Evaluation of combined idarucizumab and prothrombin complex concentrate treatment for bleeding related to dabigatran in a lethal porcine model of double trauma

Direct oral anticoagulants in trauma patients

PURPOSE OF REVIEW

Direct oral anticoagulants (DOACs) are increasingly prescribed for prevention of thromboembolic events. Thus, trauma care providers are facing a steadily raising number of injured patients on DOACs.

RECENT FINDINGS

Despite a predictable pharmacokinetic profile, the resulting plasma levels of trauma patients upon admission and bleeding risks remain uncertain. Therefore, recent guidelines recommend the measurement of DOAC plasma concentrations in injured patients. Alternatively, DOAC specific visco-elastic tests assays can be applied to identify DOAC patients at bleeding risk.Bleeding complications in trauma patients on DOACs are generally higher compared to nonanticoagulated subjects, but comparable to vitamin K antagonists (VKAs). In particular, a traumatic brain injury does not carry an increased risk of intracranial bleeding due to a DOAK intake compared to VKAs. Current studies demonstrated that up to 14% of patients with a hip fracture are on DOACs prior to surgery. However, the majority can be operated safely within a 24h time window without an increased bleeding rate.Specific antagonists facilitate rapid reversal of patients on DOACs. Idarucizumab for dabigatran, and andexanet alfa for apixaban and rivaroxaban have been approved for life threatening bleeding. Alternatively, prothrombin complex concentrate can be used. Dialysis is a potential treatment option for dabigatran and haemoabsorption with special filters can be applied in patients on FXa-inhibitors.

SUMMARY

Current guidelines recommend the measurement of DOAC plasma levels in trauma patients. Compared to VKAs, DOACs do not carry a higher bleeding risk. DOAC specific antagonists facilitate the individual bleeding management.

The Use of Large Animal Models in Trauma and Bleeding Studies

BACKGROUND

 Major trauma often results in significant bleeding and coagulopathy, posing a substantial clinical burden. To understand the underlying pathophysiology and to refine clinical strategies to overcome coagulopathy, preclinical large animal models are often used. This review scrutinizes the clinical relevance of large animal models in hemostasis research, emphasizing challenges in translating findings into clinical therapies.

METHODS

 We conducted a thorough search of PubMed and EMBASE databases from January 1, 2010, to December 31, 2022. We used specific keywords and inclusion/exclusion criteria centered on large animal models.

RESULTS

 Our review analyzed 84 pertinent articles, including four animal species: pigs, sheep, dogs, and nonhuman primates (NHPs). Eighty-five percent of the studies predominantly utilized porcine models. Meanwhile, sheep and dogs were less represented, making up only 2.5% of the total studies. Models with NHP were 10%. The most frequently used trauma models involved a combination of liver injury and femur fractures (eight studies), arterial hemorrhage (seven studies), and a combination of hemodilution and liver injury (seven studies). A wide array of coagulation parameters were employed to assess the efficacy of interventions in hemostasis and bleeding control.

CONCLUSIONS

 Recognizing the diverse strengths and weaknesses of large animal models is critical for trauma and hemorrhage research. Each model is unique and should be chosen based on how well it aligns with the specific scientific objectives of the study. By strategically considering each model's advantages and limitations, we can enhance our understanding of trauma and hemorrhage pathophysiology and further advance the development of effective treatments.

Clinical Relevance of Preclinical and Clinical Studies of Four-Factor Prothrombin Complex Concentrate for Treatment of Bleeding Related to Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) are widely used for the prevention and treatment of venous thromboembolism and stroke. When emergency reversal of DOAC-related anticoagulation is required, specific DOAC reversal agents are recommended, including idarucizumab for dabigatran reversal and andexanet alfa for apixaban and rivaroxaban reversal. However, specific reversal agents are not always available, andexanet alfa has not been approved for urgent surgery, and clinicians need to know the patient's anticoagulant medication before administering these treatments. Four-factor prothrombin complex concentrates (4F-PCCs) are recognized as nonspecific, alternative hemostatic agents for treatment of DOAC-related bleeding. Evidence from preclinical and clinical studies shows that they may reduce the anticoagulant effects of DOACs and may help control DOAC-related bleeding. However, randomized controlled trials are lacking, and most data are from retrospective or single-arm prospective studies in bleeding associated with activated factor X inhibitors. There are no clinical data showing the efficacy of 4F-PCC for the treatment of bleeding in dabigatran-treated patients. This review focuses on the current evidence of 4F-PCC use in controlling bleeding associated with DOACs and provides an expert opinion on the relevance of these data for clinical practice. The current treatment landscape, unmet needs, and future directions are also discussed.

Evaluation of the prothrombotic potential of four-factor prothrombin complex concentrate (4F-PCC) in animal models

OBJECTIVES

Acquired coagulopathy may be associated with bleeding risk. Approaches to restore haemostasis include administration of coagulation factor concentrates, but there are concerns regarding potential prothrombotic risk. The present study assessed the prothrombotic potential of four-factor prothrombin complex concentrate (4F-PCC) versus activated PCC (aPCC) and recombinant factor VIIa (rFVIIa), using three preclinical animal models.

METHODS

The first model was a modified Wessler model of venous stasis-induced thrombosis in rabbit, focusing on dilutional coagulopathy; the second model employed the same system but focused on direct oral anticoagulant reversal (i.e. edoxaban). The third model assessed the prothrombotic impact of 4F-PCC, aPCC and rFVIIa in a rat model of ferric chloride-induced arterial thrombosis.

RESULTS

In the first model, thrombi were observed at aPCC doses ≥10 IU/kg (therapeutic dose 100 IU/kg) and rFVIIa doses ≥50 μg/kg (therapeutic dose 90 μg/kg), but not 4F-PCC 50 IU/kg (therapeutic dose 50 IU/kg). The impact of 4F-PCC (up to 300 IU/kg) on thrombus formation was evident from 10 minutes post-administration, but not at 24 hours post-administration; this did not change with addition of tranexamic acid and/or fibrinogen concentrate. 4F-PCC-induced thrombus formation was lower after haemodilution versus non-haemodilution. In the second model, no prothrombotic effect was confirmed at 4F-PCC 50 IU/kg. The third model showed lower incidence of thrombus formation for 4F-PCC 50 IU/kg versus aPCC (50 U/kg) and rFVIIa (90 μg/kg).

CONCLUSIONS

These results suggest that 4F-PCC has a low thrombotic potential versus aPCC or rFVIIa, supporting the clinical use of 4F-PCC for the treatment of coagulopathy-mediated bleeding.

Prevention and Treatment of Bleeding with Direct Oral Anticoagulants

Anticoagulant-related bleeding carries considerable morbidity and mortality. Major or life-threatening bleeding is among the most severe of these complications. As the number of patients treated with direct oral anticoagulants (DOACs) continues to increase, so does the number of DOAC-related bleeding events. The incidence of CRNM bleeding related to DOAC therapy ranges from 15 to 18% per 100-year patients, while the incidence of major bleeding ranges from 2.71 to 3.6%. Many of these bleeding events can be prevented with tailored dosing regimens or proper peri-procedural management. When unable to be prevented, DOAC-related bleeding can lead to significant long-term disability or death. Management with newer reversal agents such as andexanet alfa and idarucizumab, as well as prothrombin complex concentrates, may improve outcomes for patients with DOAC-related bleeding. The purpose of this review is to explore strategies for preventing and treating bleeding in patients receiving DOACs for anticoagulant therapy.