Antithrombotic Treatment in Patients With Hemophilia: an EHA-ISTH-EAHAD-ESO Clinical Practice Guidance

Haemophilia Prophylaxis in the Age of Innovation: Exploring Opportunities for Personalized Treatment

INTRODUCTION

Recent advancements in haemophilia treatment have introduced a range of innovative therapies, including activated FVIII mimetics, ultra-extended half-life recombinant FVIII, rebalancing agents and gene therapy. These developments have transformed treatment options and expanded prophylaxis strategies.

AIM

This article reviews key criteria and personalization strategies for the optimization of prophylaxis, tailored to the unique needs of each haemophilia patient on an individual basis.

DISCUSSION AND CONCLUSION

Although these new therapies offer significant promise in controlling bleeding and enhancing quality of life, challenges such as variable efficacy, potential long-term risks and high costs remain. Additionally, the absence of validated surrogate markers for non-factor therapies limits their optimal use in clinical settings. The primary goal of haemophilia care is to provide optimal personalized treatment that enables patients to lead unrestricted lives. However, the introduction of these novel treatments necessitates a shift in treatment paradigms and the development of improved evaluation tools for better personalization. Choosing the most appropriate treatment requires careful clinical follow-up, taking into account patient preferences, disease burden, and individual and environmental factors that affect patients' lives. Ongoing research and real-world studies are essential to assess long-term efficacy and safety. In addition, improving educational resources-such as digital platforms, virtual reality tools and personalized educational materials tailored to patients' life goals-and effective patient engagement strategies will be critical to achieving successful treatment personalization and adherence.

Antithrombotic Therapy in People with Hemophilia-A Narrative Review

As the life expectancy of individuals with hemophilia continues to increase, the complexity of balancing bleeding risks and thrombotic management has become increasingly critical in people with hemophilia with or at a high risk of thrombosis. Advances in hemophilia therapies such as extended half-life coagulation factors, non-factor therapies, rebalancing agents, and gene therapy have expanded treatment options for a variety of people with hemophilia. The thrombotic risk of people with hemophilia in general are relatively low as compared to those without hemophilia. However, antithrombotic therapy for prevention and treatment for thrombosis should still be considered in some situations, even in hemophilia. This clinical focus highlights the use of antithrombotic therapy in the management of thrombosis in people with hemophilia. A multidisciplinary, personalized approach is essential for optimizing the safety and efficacy of antithrombotic therapy in people with hemophilia with or at a high risk of thrombosis. High performance computer based multidimensional data analysis may help in establishing the personalized antithrombotic therapy in the future.

How I treat quantitative fibrinogen disorders

ABSTRACT

Quantitative fibrinogen disorders, including afibrinogenemia and hypofibrinogenemia, are defined by the complete absence or reduction of fibrinogen, respectively. The diagnosis is based on the measurement of fibrinogen activity and antigen levels, which define the severity of this monogenic disorder. Afibrinogenemia is the result of homozygosity or combined heterozygosity for the causative mutations, whereas monoallelic mutations lead to hypofibrinogenemia. The bleeding phenotype varies in accordance with fibrinogen levels, ranging generally from frequent and often life-threatening bleeding in afibrinogenemia to the absence of symptoms, or mild bleeding symptoms in mild hypofibrinogenemia. The main treatment for quantitative fibrinogen disorders is fibrinogen supplementation. Despite low fibrinogen levels, a tendency for thrombosis is a characteristic of these disorders and may be exacerbated by fibrinogen supplementation. The management of surgery and pregnancy presents significant challenges regarding the amount of fibrinogen replacement and the need for thromboprophylaxis. The objective of this article is to present 4 clinical scenarios that illustrate common clinical challenges and to propose strategies for managing bleeding, thrombosis, surgery, and pregnancy.

