Evidence-based management of anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

Increased risk of volume overload with plasma compared with four-factor prothrombin complex concentrate for urgent vitamin K antagonist reversal

BACKGROUND

Plasma is commonly used for vitamin K antagonist (VKA) reversal, but observational studies suggest that it is associated with transfusion-related adverse reactions (e.g., volume overload). However, this issue has not previously been addressed in a randomized controlled trial (RCT).

STUDY DESIGN AND METHODS

Factors associated with volume overload were examined using data from two Phase IIIb RCTs comparing plasma with four-factor prothrombin complex concentrate (4F-PCC, Beriplex/Kcentra, CSL Behring) for urgent VKA reversal. VKA-treated patients with major bleeding (NCT00708435) or requiring an urgent surgical or invasive procedure (NCT00803101) were randomly assigned (1:1) to receive either plasma or 4F-PCC, concomitant with vitamin K. Adverse events (AEs) and serious AEs were prospectively captured up to Day 10 and 45, respectively. Volume overload predictors were evaluated on a univariate and multivariate basis.

RESULTS

A total of 388 patients (4F-PCC, n = 191; plasma, n = 197) were enrolled. Volume overload occurred in 34 (9%) patients (4F-PCC, n = 9; plasma, n = 25). In univariate analyses, use of plasma (vs. 4F-PCC), use of nonstudy plasma and/or platelets, race, history of congestive heart failure (CHF), and history of renal disease were associated with volume overload. In multivariate analyses, use of plasma (vs. 4F-PCC), history of CHF, and history of renal disease were independent volume overload predictors. In an additional analysis restricted to volume overload events recorded up to Day 7, only use of plasma (vs. 4F-PCC) was an independent volume overload predictor.

CONCLUSIONS

After adjusting for other potential risk factors, plasma use was independently associated with a greater risk of volume overload than 4F-PCC in patients requiring urgent VKA reversal.

Profile of betrixaban and its potential in the prevention and treatment of venous thromboembolism

Venous thromboembolism (VTE), which includes deep vein thrombosis and pulmonary embolism, is a common and potentially preventable cause of morbidity and mortality. Unfractionated heparin, low-molecular-weight heparin, and warfarin have been the cornerstone of VTE prevention and treatment but are being replaced by recently approved non-vitamin K antagonist oral anticoagulants (NOACs): dabigatran, rivaroxaban, apixaban, and edoxaban. The NOACs are at least as effective and as safe as heparins and warfarin for VTE prevention and treatment and are more convenient because they have a low propensity for food and drug interactions and are given in fixed doses without routine coagulation monitoring. The remaining limitations of currently available NOACs include their dependence on renal and hepatic function for clearance, and the lack of an approved antidote. Betrixaban is a new NOAC with distinct pharmacological characteristics: minimal renal clearance, minimal hepatic metabolism, and long half-life. It has undergone successful Phase II studies in orthopedic thromboprophylaxis, and in stroke prevention in atrial fibrillation. Currently, it is being evaluated in a Phase III trial of extended thromboprophylaxis in medical patients (APEX study). In this article, we describe the development of betrixaban, review its pharmacological profile, discuss the results of clinical trials, and examine its potential for VTE prevention and treatment.

Initial thrombolysis treatment compared with anticoagulation for acute intermediate-risk pulmonary embolism: a meta-analysis

BACKGROUND

The use of thrombolysis in patients with acute, intermediate-risk pulmonary embolism (PE) remains controversial. This meta-analysis compared the efficacy and safety of thrombolysis and anticoagulation treatments for intermediate-risk PE patients.

METHODS

Two investigators independently reviewed the literature and collected data from randomized controlled trials (RCTs) of thrombolysis for intermediate-risk PE in the PubMed, MEDLINE, EMBASE, the Cochrane Library, and Chinese Biomedical Literature Databases (CBM).

RESULTS

A total of 1,631 intermediate-risk PE patients from seven studies were included. Significant differences were not found regarding the 30-day, all-cause mortality rates between the thrombolytic and anticoagulant groups [odds ratio (OR), 0.60; 95% confident interval (CI), 0.34-1.06; P=0.08]. The rate of clinical deterioration in the thrombolytic group was lower than that in the anticoagulant group (OR, 0.27; 95% CI, 0.18-0.41; P<0.01). Recurrent PE in the thrombolytic group was also significantly lower than that in the anticoagulant group (OR, 0.34; 95% CI, 0.15-0.77; P=0.01). Comparing the thrombolytic and anticoagulation groups, the incidence of minor bleeding was significantly higher in the thrombolytic group (OR, 5.33; 95% CI, 2.85-9.97; P<0.00001), but there were no difference in the incidences of major bleeding events (OR, 2.07; 95% CI, 0.60-7.16; P=0.25).

CONCLUSIONS

Thrombolytic treatment for intermediate-risk PE patients, if not contraindicated, could reduce clinical deterioration and recurrence of PE, and trends towards a decrease in all-cause, 30-day mortality. Despite thrombolytic treatment having an increased total bleeding risk, there was no difference in the incidence of major bleeding events, compared with patients receiving anticoagulation treatment.

Survey of pharmacists' subtherapeutic INR management and anticoagulation bridging practices

WHAT IS KNOWN AND OBJECTIVE

Despite extensive warfarin use, optimal management of subtherapeutic international normalized ratios (INRs) remains unclear. This study assessed the differences in bridging practices among pharmacists with varying levels of experience, residency training and prescribing privileges.

METHODS

An electronic survey was distributed to two ambulatory care pharmacist e-mail lists. Respondents indicated if they would utilize parenteral anticoagulation bridging in 16 clinical scenarios at three therapeutic time points. The scenarios included patients with atrial fibrillation (AFib) (CHADS₂ score of 3-4), AFib (CHADS₂ score of 5-6) and venous thromboembolism (VTE). The AFib time points were as follows: anticoagulation initiation, early phase (<1 month) and maintenance phase (>1 month). VTE time points included early phase (<1 month), months 2-3 and maintenance phase (>3 months).

RESULTS AND DISCUSSION

The survey was completed by 143 respondents. In only three of the scenarios did >50% of respondents indicate they would utilize parenteral anticoagulation bridging. No statistically significant differences in bridging practices were identified between pharmacists providing anticoagulation services in different clinic settings. However, there were significant differences in bridging practices between pharmacists with varying levels of experience, residency training and prescribing privileges in some, but not all of the scenarios.

WHAT IS NEW AND CONCLUSION

The standards of care for subtherapeutic INRs warrant further definition.

