Hemorrhagic Complications of Anticoagulant Treatment

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.

Impact of an inpatient anticoagulation management service on clinical outcomes

BACKGROUND

Antithrombotic medications require careful management to avoid thrombotic or hemorrhagic complications. The benefits of specialized anticoagulation management services (AMS) in the outpatient setting are well established; less evidence of benefit in the hospital setting is available.

OBJECTIVE

To evaluate the clinical benefits of an inpatient AMS to cardiac surgery patients requiring warfarin anticoagulation therapy.

METHODS

After obtaining institutional review board approval, we conducted a retrospective, single-center, cohort study of consecutive cardiac surgery patients treated before (January 2003-May 2005) and after (June-December 2005) establishment of an inpatient AMS. Demographic and clinical characteristics as well as laboratory and clinical data were retrieved from institutional electronic databases and compared between the 2 patient cohorts. Comparisons between study groups were conducted using a chi(2) or Fisher's Exact test for categorical variables and a Student's t-test for continuous variables. Analysis of rare event data was conducted using Poisson regression analysis.

RESULTS

Of 1919 patients admitted during the study interval, 826 received warfarin (674 pre-AMS, 152 post-AMS). The number of patients with postsurgical panic international normalized ratio (INR) values declined after initiation of the AMS (pre-AMS 90/674 [13.4%] vs post-AMS 11/152 [7.2%]; p = 0.036). There was a trend toward fewer clinically significant postoperative bleeding events (pre-AMS 21/674 [3.1%] vs post-AMS 2/152 [1.3%]; p = 0.22) and fewer repeat surgeries for late postoperative bleeding (pre-AMS 8/674 [1.2%] vs post-AMS 0/152 [0%]; p = 0.08). AMS intervention was associated with a 17% decrease in the average postsurgical length of stay (13.9 days vs 11.6 days; p = 0.015).

CONCLUSIONS

A multidisciplinary AMS can improve anticoagulation management, leading to fewer panic INR values and a reduced length of hospital stay.

What is "quality of evidence" and why is it important to clinicians?

Guideline developers use a bewildering variety of systems to rate the quality of the evidence underlying their recommendations. Some are facile, some confused, and others sophisticated but complex

Warfarin: what are the clinical implications of an out-of-range-therapeutic international normalized ratio?

Warfarin is a commonly used oral anticoagulant, and has well-established clinical efficacy. However, it has a narrow therapeutic window, and a mode-of-action affected by inter-individual differences and environmental factors. The effectiveness and safety of warfarin are closely related to maintenance of the international normalized ratio (INR) within therapeutic range. A supra-therapeutic INR puts patients at risk of bleeding, whereas a sub-therapeutic INR may not protect against thromboembolic complications. Research suggests a lack of anticoagulation control during warfarin therapy in different settings. Careful monitoring of the INR is essential, especially in geriatric or cancer populations who are at an increased risk of major hemorrhage. Warfarin is an effective treatment but optimization of the risk-benefit ratio is crucial in order to maximize efficacy and safety. Here, we will assess the extent to which INRs are an issue in the management of warfarin therapy, and the effect INRs may have on clinical outcomes.

Review of the Relationship Between Venous Thromboembolism, Malignancy and Its Treatment

Venous thromboembolism is a common complication that develops in approximately 20% of patients with cancer. Presence of tumor and other risk factors, such as inflammation, surgery, obesity, and medications, have the potential to alter the intravascular coagulation homeostasis and lead to thrombosis. Although malignancy may predispose patients to venous thromboembolism, many chemotherapy agents also increase the risk. In this article, some of the agents tamoxifen, asparaginase, fluorouracil, thalidomide, lenalidomide, bevacizumab, and hematopoietic growth factors are discussed. Many patients will experience a thrombotic event despite optimal prophylaxis. Thus, this article will address the guidelines for treatment and prophylaxis of venous thromboembolism. In general, the venous thromboembolism risk should be assessed before certain antineoplastic regimens are prescribed to patients with cancer.

Application of a decision support tool for anticoagulation in patients with non-valvular atrial fibrillation

BACKGROUND

Atrial fibrillation affects more than two million Americans and results in a fivefold increased rate of embolic strokes. The efficacy of adjusted dose warfarin is well documented, yet many patients are not receiving treatment consistent with guidelines. The use of a patient-specific computerized decision support tool may aid in closing the knowledge gap regarding the best treatment for a patient.

