Comparative effectiveness of hemostatic therapy in experimental warfarin-associated intracerebral hemorrhage

Therapeutic strategies for intracerebral hemorrhage

Stroke is the second highest cause of death globally, with an increasing incidence in developing countries. Intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes. ICH is associated with poor neurological outcomes and high mortality due to the combination of primary and secondary injury. Fortunately, experimental therapies are available that may improve functional outcomes in patients with ICH. These therapies targeting secondary brain injury have attracted substantial attention in their translational potential. Here, we summarize recent advances in therapeutic strategies and directions for ICH and discuss the barriers and issues that need to be overcome to improve ICH prognosis.

CM-352 EFFICACY IN A MOUSE MODEL OF ANTICOAGULANT-ASSOCIATED INTRACRANIAL HAEMORRHAGE

BACKGROUND

Intracranial haemorrhage (ICH) is one of the major devastating complications of anticoagulation. Matrix metalloproteinases (MMPs) inhibition has been proposed as a novel pharmacological approach for ICH treatment.

OBJECTIVES

We evaluated the effects of CM-352 (MMPs-fibrinolysis inhibitor) in an experimental ICH model associated with oral anticoagulants as compared with clinically used prothrombin concentrate complex (PCC).

METHODS

ICH was induced by collagenase injection into the striatum of WT (C57BL/6J) anticoagulated mice (warfarin or rivaroxaban) and Mmp10 -/- mice. Hematoma volume and neurological deficits were measured 24h later by diaminobenzidine staining and different behavioural test. Circulating plasminogen activator inhibitor-1 (PAI-1) activity and interleukin-6 (IL-6) were measured in plasma samples and local inflammation was assessed by neutrophil infiltration. Finally, fibrinolytic effects of MMP-10 and rivaroxaban were evaluated by thromboelastometry and thrombin-activatable fibrinolysis inhibitor (TAFI) activation assays.

RESULTS

Only PCC reduced haemorrhage volume and improved functional outcome in warfarin-ICH, but both, PCC and CM-352 treatments, diminished haemorrhage volume (46%, p<0.01 and 64%, p<0.001, respectively) and ameliorated functional outcome in rivaroxaban-ICH. We further demonstrated that CM-352, but not PCC decreased neutrophil infiltration in the haemorrhage area at 24h. The effect of CM-352 could be related to MMP-10 inhibition since Mmp10-/- mice showed lower haemorrhage volume, better neurological score, reduced IL-6 levels and neutrophil infiltration, and increased PAI-1 after experimental ICH. Finally, we found that CM-352 reduced MMP-10 and rivaroxaban-related fibrinolytic effects in thromboelastometry and TAFI activation.

CONCLUSIONS

CM-352 treatment, by diminishing MMPs and rivaroxaban-associated fibrinolytic effects, might be a novel antihaemorrhagic strategy for rivaroxaban-associated ICH.

European Stroke Organisation Guideline on Reversal of Oral Anticoagulants in Acute Intracerebral Haemorrhage

The aim of the present European Stroke Organisation guideline document is to provide clinically useful evidence-based recommendation on reversal of anticoagulant activity VKA (warfarin, phenprocoumon and acenocoumarol), direct factor II (thrombin) inhibitors (dabigatran etexilat) and factor-Xa-inhibitors (apixaban, edoxaban and rivaroxaban) in patients with acute intracerebral haemorrhage. The guideline was prepared following the Standard Operational Procedure for a European Stroke Organisation guideline document and according to GRADE methodology. As a basic principle, we defined use of oral anticoagulation pragmatically: oral anticoagulation use is assumed by positive medical history unless relevant anticoagulant activity is regarded unlikely by medical history or has been ruled out by laboratory testing. Overall, we strongly recommend using prothrombin complex over no treatment and fresh-frozen plasma in patients on VKA plus vitamin K. We further strongly recommend using idarucizumab in patients on dabigatran and make a recommendation for andexanet alfa in patients on rivaroxaban and apixaban over no treatment. We make a weak recommendation on using high-dose prothrombin complex concentrate (50 IU/kg) for all patients taking edoxaban and for patients on rivaroxaban or apixaban in case andexanet alfa is not available. We recommend against using tranexamic acid and rFVIIa, outside of trials. The presented treatment recommendations aim to normalise coagulation, there is no or only indirect data on effects on functional outcome or mortality, and only little data from randomised controlled trials.

Abrogating fibrinolysis does not improve bleeding or rFVIIa/rFVIII treatment in a non-mucosal venous injury model in haemophilic rodents

Essentials The efficacy of systemic antifibrinolytics for hemophilic non-mucosal bleeding is undetermined. The effect of systemically inhibiting fibrinolysis in hemophilic mice and rats was explored. Neither bleeding nor the response to factor treatment was improved after inhibiting fibrinolysis. The non-mucosal bleeding phenotype in hemophilia A appears largely unaffected by fibrinolysis.