Thromboembolic Events After Vitamin K Antagonist Reversal With 4-Factor Prothrombin Complex Concentrate: Exploratory Analyses of Two Randomized, Plasma-Controlled Studies

STUDY OBJECTIVE

We evaluated thromboembolic events after vitamin K antagonist reversal in post hoc analyses of pooled data from 2 randomized trials comparing 4-factor prothrombin complex concentrate (4F-PCC) (Beriplex/Kcentra) with plasma.

METHODS

Unblinded investigators identified thromboembolic events, using standardized terms (such as "myocardial infarction," "deep vein thrombosis," "pulmonary embolism," and "ischemic stroke"). A blinded safety adjudication board reviewed serious thromboembolic events, as well as those referred by an independent unblinded data and safety monitoring board. We descriptively compared thromboembolic event and patient characteristics between treatment groups and included detailed patient-level outcome descriptions. We did not power the trials to assess safety.

RESULTS

We enrolled 388 patients (4F-PCC: n=191; plasma: n=197) in the trials. Thromboembolic events occurred in 14 of 191 patients (7.3%) in the 4F-PCC group and 14 of 197 (7.1%) in the plasma group (risk difference 0.2%; 95% confidence interval -5.5% to 6.0%). Investigators reported serious thromboembolic events in 16 patients (4F-PCC: n=8; plasma: n=8); the data and safety monitoring board referred 2 additional myocardial ischemia events (plasma group) to the safety adjudication board for review. The safety adjudication board judged serious thromboembolic events in 10 patients (4F-PCC: n=4; plasma: n=6) as possibly treatment related. There were 8 vascular thromboembolic events in the 4F-PCC group versus 4 in the plasma group, and 1 versus 6 cardiac events, respectively. Among patients with thromboembolic events, 3 deaths occurred in each treatment group. All-cause mortality for the pooled population was 13 per group. We observed no relationship between thromboembolic event occurrence and factor levels transiently above the upper limit of normal; there were no notable differences in median factor or proteins C and S levels up to 24 hours postinfusion start in patients with and without thromboembolic events.

CONCLUSION

The incidence of thromboembolic events after vitamin K antagonist reversal with 4F-PCC or plasma was similar and independent of coagulation factor levels; small differences in the number of thromboembolic event subtypes were observed between treatment groups.

Patients' and physicians' satisfaction with a pharmacist managed anticoagulation program in a family medicine clinic

BACKGROUND

A pharmacist managed anticoagulation service was initiated in a multi-physician family medicine clinic in December 2006. In order to determine the patient and physician satisfaction with the service, a study was designed to describe the patients' satisfaction with the warfarin education and management they received from the pharmacist, and to describe the physicians' satisfaction with the level of care provided by the pharmacist for patients taking warfarin. A self-administered survey was completed by both eligible patients receiving warfarin and physicians prescribing warfarin between December 2006 and May 2008. The patient survey collected information on patient demographics, satisfaction with warfarin education and daily warfarin management. The physician survey collected data about the satisfaction with patient education and daily anticoagulation management by the pharmacist.

RESULTS

Seventy-six of 94 (81%) patients completed the survey. Fifty-nine percent were male with a mean age of 65 years (range 24-90). Ninety-six percent agreed/strongly agreed the pharmacist did a good job teaching the importance of warfarin adherence, the necessity of INR testing and the risks of bleeding. Eighty-five percent agreed/strongly agreed the risk of blood clots was well explained, 79% felt the pharmacist did a good job teaching about dietary considerations and 77% agreed/strongly agreed the pharmacist explained when to see a doctor. All patients felt the pharmacist gave clear instructions on warfarin dosing and INR testing. Four of nine physicians (44%) completed the survey. All agreed/strongly agreed the pharmacist was competent in the care provided, were confident in the care their patients received, would like the pharmacist to continue the service, and would recommend this program to other clinics.

CONCLUSIONS

Patients and family physicians were satisfied with the pharmacist managed anticoagulation program and recommended continuation of the program. These results support the role of the pharmacist in the management of anticoagulation in a multi-physician family medicine clinic.

New strategies for effective treatment of vitamin K antagonist-associated bleeding

Vitamin K antagonists have been used as oral anticoagulants in the treatment and prevention of thromboembolic events for over half a century. Although vitamin K antagonists are effective in the management of thromboembolic events, the need for routine monitoring and the associated risk of bleeding has resulted in the development and licensing of direct oral anticoagulants for specific clinical indications. Despite these developments, vitamin K antagonists remain the oral anticoagulants of choice in many clinical conditions. Severe bleeding associated with oral anticoagulation requires urgent reversal. Several options for the reversal of vitamin K antagonist exist, including vitamin K, prothrombin complex concentrates and plasma. In this manuscript, we review current evidence and provide physicians with treatment strategies for more effective management of vitamin K antagonist-associated bleeding.

Design and rationale for RE-VERSE AD: A phase 3 study of idarucizumab, a specific reversal agent for dabigatran

Idarucizumab, a Fab fragment directed against dabigatran, produced rapid and complete reversal of the anticoagulation effect of dabigatran in animals and in healthy volunteers. The Study of the REVERSal Effects of Idarucizumab in Patients on Active Dabigatran (RE-VERSE AD™) is a global phase 3 prospective cohort study aimed at investigating idarucizumab in dabigatran-treated patients who present with uncontrollable or life-threatening bleeding, and in those requiring urgent surgery or intervention. We describe the rationale for, and design of the trial (clinicaltrials.gov NCT02104947).

Guidelines for the Management of Spontaneous Intracerebral Hemorrhage: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

PURPOSE

The aim of this guideline is to present current and comprehensive recommendations for the diagnosis and treatment of spontaneous intracerebral hemorrhage.

METHODS

A formal literature search of PubMed was performed through the end of August 2013. The writing committee met by teleconference to discuss narrative text and recommendations. Recommendations follow the American Heart Association/American Stroke Association methods of classifying the level of certainty of the treatment effect and the class of evidence. Prerelease review of the draft guideline was performed by 6 expert peer reviewers and by the members of the Stroke Council Scientific Oversight Committee and Stroke Council Leadership Committee.

RESULTS

Evidence-based guidelines are presented for the care of patients with acute intracerebral hemorrhage. Topics focused on diagnosis, management of coagulopathy and blood pressure, prevention and control of secondary brain injury and intracranial pressure, the role of surgery, outcome prediction, rehabilitation, secondary prevention, and future considerations. Results of new phase 3 trials were incorporated.