METHODS

This retrospective, observational cohort analysis of 6,123 Ohio Medicaid patients used a patient-specific computerized decision support tool that automated the complex risk-benefit analysis for anticoagulation. Adverse outcomes included acute stroke, major gastrointestinal bleeding, and intracranial hemorrhage. Cox proportional hazards models were developed to compare the group of patients who received warfarin treatment with those who did not receive warfarin treatment, stratified by the decision support tool's recommendation.

RESULTS

Our decision support tool recommended warfarin for 3,008 patients (49%); however, only 9.9% received warfarin. In patients for whom anticoagulation was recommended by the decision support tool, there was a trend towards a decreased hazard for stroke with actual warfarin treatment (hazard ratio 0.90) without significant increase in gastrointestinal hemorrhage (0.87). In contrast, in patients for whom the tool recommended no anticoagulation, receipt of warfarin was associated with statistically significant increased hazard of gastrointestinal bleeding (1.54, p = 0.03).

CONCLUSIONS

We have shown that our atrial fibrillation decision support tool is a useful predictor of those at risk of major bleeding for whom anticoagulation may not necessarily be beneficial. It may aid in weighing the benefits versus risks of anticoagulation treatment.

Comparison of risk stratification schemes to predict thromboembolism in people with nonvalvular atrial fibrillation

OBJECTIVES

We assessed 5 risk stratification schemes for their ability to predict atrial fibrillation (AF)-related thromboembolism in a large community-based cohort.

BACKGROUND

Risk schemes can help target anticoagulant therapy for patients at highest risk for AF-related thromboembolism. We tested the predictive ability of 5 risk schemes: the Atrial Fibrillation Investigators, Stroke Prevention in Atrial Fibrillation, CHADS(2) (Congestive heart failure, Hypertension, Age >or= 75 years, Diabetes mellitus, and prior Stroke or transient ischemic attack) index, Framingham score, and the 7th American College of Chest Physicians Guidelines.

METHODS

We followed a cohort of 13,559 adults with AF for a median of 6.0 years. Among non-warfarin users, we identified incident thromboembolism (ischemic stroke or peripheral embolism) and risk factors from clinical databases. Each scheme was divided into low, intermediate, and high predicted risk categories and applied to the cohort. Annualized thromboembolism rates and c-statistics (to assess discrimination) were calculated for each risk scheme.

RESULTS

We identified 685 validated thromboembolic events that occurred during 32,721 person-years off warfarin therapy. The risk schemes had only fair discriminating ability, with c-statistics ranging from 0.56 to 0.62. The proportion of patients assigned to individual risk categories varied widely across the schemes. The proportion categorized as low risk ranged from 11.7% to 37.1% across schemes, and the proportion considered high risk ranged from 16.4% to 80.4%.

CONCLUSIONS

Current risk schemes have comparable, but only limited, overall ability to predict thromboembolism in persons with AF. Recommendations for antithrombotic therapy may vary widely depending on which scheme is applied for individual patients. Better risk stratification is crucially needed to improve selection of AF patients for anticoagulant therapy.

A systematic review of secondary thromboprophylaxis in patients with antiphospholipid antibodies

OBJECTIVE

To systematically review the efficacy and safety data of different therapeutic approaches in patients with antiphospholipid antibodies (aPL) and thrombosis.

METHODS

The Medline database and references from selected reports and review articles were used. Randomized controlled trials, prospective and retrospective cohort studies, and subgroup analysis (n > 15) that focused on the secondary thromboprophylaxis in patients with aPL were selected.

RESULTS

Sixteen studies were selected. Patients with venous events and a single test for aPL showed a low recurrence rate while receiving oral anticoagulation at a target international normalized ratio (INR) of 2.0-3.0. Patients with stroke and a single positive aPL test had no increased risk compared with those without aPL. Recurrence rates in patients with definite antiphospholipid syndrome (APS) and previous venous thromboembolism were lower than in patients with arterial and/or recurrent events, both with and without therapy. Only 3.8% of recurrent events occurred at an actual INR >3.0. Mortality due to recurrent thrombosis was higher than mortality due to bleeding (18 patients versus 1 patient reported).