SUMMARY

Background Fibrinolysis may exacerbate bleeding in patients with hemophilia A (HA). Accordingly, antifibrinolytics have been used to help maintain hemostatic control. Although antifibrinolytic drugs have been proven to be effective in the treatment of mucosal bleeds in the oral cavity, their efficacy in non-mucosal tissues remain an open question of significant clinical interest. Objective To determine whether inhibiting fibrinolysis improves the outcome in non-mucosal hemophilic tail vein transection (TVT) bleeding models, and to determine whether a standard ex vivo clotting/fibrinolysis assay can be used as a predictive surrogate for in vivo efficacy. Methods A highly sensitive TVT model was employed in hemophilic rodents with a suppressed fibrinolytic system to examine the effect of inhibiting fibrinolysis on bleeding in non-mucosal tissue. In mice, induced and congenital hemophilia models were combined with fibrinolytic attenuation achieved either genetically or pharmacologically (tranexamic acid [TXA]). In hemophilic rats, tail bleeding was followed by whole blood rotational thromboelastometry evaluation of the same animals to gauge the predictive value of such assays. Results The beneficial effect of systemic TXA therapy observed ex vivo could not be confirmed in vivo in hemophilic rats. Furthermore, neither intravenously administered TXA nor congenital knockout of the fibrinolytic genes encoding plasminogen or tissue-type plasminogen activator markedly improved the TVT bleeding phenotype or response to factor therapy in hemophilic mice. Conclusions The findings here suggest that inhibition of fibrinolysis is not effective in limiting the TVT bleeding phenotype of HA rodents in non-mucosal tissues.

Cerebral Microbleeds in Murine Amyloid Angiopathy: Natural Course and Anticoagulant Effects

BACKGROUND AND PURPOSE

Cerebral microbleeds (CMBs) predispose patients to intracerebral hemorrhage. Preclinical models to examine the effects of antithrombotic treatments on the development of clinically overt intracerebral hemorrhage are needed. We examined the natural course of CMB development and the effects of long-term anticoagulation with warfarin or dabigatran on cerebral micro- and macrohemorrhage in mice overexpressing the APP23 (amyloid precursor protein).

METHODS

Repeated susceptibility-weighted magnetic resonance imaging was performed in APP23 mice at the age of 18 and 21 months, respectively. After establishing stable long-term anticoagulation effects of warfarin and dabigatran on number and total volume of CMBs, the outcome parameters were compared with nonanticoagulated control.

RESULTS

CMBs were equally located in lobar and deep brain regions, and number and total volume of CMBs increased over time. Anticoagulation with either warfarin or dabigatran did not increase CMBs in APP23 significantly. Mice treated with warfarin numerically had a higher mortality (nonanticoagulated: 31%; dabigatran: 35% versus warfarin: 55%; P=0.21). In postmortem brains of prematurely dying animals warfarin caused significantly more frequently large intracerebral hemorrhage than control and dabigatran.

CONCLUSIONS

Anticoagulation with warfarin or dabigatran for 3 to 4 months does not promote the formation of CMBs in aged APP23 mice. Nevertheless, warfarin but not dabigatran is associated with a higher risk of extensive intracerebral hemorrhage, suggesting that this model may allow preclinical safety evaluation of antithrombotic therapies.

Thrombocytopenia induced by dabigatran: two case reports

Background

Vitamin K inhibitors (e.g. warfarin) and indirect thrombin inhibitors (e.g. heparin) are widely used to prevent thromboembolic disorders (e.g. myocardial infarction, venous thromboembolism, and stroke). These agents have been mainstays of anticoagulation for people older than 60 years. However, their administration is associated with a risk of bleeding and requires careful monitoring of patients. Novel oral anticoagulants (NOACs), such as dabigatran, are significantly safer in preventing thromboembolism than warfarin and heparin (sporadically causes thrombocytopenia) and are more specific for their target protein, thrombin. The major advantage of dabigatran, a direct thrombin inhibitor, is that it reversibly inhibits both free and clot-bound thrombin by tight binding affinity and the predictable pharmacodynamic effect. A few studies, however, reported that dabigatran can cause thrombocytopenia, although the underlying mechanism remains unclear. Thus, an antidote for dabigatran was developed to prevent thrombocytopenia.

Case presentation

In this report, we discuss two cases of thrombocytopenia and purpura after dabigatran treatment. A 73-year-old man showed hemorrhagic necrotic skin lesions on his neck and right hand. He was administered dabigatran (220 mg/day) for cerebral infarction for three days and his platelet count decreased abruptly (6000/μL). This suggested that dabigatran had caused thrombocytopenia and purpura; therefore, dabigatran administration was discontinued. The results of a blood test, performed 14 days after stopping dabigatran treatment, showed that the platelet count had recovered to the normal range of more than 150,000/μL. A 75-year-old woman had taken warfarin continuously for 8 years. However, she had a new cerebral infarction. Therefore, warfarin treatment was replaced with dabigatran (300 mg/day). Her platelet count decreased (41,000/μL) significantly and dabigatran treatment was discontinued. The blood test results show that platelet counts gradually recovered to the normal range.

Conclusions

Dabigatran application may cause bleeding; therefore, careful monitoring during dabigatran treatment is required to prevent thrombocytopenia. An explanation is that the interaction of dabigatran with thrombin, because of its strong binding affinity, may cause the observed thrombocytopenia.