CONCLUSIONS

Intracerebral hemorrhage remains a serious condition for which early aggressive care is warranted. These guidelines provide a framework for goal-directed treatment of the patient with intracerebral hemorrhage.

Four-factor prothrombin complex concentrate versus plasma for rapid vitamin K antagonist reversal in patients needing urgent surgical or invasive interventions: a phase 3b, open-label, non-inferiority, randomised trial

BACKGROUND

Rapid reversal of vitamin K antagonist (VKA)-induced anticoagulation is often necessary for patients needing urgent surgical or invasive procedures. The optimum means of VKA reversal has not been established in comparative clinical trials. We compared the efficacy and safety of four-factor prothrombin complex concentrate (4F-PCC) with that of plasma in VKA-treated patients needing urgent surgical or invasive procedures.

METHODS

In a multicentre, open-label, phase 3b randomised trial we enrolled patients aged 18 years or older needing rapid VKA reversal before an urgent surgical or invasive procedure. We randomly assigned patients in a 1:1 ratio to receive vitamin K concomitant with a single dose of either 4F-PCC (Beriplex/Kcentra/Confidex; CSL Behring, Marburg, Germany) or plasma, with dosing based on international normalised ratio (INR) and weight. The primary endpoint was effective haemostasis, and the co-primary endpoint was rapid INR reduction (≤1·3 at 0·5 h after infusion end). The analyses were intended to evaluate, in a hierarchical fashion, first non-inferiority (lower limit 95% CI greater than -10% for group difference) for both endpoints, then superiority (lower limit 95% CI >0%) if non-inferiority was achieved. Adverse events and serious adverse events were reported to days 10 and 45, respectively. This trial is registered at ClinicalTrials.gov, number NCT00803101.

FINDINGS

181 patients were randomised (4F-PCC n=90; plasma n=91). The intention-to-treat efficacy population comprised 168 patients (4F-PCC, n=87; plasma, n=81). Effective haemostasis was achieved in 78 (90%) patients in the 4F-PCC group compared with 61 (75%) patients in the plasma group, demonstrating both non-inferiority and superiority of 4F-PCC over plasma (difference 14·3%, 95% CI 2·8-25·8). Rapid INR reduction was achieved in 48 (55%) patients in the 4F-PCC group compared with eight (10%) patients in the plasma group, demonstrating both non-inferiority and superiority of 4F-PCC over plasma (difference 45·3%, 95% CI 31·9-56·4). The safety profile of 4F-PCC was generally similar to that of plasma; 49 (56%) patients receiving 4F-PCC had adverse events compared with 53 (60%) patients receiving plasma. Adverse events of interest were thromboembolic adverse events (six [7%] patients receiving 4F-PCC vs seven [8%] patients receiving plasma), fluid overload or similar cardiac events (three [3%] patients vs 11 [13%] patients), and late bleeding events (three [3%] patients vs four [5%] patients).

INTERPRETATION

4F-PCC is non-inferior and superior to plasma for rapid INR reversal and effective haemostasis in patients needing VKA reversal for urgent surgical or invasive procedures.

FUNDING

CSL Behring.

Coagulation assessment with the new generation of oral anticoagulants

Long-term oral anticoagulant (OAC) therapy is used for the treatment and prevention of thrombosis and thromboembolism. As OAC use is so widespread, emergency physicians are likely to encounter patients on anticoagulant therapy in the emergency department (ED) on a regular basis, either for the same reasons as the population in general or as a result of the increased bleeding risk that OAC use entails.

The vitamin K antagonist warfarin has been the standard OAC for several decades, but recently, the newer agents dabigatran etexilate, rivaroxaban and apixaban (collectively, novel OACs, non-vitamin K OACs, or simply ‘NOACs’) have become available for long-term use. Protocols for assessing and managing warfarin-treated patients in the ED are well established and include international normalised ratio (INR) testing, which helps guide patient management. However, the INR does not give an accurate evaluation of coagulation status with NOACs, and alternative tests are therefore needed for use in emergency settings. This paper discusses what information the INR provides for a patient taking warfarin and which coagulation tests can guide the physician when treating patients on one of the NOACs, as well as other differences in emergency anticoagulation management.

Clinical Application of Genotype-guided Dosing of Warfarin in Patients with Acute Stroke

BACKGROUND

Patients with certain types of stroke need urgent anticoagulation and it is extremely important for them to achieve fast and stable anticoagulant effect and receive individualized treatment during the initiation of warfarin therapy.

METHODS

We conducted a prospective study among 210 acute stroke patients who had an indication for anticoagulation and compared the impact of CYP2C9 and VKORC1 genotype-guided warfarin dosing (PhG) with fixed dosing (NPhG) on anticoagulation control and clinical outcome between groups.

RESULTS

PhG achieved target INR values earlier, i.e., on average in 4.2 (4.1-4.7, 95% CI) days compared to NPhG (5.2 days [4.7-6.4, 95% CI]) (p = 0.0009), spent a higher percentage of time in the therapeutic INR range (76.3% [74.7-78.5, 95% CI] vs. 67.1% [64.5-69.6, 95% CI] in NPhG), and spent less time overdosed (INR > 3.1) (PhG 0.4 [0.1-0.7, 95% CI], NPhG 1.7 [1.1-2.3, 95% CI] days; p >0.000). PhG reached stable maintenance dose faster (10 [9.9-10.7, 95% CI] vs. 13.9 [13.3-14.7, 95% CI] days in controls; p = 0.0049) and had a better clinical outcome in relation to neurological deficit on admission as compared to NPhG.

CONCLUSION

We confirmed that warfarin therapy with genotype-guided dosing instead of fixed dosing reduces the time required for stabilization and improves anticoagulant control with better clinical outcome in early stages of warfarin therapy introduction among acute stroke patients, which is essential for clinical practice.

An unusual occurrence: a case of venous thromboembolism in pregnancy associated with heterotaxy syndrome

BACKGROUND

Heterotaxy is a relatively uncommon congenital anomaly that is usually diagnosed incidentally on imaging studies in adults. We present an unusual case of venous thromboembolism in a 26 year old pregnant female with Heterotaxy syndrome.

