Treatment of coumarin-associated coagulopathy: a systematic review and proposed treatment algorithms

Rethinking warfarin reversal

Warfarin and other vitamin K antagonists are very effective for the treatment and prevention of both arterial and venous thromboembolism. Recombinant factor VIIa may not be as effective as previously thought for the urgent reversal of warfarin.

Rapid Reversal of Coagulopathy in Warfarin-Related Intracranial Haemorrhages with Prothrombin Complex Concentrates

We report our initial experience using Profilnine SD, a 3-Factor prothrombin complex concentrate (PCC) in combination with fresh frozen plasma and vitamin K in seven patients admitted to our neurointensive care unit with oral anticoagulation therapy-related intracranial haemorrhage over a six-month period, to achieve rapid normalisation of the international normalised ratio (INR) and allow surgical evacuation when indicated.

Four patients presented with subdural haematomas while three had intracerebral haematomas. Six of seven patients had admission INR in the appropriate therapeutic range for oral anticoagulation therapy. The median dose of PCC administered was 28.5 IU/kg body weight (interquartile range 21.3 to 38.5 IU/kg). All four patients with subdural haematoma underwent surgical evacuation once INR was less than 1.5. Median time from computed tomography diagnosis to surgery was 275 minutes (range 102 to 420 minutes). The median time to INR normalisation post-PCC administration was shorter, at 85 minutes (range 50 to 420 minutes) for the four patients who survived, versus 10 hours (range 9 to 44 hours) in the three patients who died. Two of the three patients who died had haematoma increase, worsening midline shift and subfalcine herniation, leading to withdrawal of therapy.

Prothrombin complex concentrates should be considered for use in the urgent reversal of INR in oral anticoagulation therapy-related intracranial haemorrhage, potentially halting haematoma expansion and expediting urgent neurosurgical intervention, although data from randomised controlled trials is still lacking. The literature supporting the use of PCC is reviewed and a protocolised emergent treatment algorithm is proposed, which may help achieve earlier consistent normalisation of the INR.

Can oral vitamin K before elective surgery substitute for preoperative heparin bridging in patients on vitamin K antagonists?

BACKGROUND

After a vitamin K antagonist (VKA) overdose, 1-2 mg of oral vitamin K can lower the International Normalized Ratio (INR) to the therapeutic range.

OBJECTIVE

To establish whether oral vitamin K can substitute for heparin bridging and decrease the INR to < or = 1.5 before elective surgery.

METHODS

Patients on long-term VKAs were randomized either to heparin bridging after the last VKA dose on day -5 before surgery (group H) or to VKA treatment until day -2, followed by 1 mg of oral vitamin K on the day before surgery (group K). Blood clotting variables were assessed on days -5/-2, 1 and 0, and postoperatively. If the target INR was not achieved 2 h before incision, surgery was deferred or performed after injection of prothrombin complex concentrate (PCC).

RESULTS

In 30 of 94 included patients, baseline INR was outside the chosen range (18, INR < 2; 12, INR > 3.5), leaving 34 eligible patients in group H and 30 in group K. The groups were balanced in terms of body mass index, VKA treatment duration and indication, scheduled surgery, preoperative and postoperative hemoglobin, and blood loss. The INR was significantly higher in group K on days -1 and 0 than in group H. An INR < or = 1.5 was not achieved in 20 group K patients (66%). Surgery was postponed or performed after PCC injection in 12 of these 20 patients.

CONCLUSIONS

Oral vitamin K (1 mg) cannot substitute for heparin bridging before surgery. In addition, one-third of patients on VKAs were exposed to a risk of bleeding (overdose) or thrombosis (underdose), thus highlighting the need for new oral anticoagulants.