CM352 Reduces Brain Damage and Improves Functional Recovery in a Rat Model of Intracerebral Hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) is an acute neurological disorder with high mortality and no effective treatment. In addition to the initial bleeding event, rebleeding and hematoma expansion are associated with poor outcome in these patients. We studied the effectiveness of the new antifibrinolytic agent CM352, a short-half-life matrix metalloproteinase inhibitor, for achieving early hemostasis and improving functional recovery in a rat model of collagenase-induced ICH.

METHODS AND RESULTS

ICH was induced by striatal injection of collagenase, and 1 hour later, rats received an intravenous injection of saline (n=6) or CM352 (1 mg/kg, n=6). Hematoma (basal and after 3 and 24 hours) and lesion (14 days) volumes were quantified on T2-weighted (T2) magnetic resonance images. Neurological and functional recovery was evaluated by using Bederson score and a cylinder test (basal, 24 hours, and 14 days). Early treatment (1 hour) with CM352 was efficient reducing hematoma expansion at 3 hours (P<0.01) and, more markedly, at 24 hours (P<0.01). Decreased bleeding after antifibrinolytic treatment was accompanied by reduced interleukin-6 levels at 3 hours (P<0.05) and smaller lesion volume at 14 days (P<0.01). CM352 drastically reduced sensorimotor impairment (cylinder test) after ICH in rats at 24 hours (P<0.01) and 14 days (P<0.01). Similarly, it also attenuated neurological deficit (Bederson scale) at 24 hours (P<0.01) and 14 days (P<0.01). Interestingly, late (3 hours) CM352 administration also resulted in reduced lesion size and better functional outcome.

CONCLUSIONS

CM352, a new antifibrinolytic agent and matrix metalloproteinase inhibitor, effectively prevented hematoma growth and reduced lesion size in ICH in association with improved functional and neurological recovery.

[Oral anticoagulant-associated intracerebral haemorrhage]

Intracerebral haemorrhage during treatment with oral anticoagulants is associated with high rates of morbidity and mortality. Impaired haemostasis can lead to progressive haematomas and, therefore, it should be identified early in order to initiate measures to reverse anticoagulation. Substitution of coagulation factors is essential in the treatment of these patients, but other intensive care measures such as blood pressure control are mandatory as well.

Hemostasis in Intracranial Hemorrhage

Spontaneous non-traumatic intracerebral hemorrhage (ICH) is associated with high morbidity and mortality throughout the world with no proven effective treatment. Majority of hematoma expansion occur within 4 h after symptom onset and is associated with early deterioration and poor clinical outcome. There is a vital role of ultra-early hemostatic therapy in ICH to limit hematoma expansion. Patients at risk for hematoma expansion are with underlying hemostatic abnormalities. Treatment strategy should include appropriate intervention based on the history of use of antithrombotic use or an underlying coagulopathy in patients with ICH. For antiplatelet-associated ICH, recommendation is to discontinue antiplatelet agent and transfuse platelets to those who will undergo neurosurgical procedure with moderate quality of evidence. For vitamin K antagonist-associated ICH, administration of 3-factor or 4-factor prothrombin complex concentrates (PCCs) rather than fresh frozen plasma to patients with INR >1.4 is strongly recommended. For patients with novel oral anticoagulant-associated ICH, administering activated charcoal to those who present within 2 h of ingestion is recommended. Idarucizumab, a humanized monoclonal antibody fragment against dabigatran (direct thrombin inhibitor) is approved by FDA for emergency situations. Administer activated PCC (50 U/kg) or 4-factor PCC (50 U/kg) to patients with ICH associated with direct thrombin inhibitors (DTI) if idarucizumab is not available or if the hemorrhage is associated with a DTI other than dabigatran. For factor Xa inhibitor-associated ICH, administration of 4-factor PCC or aPCC is preferred over recombinant FVIIa because of the lower risk of adverse thrombotic events.

[Direct oral anticoagulants and acute stroke : Insights into translational research studies]

In recent years a considerable number of translational research studies on intracerebral hemorrhage and ischemic stroke have been published, which are characterized by a particular proximity to practical clinical questions. Animal research has provided insights into the pathophysiological processes and therapy effects, which have so far only been insufficiently investigated in clinical studies. This includes the effectiveness of a rapid reversal of anticoagulation in cases of anticoagulation-associated intracerebral hemorrhage and the safety of thrombolytic treatment in ischemic stroke occurring during treatment with anticoagulants. With the approval of the direct oral anticoagulants these problems have become of particular contemporary relevance. Of course, results from experimental translational studies on stroke cannot be directly translated into clinical routine. Nevertheless, these investigations help to understand the underlying processes and mechanisms and provide proof of concept data for new treatment strategies. This review summarizes the most relevant results in this field of research with a particular focus on practical clinical questions.