CASE PRESENTATION

A 26 year-old pregnant female at 13 weeks gestation suffered cardiac arrest with successful cardiac resuscitation and return of spontaneous circulation. The cardiac arrest was secondary to massive pulmonary embolism requiring thrombolytic therapy and stabilization of hemodynamics. She had extensive evaluation to determine the etiology for the pulmonary embolism and was noted to have an anatomic variation consistent with heterotaxy syndrome on imaging studies. After thrombolysis the patient was treated with UFH and then switched to enoxaparin without complication until 25 weeks of gestation when she experienced worsening abdominal pain with associated headaches, lightheadedness and elevated blood pressures needing elective induction of labor. The infant died shortly after delivery. The anticoagulation was continued for additional 3 months and she was subsequently placed on low dose aspirin to prevent recurrent venous thromboembolic episodes. She is currently stable on low dose aspirin and is into her third year after the venous thromboembolism without any recurrence.

CONCLUSION

To our knowledge, this is the first reported case of venous thromboembolism in pregnancy associated with heterotaxy syndrome. A discussion on pathophysiology of venous thromboembolism in pregnancy and heterotaxy syndrome has been undertaken along with treatment approach in such situations.

Overview of venous thrombosis in inflammatory bowel disease

Thrombosis in inflammatory bowel disease (IBD) is an increasingly noted extraintestinal manifestation with high morbidity and mortality. While controlling the activity of the disease with the appropriate therapy, thromboembolism prophylaxis should be applied to all patients. All common risk factors for thromboembolism are also valid for patients with IBD; however, it is clear that uncontrolled disease and hospitalization are major disease-specific risk factors for venous thromboembolism in patients with IBD. Pharmacological thromboprophylaxis with currently available anticoagulants does not increase the risk of further bleeding in patients with IBD with mild-to-moderate bleeding. In severe bleeding or with increased risk of further bleeding due to other comorbid conditions, thromboprophylaxy with mechanical methods should be the treatment option. Whether thrombosis is the cause or the result of intestinal inflammation remains to be elucidated, and other issues in the etiology, such as the role of intestinal flora in thrombosis pathogenesis, will be the subject of future studies.

Variability in the international normalised ratio (INR) in patients with antiphospholipid syndrome and positive lupus anticoagulant: should the INR targets be higher?

We present the case of a 34-year-old woman with a history of antiphospholipid syndrome with triple positivity for antiphospholipid antibodies, who had multiple thrombotic events, predominantly pulmonary embolic events, despite treatment with enoxaparin. She is currently on warfarin, with which she has been adequately controlled most of the time, presenting with only one haemorrhagic event consisting of haematuria and prolonged international normalised ratio (INR) without bleeding. This kind of patient represents a challenge for clinicians, particularly due to INR therapeutic targets, which should be higher than recommended in other patients due to the lupus anticoagulant positivity.

Evaluation of a fixed, weight-based dose of 3-factor prothrombin complex concentrate without adjunctive plasma following warfarin-associated intracranial hemorrhage

INTRODUCTION

Data regarding use of prothrombin complex concentrate (PCC) for international normalization ratio (INR) reversal in warfarin-associated intracranial hemorrhage (wICH) is variable with regards to dosages, adjunctive agents, and product choice. In 2012, we implemented a fixed, weight-based [30 IU/kg] dosing protocol of 3-factor PCC (3PCC) utilizing a rapid infusion rate and no requirement for fresh frozen plasma (FFP) following factor product administration. We aimed to evaluate the impact of this protocol on immediate and delayed INR reversal in patients admitted with wICH in the absence of FFP co-administration.

METHODS

We conducted a retrospective review of patients receiving 3PCC following wICH between January 1, 2012 and December 10, 2013. The primary objective was to determine the percentage of patients achieving goal INR (≤1.4) following 3PCC administration. Patients were excluded if their bleed was not intracranial in origin, received a dose outside of the specified protocol, or were given FFP as an adjunctive agent.

RESULTS

We included 35 patients with a mean presenting INR of 3.2 ± 1.3. Thirty patients (85.7%) achieved goal INR (≤1.4) following one dose of 3PCC. The mean INR after infusion of 3PCC was 1.3 ± 0.2. The median duration between 3PCC infusion and subsequent INR was 48.0 min (30-70.1 min). Vitamin K was utilized in 33 (94.3%) patients. No patient experienced a thromboembolic event within 7 days of 3PCC administration.

CONCLUSIONS

Fixed, weight-based dosing of 3PCC without adjunctive FFP resulted in high rates of complete INR reversal without significant adverse events.

A guide to the use of anticoagulant drugs in children

Increasing thrombotic complications in children with complex medication conditions have led to more widespread use of anticoagulants [Raffini et al. in Pediatrics 124(4):1001-8, 2009]. While current guidelines for the management of antithrombotic therapy in neonates and children exist, they are based on low- and very low-quality evidence [Monagle et al. in Chest 141(2 Suppl):e737-801S, 2012]. Despite numerous differences, current anticoagulation practice is largely extrapolated from adult studies. This is sub-optimal, particularly in neonates who have a rapidly evolving hemostatic system. The majority of pediatric patients have underlying medical conditions that may significantly influence drug choice and bleeding risk. This article reviews the use of anticoagulants in children with thrombosis, focusing on practical aspects such as dosing, monitoring, and complications. Low molecular weight heparin has become the preferred anticoagulant in children, although unfractionated heparin and warfarin remain frequently used. Other anticoagulants, including fondaparinux, direct thrombin inhibitors, and the newer target-specific oral anticoagulants are also discussed. Given the many unique challenges surrounding the use of anticoagulants in children, pediatric hospitals should have written practice guidelines as well as experienced providers to care for children with thrombosis. This is an evolving field, and further studies of the use of anticoagulants in neonates and children are greatly needed to help optimize care.

Spontaneous iliopsoas muscle haematoma as a complication of anticoagulation in acute cerebral venous thrombosis: to stop or not to stop (the anticoagulation)?

Spontaneous iliopsoas muscle haematoma is an infrequent complication of anticoagulation, potentially causing neurological dysfunction through compression of the femoral nerve or lumbar plexus. The authors report the case of a puerperal woman admitted for an extensive cerebral venous thrombosis. Anticoagulation was started, with clinical improvement. The patient later reported low back pain irradiating to the right thigh and developed neurological impairment consistent with lumbar plexus dysfunction. A pelvic CT scan revealed a right iliopsoas muscle haematoma. Considering the risk of anticoagulation suspension, a conservative approach was chosen, with maintenance of anticoagulation. Clinical and functional improvement occurred, with mild right hip and knee flexion paresis as sequelae. Anticoagulation complications are challenging, especially when interruption of anticoagulation may threaten vital and functional outcomes. Therefore, a careful evaluation is essential, since no clinical guidelines are available. In this case, continuing anticoagulation provided a good functional outcome.