Emerging Therapies in Hemophilia: Improving Equitable Access to Care

In recent years, gene therapy and bio-engineered hemostatic molecules have revolutionized treatment for people with hemophilia. These innovative therapies aim to decrease treatment burden and improve patient quality of life. Additional novel therapies, including next-generation mimetics and agents that rebalance hemostasis, are currently being evaluated in clinical trials. Technological advances such as point-of-care musculoskeletal ultrasound and artificial intelligence may improve patient diagnostic and treatment outcomes. However, for the majority of patients with hemophilia worldwide, diagnosis and effective treatment are inaccessible. Achieving health equity for all hemophilia patients requires improved identification of barriers to optimal care, including socioeconomic status, race/ethnicity, gender, disease severity, inhibitor status, age, and use of Hemophilia Treatment Centers. Access to novel hemophilia therapies should be ensured for all patients. Approaches to improving equity include a decision-making partnership between the patient and clinician, stakeholder engagement, and pharmaceutical industry support. The development of novel hemophilia therapies should be leveraged with a patient-centered care approach to improve health equity for all patients.

Use of antithrombotic therapy in patients with hemophilia: a selected synopsis of the European Hematology Association - International Society on Thrombosis and Haemostasis - European Association for Hemophilia and Allied Disorders - European Stroke Organization Clinical Practice Guidance document

Here, we summarize the European Hematology Association - International Society on Thrombosis and Haemostasis - European Association for Hemophilia and Allied Disorders - European Stroke Organization Clinical Practice Guidance document recommendations on antithrombotic therapy for cardiovascular indications among patients with hemophilia. This summary includes a discussion on primary and secondary prevention of venous and arterial thrombosis. The guidance document considers distinct and controversial challenges presented by various clinical scenarios in this aging patient population and provides thoughtful recommendations to assist the hemophilia care provider in clinical decision-making.

Clots and bleeds: the outcomes of percutaneous coronary intervention in hemophilia patients with acute coronary syndrome

BACKGROUND

Hemophilia is a disease characterized by a high risk of bleeding. With advances in treatment, life expectancy and aging-associated diseases such as coronary artery disease have increased. Our primary objective is to assess for major adverse outcomes, mortality, and length of hospital stay in individuals with hemophilia presenting for acute coronary syndrome (ACS) and undergoing percutaneous coronary intervention (PCI).

METHODS

Our retrospective cohort study analyzed data from the Nationwide Inpatient Sample Database (NIS) for 2018 to investigate the outcomes of ACS management with PCI in adults with and without hemophilia. We used ICD-10 codes to exclude patients with significant comorbidities and identify those with ACS undergoing PCI. Propensity score matching and multivariable logistic regression were employed to account for over 20 baseline characteristics, mitigating confounding factors.

RESULTS

The incidence of gastrointestinal bleeding (11.0% vs. 2.8%, p < 0.001), hemorrhagic stroke (10.0% vs. 1.4%, p < 0.001), and retroperitoneal hemorrhage (5.6% vs. 1.4%, p < 0.001) was significantly higher in individuals with hemophilia undergoing PCI compared to those without hemophilia. Additionally, venous thromboembolism (VTE) incidence was notably higher in the hemophilia cohort (6.6% vs. 2.4%, p = 0.027). The hemophilia cohort also experienced a higher mortality rate (7.1% vs. 3.3%, p = 0.037) and longer hospital stays.

CONCLUSION

Patients with hemophilia undergoing PCI are at a significantly greater risk of adverse events, increased mortality, and longer hospital stays than the general population. To mitigate the risk of unfavorable outcomes, it is crucial to ensure adequate replenishment of coagulation factors and establish close collaboration between cardiologists and hematologists.

Comparison of the effects on coagulation function and safety of bivalirudin and heparin in patients undergoing percutaneous coronary intervention: A randomized trial

BACKGROUND

To analyze the effects on coagulation function and safety of bivalirudin and heparin in patients undergoing percutaneous coronary intervention (PCI) and provide clinical evidence for their application.

METHODS

A total of 42 patients with coronary heart disease undergoing PCI treatment from July 2019 to January 2022 at Datong Third People's Hospital in China were divided into 2 groups: the bivalirudin group and the heparin group. The former received perioperative administration of bivalirudin, while the latter received heparin. After 24 hours of treatment, blood indicators, coagulation functions, as well as cardiac, hepatic, and renal markers were evaluated. Additionally, Thrombolysis In Myocardial Infarction (TIMI) flow graded infarct-related vessel blood flow was assessed in both groups. Adverse cardiovascular and cerebrovascular events were monitored for a duration of 12 months.