Management of neurologic complications of coagulopathies

Coagulopathy is common in intensive care units (ICUs). Many physiologic derangements lead to dysfunctional hemostasis; these may be either congenital or acquired. The most devastating outcome of coagulopathy in the critically ill is major bleeding, defined by transfusion requirement, hemodynamic instability, or intracranial hemorrhage. ICU coagulopathy often poses complex management dilemmas, as bleeding risk must be tempered with thrombotic potential. Coagulopathy associated with intracranial hemorrhage bears directly on prognosis and outcome. There is a paucity of high-quality evidence for the management of coagulopathies in neurocritical care; however, data derived from studies of patients with intraparenchymal hemorrhage may inform treatment decisions. Coagulopathy is often broadly defined as any derangement of hemostasis resulting in either excessive bleeding or clotting, although most typically it is defined as impaired clot formation. Abnormalities in coagulation testing without overt clinical bleeding may also be considered evidence of coagulopathy. This chapter will focus on acquired conditions, such as organ failure, pharmacologic therapies, and platelet dysfunction that are associated with defective clot formation and result in, or exacerbate, intracranial hemorrhage, specifically spontaneous intraparenchymal hemorrhage and traumatic brain injury.

Oral anticoagulant therapy in atrial fibrillation patients at high stroke and bleeding risk

Atrial fibrillation (AF) is associated with a 5-fold greater risk of ischemic stroke or systemic embolism compared with normal sinus rhythm. Cardioembolic AF-related strokes are often more severe, fatal or associated with greater permanent disability and higher recurrence rates than strokes of other aetiologies. These strokes may be effectively prevented with oral anticoagulant (OAC) therapy, using either vitamin K antagonists (VKAs) or non-vitamin K antagonist OACs (NOACs) such as the direct thrombin inhibitor dabigatran or direct factor Xa inhibitors rivaroxaban, apixaban or edoxaban. Most AF patients have a positive net clinical benefit from OAC, excluding those with AF and no conventional stroke risk factors. Balancing the risks of stroke and bleeding is necessary for optimal use of OAC in clinical practice, and modifiable bleeding risk factors must be addressed. Concerns remain over 'non-changeable' bleeding risk factors such as older age, significant renal or hepatic impairment, prior stroke(s) or prior bleeding event(s) and active malignancies. Such AF patients are often termed 'special' AF populations, due to their 'special' risk profile that includes increased risks of both thromboembolic and bleeding events, and due to fear of bleeding complications these AF patients are often denied OAC. Evidence shows, however, that the absolute benefits of OAC are the greatest in patients at the highest risk, and NOACs may offer even a greater net clinical benefit compared to warfarin particularly in these high risk patients. In this review article, we summarize available data on stroke prevention in AF patients at increased risk of both stroke and bleeding and discuss the use of NOACs for thromboprophylaxis in these 'special' AF populations.

Warfarin pretreatment reduces cell death and MMP-9 activity in experimental intracerebral hemorrhage

Little is known about the pathophysiology of oral anticoagulation-associated intracerebral hemorrhage (OAC-ICH). We compared hematoma volume, number of terminal deoxynucleotidyl dUTP nick-end labeling (TUNEL)-positive cells (indicating cell death), MMP-9 levels, and perilesional edema formation between warfarin-treated mice and controls. Intracerebral hemorrhage was induced by an injection of collagenase into the right striatum. Twenty-four hours later, hematoma volume was measured using a photometric hemoglobin assay. Cell death was quantified using TUNEL staining. MMP-9 levels were determined by zymography, and edema formation was assessed via the wet-dry method. Warfarin increased hematoma volume by 2.6-fold. The absolute number of TUNEL-positive cells in the perihematomal zone was lower in warfarin-treated animals (300.5 ± 39.8 cells/mm2) than in controls (430.5 ± 38.9 cells/mm2; p = 0.034), despite the larger bleeding volume. MMP-9 levels were reduced in anticoagulated mice as compared to controls (p = 0.018). Perilesional edema formation was absent in warfarin mice and modestly present in controls. Our results suggest differences in the pathophysiology of OAC-ICH compared to intracerebral hemorrhage occurring under normal coagulation. A likely explanation is that thrombin, a strong inductor of apoptotic cell death and blood-brain barrier disruption, is produced to a lesser extent in OAC-ICH. In humans, however, we assume that the detrimental effects of a larger hematoma volume in OAC-ICH by far outweigh potential protective effects of thrombin deficiency.

The effects of Amicar and TXA on lumbar spine fusion in an animal model

STUDY DESIGN

Animal model.

OBJECTIVE

To determine whether aminocaproic acid (Amicar) and tranexamic acid (TXA) inhibit spine fusion volume.

SUMMARY OF BACKGROUND DATA

Amicar and TXA are antifibrinolytics used to reduce perioperative bleeding. Prior in vitro data showed that antifibrinolytics reduce osteoblast bone mineralization. This study tested whether antifibrinolytics Amicar and TXA inhibit spine fusion.

METHODS

Posterolateral L4-L6 fusion was performed in 50 mice, randomized into groups of 10, which received the following treatment before and after surgery: (1) saline; (2) TXA 100 mg/kg; (3) TXA 1000 mg/kg; (4) Amicar 100 mg/kg; and (5) Amicar 1000 mg/kg. High-resolution plane radiography was performed after 5 weeks and micro-CT (computed tomography) was performed at the end of the 12-week study. Radiographs were graded using the Lenke scale. Micro-CT was used to quantify fusion mass bone volume. One-way analysis of variance by ranks with Kruskal-Wallis testing was used to compare the radiographical scores. One-way analysis of variance with least significant difference post hoc testing was used to compare the micro-CT bone volume.