Factors influencing warfarin response in hospitalized patients

The objective of this study was to investigate the influence of simultaneous factors that potentially keep patients far from achieving target INR range at discharge in hospitalized patients. Prospective cross-sectional observational study conducted at the Cardiology Department and Intensive Care Unit (ICU) of the Assiut University Hospitals. One-hundred and twenty patients were enrolled in the study from July 2013 to January 2014. Outcome measures were discharge INRs, bleeding and thromboembolic episodes. Bivariate analysis and multinomial logistic regression were conducted to determine independent risk factors that can keep patients outside target INR range.

Patients who were newly initiated warfarin on hospital admission were given low initiation dose (2.8 mg ± 0.9). They were more likely to have INR values below 1.5 during hospital stay, 13 (27.7%) patients compared with 9 (12.3%) previously treated patients, respectively (p = .034). We found that the best predictors of achieving below target INR range relative to within target INR range were; shorter hospital stay periods (OR, 0.82 for every day increase [95% CI, 0.72–0.94]), being a male patient (OR, 2.86 [95% CI, 1.05–7.69]), concurrent infection (OR, 0.21 [95% CI, 0.07–0.59]) and new initiation of warfarin therapy on hospital admission (OR, 3.73 [95% CI, 1.28–10.9]).

Gender, new initiation of warfarin therapy on hospital admission, shorter hospital stay periods and concurrent infection can have a significant effect on discharge INRs. Initiation of warfarin without giving loading doses increases the risk of having INRs below 1.5 during hospital stay and increases the likelihood of a patient to be discharged with INR below target range. Following warfarin dosing nomograms and careful monitoring of the effect of various factors on warfarin response should be greatly considered.

Potential antidotes for reversal of old and new oral anticoagulants

The prescription of new oral anticoagulants is on the rise. As opposed to vitamin K antagonists and heparins the new agents have single targets in the coagulation cascade, more predictable pharmacokinetics and they lack validated and available antidotes. In general, the new agents have similar or lower bleeding risk than vitamin K antagonists, especially risk of intracranial bleeding. Risk factors for bleeding are typically the same for old and new anticoagulants. Old age, renal dysfunction and concomitant antiplatelet agents seem to be recurring risk factors. Adequate supportive care and temporary removal of all antithrombotic agents constitute the basis for management of serious bleeding complications. With the exception of vitamin K (for vitamin K antagonists) and protamine (for heparin) the same array of prohemostatic agents--unactivated or activated prothrombin complex concentrate, and activated factor VIIa--have been tried for almost all anticocoagulants in different models, and for some agents also in patients, with varying success. Hemodialysis can reduce the level of dabigatran efficiently and activated charcoal may be used for very recent oral ingestion of lipophilic agents. In view of the shorter half life of the new agents compared to warfarin the need for reversal agents may be less critical. Nevertheless, highly specific reversal agents for the thrombin- and factor Xa-inhibitors are under development and might be available within two years.

Oral anticoagulation: a critique of recent advances and controversies

There have recently been significant advances in the field of oral anticoagulation, but these have also led to many controversies. Warfarin is still the commonest drug used for clotting disorders but its use is complicated owing to wide inter-individual variability in dose requirement and its narrow therapeutic index. Warfarin dose requirement can be influenced by both genetic and environmental factors. Two recent randomized controlled trials (RCTs) came to different conclusion regarding the utility of genotype-guided dosing; we critically explore the reasons for the differences. The new generation of oral anticoagulants have been demonstrated to be as efficacious as warfarin, but further work is needed to evaluate their safety in real clinical settings.

An evaluation of intravenous vitamin k for warfarin reversal: are guideline recommendations being followed?

BACKGROUND

Vitamin K antagonists (eg, warfarin) remain the mainstay of anticoagulation therapy in the United States, with over 22 million prescriptions being filled annually. Unfortunately, warfarin therapy is difficult to manage and increases bleeding risk. The 2012 American College of Chest Physicians guidelines created a warfarin reversal algorithm that suggested the stringent use of intravenous vitamin K.

OBJECTIVE

The purpose of this evaluation was to determine the rates of adherence with guideline recommendations in clinical practice.

METHOD

A convenience sample of 3 months of intravenous vitamin K medication administration data (September to November 2013) was obtained to conduct a retrospective review. Patients with underlying hepatic dysfunction or lack of warfarin therapy were excluded. Vitamin K use was evaluated for consistency with the 2012 guidelines.

RESULTS

A total of 364 patients were reviewed and 119 were included. Vitamin K utilization was consistent with guideline recommendations for a total of 30 (25.2%) patients. The most common site of active bleeding requiring reversal was head bleeds, consisting of 56.6% of bleeds. A single dose of 10 mg of vitamin K was the most frequently used dosing strategy. Fresh frozen plasma (73.3%) and four-factor prothrombin complex concentrate (36.7%) were the most commonly used factor products.

CONCLUSION

This evaluation demonstrates that there is a difference between clinical judgment and guideline adherence. True adherence with the guidelines may not be necessary; however, there is room for improvement in both the appropriateness and safety of intravenous vitamin K use.

Warfarin-induced skin necrosis

BACKGROUND

Warfarin is a frequently used oral anticoagulant in the treatment and prevention of various medical conditions. One uncommon adverse effect that can occur following the initiation of therapy is warfarin-induced skin necrosis. Because it is a rare effect with an undetermined pathophysiology of disease, the treatment is not well established.

CASE

A 52-year-old female was prescribed warfarin and enoxaparin for a newly diagnosed deep vein thrombosis (DVT) in the left lower extremity. On day 4 of therapy, the patient had a supra-therapeutic international normalized ratio (INR), prompting the discontinuation of enoxaparin and a decrease in the warfarin dose. The patient returned to the emergency department on day 7 of treatment with a purple, cold, and extremely painful right foot with punctate areas of necrosis and petechiae proximal to the discoloration. The patient's INR was found to be 10.64. Following the diagnosis of warfarin-induced skin necrosis, the patient was administered vitamin K intravenously and fresh frozen plasma (FFP) to reverse the effects of warfarin and promote protein C and S synthesis. Once the patient's INR was no longer supratherapeutic, subcutaneous enoxaparin was re-started as treatment for the known recent DVT. The patient's necrotic foot began to improve and she was discharged home with an anticipated full recovery.

CONCLUSIONS

Based on the proposed pathophysiology of disease, adequate bridge therapy may decrease the likelihood of developing this life-threatening condition. Early recognition and treatment with intravenous vitamin K, FFP or 4-factor prothrombin complex concentrate, and continued wound care are essential to prevent further complications.

