Impact of a Computerized Antithrombotic Risk Assessment Tool on the Prescription of Thromboprophylaxis in Atrial Fibrillation: Hospital Setting

The computerized antithrombotic risk assessment tool (CARAT) is an online decision-support algorithm that facilitates a systematic review of a patient's stroke risk, bleeding risk, and pertinent medication safety considerations, to generate an individualized treatment recommendation. The CARAT was prospectively applied across 2 hospitals in the greater Sydney area. Its impact on antithrombotics utilization for thromboprophylaxis in patients with nonvalvular atrial fibrillation was evaluated. Factors influencing prescribers' treatment selection were identified. The CARAT recommended a change in baseline therapy for 51.8% of patients. Among anticoagulant-eligible patients (ie, where the risk of stroke outweighed the risk of bleeding) using "nil therapy" or antiplatelet therapy at baseline, the CARAT recommended an upgrade to warfarin in 60 (30.8%) patients. For those in whom the bleeding risk outweighed the stroke risk, the CARAT recommended a downgrade from warfarin to safer alternatives (eg, aspirin) in 37 (19%) patients. Among the "most eligible" (ie, high stroke risk, low bleeding risk, no contraindications; n = 75), the CARAT recommended warfarin for all cases. Discharge therapy observed a marginal increase in anticoagulation prescription in eligible patients (n = 116; 57.8% vs 64.7%, P = .35) compared to baseline. Predictors of warfarin use (vs antiplatelets) included congestive cardiac failure, diabetes mellitus, and polypharmacy. The CARAT was able to optimize the selection of therapy, increasing anticoagulant use among eligible patients. With the increasing complexity of decision-making, such tools may be useful adjuncts in therapy selection in atrial fibrillation. Future studies should explore the utility of such tools in selecting therapies from within an expanded treatment armamentarium comprising the non-vitamin K antagonist oral anticoagulants.

Managing Extended Oral Anticoagulation After Unprovoked Venous Thromboembolism

Venous thromboembolism (VTE), which includes deep venous thrombosis and pulmonary embolism, is a major public health problem associated with increased morbidity and mortality. Despite the high recurrence risk associated with unprovoked VTE, extended anticoagulation remains controversial. Oral antithrombotic agents for extended VTE treatment comprise the vitamin K antagonists, aspirin, and the direct oral anticoagulants (also known as target-specific oral anticoagulants and formerly known as the new or novel oral anticoagulants) including rivaroxaban, dabigatran, apixaban, and edoxaban. The efficacy of these anticoagulants in reducing the risk of VTE recurrence (>80%-90% relative risk reduction) is offset by the risk of major bleeding that approaches 3% per year. Stratifying risks of recurrence and bleeding to identify patients at low, intermediate, or high risk and carefully considering the pharmacologic profile of the antithrombotic agents will help clinicians in choosing the optimal anticoagulant and duration and/or surveillance strategy. This review will discuss the current guidelines for extended VTE treatment, review the clinical trials involving the direct oral anticoagulants, and present the clinical considerations and concerns involving extended therapy.

Major Bleeding and Hemorrhagic Stroke With Direct Oral Anticoagulants in Patients With Renal Failure: Systematic Review and Meta-Analysis of Randomized Trials

BACKGROUND

Direct oral anticoagulants (DOACs) are used as an alternative for traditional antithrombotic therapy. However, the safety profile of DOACs in patients with renal failure (RF) has not been determined.

METHODS

A systematic review was performed assessing the reported safety of DOACs compared with vitamin K antagonists (VKAs) in patients with RF and estimated creatinine clearance (eCrCL) < 50 mL/min and eCrCL 50 to 80 mL/min. MEDLINE, EMBASE, Cochrane, and the Clinical Trials Registry (ClinicalTrials.gov) were searched for randomized clinical trials up to November 2015. The data were pooled by using both traditional frequentist and Bayesian random effects models.

RESULTS

Nine trials met the inclusion criteria. Among 94,897 participants, 54,667 (58%) had RF. Compared with VKAs, DOACs were associated with a significantly decreased risk for major bleeding in patients with eCrCL 50 to 80 mL/min (risk ratio, 0.87 [95% CI, 0.81-0.93]) and a nonsignificant decrease in the risk for major bleeding in patients with eCrCL < 50 mL/min (risk ratio, 0.83 [95% CI, 0.68-1.02]); there was evidence of significant heterogeneity. Indirect comparisons, using Bayesian network analysis, indicated that apixaban was associated with a decreased rate of major bleeding compared with other DOACs in patients with eCrCL < 50 mL/min. DOACs were associated with a significant decrease in the risk for hemorrhagic stroke compared with VKAs in patients with eCrCL < 50 mL/min and 50 to 80 mL/min.