RESULTS

The average±standard deviation bone volume/total volume (%) measured in the saline, TXA 100 mg/kg, TXA 1000 mg/kg, Amicar 100 mg/kg, and Amicar 1000 mg/kg groups were 10.8±2.3%, 9.7±2.2%, 13.4±3.2%, 15.5±5.2%, and 17.9±3.5%, respectively. There was a significant difference in the Amicar 100 mg/kg (P<0.05) and Amicar 1000 mg/kg (P<0.001) groups compared with the saline group. There was greater bone volume in the Amicar groups compared with the TXA group (P<0.001). There was more bone volume in the TXA 1000 mg/kg group compared with TXA 100 mg/kg (P<0.05) but the bone volume in neither of the TXA groups was different to saline (P=0.49). There were no between-group differences observed using plane radiographical scoring.

CONCLUSION

Amicar significantly "enhanced" the fusion bone mass in a dose-dependent manner, whereas TXA did not have a significant effect on fusion compared with saline control.These data are in contrast to prior in vitro data that antifibrinolytics inhibit osteoblast bone mineralization.

LEVEL OF EVIDENCE

N/A.

Management of anticoagulant-related intracranial hemorrhage: an evidence-based review

The increased use of anticoagulants for the prevention and treatment of thromboembolic diseases has led to a rising incidence of anticoagulant-related intracranial hemorrhage (AICH) in the aging western population. High mortality accompanies this form of hemorrhagic stroke, and significant and debilitating long-term consequences plague survivors. Although management guidelines for such hemorrhages are available for the older generation anticoagulants, they are still lacking for newer agents, which are becoming popular among physicians. Supportive care, including blood pressure control, and reversal of anticoagulation remain the cornerstone of acute management of AICH. Prothrombin complex concentrates are gaining popularity over fresh frozen plasma, and reversal agents for newer anticoagulation agents are being developed. Surgical interventions are options fraught with complications, and are decided on a case-by-case basis. Our current state of understanding of this condition and its management is insufficient. This deficit calls for more population-based studies and therapeutic trials to better evaluate risk factors for, and to prevent and treat AICH.

Tranexamic acid for spontaneous intracerebral hemorrhage: a randomized controlled pilot trial (ISRCTN50867461)

BACKGROUND

Spontaneous intracerebral hemorrhage (ICH) can be devastating, particularly if hematoma expansion (HE) occurs. Tranexamic acid (TA), an antifibrinolytic drug, significantly reduced mortality in bleeding patients after trauma in the large CRASH-2 trial. The CRASH-2 ICH substudy found that TA nonsignificantly reduced mortality and dependency in traumatic ICH. The aim of this study was to assess the feasibility of performing a randomized controlled trial of tranexamic acid in spontaneous ICH, ahead of a definitive study.

METHODS

We performed a single-center, prospective, randomized (2:1), double-blind, placebo-controlled blinded endpoint trial of TA (intravenous 1 g bolus, 1 g infusion/8 h) in acute (<24 hours) spontaneous ICH. The primary objective was to test the feasibility of recruiting to the trial. Other objectives included tolerability (adverse events) and the effect of TA on HE and death and dependency.

RESULTS

The trial was feasible, with 24 patients enrolled (TA, n=16; placebo, n=8) between March 2011 and March 2012, and acceptable-only 3 patients declined to participate. All patients received the correct randomized treatment; 1 patient in the TA group did not complete the infusion because of neurologic deterioration. There were no significant differences in secondary outcomes including adverse events, HE, death, and dependency. One patient in the TA group had a deep vein thrombosis .

CONCLUSIONS

This, the first randomized controlled trial of TA in ICH, found that the protocol could be delivered on schedule (2 patients/mo) and was feasible. Larger studies are needed to assess safety and efficacy of TA in ICH.

Rivaroxaban does not increase hemorrhage after thrombolysis in experimental ischemic stroke

The management of acute ischemic stroke during anticoagulation with a novel oral anticoagulant (NOAC) is challenging because intravenous thrombolysis is contraindicated because of a putative increased risk of intracerebral hemorrhagic complications. We examined the risk of secondary postischemic hemorrhage after thrombolysis in rodents pretreated with rivaroxaban or warfarin. Mice were pretreated with either rivaroxaban (30 mg/kg), warfarin (target international normalized ratio 2 to 3) or vehicle. After 2 or 3 hours, middle cerebral artery occlusion (MCAO), mice received 9 mg/kg recombinant tissue plasminogen activator. Twenty-four hours after MCAO, secondary hemorrhage was quantified using a macroscopic hemorrhage score and hemoglobin spectrophotometry. Blood-brain barrier (BBB) permeability was measured by Evans Blue spectrofluorometry. To increase the validity of our findings, experiments were also performed using a thromboembolic model in anticoagulated rats. Infarct size did not differ among groups. Pretreatment with warfarin led to significantly more secondary hemorrhage compared with rivaroxaban and nonanticoagulated controls after 2- and 3-hour ischemia in mice as well as in rats. Blood-brain barrier permeability was significantly higher in the warfarin group compared with rivaroxaban and control. Thus, rivaroxaban in contrast to warfarin does not increase secondary hemorrhage after thrombolysis in experimental cerebral ischemia. Less effects of rivaroxaban on postischemic BBB permeability may account for this difference.