RESULTS

The Activated clotting time (ACT), D-dimer (D-D), and prothrombin time (PT) levels in the bivalirudin group were significantly lower than those in the heparin group (P < .05). Both the bivalirudin and heparin groups showed significant improvement in TIMI flow grade after PCI (P < .05). The levels of Creatine Kinase-MB (CK-MB), N-terminal Pro-B-type Natriuretic Peptide (NT-proBNP) in the bivalirudin group were significantly lower than those in the heparin group (P < .05). There were no serious adverse cardiovascular and cerebrovascular events in either group.

CONCLUSION

Bivalirudin has a slightly superior impact on coagulation function and safety profile in patients undergoing PCI compared to heparin, and the preventive effect of both on postoperative cardiovascular events is similar.

Expert Opinion for Defining a Severe Bleeding Phenotype to Guide Prophylaxis in Patients with Nonsevere Hemophilia

Prophylaxis is the standard of care for patients with severe hemophilia, patients with moderate hemophilia, or those with another congenital bleeding disorder that is associated with a severe bleeding phenotype and/or a high risk of spontaneous life-threatening bleeding. Patients with nonsevere hemophilia (factor VIII [FVIII] ≥ 1%) may also have a bleeding phenotype that requires prophylaxis. To date, however, there are no clear criteria as to when prophylaxis is indicated in these patients. Also, the term "severe bleeding phenotype (SBPT)" is neither included in the definitions of the International Society on Thrombosis and Haemostasis (ISTH) nor specified in the World Federation of Hemophilia (WFH) guidelines. Based on our personal experience and available evidence, we propose the criteria we use to define an SBPT and when we consider offering prophylaxis in patients with nonsevere hemophilia. Our proposals can be the basis for discussions in the community about the assessment of SBPT and the initiation of prophylaxis in patients with nonsevere hemophilia without inhibitors.

Thrombin generation to evaluate the complex hemostatic balance of hemophilia A plasma containing direct oral anticoagulant and supplemented by factor VIII

Background

The incidence of cardiovascular diseases is increasing in persons with hemophilia A (HA). Therefore, anticoagulant therapy based on direct oral anticoagulants (DOACs) may be needed, despite the bleeding risk. In case of surgery or bleeding, such patients may be concomitantly treated with emicizumab (routine prophylaxis), factor (F)VIII products, and DOAC. Their concomitant presence constitutes a hemostatic challenge. Recent international guidelines stated that data are scarce on the hemostatic balance of plasma samples from patients with HA receiving emicizumab and DOAC.

Objectives

The aim of this observational study was to assess the coagulation of FVIII-deficient plasma spiked with DOAC and emicizumab and to evaluate the effects of FVIII addition.

Methods

Prothrombin time, activated partial thromboplastin time, and thrombin generation (TG) using the calibrated automated thrombogram method were evaluated in aliquots of a commercial severe HA plasma supplemented with emicizumab (0, 12.5, 25, 50, and 100 ng/mL), DOAC (0, 50, 100, 200, and 400 ng/mL of apixaban, rivaroxaban, edoxaban, or dabigatran) and FVIII (0%, 5%, 15%, 50%, and 100%).

Results

DOAC rapidly induced a TG decrease. Emicizumab could counter this effect only for the lowest DOAC dose. FVIII addition to the FVIII-deficient plasma containing a DOAC and emicizumab improved TG and countered the anticoagulant effect of DOAC at ≤100 ng/mL.

Conclusion

Our findings indicate that FVIII can be safely used with emicizumab to counter the anticoagulant effect of DOAC at ≤100 ng/mL. The TG assay is an efficient tool to monitor plasma containing anti-FXa DOAC, but not dabigatran (anti-FIIa).

Treatment of thrombotic cardiovascular diseases in people with haemophilia: A Japanese consensus study

INTRODUCTION

Cardiovascular diseases (CVD) that require long-term anticoagulant and antiplatelet therapy presents a problem in people with haemophilia (PWH) who receive factor replacement therapy to reduce bleeding risk. Currently, there are no Japanese guidelines for the management of PWH with CVD.