Coagulopathy in critically ill patients: part 2-soluble clotting factors and hemostatic testing

This manuscript provides an overview of how to interpret in vitro clotting studies and how to select studies to evaluate patients with bleeding disorders in the ICU. It provides a practical approach to understanding the complex subject of clotting factor abnormalities, including the most common problems of preanalytical error and anticoagulation therapy. Limitations and pitfalls of diagnostic testing are highlighted.

Prothrombin complex concentrate in surgical patients: retrospective evaluation of vitamin K antagonist reversal and treatment of severe bleeding

Introduction

Prothrombin complex concentrates are recommended for rapid reversal of vitamin K anticoagulants. As they normalize levels of vitamin K dependent clotting factors and re-establish hemostasis, they may also be used as adjunctive therapy in patients with major bleeding. The aim of this study was to retrospectively evaluate the efficacy of prothrombin complex concentrates in the surgical setting.

Methods

The case notes of 50 patients requiring urgent oral anticoagulation reversal (n = 12) or with severe perioperative coagulopathic bleeding (n = 38) who received an infusion of prothrombin complex concentrate (Beriplex P/N(R) 500) at the surgical department of the University of Munich Hospital, Germany were retrospectively reviewed. Efficacy of prothrombin complex concentrate application was evaluated using the Quick test, reported as an international normalized ratio, hemodynamic measurements and requirement for blood products. Safety assessments included whole blood hemoglobin levels and specific parameters of organ dysfunction.

Results

Baseline characteristics were comparable, except that mean baseline international normalized ratio and hemoglobin levels were significantly higher (P < 0.01) in anticoagulation reversal than in bleeding patients. In anticoagulation reversal, the international normalized ratio was significantly reduced (from 2.8 +/- 0.2 at baseline to 1.5 +/- 0.1, P < 0.001) after one prothrombin complex concentrate infusion (median dose 1500 IU; lower quartile 1,000, upper quartile 2,000). No major bleeding was observed during surgery after prothrombin complex concentrate administration. Only one patient received platelets and red blood cell transfusion after prothrombin complex concentrate administration. In bleeding patients, infusion of prothrombin complex concentrate (median dose 2,000 IU; lower quartile 2,000, upper quartile 3,000) significantly reduced the INR from 1.7 +/- 0.1 at baseline to 1.4 +/- 0.1 (P < 0.001). This decrease was unrelated to fresh frozen plasma or vitamin K administration. Bleeding stopped after prothrombin complex concentrate administration in 4/11 (36%) patients with surgical bleeding and 26/27 (96%) patients with diffuse bleeding. Hemoglobin levels increased significantly from baseline in bleeding patients (P < 0.05) and mean arterial pressure stabilized (P < 0.05). No thrombotic events or changes in organ function were reported in any patient.

Conclusions

Prothrombin complex concentrate application effectively reduced international normalized ratios in anticoagulation reversal, allowing surgical procedures and interventions without major bleeding. In bleeding patients, the improvement in coagulation after prothrombin complex concentrate administration was judged to be clinically significant.

INR deviations in hemodialyzed patients under low dose oral anticoagulant therapy

The aim of this retrospective study was to evaluate the International Normalized Ratio (INR) in hemodialyzed uremic patients under treatment with oral anticoagulation drugs. Eleven out of one hundred and forty-two uremic hemodialyzed patients in our unit were included in the study. These 11 patients aged from 70 to 85 (mean: 76 years) were under oral anticoagulation treatment for protection from thromboembolic events. They received 1 mg acenocumarol daily with the therapeutic goal of achieving an INR between 2 and 2.5 units. During the last year, the number of total INR determinations was 129. Based on the INR levels, measurements were classified into three categories of anticoagulation, termed "under-anticoagulation", "target-anticoagulation", and "over-anticoagulation". The number, the percentage, and the mean value (+/-SD) of INR measurements for each category, respectively, were under-anticoagulation: 39, 30%, 1.78 +/- 0.14; target-anticoagulation: 48, 37.5%, 2.20 +/- 0.14; and over-anticoagulation: 42, 32.5%, 3.14 +/- 0.64. The mean value +/-SD of all INR determinations (n=129) was 2.34 +/-0.65. No thromboembolic or major bleeding events occurred in our patients with these INR. In conclusion, in elderly, hemodialyzed uremic patients with indications for oral anticoagulation treatment, adequate and safe INR levels can be achieved in a high proportion without serious deviations from the therapeutic goal by using low doses of drugs. Therefore, oral anticoagulation therapy should not be considered automatically contra-indicated in this patient group.