Rapid reversal of warfarin-associated hemorrhage in the emergency department by prothrombin complex concentrates

Life-threatening warfarin-associated hemorrhage is common, with a high mortality. In the United States, the most commonly used therapies--fresh frozen plasma and vitamin K--are slow and unpredictable and can result in volume overload. Outside of the United States, prothrombin complex concentrates are often used instead; these pooled plasma products reverse warfarin anticoagulation in minutes rather than hours. This article reviews the literature relating to warfarin reversal with fresh frozen plasma, prothrombin complex concentrates, and recombinant factor VIIa and provides elements for a management protocol based on this literature.

Intracerebral hemorrhage in patients receiving oral anticoagulation therapy

Intracerebral hemorrhage (ICH) in patients with oral anticoagulation therapy is an increasingly prevalent problem in large part due to the aging population and the increased use of anticoagulants for patients at high risk of thrombosis. Warfarin has been virtually the only outpatient anticoagulant choice until fairly recently. The development of subcutaneously injected heparinoids, and more recently, of direct thrombin inhibitors, has made the treatment and prognostication of ICH in anticoagulated patients more difficult. In this review, we will review the current state of diagnosis, prognostication, and treatment for patients with this often-devastating type of bleeding. We will focus on warfarin therapy, because the preponderance of evidence comes from studies of warfarin treatment. Where there is evidence, we will contrast warfarin with some of the newer treatment modalities. We review the evidence of the 4 major reversal agents for warfarin, vitamin K, prothrombin complex concentrates, activated factor VII, and fresh frozen plasma as well as rational treatment choices. We offer possible treatments for the newer anticoagulants based on the limited evidence available. Finally, we review recommendations from the major societies and studies that support early and aggressive therapies in intensive care units with dedicated neurological specialists.

Anticoagulation with dabigatran does not increase secondary intracerebral haemorrhage after thrombolysis in experimental cerebral ischaemia

Dabigatran etexilate (DE) has recently been introduced for stroke prevention in atrial fibrillation, but management of acute ischaemic stroke during therapy with DE is a challenge. Thrombolysis is contraindicated because of a presumed increased risk of intracerebral haemorrhagic complications. We studied in different ischaemia models whether DE increases secondary haemorrhage after thrombolysis. C57BL/6 mice were anticoagulated with high-dose DE or warfarin. After 2 hour (h) or 3 h transient filament MCAO, rt-PA was injected. At 24 h after MCAO, secondary haemorrhage was quantified using a macroscopic haemorrhage score and haemoglobin spectrophotometry. Post-ischaemic blood-brain-barrier (BBB) damage was assessed using Evans blue. To increase the validity of findings, the duration of anticoagulation was prolonged in mice (5 x DE over 2 days), and the effect of DE after thrombolysis was also examined in thromboembolic MCAO in rats.Pretreatment with warfarin resulted in significantly more secondary haemorrhage (mean haemorrhage score 2.6 ± 0.2) compared to non-anticoagulated animals (1.7 ± 0.3) and DE (9 mg/kg, 1.6 ± 0.3) in 2 h ischaemia. Also after a 3 h period of ischaemia, haemorrhage was more severe in animals anticoagulated with warfarin compared to 9 mg/kg DE and non-anticoagulated control. Prolonged or enteral dabigatran pretreatment led to identical results. Also, thrombolysis after thromboembolic MCAO in rats did not induce more severe bleeding in DE-treated animals. Mice pretreated with warfarin had higher BBB permeability and increased activation of matrix-metalloproteinase 9. In conclusion, DE does not increase the risk of secondary haemorrhage after thrombolysis in various rodent models of ischaemia and reperfusion. The implications of this finding for stroke patients have to be determined in the clinical setting.

Intracerebral haemorrhage associated with antithrombotic treatment: translational insights from experimental studies

Little is known about the pathophysiology of intracerebral haemorrhage that occurs during anticoagulant treatment. In observational studies, investigators have reported larger haematoma volumes and worse functional outcome in these patients than in those with intracerebral haemorrhage and a normal coagulation status. The need to prevent extensive haematoma enlargement by rapid reversal of the anticoagulation seems intuitive, although no evidence is available from randomised clinical trials. New oral anticoagulants, such as the direct thrombin inhibitor dabigatran and the factor Xa inhibitor rivaroxaban, have been approved recently; however, intracerebral haemorrhage during dabigatran or rivaroxaban anticoagulation has not been characterised, and whether anticoagulation reversal can be beneficial in this scenario is unknown. In a translational approach, new experimental models have been developed to study anticoagulation-associated intracerebral haemorrhage in more detail and to test treatment strategies. Vitamin k antagonists enlarge haematoma volumes and worsen functional outcome in animal models. Rapid reversal of anticoagulation in the experimental setting prevents prolonged haematoma expansion and improves outcome. The new oral anticoagulants increase intracerbral haemorrhage volumes less than does warfarin. Haemostatic approaches that have been used for vitamin k-associated intracerebral haemorrhage also seem to be effective in intracerebral haemorrhage associated with the new anticoagulants. These experimental studies are valuable for filling gaps in knowledge, but the results need careful translation into routine clinical practice.