AIM

To develop expert guidance on managing CVD in PWH in Japan.

METHODS

A steering committee of four experts (two haemophilia specialists, one thrombosis specialist, one cardiologist) identified 44 statements related to five key themes. An online questionnaire was produced comprising a mix of 4-point Likert scale and multiple-choice questions that was sent to specialists in the management of PWH with CVD in Japan. Consensus was defined as high or very high if a respective ≥75% or ≥90% of respondents agreed with a statement.

RESULTS

Of 16 potential respondents, responses were received from 15 specialists. Of the Likert scale questions, 71% (29/41) achieved ≥90% agreement (very strong agreement), 17% (7/41) achieved 75%-89% agreement (strong agreement) and 15% (6/41) did not achieve consensus agreement. The three multiple-choice questions failed to identify a strong preference. Agreement on specific target trough clotting factor levels for managing certain clinical situations, such as when in the presence of non-valvular atrial fibrillation or myocardial infarction, was also achieved.

CONCLUSION

The results of this consensus study provide a framework for cardiologists and haematologists to manage PWH who are at risk of, or who have, CVD. Implementation of the recommendations provided herein may improve outcomes for PWH with CVD.

Reducing the risk of atherosclerotic cardiovascular disease in people with hemophilia: the importance of primary prevention

Revolutionary advances in the treatment of hemophilia has led to a significant improvement in life expectancy. Associated with this has been an increase in age-related diseases especially atherosclerotic cardiovascular disease (CVD). While people with hemophilia (PWH) develop atherosclerosis at rates similar to those of the general population, rates of atherothrombosis and mortality related to CVD have been much lower, due to their hypocoagulable state. Changing treatment paradigms, aimed at reducing the risk of bleeding by improving hemostasis to levels approaching normality, has meant that the protection they are thought to have had may be lost. CVD risk factors are just as common in PWH as in the general population, but appear to be undertreated. In particular, primary prevention of CVD is vital in all individuals, but particularly in PWH as treatment of established CVD can be difficult. Active identification and management of CVD risk factors, such as obesity, physical inactivity, hypertension, and hypercholesterolemia, is required. In particular, statins have been shown to significantly reduce cardiovascular and all-cause mortality with few adverse events and no increased risk of bleeding in the general population, and their use needs urgent assessment in PWH. Further longitudinal research into preventing CVD in PWH, including accurate CVD risk assessment, is required to optimize prevention and management.

Challenges in ageing persons with haemophilia

As treatments for individuals with inherited bleeding disorders improve, life expectancy increases and is approaching that of the normal population. Concomitant with this we are now seeing the problems of ageing in the bleeding disorder population. Although the clear-cut association between low clotting factor levels and risk of bleeding is well recognised, a relationship between high levels, some non-factor therapies and thrombotic risk also exists. The management of thrombosis in persons with inherited bleeding disorders is complex but manageable with modern treatments and collaboration in decision making between health care professionals and patients. Despite the improvements in treatment and reduction in bleeding, mostly musculoskeletal pain continues to be a major issue with advancing age. The management of pain amongst older people with haemophilia who may have multiple comorbidities should involve a person-centred, holistic, multi-disciplinary approach to support and optimise long-term physical functioning and overall quality of life.

Rates of venous thromboembolism and use of thromboprophylaxis after major orthopedic surgery in patients with congenital hemophilia A or B: a systematic review

BACKGROUND

Venous thromboembolism (VTE) is a well-recognized complication after total joint replacement (TJR). Persons with hemophilia A or B are considered at low postoperative VTE risk due to their coagulation factor deficiencies, and administering pharmacologic thromboprophylaxis is often considered contraindicated. However, using factor replacement therapy could increase the postoperative VTE risk.

OBJECTIVES

To analyze best available evidences of VTE rates in persons with hemophilia A or B undergoing lower limb TJR and the use of postoperative pharmacologic thromboprophylaxis.

METHODS

We systematically screened 4 online biomedical databases to identify studies reporting VTE rates in patients with hemophilia after TJR. Case reports and case series with less than 10 patients were excluded.