[Bleeding complications due to anticoagulatoric therapy]

Anticoagulation is a standard treatment in patients with thrombosis and commonly used in surgical procedures for primary thrombosis prophylaxis. The occurrence of bleeding episodes is the predominant treatment complication. Although monitoring of hemostatic parameters reduces the risk of bleeding, bleedings occur in approximately 10% of patients. Besides standard life saving procedures it is crucial to ensure sufficient coagulation by administering factor concentrates (e.g. fresh frozen plasma, prothrombin complex, recombinant factor VIIa), platelet concentrates and fluid. Specific antidotes are not available for the majority of anticoagulant agents.

Epidemiology and management of bleeding in patients using vitamin K antagonists

Vitamin K antagonists are effective in the prevention and treatment of a variety of arterial and venous thrombotic disorders, but are associated with an increased risk of serious bleeding complications. According to well documented studies of patients using vitamin K antagonists, the incidence of major bleeding is 0.5% per year and the incidence of intracranial bleeding is 0.2% per year, however, in real life practice this incidence may be even higher. Risk factors for bleeding are the intensity of anticoagulation, the management strategy to keep the INR in the desired range, and patient characteristics. In case of serious bleeding complications in a patient who uses vitamin K antagonists, this anticoagulant treatment can be quickly reversed by administration of vitamin K or coagulation factor concentrates.

Coagulation disorders in the ICU

Disorders of hemostasis and thrombosis are frequently encountered in the ICU setting. Understanding the relevance of laboratory findings is essential in providing appropriate therapy. Various blood products and hemostatic agents are available to assist in the control of bleeding, and several different classes of anticoagulants are now available for use. Appropriate use of these agents maximizes therapeutic effect while minimizing complications. Use of fresh frozen plasma, cryoprecipitate, and other hemostatic agents should generally be reserved for those who have active bleeding, those undergoing invasive procedures, and those at high risk for bleeding because of their underlying diagnoses or because of associated hematologic derangements.

Bench-to-bedside review: Optimising emergency reversal of vitamin K antagonists in severe haemorrhage - from theory to practice

Critical care physicians are increasingly facing patients receiving oral anticoagulation for either cessation of major haemorrhage or to reverse the effects of vitamin K antagonists ahead of emergency surgery. Rapid reversal of anticoagulation is particularly essential in cases of life-threatening bleeding. In these situations, guidelines recommend the concomitant administration of prothrombin complex concentrates (PCCs) and oral or intravenous vitamin K for the fastest normalisation of the international normalised ratio (INR). Despite their universal recommendation, PCCs remain underused by many physicians who prefer to opt for fresh frozen plasma despite its limitations in anticoagulant reversal, including time to reverse INR and high risk of transfusion-related acute lung injury. In contrast, the lower volume required to normalise INR with PCCs and the room temperature storage facilitate faster preparation and administration time, thus increasing the speed at which haemorrhages can be treated. PCCs therefore allow faster, more reliable and complete reversal of vitamin K anticoagulation, especially when administered immediately following confirmation of haemorrhage. In the emergency setting, probabilistic dosing may be considered.