CONCLUSION

For patients with definite APS, we recommend prolonged warfarin therapy at a target INR of 2.0-3.0 in APS patients with first venous events and >3.0 for those with recurrent and/or arterial events. For patients with venous thromboembolism or stroke and a single positive aPL test, we recommend further testing to determine if they have a persisting antibody. If they do not, the same therapy as for the general population should be used (warfarin at a target INR of 2.0-3.0 and low-dose aspirin, respectively).

Medical management of brain tumor patients

Brain tumors can present challenging medical problems. Seizures, peritumoral edema, venous thromboembolism, fatigue, and cognitive dysfunction can complicate the treatment of patients who have primary or metastatic brain tumors. Effective medical management results in decreased morbidity and mortality and improved quality of life for affected patients.

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.

How we diagnose and treat thrombotic manifestations of the antiphospholipid syndrome: a case-based review

Antiphospholipid antibodies including anticardiolipin antibodies, lupus anticoagulants, and anti–β2 glycoprotein-1–specific antibodies may identify patients at elevated risk of first or recurrent venous or arterial thromboembolism. Traditionally, published case series supplemented by anecdotal experience have formed the basis of management of patients with these autoantibodies. Over the past several years, studies have described the management of patients with key clinical manifestations of antiphospholipid antibodies, including patients with antiphospholipid antibody syndrome. As a result, evidence-based treatment recommendations are possible for selected patients with, or at risk of, thrombosis in the setting of antiphospholipid antibodies. Unfortunately, most patients encountered in clinical practice do not correspond directly with those enrolled in clinical trials. For such patients, treatment recommendations are based on experience, extrapolation, and less rigorous evidence. This article proposes 5 cases typical of those found in clinical practice and provides recommendations for therapy focused on a series of clinical questions. Whenever possible, the recommendations are based on evidence; however, in many cases, insufficient evidence exists, so the recommendation is experiential.

Potentiation of fluindione or warfarin by dexamethasone in multiple myeloma and AL amyloidosis

OBJECTIVES

Patients with primary systemic (AL) amyloidosis or multiple myeloma are frequently treated with cyclic dexamethasone (DXM) courses and often require oral anticoagulants. We previously reported a strong potentiation of oral anticoagulants with intravenous methylprednisolone and observed a similar potentiation with DXM in 3 patients, which led us to prospectively investigate the interaction between DXM and oral anticoagulants.

METHODS

Nine patients with multiple myeloma (n=6) or AL amyloidosis (n=3), including 6 prospective patients, taking fluindione (n=8) or warfarin (n=1), were studied for a total of 10 cycles. DXM (40 mg/day for 4 days every 28 days) was administered alone (n=4) or with melphalan (n=5). One patient was studied for 2 consecutive cycles after a moderate increase in the international normalized ratio (INR) during the first course of DXM. International normalized ratio (INR) was measured serially during DXM administration. Plasma oral anticoagulant concentrations were measured for 5 cycles.

RESULTS

The mean INR increased from 2.75 (range: 1.80-3.6) at baseline to 5.22 (3.09-7.07) after DXM. Oral anticoagulants were transiently stopped during 8 cycles and 1 mg oral vitamin K was given during 2. No serious bleeding was observed. Plasma oral anticoagulant concentrations increased after DXM administration. In controls receiving DXM without oral anticoagulants, DXM alone did not increase prothrombin time.

CONCLUSION

High dose DXM can potentiate oral anticoagulants and elevate INR substantially. INR should therefore be monitored repeatedly during concomitant administration of these 2 drugs to allow individual adaptation of oral anticoagulant doses.

Pharmacokinetics, efficacy, and safety of LMWHs in venous thrombosis and stroke in neonates, infants and children

Since the early nineties it has been shown that low molecular weight heparin (LMWH) has significant advantages over unfractionated heparin and oral anticoagulants for both the treatment and the prevention of thrombosis, not only in adults, but also in children. The present review was based on an 'EMBASE', 'Medline' and 'PubMed' search including literature published in any language since 1980 on LMWH in neonates, infants and children. It included paediatric pharmacokinetic studies, the use of LMWH in children with venous thrombosis, LMWH administration in paediatric patients with ischaemic stroke, and its use in order to prevent symptomatic thromboembolism in children at risk. An increasing rate of off-label use of LMWH in children has been reported, showing that LMWHs offer important benefits to children with symptomatic thromboembolic events and poor venous access. Two well-conducted pharmacokinetic studies in this age group showed that neonates and younger infants require higher LMWH doses than older children to achieve the targeted anti-Xa levels, due to an increased extra vascular clearance. Recurrent symptomatic thromboses under LMWH occur in approximately 4% of children treated for venous thrombosis, and in 7% of children treated for stroke; major bleed was documented in 3% of children with therapeutic target LMWH anti-Xa levels, whereas minor bleeding was reported in approximately 23% of children receiving either therapeutic or prophylactic doses, respectively. Further randomized controlled trials are recommended to evaluate the optimum duration and application for different LMWH indications in children.