RESULTS

Twenty-six observational studies were included in this systematic review, reporting 1181 TJRs in patients with hemophilia A or B. Eight studies had VTE rates as the primary outcome. Five studies reported screen-detected VTE, while 21 reported symptomatic VTE events. Overall, 17 VTE events were reported (1.4%; 95% CI, 0.9%-2.3%), including 10 (6.6%) after 151 surgeries with postoperative VTE screening and 7 (0.7%) after 1080 surgeries without postoperative screening. Thromboprophylaxis protocols were specified in 21 studies; postoperative thromboprophylaxis was used in 15 (1.3%) surgeries. This information was not available for 29.0% of the analyzed population.

CONCLUSION

Despite the low thromboprophylaxis use in patients with hemophilia, rates of symptomatic VTE after TJR appeared to be low. We also highlighted the need to better report the thrombotic outcome in persons with hemophilia to face the ongoing changes in the hemophilia landscape.

Safety and efficacy of combined dual antiplatelet therapy and factor VIII prophylaxis in patients with haemophilia A after acute coronary syndrome

INTRODUCTION

The increased life expectancy of patients with haemophilia A (HA) has led to a growing prevalence of cardiovascular risk factors and events. There is still scarce evidence on the safety and appropriate duration of dual antiplatelet therapy (DAPT) after acute coronary syndrome (ACS) in HA patients.

AIM

We describe our experience on the clinical management of Italian HA patients after ACS.

METHODS

Nine patients with congenital HA treated with DAPT after a revascularization procedure performed for ACS have been enrolled and followed at the Angelo Bianchi Bonomi Haemophilia and Thrombosis Center in Milan between 2005 and September 2022. The safety and efficacy of DAPT with or without FVIII prophylaxis were assessed.

RESULTS

Ten ACS events occurred in the nine HA patients (four mild and five severe). All events were treated with percutaneous transluminal coronary angioplasty with deployment of 1 to 3 drug-eluting stents followed by DAPT for 1-12 months. All patients except one were treated with FVIII prophylaxis during DAPT aimed at achieving FVIII trough levels ≥20-30 IU/dL. DAPT was effective in all cases in preventing early ACS recurrence, with only a late recurrence. We observed two clinically relevant non-major bleeds (one in a patient without FVIII prophylaxis) and three minor bleeds. No venous thrombosis occurred.

CONCLUSION

The long-term secondary antithrombotic prevention consisting of DAPT and FVIII prophylaxis achieving a trough level of 20-30 IU/dL can be effective and safe in HA patients.

Portal vein thrombosis in a patient with severe hemophilia B: A challenging balanced management

Key Clinical Message

The increased life expectancy in patients with hemophilia (PwH) over the last years has raised the incidence of comorbidities, including thromboembolic events. Thromboembolic events are rare in PwH and most of them occur in the presence of exogenous risk factors. There is still scarce scientific evidence on the optimal antithrombotic treatment and management approach in this population.

Abstract

In the hemophilic population thromboembolic events are rare. Most of them are often multifactorial and occur in the presence of both exogenous (orthopedic surgery, intensive replacement therapy, use of central venous catheters…) and endogenous (cardiovascular diseases) risk factors. We describe the case of a 43-year-old patient with severe hemophilia B (sHB) receiving prophylaxis with eftrenonacog alfa (rFIXFc) and antithrombotic treatment due to portal vein thrombosis. The patient was treated with extended half- life factor IX (EHL-FIX) prophylaxis maintaining higher trough levels to avoid new bleeding episodes associated to the underlying disease and the use of antithrombotic therapy with low molecular weight heparin. EHL-FIX concentrates allow prolonged intervals between intravenous infusions and higher hemostatic protection thanks to increased factor trough levels. This current case report provides clinical evidence in antithrombotic management in a patient with severe hemophilia B.

Comparative safety review of antithrombotic treatment options for patients with atrial fibrillation undergoing percutaneous coronary intervention

INTRODUCTION

Balancing antithrombotic therapy for atrial fibrillation (AF) patients undergoing percutaneous coronary intervention (PCI) remains a clinical challenge due to coexisting thrombogenic risks. This review emphasizes the delicate balance required to prevent ischemic events while minimizing bleeding complications, particularly in the context of risk assessment.