CONCLUSIONS

As a class, DOACs are associated with a reduced risk for hemorrhagic stroke compared with VKAs in patients with RF. However, DOACs may differ from each other in their relative risk for major bleeding in patients with eCrCL < 50 mL/min.

TRIAL REGISTRY

PROSPERO registry; No.: CRD42014013730; URL: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42014013730.

Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report

BACKGROUND

We update recommendations on 12 topics that were in the 9th edition of these guidelines, and address 3 new topics.

METHODS

We generate strong (Grade 1) and weak (Grade 2) recommendations based on high- (Grade A), moderate- (Grade B), and low- (Grade C) quality evidence.

RESULTS

For VTE and no cancer, as long-term anticoagulant therapy, we suggest dabigatran (Grade 2B), rivaroxaban (Grade 2B), apixaban (Grade 2B), or edoxaban (Grade 2B) over vitamin K antagonist (VKA) therapy, and suggest VKA therapy over low-molecular-weight heparin (LMWH; Grade 2C). For VTE and cancer, we suggest LMWH over VKA (Grade 2B), dabigatran (Grade 2C), rivaroxaban (Grade 2C), apixaban (Grade 2C), or edoxaban (Grade 2C). We have not changed recommendations for who should stop anticoagulation at 3 months or receive extended therapy. For VTE treated with anticoagulants, we recommend against an inferior vena cava filter (Grade 1B). For DVT, we suggest not using compression stockings routinely to prevent PTS (Grade 2B). For subsegmental pulmonary embolism and no proximal DVT, we suggest clinical surveillance over anticoagulation with a low risk of recurrent VTE (Grade 2C), and anticoagulation over clinical surveillance with a high risk (Grade 2C). We suggest thrombolytic therapy for pulmonary embolism with hypotension (Grade 2B), and systemic therapy over catheter-directed thrombolysis (Grade 2C). For recurrent VTE on a non-LMWH anticoagulant, we suggest LMWH (Grade 2C); for recurrent VTE on LMWH, we suggest increasing the LMWH dose (Grade 2C).

CONCLUSIONS

Of 54 recommendations included in the 30 statements, 20 were strong and none was based on high-quality evidence, highlighting the need for further research.

New approaches to inhibiting platelets and coagulation

Ischemic heart disease and stroke are major causes of death and morbidity worldwide. Coronary and cerebrovascular events are a consequence of thrombus formation caused by atherosclerotic plaque rupture or embolism, both of which result from platelet activation and aggregation and thrombin-mediated fibrin generation via the coagulation cascade. Current and emerging antiplatelet and anticoagulant agents are evolving rapidly. The use of aspirin for primary prevention continues to be controversial, as are the doses appropriate for secondary prevention. Development of new oral and intravenous adenosine diphosphate P2Y12 inhibitors and novel antiplatelet agents continues to transform the landscape of antiplatelet therapy. Oral anticoagulation has advanced with the use of direct thrombin and factor Xa inhibitors that do not require therapeutic monitoring. In this review, we discuss the pharmacology and growing clinical evidence for traditional and new antiplatelet and anticoagulant therapies.

Impact of advanced age on management and prognosis in atrial fibrillation: insights from a population-based study in general practice

OBJECTIVES

to examine the use of antithrombotic therapy and predictors of stroke and death in very elderly (≥85 years) atrial fibrillation (AF) patients in a general practice cohort from the UK.

DESIGN

retrospective, observational cohort study; 12-month follow-up period.

SETTING

eleven general practices serving the town of Darlington, England representing a population of 105,000 patients.

PATIENTS

two thousand two hundred and fifty-nine patients with a history of AF, 561 (24.8%) aged ≥85 years.

MAIN OUTCOME MEASURES

use of antithrombotic therapy by age group and predictors of stroke and death.