Use of newer anticoagulants in patients with chronic kidney disease

PURPOSE

The current indications, dosing, and practical considerations for use of newer anticoagulants in patients with various degrees of renal impairment who do not require dialysis are reviewed.

SUMMARY

Kidney function should generally be evaluated in all patients commencing anticoagulant therapy. As in the general population, hospitalized patients with impaired renal function most often have impairment that is mild to moderate in severity. Drug dosing in patients with chronic kidney disease may require that adjustment be made to the usual loading or maintenance dose of a drug. Newer anticoagulants with labeling approved by the Food and Drug Administration for venous thromboembolism (VTE) prophylaxis, treatment, or both include the low-molecular-weight heparins (LMWHs) and the factor Xa inhibitor fondaparinux. Some LMWHs are also indicated for the management of patients with acute coronary syndrome (ACS). All of the newer anticoagulants currently available for the management of VTE and ACS have approved labeling for use in patients with mild-to-moderate renal impairment. Currently available LMWHs, factor Xa inhibitors, and direct thrombin inhibitors (excluding argatroban) are eliminated primarily by the kidneys, so dosing in patients with severe renal impairment may require cautious dosage reduction or increased monitoring for bleeding and thromboembolic complications or both. Unfractionated heparin is the preferred anticoagulant for use in most of these patients.

CONCLUSION

Newer anticoagulants should be used with caution in patients with mild-to-moderate renal impairment. Unfractionated heparin remains the preferred anticoagulant in most patients with severe renal impairment even though its use is associated with increased bleeding in this population. Dosing of newer anticoagulants, except argatroban, requires cautious dosage reduction and increased monitoring for complications.

Inferior vena cava filters in the management of venous thromboembolism

Inferior vena cava (IVC) filters, both retrievable and permanent, are indicated for the prevention of pulmonary embolism (PE) in patients contraindicated for anticoagulant therapy, in those with anticoagulant therapy complications, and perhaps for those with recurrent PE despite therapeutic anticoagulation. Because of the lack of randomized controlled trials (only 1 has been published), clinicians have little evidence-based information to assist them in determining proper use of IVC filters. The introduction of retrievable filters and the ease of insertion have stimulated increased use of these devices without strong evidence or follow-up to assess either efficacy or longer-term clinical outcomes. Current evidence-based guidelines recommend IVC filter insertion only in patients with proven venous thromboembolism and an absolute contraindication for anticoagulation.

Determinants and measures of quality in oral anticoagulation therapy

BACKGROUND

Anticoagulation management services or clinics have been recommended as the preferred method in the long-term management of oral anticoagulation with vitamin K antagonists and have been shown to increase the time patients spend in the therapeutic range. This surrogate marker of the quality of anticoagulation control is a well accepted predictor of bleeding and thromboembolic events and is generally used as a quality measure. However, the method of calculating the time in the therapeutic range can give different results and there is no consensus on the methodology that should be used or the benchmark targets that should be aimed for. Additionally, the expected rates of bleeding and thromboembolic complications are dependent on the indications for anticoagulation in the patient population being evaluated. These issues need to be taken into account when setting quality standards for anticoagulation clinics.

METHODS

An informal survey and group discussion with anticoagulation clinic personnel attending a workshop at the 9th National Conference on Anticoagulant Therapy was used to generate a list of pragmatic barriers to measuring these quality indicators and to share ideas on other quality markers. A narrative review of selected literature was used throughout the workshop to exemplify potential benchmark rates for therapeutic time in range, bleeding, and thromboembolic complication rates.