AREAS COVERED

This review spans from 2010 to October 2023, exploring the complexities of antithrombotic management for AF patients undergoing PCI. It stresses the need for personalized treatment decisions to optimize antithrombotic therapies effectively.

EXPERT OPINION

The evolving evidence supports double antithrombotic therapy (DAT) over triple antithrombotic therapy (TAT) for these patients, showcasing a more favorable safety profile without compromising efficacy. Non-vitamin K antagonist oral anticoagulant (NOAC)-based DAT strategies exhibit superiority in reducing major bleeding events while effectively preventing ischemic events. Recommendations from the 2023 European Society of Cardiology (ESC) Guidelines advocate for NOAC-based DAT post-PCI, endorsing safer antithrombotic profiles.Challenges persist for specific patient categories requiring both oral anticoagulants and antiplatelets, necessitating personalized approaches. Future advances in intravascular imaging and novel coronary stent technologies offer promising avenues to optimize outcomes and influence antithrombotic strategies in AF-PCI patients.

Management of anticoagulation and factor XIII replacement in a patient with severe factor XIII deficiency and recurrent venous thromboembolic disease: case report and review of literature

Background

Thrombotic events in congenital factor (F)XIII deficiency are extremely rare. To our knowledge, we describe the first case of severe congenital FXIII deficiency associated with recurrent venous thrombotic events.

Key Clinician Question

How to deal with anticoagulation treatment in patients with severe FXIII deficiency?

Clinical Approach

The patient was treated with rivaroxaban and plasma-derived FXIII substitution therapy as prophylaxis without bleeding complications. We aimed at FXIII trough levels of 50% during the loading doses of rivaroxaban, then 30% during the maintenance dose of rivaroxaban, and finally 20% during the long-term use of prophylactic dose of rivaroxaban.

Conclusion

Treatment of thrombotic events with rivaroxaban in patients with severe bleeding disorders seems to be safe, requiring an adaptation of the intensity of the replacement therapy.

[Methodological recommendations for surgical care in patients with hemophilia A receiving prophylactic therapy with emicizumab]

Methodological recommendations for surgical care in patients with hemophilia A receiving prophylactic therapy with emicizumab. Recommendations of the expert group. Moscow, 2024.

Should we consider caplacizumab as routine treatment for acute thrombotic thrombocytopenic purpura? An expert perspective on the pros and cons

INTRODUCTION

Immune thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening disorder. Caplacizumab has been the latest drug incorporated into the initial treatment of acute episodes, allowing for faster platelet recovery and a decrease in refractoriness, exacerbation, thromboembolic events, and mortality. However, caplacizumab is also associated with a bleeding risk and higher treatment costs, which prevent many centers from using it universally.

AREAS COVERED

Studies that included iTTP and/or caplacizumab to date were selected for this review using PubMed and MEDLINE platforms. We describe outcomes in the pre-caplacizumab era and after it, highlighting the benefits and risks of its use early in frontline, and also pointing out special situations that require careful management.

EXPERT OPINION

It is clear that the availability of caplacizumab has significantly and favorably impacted the management of iTTP patients. Whether this improvement is cost-effective still remains uncertain, and data on long-term sequelae and different healthcare systems will help to clarify this point. In addition, evidence of the bleeding/thrombotic risk of iTTP patients under this drug needs to be better addressed in future studies.

Outcomes of Emicizumab in Acquired Hemophilia Patients: A Systematic Review

BACKGROUND

Emicizumab, a bispecific factor VIII mimetic antibody, was approved in 2018 for bleeding prophylaxis in congenital hemophilia A with or without inhibitors. Since then, several case reports and case series have described the off-label use of emicizumab in acquired hemophilia A (AHA), and data from two clinical trials were recently published (AGEHA, GTH-AHA-EMI).

OBJECTIVES

To describe the reported data on the outcomes of emicizumab, highlighting its benefit/risk profile in treatment.

METHODS

We conducted a literature search in PubMed, Scopus, Cochrane, and Google Scholar up to August 2024, including all scientific articles reporting clinical outcomes of emicizumab use in patients with AHA.