Emergency reversal of antithrombotic treatment

The most important adverse effect of antithrombotic treatment is the occurrence of bleeding. In case of serious or even life-threatening bleeding in a patient who uses anticoagulant agents or when a patient on anticoagulants needs to undergo an urgent invasive procedure, anticoagulant treatment can be reversed by various specific strategies. Heparin and heparin derivatives can be counteracted by protamine sulphate, whereas the anticoagulant effect of vitamin K antagonists may be neutralized by administration of vitamin K or prothrombin complex concentrates. The anti-hemostatic effect of aspirin and other anti-platelet strategies can be corrected by the administration of platelet concentrate or desmopressin, if needed. Recently, a new generation of anticoagulants with a greater specificity towards activated coagulation factors has been introduced and most of these agents are presently being evaluated in clinical studies. The new generation anticoagulants include specific inhibitors of factor IIa, factor Xa (including pentasaccharides) and agents that interfere with tissue factor activity. A limitation of this new class of anticoagulants may be the lack of an appropriate strategy to reverse the effect if a bleeding event occurs, although in some cases the administration of recombinant factor VIIa may be an option.

The c.-1639g>A polymorphism of the VKORC1 gene and his influence on the therapeutic response during oral anticoagulants use

Background/Aim. A single nucleotide polymorphism c.- 1639G>A in the promoter region of vitamin K-epoxide reductase (VKORC1) gene has been found to account for most of the variability in response to oral anticoagulants (OA). The aim of the study was to determine the incidence and the effect of c.-1639G>A polymorphism on the acenocoumarol dosage requirements in the group of patients under stable anticoagulation, and to estimate the variability in response to OA. Methods. Our study included 200 consecutive patients requiring low (n = 43), medium (n = 127) and high (n = 30) acenocoumarol dose. Results. Out of 43 low dose patients, 40 (93 %) carried the A allele. The A allele was less frequent in the group of 30 patients requiring high dose: among these patients 13 (43.3%) carried the A allele in the heterozygous form and none of them carried AA genotype. The patients with GG genotype required 2.6 times higher dose than the patients carriers of AA genotype (p < 0.0001). In 33 patients (16.5%) the overdose occurred during the initiation of anticoagulant therapy and in 11 patients (5.5%) it was associated with bleeding. Out of the group of 33 overdosed patients, 27 and 6 patients carried AA and GA genotype, respectively (p < 0.000001). Conclusion. VKORC1 significantly influenced OA dose and predicted individuals predisposed to unstable anticoagulation. The carriers of AA genotype required 2.6 time lower doses of OA than the carriares of GG genotype. Pharmacogenetic testing could predict a high risk of overdose among 28.5 % of our patients - carriers of AA genotype, before anticoagulation therapy initiation.

Warfarin reversal in anticoagulant-associated intracerebral hemorrhage

Anticoagulant-associated intracerebral hemorrhage (ICH) is a devastating disease, causing death in half of patients and permanent disability in the majority of survivors. The finding that patients often continue bleeding after hospital presentation offers the possibility that emergency warfarin reversal may improve outcomes. As no clinical trials have demonstrated the superiority of any one treatment strategy, various treatment options are available. Intravenous vitamin K is the definitive therapy; however, as monotherapy it can require many hours to take effect. Therefore, it is often considered an adjunct agent. Coagulation factors can be repleted with fresh frozen plasma (FFP), which is widely available and relatively low cost, but can require substantial time to deliver in real-world settings. A number of coagulation factor products collectively termed prothrombin complex concentrates (PCCs) are widely available that can rapidly provide many or all the vitamin K-dependent coagulation factors. Recombinant activated factor VII is used in many centers for this purpose, as it is thought to provide a procoagulant effect that may compensate for the lack of the other critical factors. Until clinical trials demonstrate the superiority of any one means of warfarin reversal, a number of expert guidelines from national organizations are available to help local providers guide therapy. At our institution, we have focused on improving the rapid and reliable delivery of a combination of intravenous vitamin K and FFP, with continued re-dosing until the desired INR lowering is achieved.