RESULTS

Approximately 65% of the workshop attendees measure time in range in their anticoagulation clinics, however, only 15% used the linear interpolation method which has a quality measurement target of 65%. Less than half of the attendees measure bleeding or complication rates and very few adjust these rates based on the indication for anticoagulation. There was strong agreement regarding pragmatic barriers to collect this information and difficulties in extrapolating standards from the literature. Several clinics also measure the percent of extremely high International Normalized Ratios (INR) and also track late patients.

CONCLUSIONS

Using clinical trial bleeding and thromboembolic complication rates to set quality measurement targets for anticoagulation clinics may not be appropriate, given the inherent difference in these patient populations. Additionally, there are pragmatic issues affecting the completeness and accuracy of adverse event gathering outside of a trial scenario that could be misleading. The time in the therapeutic range, however, is relatively easy to calculate and is a well substantiated surrogate marker for complication rates and should be a standard quality indicator. Benchmark targets for time in range are dependent on the methodology used in the calculation and should be adjusted accordingly.

Risk of warfarin-related bleeding events and supratherapeutic international normalized ratios associated with complementary and alternative medicine: a longitudinal analysis

STUDY OBJECTIVE

To determine the risk of bleeding and supratherapeutic international normalized ratios (INRs) associated with use of complementary and alternative medicine (CAM) in patients receiving warfarin.

DESIGN

Prospective, longitudinal study.

SETTING

An acute care, academic and research hospital in Canada.

PATIENTS

A total of 171 adults who were prescribed warfarin anticoagulation therapy for an expected duration of at least 4 months after enrollment.

INTERVENTION

Patients were asked to complete a 16-week diary by recording bleeding events and exposure to factors previously reported to increase the risk of bleeding and supratherapeutic INRs, including CAM consumption.

MEASUREMENTS AND MAIN RESULTS

Prescription, medical, and laboratory records were reviewed. Risk factors for bleeding events and supratherapeutic INR (at least 0.5 units above the target range) were evaluated longitudinally by using generalized estimating equation (GEE) modeling. Of the 171 patients completing a diary, 87 (51%) reported at least one bleeding event and 36 (21%) had a supratherapeutic INR. Seventy-three patients (43%) indicated they had used at least one CAM product previously reported to interact with warfarin. Warfarin use of less than 3 months' duration was the only statistically significant risk factor identified for supratherapeutic INR. The CAM therapies associated with an increased risk of self-reported bleeding included cayenne, ginger, willow bark, St. John's wort, and coenzyme Q(10). Use of more than one CAM while receiving warfarin was also a significant risk factor. Two CAMs were independently associated with an increased risk of self-reported bleeding: coenzyme Q(10) (odds ratio [OR] 3.69, 95% confidence interval [CI] 1.88-7.24) and ginger (OR 3.20, 95% CI 2.42-4.24). Other risk factors significantly associated with increased bleeding included high target INR (2.5-3.5), diarrhea, acetaminophen use, increased alcohol consumption, and increased age.

CONCLUSIONS

The use of CAM by patients receiving warfarin is common, and consumption of coenzyme Q(10) or ginger appears to increase the risk of bleeding in this population.

Racial/ethnic differences in the risk of intracranial hemorrhage among patients with atrial fibrillation

OBJECTIVES

This study was designed to study racial/ethnic differences in the risk for intracranial hemorrhage (ICH) and the effect of warfarin on ICH risk among patients with atrial fibrillation (AF).

BACKGROUND

Nonwhites are at greater risk for ICH than whites in the general population. Whether this applies to patients with AF and whether warfarin therapy is associated with comparable risk of ICH in nonwhites are unknown.

METHODS

We retrospectively identified a multiethnic stroke-free cohort hospitalized with nonrheumatic AF. Warfarin use and anticoagulation intensity were assessed by searching pharmacy and laboratory records. Crude ICH event rates were calculated by Poisson regression. Cox proportional hazard models were constructed to assess the independent effect of race/ethnicity on ICH after adjusting for age, gender, hypertension, diabetes, heart failure, and warfarin exposure.

RESULTS

Between 1995 and 2000, we identified 18,867 qualifying AF hospitalizations (78.5% white, 8% black, 9.5% Hispanic, and 3.9% Asian) and 173 qualifying ICH events over 3.3 years follow-up. Achieved anticoagulation intensity was lower among blacks but not different between the other groups. Warfarin was associated with increased ICH risk in all races, but the magnitude of risk was greater among nonwhites. There were no gender differences. The hazard ratio for ICH with whites as referent was 4.06 for Asians (95% confidence interval [CI] 2.47 to 6.65), 2.06 for Hispanics (95% CI 1.31 to 3.24), and 2.04 (95% CI 1.25 to 3.35) for blacks.