[The 2013 Seville Consensus Document on alternatives to allogenic blood transfusion. An update on the Seville Document]

Since allogeneic blood transfusion (ABT) is not harmless, multiple alternatives to ABT (AABT) have emerged, though there is great variability in their indications and appropriate use. This variability results from the interaction of a number of factors, including the specialty of the physician, knowledge and preferences, the degree of anemia, transfusion policy, and AABT availability. Since AABTs are not harmless and may not meet cost-effectiveness criteria, such variability is unacceptable. The Spanish Societies of Anesthesiology (SEDAR), Hematology and Hemotherapy (SEHH), Hospital Pharmacy (SEFH), Critical Care Medicine (SEMICYUC), Thrombosis and Hemostasis (SETH) and Blood Transfusion (SETS) have developed a Consensus Document for the proper use of AABTs. A panel of experts convened by these 6 Societies have conducted a systematic review of the medical literature and have developed the 2013 Seville Consensus Document on Alternatives to Allogeneic Blood Transfusion, which only considers those AABT aimed at decreasing the transfusion of packed red cells. AABTs are defined as any pharmacological or non-pharmacological measure aimed at decreasing the transfusion of red blood cell concentrates, while preserving patient safety. For each AABT, the main question formulated, positively or negatively, is: « Does this particular AABT reduce the transfusion rate or not?» All the recommendations on the use of AABTs were formulated according to the Grades of Recommendation Assessment, Development and Evaluation (GRADE) methodology.

[The 2013 Seville Consensus Document on alternatives to allogenic blood transfusion. An update on the Seville Document]

Since allogeneic blood transfusion (ABT) is not harmless, multiple alternatives to ABT (AABT) have emerged, though there is great variability in their indications and appropriate use. This variability results from the interaction of a number of factors, including the specialty of the physician, knowledge and preferences, the degree of anemia, transfusion policy, and AABT availability. Since AABTs are not harmless and may not meet cost-effectiveness criteria, such variability is unacceptable. The Spanish Societies of Anesthesiology (SEDAR), Hematology and Hemotherapy (SEHH), Hospital Pharmacy (SEFH), Critical Care Medicine (SEMICYUC), Thrombosis and Hemostasis (SETH) and Blood Transfusion (SETS) have developed a Consensus Document for the proper use of AABTs. A panel of experts convened by these 6 Societies have conducted a systematic review of the medical literature and have developed the 2013 Seville Consensus Document on Alternatives to Allogeneic Blood Transfusion, which only considers those AABT aimed at decreasing the transfusion of packed red cells. AABTs are defined as any pharmacological or non-pharmacological measure aimed at decreasing the transfusion of red blood cell concentrates, while preserving patient safety. For each AABT, the main question formulated, positively or negatively, is: "Does this particular AABT reduce the transfusion rate or not?" All the recommendations on the use of AABTs were formulated according to the Grades of Recommendation Assessment, Development and Evaluation (GRADE) methodology.

Anticoagulation-related intracranial hemorrhages

Unfractionated heparin, low molecular weight heparin, and warfarin are often used for patients at high risk of thromboembolism and are associated with increased risk of major and even life threatening hemorrhages. They are in use for a long time and have treatment strategies in place in an event of life threatening intracranial hemorrhage. The advent of newer anticoagulants, direct thrombin inhibitors (dabigatran) and two factor Xa inhibitors (rivaroxaban and apixaban), has increased the options of anticoagulation for patients with atrial fibrillation and venous thrombosis, but at the same time, in the absence of an antidote, they have created a great challenge for treating physicians to manage intracranial bleeding related to these agents. In this paper, we will briefly summarize the state of knowledge regarding the risk of anticoagulation-related ICH, and review basic concepts on anticoagulation reversal and the general management of patients with this complication.

Prothrombin complex concentrates reduce blood loss in murine coagulopathy induced by warfarin, but not in that induced by dabigatran etexilate

BACKGROUND

Both established oral anticoagulants such as warfarin and newer agents such as dabigatran etexilate (DE) effectively prevent thromboembolic disease, but may provoke bleeding. Limited clinical data exist linking oral anticoagulant reversal and bleeding tendency, as opposed to surrogate laboratory markers.

OBJECTIVE

 To quantify bleeding in warfarin-anticoagulated and DE-anticoagulated mice by tail transection with or without pretreatment with potential reversal agents: prothrombin complex concentrate (PCC); activated PCC (APCC); recombinant factor VIIa (rFVIIa); or murine fresh-frozen plasma (FFP).

METHODS

CD1 mice were given warfarin or DE by gavage, and the effects on in vitro coagulation assays, volume of blood loss and the bleeding time following tail transection injury were evaluated with different reversal agents.

RESULTS

PCC (14.3 IU kg(-1) ), but not rFVIIa (3 mg kg(-1) ) or FFP (12 mL kg(-1) ), normalized blood loss and bleeding time in mice with warfarin-induced elevations of mean prothrombin time at two intensities (prothrombin time ratios of either 4.3 or 24). Neither separate nor combined PCC and/or rFVIIa treatment nor APCC (100 U kg(-1) ) treatment significantly reduced blood loss in mice anticoagulated with 60 mg kg(-1) DE 75 min prior to tail transection. Both combined PCC plus rFVIIa treatment and APCC treatment significantly reduced bleeding time in the DE-treated mice.