Warfarin dose requirements in a patient with the CYP2C9*14 allele

We describe a 64-year-old male of Indian descent with a history of atrial fibrillation who was started on warfarin after hospital admission for acute stroke. He received genotype-guided warfarin dosing as per the standard-of-care at our hospital, with daily dose recommendations provided by the pharmacogenetics service. Genotyping revealed the rare CYP2C9*1/*14 genotype and warfarin insensitive VKORC1 -1639GG and CYP4F2 433Met/Met genotypes. The patient received an initial warfarin loading dose of 4 mg for 2 days, followed by 2-3 mg/day for the following 11 days. He reached a therapeutic international normalized ratio on day 5, which was maintained over the following week. This report adds to the limited data of the effects of the CYP2C9*14 allele on warfarin dose requirements.

Influence of VKORC1 gene polymorphisms on the effect of oral vitamin K supplementation in over-anticoagulated patients

Significant inter-individual variability on the effect of vitamin K to reverse overanticoagulation has been identified. Genetic polymorphisms of the vitamin K epoxide reductase complex subunit 1 (VKORC1) gene might explain in part this variability. The objective of this study was to evaluate the influence of VKORC1 -1639G>A and 3730G>A polymorphisms on the effect of oral vitamin K supplementation in overanticoagulated patients. We performed an interventional trial of oral vitamin K supplementation in over-anticoagulated outpatients (international normalized ratio [INR] ≥ 4). Subjects received vitamin K (2.5-5.0 mg) according to baseline INR and were genotyped by real time polymerase chain reaction (PCR). INR values were determined at 3, 6, 24 and 72 h after supplementation. We evaluated 33 outpatients, 61 % were males, with a mean age of 62 ± 12 years old. There was a significant decrease in INR values over time for both polymorphisms after oral vitamin K. At 3 h after supplementation, patients carrying the G allele for the -1639G>A polymorphism had a greater decrease in INR values compared to AA patients (p < 0.05 for difference among groups; p < 0.001 for time variation; p = 0.001 for time × group interaction), with differences of -1.01 for GG versus AA (p = 0.003) and -0.84 for GA versus AA (p = 0.024). Mean INR value at 24 h was 1.9 ± 0.6 and at 72 h was 2.1 ± 0.7, with no differences among genotypes. No significant interaction was identified between the 3730G>A polymorphism and vitamin K supplementation. Our study indicated that the VKORC1 -1639G>A polymorphism plays a role in the response to acute vitamin K supplementation in over-anticoagulated patients, with faster decrease of INR value in patients carrying the G allele.

Global assays and the management of oral anticoagulation

Coagulation tests range from global or overall tests to assays specific to individual clotting factors and their inhibitors. Whether a particular test is influenced by an oral anticoagulant depends on the principle of the test and the type of oral anticoagulant. Knowledge on coagulation tests applicable in monitoring status and reversal of oral anticoagulation is a prerequisite when studying potential reversal agents or when managing anticoagulation in a clinical setting. Specialty tests based on the measurement of residual activated factor X (Xa) or thrombin activity, e.g., are highly effective for determining the concentration of the new generation direct factor Xa- and thrombin inhibitors, but these tests are unsuitable for the assessment of anticoagulation reversal by non-specific prohemostatic agents like prothrombin complex concentrate (PCC) and recombinant factor VIIa (FVIIa). Global coagulation assays, in this respect, seem more appropriate. This review evaluates the current status on the applicability of the global coagulation assays PT, APTT, thrombin generation and thromboelastography in the management of oral anticoagulation by vitamin K antagonists and the direct factor Xa and thrombin inhibitors. Although all global tests are influenced by both types of anticoagulants, not all tests are useful for monitoring anticoagulation and reversal thereof. Many (pre)analytical conditions are of influence on the assay readout, including the oral anticoagulant itself, the concentration of assay reagents and the presence of other elements like platelets and blood cells. Assay standardization, therefore, remains an issue of importance.

The risks of thromboembolism vs. recurrent gastrointestinal bleeding after interruption of systemic anticoagulation in hospitalized inpatients with gastrointestinal bleeding: a prospective study

OBJECTIVES

Anticoagulants carry a significant risk of gastrointestinal bleeding (GIB). Data regarding the safety of anticoagulation continuation/cessation after GIB are limited. We sought to determine the safety and risk of continuation of anticoagulation after GIB.

METHODS

We conducted a prospective observational cohort study on consecutive patients admitted to the hospital who had GIB while on systemic anticoagulation. Patients were classified into two groups at hospital discharge after GIB: those who resumed anticoagulation and those who had anticoagulation discontinued. Patients in both groups were contacted by phone 90 days after discharge to determine the following outcomes: (i) thromboembolic events, (ii) hospital readmissions related to GIB, and (iii) mortality. Univariate and multivariate Cox proportional hazards were used to determine factors associated with thrombotic events, rebleeding, and death.

RESULTS

We identified 197 patients who developed GIB while on systemic anticoagulation (n=145, 74% on warfarin). Following index GIB, anticoagulation was discontinued in 76 patients (39%) at discharge. In-hospital transfusion requirements, need for intensive care unit care, and etiology of GIB were similar between the two groups. During the follow-up period, 7 (4%) patients suffered a thrombotic event and 27 (14%) patients were readmitted for GIB. Anticoagulation continuation was independently associated on multivariate regression with a lower risk of major thrombotic episodes within 90 days (hazard ratio (HR)=0.121, 95% confidence interval (CI)=0.006-0.812, P=0.03). Patients with any malignancy at time of GIB had an increased risk of thromboembolism in follow-up (HR=6.1, 95% CI=1.18-28.3, P=0.03). Anticoagulation continuation at discharge was not significantly associated with an increased risk of recurrent GIB at 90 days (HR=2.17, 95% CI=0.861-6.67, P=0.10) or death within 90 days (HR=0.632, 95% CI=0.216-1.89, P=0.40).

CONCLUSIONS

Restarting anticoagulation at discharge after GIB was associated with fewer thromboembolic events without a significantly increased risk of recurrent GIB at 90 days. The benefits of continuing anticoagulation at discharge may outweigh the risks of recurrent GIB.

P-glycoprotein: a clue to vitamin K antagonist stabilization

BACKGROUND

Acenocoumarol is a vitamin K antagonist used in some European countries. As warfarin, this drug is characterized by a narrow therapeutic index and a large interindividual variability.

AIM

The objective of this study was to assess the involvement of ABCB1 polymorphisms on acenocoumarol treatment.