[Bleeding risk and perioperative management of patients anticoagulated with vitamin K antagnosists]

There is little consensus on the optimal perioperative management for most patients on oral anticoagulation with vitamin K antagonists. Bridging therapy is not recommended for the majority of patients on oral anticoagulation as most are at low risk for perioperative stroke. Though most clinicians choose an aggressive perioperative strategy for patients with high thromboembolic risk (e.g., mechanical mitral valve replacement) by withholding warfarin perioperatively and the use of full-dose heparin, prophylactic dose heparin is given for lower risk cagegories (e.g., bileaflet aortic valve replacement and atrial fibrillation). The amount of increase in postoperative major bleeding when full-dose anticoagulation is administered soon after surgery is the factor in the decision with the least available data. The optimal method for returning the International Normalized Ratio (INR) to the desired range preoperatively depends upon its degree of initial elevation and whether or not clinically significant bleeding is present. Rapid reversal of excessive anticoagulation should be undertaken in patients with serious bleeding at any degree of anticoagulation. Vitamin K therapy is an effective treatment for INR prolongation in patients with vitamin K-associated coagulopathy; coagulation factor replacement is required, in addition, in patients with major bleeding or with an indication for immediate correction of their INR. Patients receiving prothrombin complex concentrate have a more rapid and more complete reversal of their anticoagulation as compared with fresh frozen plasma.

Laryngeal dyspnea in relation to an interaction between acenocoumarol and topical econazole lotion

BACKGROUND

Bleeding is the most serious complication of oral anticoagulant therapy used for the prevention of thromboembolic complications. Drug-drug interactions are an important concern, as they may increase drug toxicity and, in the case of anticoagulant therapies, increase the risk of hemorrhage.

CASE SUMMARY

An 84-year-old woman presented to the emergency department with a bilateral cervical hematoma and symptoms of upper-airway obstruction that had been increasing for 72 hours, with dyspnea and difficulty speaking developing in the previous 24 hours. Transnasal fiberoptic laryngoscopy revealed a significant laryngeal hematoma, as well as a hematoma on the floor of the mouth and in the tonsil area. Laboratory abnormalities included a prothrombin time < 10%, an international normalized ratio exceeding the laboratory limits, and an activated partial thromboplastin time >120 seconds. The patient had been receiving acenocoumarol 4 mg/d for 10 years for episodes of atrial fibrillation and recurrent deep venous thrombosis. Seventeen days earlier, she had received a prescription for topical econazole lotion 1% to be applied 3 times daily for 1 month to treat a dermatitis affecting 12% of the body surface. The patient was admitted to the intensive care unit for treatment of respiratory failure, where oxygen was delivered by face mask. The coagulation disorders were treated with prothrombin complex concentrate 30 IU/kg IV and vitamin K1 10 mg IV, and values normalized within 36 hours. Surgical evacuation of the laryngeal hematoma was not necessary. After 48 hours, improvement in the patient's respiratory symptoms allowed transfer to the ear, nose, and throat unit, where daily endoscopic examination was performed. Aspirin was substituted for acenocoumarol, and the patient returned home after 10 days without sequelae. Based on a Naranjo score of 7, this episode was probably related to an interaction between acenocoumarol and econazole.

CONCLUSION

This report describes a case of a probable interaction between topical econazole lotion 1% and acenocoumarol that resulted in overanticoagulation and a life-threatening laryngeal hematoma in this elderly patient.