CONCLUSIONS

Our data suggest that PCC treatment prevents excess bleeding much more effectively in warfarin-induced coagulopathy than in DE-induced coagulopathy.

Reversal of drug-induced anticoagulation: old solutions and new problems

Anticoagulant drugs are taken by millions of patients throughout the world. Warfarin has been the most widely prescribed anticoagulant for decades. In recent years, new oral anticoagulants have been approved for use, are being positioned as alternatives to warfarin, and represent an enormous market opportunity for pharmaceutical companies. Requests for urgent reversal of anticoagulants are not uncommon especially in the setting of critical bleeding. This review summarizes information on reversal of warfarin by vitamin K, plasma, prothrombin complex concentrates, and recombinant VIIa. In addition, we emphasize the lack of current evidence supporting reversibility of the new oral direct thrombin inhibitors and Factor Xa inhibitors. This review is presented to assist transfusion medicine specialists, hematologists, and other clinicians who prescribe blood components for reversal of drug-induced anticoagulation.

Intracerebral haemorrhage: mechanisms of injury and therapeutic targets

Intracerebral haemorrhage accounts for about 10-15% of all strokes and is associated with high mortality and morbidity. No successful phase 3 clinical trials for this disorder have been completed. In the past 6 years, the number of preclinical and clinical studies focused on intracerebral haemorrhage has risen. Important advances have been made in animal models of this disorder and in our understanding of mechanisms underlying brain injury after haemorrhage. Several therapeutic targets have subsequently been identified that are now being pursued in clinical trials. Many clinical trials have been based on limited preclinical data, and guidelines to justify taking preclinical results to the clinic are needed.

Hemostatic Therapy in Experimental Intracerebral Hemorrhage Associated With the Direct Thrombin Inhibitor Dabigatran

Background and Purpose—

Dabigatran-etexilate (DE) recently has been approved for stroke prevention in atrial fibrillation. However, lack of effective antagonists represents a major concern in the event of intracerebral hemorrhage (ICH). The aims of the present study were to establish a murine model of ICH associated with dabigatran, and to test the efficacy of different hemostatic factors in preventing hematoma growth.

Methods—

In C57BL/6 mice receiving DE (4.5 or 9.0 mg/kg), in vivo and in vitro coagulation assays and dabigatran plasma levels were measured repeatedly. Thirty minutes after inducing ICH by striatal collagenase injection, mice received an intravenous injection of saline, prothrombin complex concentrate (PCC; 100 U/kg), murine fresh-frozen plasma (200 μL), or recombinant human factor VIIa (8.0 mg/kg). ICH volume was quantified on brain cryosections 24 hours later.

Results—

DE substantially prolonged tail vein bleeding time and ecarin clotting time for 4 hours corresponding to dabigatran plasma levels. Intracerebral hematoma expansion was observed mainly during the first 3 hours on serial T2* MRI. Anticoagulation with high doses of DE increased the hematoma volume significantly. PCC and, less consistently, fresh-frozen plasma prevented excess hematoma expansion caused by DE, whereas recombinant human factor VIIa was ineffective. Prevention of hematoma growth and reversal of tail vein bleeding time by PCC were dose-dependent.

Conclusions—

The study provides strong evidence that PCC and, less consistently, fresh-frozen plasma prevent excess intracerebral hematoma expansion in a murine ICH model associated with dabigatran. The efficacy and safety of this strategy must be further evaluated in clinical studies.

Recombinant activated coagulation factor VII and prothrombin complex concentrates are equally effective in reducing hematoma volume in experimental warfarin-associated intracerebral hemorrhage

BACKGROUND AND PURPOSE

Based on an experimental model of warfarin-associated intracerebral hemorrhage, we investigated whether the rapid reversal of anticoagulation using prothrombin complex concentrates (PCC) or recombinant activated coagulation factor VII (rFVIIa) reduces hematoma volume.

METHODS

Mice were orally pretreated with warfarin (2 mg/kg). Intracerebral hemorrhage was induced by collagenase injection into the right striatum. Forty-five minutes later, PCC (100 IE/kg), rFVIIa (1 mg/kg), or an equal volume of saline was administered intravenously. Hematoma volume after 24 hours was quantified using a photometric hemoglobin assay.

RESULTS

International normalized ratio was 4.3±0.4 in saline-treated mice, 0.9±0.1 in rFVIIa mice, and 1.4±0.2 in PCC mice. Intracerebral hemorrhage volume was 29.0±19.7 μL in the saline group (n=7), 8.6±4.3 μL in the rFVIIa group (n=6), and 6.1±1.8 μL in the PCC group (n=7; analysis of variance between-group differences P=0.004; post hoc rFVIIa versus saline P=0.021; PCC versus saline P=0.007). No significant difference was found between PCC- and rFVIIa-treated animals.

CONCLUSIONS

Our results suggest that PCC and rFVIIa are equally effective in restoring coagulation and preventing excessive hematoma growth in acute warfarin-associated intracerebral hemorrhage.