MATERIALS & METHODS

An observational cohort study was conducted to assess whether there is an association between the presence of the allelic variants of the ABCB1 gene coding for P-glycoprotein and acenocoumarol stabilization and daily doses during the first 35 days of treatment.

RESULTS

One hundred and fifteen patients met the inclusion criteria. The results of the clinical study showed that carriers of ABCB1 c.3435TT were more rapidly stabilized than wild-type patients (HR: 2.97, 95% CI: 1.23-7.18; p = 0.02). The same tendency was observed for the ABCB1 c.2677GT and 2677TT genotypes compared with ABCB1 c.2677GG. The ABCB1 c.2677TT genotype was also associated with a significant increase in doses of acenocoumarol (p = 0.03), the same tendency was observed with the ABCB1 c.3435TT genotype compared with the wild-type patients.

CONCLUSION

These data suggest that ABCB1 polymorphisms could be involved in the response to acenocoumarol treatment.

Timing of discharge follow-up for acute pulmonary embolism: retrospective cohort study

Introduction

Historically, emergency department (ED) patients with pulmonary embolism (PE) have been admitted for several days of inpatient care. Growing evidence suggests that selected ED patients with PE can be safely discharged home after a short length of stay. However, the optimal timing of follow up is unknown. We hypothesized that higher-risk patients with short length of stay (<24 hours from ED registration) would more commonly receive expedited follow up (≤3 days).

Methods

This retrospective cohort study included adults treated for acute PE in six community EDs. We ascertained the PE Severity Index risk class (for 30-day mortality), facility length of stay, the first follow-up clinician encounter, unscheduled return ED visits ≤3 days, 5-day PE-related readmissions, and 30-day all-cause mortality. Stratifying by risk class, we used multivariable analysis to examine age- and sex-adjusted associations between length of stay and expedited follow up.

Results

The mean age of our 175 patients was 63.2 (±16.8) years. Overall, 93.1% (n=163) of our cohort received follow up within one week of discharge. Fifty-six patients (32.0%) were sent home within 24 hours and 100 (57.1%) received expedited follow up, often by telephone (67/100). The short and longer length-of-stay groups were comparable in age and sex, but differed in rates of low-risk status (63% vs 37%; p<0.01) and expedited follow up (70% vs 51%; p=0.03). After adjustment, we found that short length of stay was independently associated with expedited follow up in higher-risk patients (adjusted odds ratio [aOR] 3.5; 95% CI [1.0–11.8]; p=0.04), but not in low-risk patients (aOR 2.2; 95% CI [0.8–5.7]; p=0.11). Adverse outcomes were uncommon (<2%) and were not significantly different between the two length-of-stay groups.

Conclusion

Higher-risk patients with acute PE and short length of stay more commonly received expedited follow up in our community setting than other groups of patients. These practice patterns are associated with low rates of 30-day adverse events.

Gastrointestinal bleeding and anticoagulant or antiplatelet drugs: systematic search for clinical practice guidelines

Gastrointestinal (GI) bleeding is a frequently encountered and very serious problem in emergency room patients who are currently being treated with anticoagulant or antiplatelet medications. There is, however, a lack of clinical practice guidelines about how to respond to these situations. The goal of this study was to find published articles that contain specific information about how to safely adjust anticoagulant and antiplatelet therapy when GI bleeding occurs.The investigators initiated a global search on the PubMed and Google websites for published information about GI bleeding in the presence of anticoagulant or antiplatelet therapy. After eliminating duplicate entries, the medical articles that remained were screened to narrow the sets of articles to those that met specific criteria. Articles that most closely matched study criteria were analyzed in detail and compared to determine how many actual guidelines exist and are useful.We could provide only minimal information about appropriate therapeutic strategies because no articles provided sufficient specific advice about how to respond to situations involving acute GI bleeding and concurrent use of anticoagulant or antiplatelet drugs. Only 4 articles provided enough detail to be of any use in an emergency situation.Clinical practice guidelines and also clinical trials for GI hemorrhaging should be expanded to state in which situations the use of anticoagulant or antiplatelet drugs should be suspended and the medications should later be resumed, and they should state the level of risk for any particular action.

Evaluation of the appropriateness of frozen plasma usage after introduction of prothrombin complex concentrates: a retrospective study

BACKGROUND

Prothrombin complex concentrates (PCCs) can be used instead of frozen plasma (FP) transfusion to reverse the effect of warfarin. Audits have demonstrated over usage of FP transfusions even before the introduction of PCC. The objective of this study was to determine the appropriateness of current FP transfusion practice in the current era since the introduction of PCCs.

METHODS

A retrospective cohort study of consecutive patients receiving FP over 3 months was carried out. Each episode of FP use over a 24-h period was adjudicated independently by two reviewers as appropriate (consistent with Canadian/AABB guidelines), appropriate but inconsistent with guidelines or inappropriate. Discrepancies were resolved by a third reviewer. Use of FP to reverse warfarin was considered inappropriate. FP usage from previous years was assessed as baseline.

RESULTS

During the study period, 111 FP transfusions were administered. 74.8% of FP usage occurred in the ICU. The proportion of FP transfusions that were deemed appropriate, inconsistent yet appropriate or inappropriate were 33/89 (37.1%), 16/89 (18.0%) and 40/89 (44.9%), respectively, when use of FP for therapeutic plasma exchange was excluded. The most common reasons for inappropriate use were the absence of bleeding with an increased INR or warfarin reversal.

CONCLUSION

Our study is the first to audit FP transfusions in the post-PCC era in Canada. FP usage remains inappropriately high in INR prolongation without another indication or to reverse warfarin. Targeted interventions to reduce FP usage in the future should focus on the ICU and on education about warfarin reversal.

Strategies for urgent reversal of target-specific oral anticoagulants

The direct thrombin inhibitor dabigatran and factor Xa inhibitors rivaroxaban and apixaban are US Food and Drug Administration (FDA)-approved target-specific oral anticoagulants (TSOACs) that have emerged onto the market for use in some indications similar to those for warfarin; in addition, edoxaban is seeking FDA approval. Similar indications include reducing the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation for all 3 agents, for the prevention of deep vein thrombosis that may lead to pulmonary embolism in patients undergoing hip or knee surgery for rivaroxaban and apixaban, and for the treatment and prevention of deep vein thrombosis and pulmonary embolism. As anticoagulants, they are all associated with a risk of bleeding, and, unfortunately, there are no approved antidotes for reversal of these agents. A number of small studies in human subjects and in human/animal models exposed to TSOACs have evaluated the use of activated charcoal, hemodialysis for dabigatran, or clotting factor concentrates for their ability to neutralize the anticoagulant effects or reduce drug concentrations of TSOACs. Clotting factor concentrates that have been used include prothrombin complex concentrates and recombinant factor VII. This review examines studies and case reports evaluating these strategies for expedited or emergent reversal of TSOACs.