RESULTS

Thirty-two studies were included in the final review, covering a total of 171 AHA patients. The majority started emicizumab for active bleeding management and prophylaxis with various regimens. Follow-up duration and remission criteria varied. Two clinical trials supported the use of emicizumab for bleeding prophylaxis with a new dosing regimen and completion criteria. Bleeding was well managed in all cases, with no major recurrent bleeds. Some adverse events were reported : 3 cases of deep venous thrombosis, 2 cases of stroke, and 2 cases of anti-emicizumab drug antibodies developing in patients with thromboembolic risk factors.

CONCLUSIONS

Based on published data, emicizumab appears to be effective in bleeding management and prophylaxis in AHA patients, with a favorable benefit/risk profile.

The in vitro effect of anticoagulant agents on coagulation and fibrinolysis in the presence of emicizumab in the plasmas from patients with haemophilia A

INTRODUCTION

Emicizumab is used as hemostatic prophylaxis for patients with hemophilia A (PwHA), irrespective of the presence of inhibitors. Although bacterial infection can lead to a procoagulant state, there is limited information on coagulation and fibrinolysis potentials in emicizumab-treated PwHA and on the use of anticoagulants in such cases.

AIM

We examined whether anticoagulants affect the coagulation and fibrinolysis potentials in plasma from PwHA spiked with emicizumab.

METHODS

Plasma from PwHA was in vitro supplemented with emicizumab (50 μg/mL; emi-plasma) and anticoagulants (recombinant thrombomodulin (rTM), nafamostat mesylate (NM), unfractionated heparin (UFH), or low-molecular-weight heparin (LMH)). PwHA plasma spiked with rFVIII (1 IU/mL) was used as a reference (ref-plasma). The coagulation and fibrinolysis potentials in plasma was measured by thrombin and plasmin generation assay (T/P-GA) and clot-fibrinolysis waveform analysis (CFWA).

RESULTS

In T/P-GA and CFWA, coagulation potentials (maximum coagulation velocity; |min1|, and peak thrombin; Th-Peak) in plasma rose with increasing concentrations of emicizumab and rFVIII, but fibrinolytic potentials (peak plasmin; Plm-Peak, and maximum fibrinolytic velocity; |FL-min1|) remained unchanged. Adding rTM, NM, and UFH to emi-plasma suppressed coagulation and fibrinolysis potentials, similar to ref-plasma. Regarding the heparin, UFH and LMH inhibited the improved coagulation in emi-plasma. UFH inhibited fibrinolysis as well, but LMH did not.

CONCLUSIONS

Anticoagulants could exhibit the inhibitory effects on the coagulation and fibrinolysis potentials in plasma from PwHA spiked with emicizumab, similar to those in normal plasma.

Role of red blood cells in clinically relevant bleeding tendencies and complications

The multiple roles of red blood cells (RBCs) are often neglected as contributors in hemostasis and thrombosis. Proactive opportunities to increase RBC numbers, either acutely or subacutely in the case of iron deficiency, are critical as RBCs are the cellular elements that initiate hemostasis together with platelets and stabilize fibrin and clot structure. RBCs also possess several functional properties to assist hemostasis: releasing platelet agonists, promoting shear force-induced von Willebrand factor unfolding, procoagulant capacity, and binding to fibrin. Additionally, blood clot contraction is important to compress RBCs to form a tightly packed array of polyhedrocytes, making an impermeable seal for hemostasis. All these functions are important for patients having intrinsically poor capacity to cease bleeds (ie, hemostatic disorders) but, conversely, can also play a role in thrombosis if these RBC-mediated reactions overshoot. One acquired example of bleeding with anemia is in patients treated with anticoagulants and/or antithrombotic medication because upon initiation of these drugs, baseline anemia doubles the risk of bleeding complications and mortality. Also, anemia is a risk factor for reoccurring gastrointestinal and urogenital bleeds, pregnancy, and delivery complications. This review summarizes the clinically relevant properties and profiles of RBCs at various steps of platelet adhesion, aggregation, thrombin generation, and fibrin formation, including both structural and functional elements. Regarding patient blood management guidelines, they support minimizing transfusions, but this approach does not deal with severe inherited and acquired bleeding disorders where a poor hemostatic propensity is exacerbated by limited RBC availability, for which future guidance will be needed.