CONCLUSIONS

Nonwhites with AF were at greater risk for warfarin-related ICH. Blacks, Hispanics, and Asians were at successively greater ICH risk than whites.

Oral anticoagulant and antiplatelet therapy and peripheral arterial disease

BACKGROUND

Atherosclerotic peripheral arterial disease is associated with an increased risk of myocardial infarction, stroke, and death from cardiovascular causes. Antiplatelet drugs reduce this risk, but the role of oral anticoagulant agents in the prevention of cardiovascular complications in patients with peripheral arterial disease is unclear.

METHODS

We assigned patients with peripheral arterial disease to combination therapy with an antiplatelet agent and an oral anticoagulant agent (target international normalized ratio [INR], 2.0 to 3.0) or to antiplatelet therapy alone. The first coprimary outcome was myocardial infarction, stroke, or death from cardiovascular causes; the second coprimary outcome was myocardial infarction, stroke, severe ischemia of the peripheral or coronary arteries leading to urgent intervention, or death from cardiovascular causes.

RESULTS

A total of 2161 patients were randomly assigned to therapy. The mean follow-up time was 35 months. Myocardial infarction, stroke, or death from cardiovascular causes occurred in 132 of 1080 patients receiving combination therapy (12.2%) and in 144 of 1081 patients receiving antiplatelet therapy alone (13.3%) (relative risk, 0.92; 95% confidence interval [CI], 0.73 to 1.16; P=0.48). Myocardial infarction, stroke, severe ischemia, or death from cardiovascular causes occurred in 172 patients receiving combination therapy (15.9%) as compared with 188 patients receiving antiplatelet therapy alone (17.4%) (relative risk, 0.91; 95% CI, 0.74 to 1.12; P=0.37). Life-threatening bleeding occurred in 43 patients receiving combination therapy (4.0%) as compared with 13 patients receiving antiplatelet therapy alone (1.2%) (relative risk, 3.41; 95% CI, 1.84 to 6.35; P<0.001).

CONCLUSIONS

In patients with peripheral arterial disease, the combination of an oral anticoagulant and antiplatelet therapy was not more effective than antiplatelet therapy alone in preventing major cardiovascular complications and was associated with an increase in life-threatening bleeding. (ClinicalTrials.gov number, NCT00125671 [ClinicalTrials.gov].).

The headache over warfarin in British neurosurgical intensive care units: a national survey of current practice

OBJECTIVE

To ascertain current British practice regarding the emergency medical management of patients who sustain a spontaneous intracerebral haemorrhage (ICH) whilst receiving warfarin therapy and to compare this with established national and international guidelines.

DESIGN

Standardised, telephone based, questionnaire survey.

SETTING

All 32 adult British neuroscience intensive care units (ICUs)

PARTICIPANTS

Duty consultant of each neuroscience ICU.

RESULTS

Response rate was 100%. The international normalised ratio (INR) would be reversed by over 90% of ICU consultants treating patients on warfarin with an ICH, except patients with mechanical heart valves (MHV), when only 59.4% would reverse. Prothrombin complex concentrate (PCC) was used by 15 ICUs (46.9%); however, only six units (18.8%) apply reversal strategies with PCC and intravenous vitamin K in accordance with national guidelines. Fresh frozen plasma (FFP) continues to be used by 71.9% of the ICUs. A protocol for warfarin reversal in ICH was present in five ICUs, of which four followed national guidelines. None of the units that use FFP had a protocol. Following ICH, two-thirds of the ICUs (65.6%) would commence bridging heparinisation in the first 4 days for MHV patients and 25% would recommence warfarin before, and 64.5% after, 7 days.

CONCLUSION

There is considerable variation in practice amongst clinicians who regularly manage these patients and, in most cases (81.2%), practice is not in keeping with national or international guidelines. This study has demonstrated the need amongst senior ICU clinicians for a heightened awareness of current treatment recommendations and the availability of effective haemostatic therapies.