Postoperative venous thrombotic events in Asian elderly patients with surgically treated hip fractures with and without chemoprophylaxis

BACKGROUND AND PURPOSE

Chemothromboprophylaxis for hip fracture surgery has been under-practiced in Asia. We investigate the postoperative incidence of venous thrombotic events (VTE) in elderly Asian patients with hip fractures.

PATIENTS AND METHODS

Patients over 60 years old with surgically treated hip fractures were reviewed. All patients followed a hip fracture protocol, which included a post-operative ultrasound Doppler venous scan of both lower limbs five days after injury to detect any deep vein thrombosis (DVT). All patients were given mechanical prophylaxis. Patients who had additional chemoprophylaxis were included.

RESULTS

From 2010 to 2012, 454 patients were reviewed. The overall incidence of DVT was 6.4% (29 patients). The incidence of PE was 1.3% (six patients). There was no significant correlation between DVT and age, gender, race, hypertension, diabetes mellitus, end stage renal failure, type of fracture and operation, preoperative haemoglobin, platelet count or urea and creatinine levels. Sixteen DVTs (55.2%) were on the ipsilateral side as the fracture, eight (27.6%) were on the contralateral side and five (17.2%) were bilateral. Chemoprophylaxis was not given to 399 patients, of which 27 (6.8%) developed DVT. Ten (2.5%) were proximal DVTs in which four (1%) developed PE. One (0.25%) patient developed PE without DVT. Fifty-five patients were on chemoprophylaxis, of which two (3.6%) developed DVT. Both were proximal DVTs with one subsequently developing PE.

CONCLUSIONS

The incidence of VTE in Asian patients may be lower compared to Western populations when mechanical prophylaxis is used. Chemoprophylaxis may assist in reducing the rates of DVT but not PE. The low incidence may not justify the use of routine chemoprophylaxis.

Recurrent venous thromboembolism in a patient with heterozygous factor v leiden mutation

OBJECTIVE

To report a patient case identifying risk for recurrent venous thromboembolism (VTE) associated with heterozygous Factor V Leiden mutation.

CASE SUMMARY

A 54-year-old Caucasian male was diagnosed with heterozygous Factor V Leiden mutation in 2008 after experiencing a deep vein thrombosis (DVT) and bilateral pulmonary embolism. The patient was treated appropriately and started on anticoagulation therapy with warfarin through an anticoagulation management clinic. After approximately 17 months of warfarin therapy without incident, warfarin was discontinued. Within 2 months after discontinuation of anticoagulation therapy, the patient experienced his second DVT and left pulmonary artery embolus.

DISCUSSION

The risk of recurrent venous thromboembolism (VTE) in patients with heterozygous Factor V Leiden mutation is documented as an approximate 1.4-fold increase compared to patients without thrombophilia. However, the risk increases dramatically when nonreversible (age) or reversible risk factors (obesity, smoking, and long air flights) are present in this population.

CONCLUSION

Based on recent literature, heterozygous Factor V Leiden mutation exponentially increases the risk of recurrent VTE, especially in the presence of other risk factors. Health care providers should complete a comprehensive review of the patients' other risk factors when deciding on duration of anticoagulation therapy for patients with positive heterozygous Factor V Leiden mutation.

Effect of Intravenous Versus Subcutaneous Phytonadione on Length of Stay for Patients in Need of Urgent Warfarin Reversal

This institutional review board-approved retrospective cohort study evaluated the impact of intravenous versus subcutaneous phytonadione on length of stay in hospitalized patients requiring urgent warfarin reversal. All patients were 18 years or older, on warfarin therapy with an international normalized ratio (INR) between 3.1 and 10.0, and had warfarin therapy restarted at discharge. Patients who received intramuscular or oral phytonadione, phytonadione by more than 1 route, fresh frozen plasma, or any other blood products containing clotting factors, patients with active or severe liver disease, and patients who received other forms of anticoagulation were excluded. A total of 4425 patients receiving phytonadione were evaluated and 79 patients were included. Baseline characteristics were similar between the intravenous and subcutaneous groups, including mean age, gender, warfarin indication, Charlson comorbidity index, and indication for phytonadione. Geometric mean length of stay in the intravenous group was 211.7 hours compared with 191.0 hours in the subcutaneous group (P = 0.47). Though intravenous phytonadione administration resulted in significantly lower INRs at all time points <36 hours, geometric mean time to restart of warfarin therapy was not impacted (66.3 hours vs. 64.1 hours, P = 0.72). Despite demonstrating significantly greater INR reductions, hospital length of stay and time to restart of warfarin therapy were not improved with the administration of intravenous over subcutaneous phytonadione.

Warfarin-induced skin necrosis

BACKGROUND

Warfarin is a frequently used oral anticoagulant in the treatment and prevention of various medical conditions. One uncommon adverse effect that can occur following the initiation of therapy is warfarin-induced skin necrosis. Because it is a rare effect with an undetermined pathophysiology of disease, the treatment is not well established.

CASE

A 52-year-old female was prescribed warfarin and enoxaparin for a newly diagnosed deep vein thrombosis (DVT) in the left lower extremity. On day 4 of therapy, the patient had a supra-therapeutic international normalized ratio (INR), prompting the discontinuation of enoxaparin and a decrease in the warfarin dose. The patient returned to the emergency department on day 7 of treatment with a purple, cold, and extremely painful right foot with punctate areas of necrosis and petechiae proximal to the discoloration. The patient's INR was found to be 10.64. Following the diagnosis of warfarin-induced skin necrosis, the patient was administered vitamin K intravenously and fresh frozen plasma (FFP) to reverse the effects of warfarin and promote protein C and S synthesis. Once the patient's INR was no longer supratherapeutic, subcutaneous enoxaparin was re-started as treatment for the known recent DVT. The patient's necrotic foot began to improve and she was discharged home with an anticipated full recovery.

CONCLUSIONS

Based on the proposed pathophysiology of disease, adequate bridge therapy may decrease the likelihood of developing this life-threatening condition. Early recognition and treatment with intravenous vitamin K, FFP or 4-factor prothrombin complex concentrate, and continued wound care are essential to prevent further complications.