Bleeding risk and the management of bleeding complications in patients undergoing anticoagulant therapy: focus on new anticoagulant agents

For more than 60 years, heparin and coumarin have been mainstays of anticoagulation therapy. They are widely available, inexpensive, effective, and have specific antidotes but are regarded as problematic because of their need for careful monitoring. In addition, coumarin has a delayed onset of action, interacts with many medications, has a narrow therapeutic window, and is paradoxically prothrombotic in certain settings (ie, can precipitate “coumarin necrosis”). Heparin may require monitoring of its therapeutic effect and can also cause thrombosis (heparin-induced thrombocytopenia/thrombosis syndrome). These limitations have led to the development of new anticoagulants with the potential to replace current agents. These newer agents fall into 2 classes, based on whether they are antithrombin dependent (low-molecular-weight heparin, fondaparinux) or antithrombin independent (direct inhibitors of factor Xa and thrombin [factor IIa]). This paper addresses newer anticoagulants, reviewing their efficacy and limitations, and focuses on the risk of major bleeding that may complicate their use. In contrast to heparin and coumarin, none of these newer agents has a specific antidote that completely reverses its anticoagulant effect. Available data on the efficacy and safety of current and experimental agents for anticoagulant reversal are reviewed, and a plan for management of anticoagulant-induced bleeding is presented.

Vitamin K and thrombosis

Vitamin K was discovered in the 1930s during cholesterol metabolism experiments in chickens. It is a fat-soluble vitamin which occurs naturally in plants as phylloquinone (vitamin K1) and is produced by gram-negative bacteria in the human gastrointestinal tract as menaquinone (vitamin K2). This vitamin was found to be essential for normal functioning of hemostasis. In addition, a number of clinical conditions in which vitamin K deficiency was found to be the underlying pathophysiologic problem were discovered. These conditions include hemorrhagic disease of the newborn, obstructive jaundice, and malabsorption syndromes. The importance of this vitamin has become more apparent with the discovery of the anticoagulant warfarin which is a vitamin K antagonist. There are millions of patients on this therapy for a variety of thrombogenic conditions such as atrial fibrillation, deep vein thrombosis, pulmonary embolism, and prosthetic cardiac valves. The wide use of this narrow therapeutic index drug has resulted in significant risk for major bleeding. Vitamin K serves as one of the major reversing agent for patients over-anticoagulated with warfarin. In the past few years, research has focused on new areas of vitamin K metabolism, which include bone and endovascular metabolism; cell growth, regulation, migration, and proliferation; cell survival, apoptosis, phagocytosis, and adhesion. These new areas of research highlight the significance of vitamin K but raise new clinical questions for patients who must be maintained on long-term warfarin therapy.

Key concepts in the management of difficult hemorrhagic cases

Goals of hemorrhage management involve promoting coagulation and reducing fibrinolysis to enhance clot formation and stability, and minimizing hemorrhagic expansion to reduce the likelihood of adverse outcomes. The optimal hemostatic regimen to obtain these goals will differ according to the clinical scenario. Two hypothetical cases of patients with hemorrhage are presented that are typical of those encountered by clinical pharmacists who practice in centers that treat trauma or surgical patients or patients in need of emergency or critical care because of serious bleeding. To maximize therapy, the clinician must be aware of how best to clinically apply hemostatic agents, their comparative benefits and disadvantages, and the optimal methods for monitoring their effectiveness and toxicities.

Emergency correction of coagulation before major surgery in two elderly patients on oral anticoagulation

Recommendations for urgent reversal of oral anticoagulation with vitamin K1 antagonists are largely derived from case series employing empirical dosing regimens with vitamin K1 and prothrombin complex concentrates. Data on the use of prothrombin complex concentrates in this indication are scarce in the elderly who are at high risk of both hemorrhagic and thrombotic complications. The two cases presented here describe patients older than 75 years who underwent rapid International Normalized Ratio (INR) reversal with prothrombin complex concentrates for surgical treatment of a bleeding ruptured spleen and for emergency surgery of a dissecting aorta. Both patients had their INRs rapidly corrected to <or= 1.6 and underwent operation without complications. Evidence on treatment of patients who present with elevated INR and who have major bleeding or need to undergo emergency surgery is based mainly on observational studies. The two elderly patients presented here underwent successful emergency surgery after their INRs had been corrected with the intravenous use of vitamin K1 in combination with prothrombin complex concentrate that was administered according to current guideline recommendations.