Atrial fibrillation in the elderly

Atrial fibrillation is increasingly prevalent among older adults. It causes approximately 24% of strokes in patients aged 80 to 89 years. The management of atrial fibrillation is directed at preventing thromboembolism and controlling the heart rate and rhythm. Stroke prevention is most effectively accomplished through administering anticoagulants such as warfarin, although older patients have higher hemorrhagic risk. Cognitive dysfunction, functional impairments, and increased fall risk further complicate warfarin management in elderly patients. The use of risk stratification schemes can help guide the anticoagulation decision, although the benefits of warfarin generally outweigh the risks in most older patients with atrial fibrillation. Pharmacologic rate control has been shown to result in similar outcomes compared with pharmacologic restoration of sinus rhythm and should be the initial therapy for elderly patients. Anti-arrhythmic medications should be selected based on an individual patient's coexisting medical conditions. In symptomatic patients who fail pharmacologic therapy, invasive strategies such as AV nodal ablation may help improve quality of life and symptoms, although such strategies do not obviate the need for antithrombotic therapy.

Incidence and predictors of severe bleeding during warfarin treatment

BACKGROUND

Optimal warfarin prescription requires correct, individualized assessment of the warfarin-related bleeding risk, which randomised controlled trials may underestimate . Observational studies have reported a range of bleeding risks that differ 40-fold. This variation may be caused by time trends, variation in bleeding definition and study subject selection. We investigated the incidence of, and risk factors for severe bleeding in un-selected warfarin-treated patients from Sweden.

METHODS

Between 2001 and 2005, 40 centres recruited warfarin-naïve patients commencing warfarin therapy and followed them prospectively with continuous registration of clinical data. The primary outcome was severe bleeding, according to the WHO universal definition of severe adverse drug reactions. The influence of potential risk factors was investigated by means of a Cox proportional-hazards model.

RESULT

A total of 1523 patients contributed 1276 warfarin-exposed patient-years. The incidence of first-time severe bleeding was 2.3 per 100 patient-years (95% confidence interval 1.4 to 3.1). Male sex and use of drugs potentially interacting with warfarin were the only independent risk factors of severe bleeding, with hazard ratios of 2.8 and 2.3, respectively. Age, target International Normalized Ratio (INR), time spent outside target INR range, and warfarin dose requirement were not significantly associated with bleeding risk.

CONCLUSIONS

The risk of severe bleeding in a large naturalistic, prospective cohort of first-time warfarin users was lower than reported in some previous reports. Male gender was an independent predictor of severe bleeding as was the receipt of warfarin-interacting medications at the onset of anticoagulation therapy. Further studies are required to evaluate the effect these findings may have on the quality of current risk-benefit analysis involved in warfarin prescription.

Standard therapies for pulmonary arterial hypertension

After half a century of clinical experience and research, management of pulmonary arterial hypertension remains a challenge. Currently, data to support the use of standard therapies for pulmonary arterial hypertension (oxygen supplementation, diuretics, digoxin, anticoagulation, and calcium channel blockers) are mostly retrospective, uncontrolled prospective, or derived from other diseases with similar but not identical manifestations. In the absence of any further prospective, controlled studies, it is reasonable to use these therapies when they are tolerated. When these therapies are poorly tolerated, however, the threshold for discontinuation should be low.

Factors impacting thromboembolism after bariatric body contouring surgery

BACKGROUND

The purpose of this study was to define the risk of venous thromboembolism within the massive weight loss population undergoing body contouring procedures.

METHODS

Retrospective analysis of massive weight loss patients who had body contouring operations between March of 1998 and September of 2004 was performed. Patient factors studied included age, gender, medical comorbidities including history of thromboembolic complications, depression, tobacco use, preoperative/postoperative body mass index, surgery, and transfusion.

RESULTS

There were 138 cases, and the female-to-male ratio was 5:1. Procedures were often combined: 128 patients had abdominal surgery, 36 had a back lift, 41 had brachioplasty, 29 had chest surgery, and 47 had a thigh lift. The most common complications were related to healing (n = 28) and seroma (n = 18). Three patients had postoperative deep venous thrombosis requiring anticoagulation, and one had a fatal pulmonary embolism, making the overall venous thromboembolism risk 2.9 percent. The mean body mass index at contour was 48.5 for patients with venous thromboembolism versus 31.8 for patients who did not develop venous thromboembolism (p = 0.01). Looking at this subgroup of 45 patients, the risk of venous thromboembolism was 8.9 percent, with no risk found in patients with a body mass index less than 35 (p = 0.01).

