of Rivaroxaban in Patients with Venous Thromboembolism and Active Malignancy: A Single-Center Registry

OBJECTIVE

The purpose of this study is to evaluate the efficacy and safety of rivaroxaban in patients with venous thromboembolism and active malignancy, given the paucity of clinical data with the use of direct Xa inhibitors in this high-risk population.

PATIENTS AND METHODS

Consecutive patients treated with rivaroxaban for deep vein thrombosis or pulmonary embolism, enrolled into Mayo Thrombophilia Clinic Direct Oral Anticoagulants Registry between March 1, 2013, and April 30, 2015, were followed prospectively to evaluate the efficacy and safety of this therapy.

RESULTS

Of the 404 venous thromboembolism patients in the registry, 296 received rivaroxaban and had at least 3 months of follow-up. Of these, 118 (40%) had active malignancy (51% female, mean age 66 ± 10 years) and 178 had no cancer (47% female, mean age 55 ± 15 years). The 3 most common cancer locations were genitourinary (23.6%), gastrointestinal (20.3%), and lung (13.5%). There was no difference in venous thromboembolism recurrence between the malignant (3.3%) and the nonmalignant (2.8%) venous thromboembolism groups (P = .533). Borderline higher rates for major bleeding (P = .06) and nonmajor clinically relevant bleeding (P = .08) were observed in patients with cancer.

CONCLUSIONS

The "real world" effectiveness and safety of rivaroxaban is similar for venous thromboembolism patients with and without active malignancy.

Direct Oral Anticoagulants in Cirrhosis

OPINION STATEMENT

The risk of thrombosis in patients with chronic liver disease is increasingly recognized. As patients with cirrhosis develop indications for anticoagulation therapy (e.g., venous thromboembolism, portal vein thrombosis, or atrial fibrillation), providers are left to make difficult decisions when selecting therapeutics with little evidence to rely on. Current practice supports the use of low molecular weight heparin or vitamin K antagonists in select patients with cirrhosis requiring anticoagulation. While traditional anticoagulants may be safe and effective in select patients with compensated cirrhosis, the use of direct oral anticoagulants (DOAC) is more controversial. DOAC are desirable as they do not require routine monitoring and can be taken orally. Unfortunately, patients with chronic liver disease were excluded from clinical trials that demonstrated efficacy and safety when compared to traditional anticoagulation. Data are now emerging that support the use of DOAC in well-compensated cirrhosis patients. However, further study is needed with all (traditional and DOAC) anticoagulation medications in patients with cirrhosis to better ensure safety and further understand pharmacologic properties in this challenging population.

The Role of New Oral Anticoagulants (NOACs) in Cancer Patients

New oral anticoagulants (NOACs) are likely to have a major impact in the next few years, changing clinical practice of anticoagulation therapy. Evidence on its efficacy and superiority to vitamin K antagonists (VKAs) in treating non-cancer patients have been reported in a few clinical trials. However, patients with cancer are complicated by the prothrombotic nature of the disease, need for potentially invasive surgery and interventions, and altered drug handling. This chapter examines the available evidence and guidelines on the use of NOAC in patients with cancer.

An early evaluation of bleeding-related hospital readmissions among hospitalized patients with nonvalvular atrial fibrillation treated with direct oral anticoagulants

OBJECTIVE

Clinical trials have demonstrated that direct oral anticoagulants (DOACs) are efficacious in reducing stroke risk among patients with nonvalvular atrial fibrillation (NVAF) with differences in the reduction of bleeding risks vs. warfarin. The objective of this study was to assess bleeding-related hospital readmissions among hospitalized NVAF patients treated with dabigatran, rivaroxaban, and apixaban in the US.

RESEARCH DESIGN AND METHODS

Patients (≥18 years) with a discharge diagnosis of NVAF who received apixaban, dabigatran, or rivaroxaban during hospitalization were identified from the Premier Hospital database (1 January 2012-31 March 2014) and the Cerner Health Facts hospital database (1 January 2012-31 August 2014). Patients identified from each database were analyzed separately and grouped into three cohorts depending on which DOAC was received. Patient characteristics, hospital resource use and costs, and frequency of readmissions within 1 month were evaluated.

RESULTS

Among study populations identified from the Premier database (N = 74,730) and the Cerner database (N = 14,201), patients who received apixaban were older, had greater comorbidity, and had higher stroke and bleeding risks. After controlling for patient characteristics, including comorbidity and stroke and bleeding risks, compared with patients who received apixaban during their index hospitalizations, the odds of bleeding-related hospital readmissions were significantly greater by 1.4-fold (p < 0.01) for patients who received rivaroxaban and 1.2-fold (p = 0.16) numerically greater for patients who received dabigatran among patients identified from the Premier Hospital database. Among patients in the Cerner Health Facts hospital database, bleeding-related hospital readmissions were significantly greater by 1.6-fold (p = 0.04) for patients who received rivaroxaban and 1.3-fold (p = 0.30) numerically greater for patients who received dabigatran compared to patients who received apixaban.

LIMITATIONS

No causal relationship between treatment and outcomes can be concluded.

CONCLUSIONS

NVAF patients using different DOACs had different characteristics, including stroke and bleeding risks. Use of rivaroxaban, compared to apixaban was associated with significantly greater risk of bleeding-related readmissions across two database claims analyses.

Thrombin generation and other coagulation parameters in a patient with homozygous congenital protein S deficiency on treatment with rivaroxaban

Rivaroxaban, which targets factor Xa and does not reduce proteins C/S, was chosen to treat a 6-year-old girl with homozygous protein S (PS) deficiency who developed skin necrosis while on warfarin. Owing to the lack of experience with rivaroxaban in children, the girl was started with 5 mg once-daily, which was gradually increased to 40 mg daily. The increasing dosage was driven by the need to avoid recurrence of skin necrosis. During dose-escalation, four pharmacokinetics assays were carried out measuring drug plasma concentrations and their effect on hemostatic parameters. We report the laboratory work-up, with special reference to parameters of thrombin-generation. Rivaroxaban concentrations by HPLC were correlated with those by the anti-factor Xa assay (r(2) = 0.92, p < 0.01), but there was an overestimation by HPLC. Thrombin-generation parameters, such as the area under the curve (referred to as ETP), peak-thrombin, and velocity-index, when measured after addition of thrombomodulin, showed unexpected changes: ETP decreased, but peak-thrombin and velocity-index increased. Similar patterns were obtained in a PS-depleted plasma and in plasma from patients with heterozygous PS deficiency, but not in plasma from controls. In conclusion, these preliminary results suggest that PS may be a determinant of velocity and peak-thrombin, but not of the total amount of thrombin generated.

Current and developing strategies for monitoring and reversing direct oral anticoagulants in patients with non-valvular atrial fibrillation

OBJECTIVE

In light of the increasing clinical utilization of the direct oral anticoagulants (DOACs) among patients with non-valvular atrial fibrillation, this review evaluates strategies for monitoring and reversing the anticoagulant effect of these agents.

METHODS

We summarize the data currently available for laboratory monitoring and reversal of DOACs. Relevant literature was identified using search terms pertaining to oral anticoagulants, reversal agents, and laboratory monitoring using Pubmed, clinicaltrials.gov, and abstracts from recent major cardiovascular meetings.

RESULTS

Significant user appeal for the DOACs stems from the reliable pharmacokinetics of these agents, which render routine laboratory monitoring unnecessary for general use, as well as lower rates of bleeding as compared to warfarin. However, readily available laboratory tests have not been clinically validated for use with these agents. The ability to measure the anticoagulant effect of a DOAC in selected situations (e.g. serious bleeding, overanticoagulation, emergent procedures, and compliance monitoring) remains an unmet clinical need. Further, there is a paucity of data to guide treatment in patients receiving DOACs who experience a serious hemorrhage.

CONCLUSION

While evidence-based recommendations cannot be definitively provided for management of DOAC-related bleeding events at present, several targeted reversal agents are currently in development, and hold promise for solving this important clinical problem.

[Management of new oral anticoagulants in gastrointestinal bleeding and endoscopy]

New oral direct anticoagulants agents are alternatives to warfarin for long-term anticoagulation in a growing number of patients that require long-term anticoagulation for atrial fibrillation, deep venous thrombosis and pulmonary embolism. These new agents with predictable pharmacokinetic and pharmacodynamics profiles offer a favorable global safety profile, but increased gastrointestinal bleeding compared to the vitamin K antagonists. Many gastroenterologists are unfamiliar and may be wary of these newer drugs, since Clinical experience is limited and no specific antidote is available to reverse their anticoagulant effect. In this article the risk of these new agents and, how to manage these agents in both the presence of acute gastrointestinal bleeding and in patients undergoing endoscopic procedures is reviewed.

Efficacy and safety of direct oral anticoagulants in patients undergoing cardioversion for atrial fibrillation: A systematic review and meta-analysis of the literature

BACKGROUND

DOACs are increasingly used in patients with NVAF. Information on efficacy and safety of these compounds in patients undergoing electrical or pharmacological cardioversion is limited. Thus, we performed a systematic review and a meta-analysis of the literature to address this issue.

METHODS

Randomized controlled trials comparing the efficacy and safety of DOACs and VKAs in patients with NVAF were systematically searched in Medline, Web of Science, Scopus, Cochrane, and EMBASE databases (up to September 2014). Pooled relative risk (RR) and the corresponding 95% confidence interval (CI) were calculated for each outcome.