CONCLUSIONS

The risk of venous thromboembolism with contouring surgery for massive weight loss is comparable to that for gastric bypass surgery. Body mass index in the obese range appears to be a leading risk factor. The authors' data support routine prophylaxis against venous thromboembolism. Recommendations for high-risk patients are discussed.

Targeting Ligand-Induced Binding Sites on GPIIb/IIIa via Single-Chain Antibody Allows Effective Anticoagulation Without Bleeding Time Prolongation

Objective— Therapeutic anticoagulation is widely used, but limitations in efficacy and bleeding complications cause an ongoing search for new agents. However, with new agents developed it seems to be an inherent problem that increased efficiency is accompanied by an increase in bleeding complications. We investigate whether targeting of anticoagulants to activated platelets provides a means to overcome this association of potency and bleeding.

Methods and Results— Ligand-induced binding sites (LIBS) on fibrinogen/fibrin-binding GPIIb/IIIa represent an abundant clot-specific target. We cloned an anti-LIBS single-chain antibody (scFv anti-LIBS ) and genetically fused it with a potent, direct factor Xa (fXa) inhibitor, tick anticoagulant peptide (TAP). Specific antibody binding of fusion molecule scFv anti-LIBS -TAP was proven in flow cytometry; anti-fXa activity was demonstrated in chromogenic assays. In vivo anticoagulative efficiency was determined by Doppler-flow in a ferric chloride–induced carotid artery thrombosis model in mice. ScFv anti-LIBS -TAP prolonged occlusion time comparable to enoxaparine, recombinant TAP, and nontargeted mutant-scFv-TAP. ScFv anti-LIBS -TAP revealed antithrombotic effects at low doses at which the nontargeted mutant-scFv-TAP failed. In contrast to the other anticoagulants tested, bleeding times were not prolonged by scFv anti-LIBS -TAP.

Conclusions— The novel clot-targeting approach of anticoagulants via single-chain antibody directed against a LIBS-epitope on GPIIb/IIIa promises effective anticoagulation with reduced bleeding risk.

Assessing the outcome of systemic tissue plasminogen activator for the management of venous and arterial thrombosis in pediatrics

This study sought to ascertain the outcomes of systemic thrombolytic therapy used in a cohort of infants and children. Complete thrombus resolution was achieved in 81% of patients with arterial thromboses (n=16) compared to 0% of children with venous thromboses (n=10). A major bleeding rate of 11.5% occurred across the entire cohort (n=3, all arterial). In our cohort, no patient with venous thromboembolism achieved complete resolution of their thrombosis after thrombolytic therapy. More cohort studies reporting the outcome of uniform protocols of thrombolytic therapy in children are required.

Heparin Inhibits NF-κB Activation and Increases Cell Death in Cerebral Endothelial Cells after Oxygen-Glucose Deprivation

Heparin is a classic anticoagulant that is commonly used in the treatment of acute ischemic stroke (AIS). Its use remains controversial, however, due to the risk of cerebral hemorrhagic transformation. In addition to anticoagulant effects, diverse effects on transcription factors can be caused by heparin. Among the transcription factors potentially affected is nuclear factor kappa B (NF-kappaB), a protein that is reportedly related to the survival of cerebral endothelial cells. We investigated the effect of heparin on NF-kappaB activation and cell death following oxygen-glucose deprivation (OGD), an experimental model of AIS. We subjected bEnd.3 cells from a murine cerebral microvascular endothelial cell line to OGD. We examined the effect of heparin on OGD-induced NF-kappaB activation and its mechanism of action, using electrophoretic mobility shift assays, reporter gene analysis, real-time RT-PCR, Western blot analysis, and confocal microscopy. We also measured the effect of heparin on OGD-induced cell death using an MTT assay. Heparin inhibited both tumor necrosis factor alpha- and OGD-induced NF-kappaB activation. Heparin was taken up by endocytosis and then entered the nucleus. Heparin did not affect the nuclear translocation of NF-kappaB, but instead inhibited the DNA binding of NF-kappaB in the nucleus. Cells were more susceptible to OGD-induced cell death after heparin treatment. Besides producing an anticoagulation effect, heparin also inhibits NF-kappaB activation, resulting in increased susceptibility to OGD-induced cell death. This effect may be responsible for hemorrhagic transformation in patients following heparin treatment for AIS.