RESULTS

Four randomized controlled trials (3635 patients), for a total of 4517 cardioversions (2869 with DOACs and 1648 with VKAs), were included in the analysis. DOACs and VKAs appeared equally effective in the prevention of stroke/systemic embolism (0.41% vs 0.61%; RR: 0.73, 95% CI: 0.31, 1.72; P=0.48) and of post-cardiovascular death (0.52% vs 0.81%; RR: 0.73, 95% CI: 0.27, 2.03; P=0.55), with a similar risk of major bleeding complications (0.81% vs 0.60%; RR: 1.23, 95% CI: 0.55, 2.71). Heterogeneity among studies was generally absent. Furthermore, the Weighted Mean Incidence (WMI) of complications appeared very low in patients randomized to DOACs (WMI: 0.6% and 0.9% for stroke/systemic embolism and major bleeding, respectively).

CONCLUSION

Our results suggest that DOACs are at least as effective and safe as VKAs in patients with NVAF undergoing to an electrical or pharmacological cardioversion. Thus, DOACs may be considered a valid and practical alternative to VKAs.

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

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

Effect of body weight on efficacy and safety of direct oral anticoagulants in the treatment of patients with acute venous thromboembolism: a meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the effect of body weight (BW) on safety and efficacy of direct oral anticoagulants (DOACs).

METHODS

We performed a meta-analysis of randomized controlled trials (RCTs) comparing DOACs with vitamin K antagonists (VKA) in patients with venous thromboembolism (VTE). Efficacy (prevention of recurrent VTE or VTE-related death) and safety (occurrence of major or clinically relevant non-major bleeding) outcomes were stratified according to patients' BW (low, normal, and high).

RESULTS

Six RCTs with a total of 27,023 patients were included. DOACs showed a similar efficacy to VKA in patients with high BW, normal BW, and low BW (RR 0.98, 95% CI 0.72, 1.35; RR 0.91, 95% CI 0.75, 1.09; and RR 0.84, 95% CI 0.57, 1.24, respectively). Safety was comparable among DOACs and VKA in patients with high BW and low BW (RR 0.93, 95% CI 0.65, 1.32; and RR 0.80, 95% CI 0.54, 1.20), whereas DOACs were marginally safer than VKA in normal-BW subjects (RR 0.82, 95% CI 0.67, 1.00). However, the difference among DOACs and VKA in the rate of bleeding episodes appeared similar in the three BW groups.

CONCLUSIONS

Results of our meta-analysis suggested that DOACs might be a safe and effective therapeutic option for the treatment of acute VTE even in the patients with extreme body weights. However, other studies with larger study populations are warranted to confirm our findings.

[Proper use of apixaban: an outline for clinical practice]

Apixaban is a direct inhibitor of coagulation factor Xa. Superior efficacy over aspirin and antivitamin K has been shown in the prevention of stroke and systemic embolism during non-valvular atrial fibrillation with a more favorable safety profile, even though the risk of hemorrhage cannot be ignored, considering its mechanism of action. The recommended dose is 5mg twice daily which can be reduced to 2.5mg depending on the individual risk. Apixaban is also indicated for the treatment of venous thromboembolism but reimbursement has not yet been accepted in France for this indication. As with all direct oral anticoagulants, no routine biological monitoring is required, nevertheless their use may have an impact on all coagulation tests, eventually hampering interpretation. In particular clinical circumstances where a measure of anticoagulant efficacy is deemed necessary, specific assay of anti-Xa activity is appropriate, the result being expressed as concentration of the anticoagulant used. It is therefore necessary to state the name of the medicine for which the assay is requested. With these new anticoagulants, management of hemorrhagic events can be more difficult due to the lack of a specific antidote. Pro-hemostatic substances have exhibited efficacy in animal models but results are still insufficiently documented in clinical practice. Local or locoregional hemostasis measurements, when possible, are an essential factor in the treatment of hemorrhagic events.

Failure of dabigatran and rivaroxaban to prevent thromboembolism in antiphospholipid syndrome: a case series of three patients

Direct oral factor inhibitors (DOFIs) are an attractive alternative to vitamin K antagonists (VKA) for the treatment of patients with antiphospholipid syndrome (APS). In the absence of prospective, randomised trial data, reports of therapeutic failures in clinical practice alert clinicians to potential limitations of DOFI therapy for this indication. Data for all cases were collected from a centralised system that contains complete medical records of all patients treated and followed at Mayo Medical Center. We present here three consecutive APS patients who had had no thromboembolism recurrence on warfarin but were switched to DOFIs. The diagnosis of APS was established according to currently recommended criteria. The three cases were as follows: A woman with primary APS developed thrombotic endocarditis with symptomatic cerebral emboli after transition to dabigatran. A second woman with primary APS experienced ischemic arterial strokes and right transverse-sigmoid sinus thrombosis after conversion to rivaroxaban. A man with secondary APS suffered porto-mesenteric venous thrombosis after switching to rivaroxaban. None of these patients had failed warfarin prior to the transition to DOFIs. Based on these three cases, we advocate caution in using DOFIs for APS patients outside of a clinical trial setting, until further data becomes available.