RESULTS

five hundred and sixty-one (24.8%) AF patients aged ≥85 years (mean (SD) age 89 (4) years; 66% female) identified with a mean CHA2DS2-VASc score of 4.6 (SD 1.4). Thirty-six per cent received oral anticoagulation (OAC) compared with 57% in the 75-84 years age group. Forty-nine per cent of the very elderly received antiplatelet (AP) monotherapy; recorded OAC contraindications and declines were greatest among those aged ≥85 years. Stroke risk was highest among the very elderly (5.2% per annum), despite anticoagulation (3.9%). Multivariate analyses demonstrated an increased risk of stroke with AP monotherapy (odds ratio (OR) 2.45, 95% confidence intervals (CIs) 1.05-5.70) and a significant reduction in all-cause mortality with OAC therapy (OR 0.59, 95% CI 0.36-0.99).

CONCLUSION

the majority of very elderly AF patients in general practice do not receive OAC despite their higher stroke risk; almost half received AP monotherapy. AP use independently increased the risk of stroke, signifying that effective stroke prevention requires OAC regardless of age, except where true contraindications exist.

The WATCHMAN device for stroke prophylaxis in atrial fibrillation: an evolving niche

Atrial fibrillation is associated with a markedly increased risk of thromboembolic stroke. At present, lifelong antithrombotic therapy with warfarin or a novel oral anticoagulant is indicated for prophylaxis in the majority of patients. Left atrial appendage occlusion devices have been developed as an alternative to these agents, aiming to avoid issues around consistency of anticoagulation, bleeding risk, and drug-related side effects. The best evidence is available for Boston Scientific's WATCHMAN device. The safety and efficacy of WATCHMAN and other similar devices have been questioned, although the increasing body of evidence supports a role in selected settings. A recently updated randomized controlled trial of WATCHMAN (WATCHMAN Left Atrial Appendage System for Embolic PROTECTion in Patients with Atrial Fibrillation [PROTECT-AF]) demonstrates its noninferiority to warfarin and suggests an advantage in terms of functional outcome for patients, with superior net clinical benefit 6 to 9 months after starting treatment. The procedural risk associated with device implantation remains substantial, although improving device design and increasing operator experience means that this should decrease in the future. As the body of data and overall experience around WATCHMAN grow, it may come to be recognized as the best option in selected patients.

Safety of gastrointestinal endoscopic biopsy in patients taking antithrombotics

BACKGROUND AND AIM

Current Japanese gastrointestinal (GI) endoscopic guidelines permit endoscopic biopsy without cessation of antiplatelet agents and warfarin in patients with a therapeutic range of prothrombin time-international normalized ratio (PT-INR) levels, although the evidence levels are low. We evaluated the safety of endoscopic biopsy in patients currently taking antithrombotics.

METHODS

Consecutive patients receiving antithrombotics who underwent GI endoscopy from August 2012 to August 2013 were enrolled. Adverse events and endoscopic hemostasis after biopsy were evaluated. PT-INR level was measured in patients taking warfarin the day before endoscopy.

RESULTS

Among 7939 patients undergoing endoscopy, 1034 patients (13.0%, 706 men and 328 women, average age 72.8 years) were receiving antithrombotics. Antithrombotics included aspirin (44.8%), warfarin (34.7%), thienopyridine (16.1%), cilostazol (10.3%), dabigatran (4.8%) etc. PT-INR levels in patients taking warfarin were >3.0 in 13 patients (4.3%), between 2.5 and 3.0 in 18 patients (6.0%), <2.5 in 269 patients (89.7%). Two hundred and six patients received endoscopic biopsy while taking aspirin (51.2%), warfarin (22.8%), and thienopyridine (13.6%). Endoscopic hemostasis was required in three patients after endoscopic biopsy (spraying thrombin in two patients, spraying thrombin and clipping in one patient). There were no major complications. The incidence of endoscopic hemostasis after biopsy in patients without antithrombotic cessation was not significantly different than in the controls not taking antithrombotics (1.5% vs 0.98%, P = 0.51).

CONCLUSION

Endoscopic biopsy did not increase the bleeding risk despite not stopping antithrombotics prior to biopsy even among patients taking warfarin whose PT-INR was within the therapeutic range.

Trials of novel oral anticoagulants for stroke prevention in patients with non-valvular atrial fibrillation

Patients with non-valvular atrial fibrillation (AF) face an increased risk of stroke compared with those in normal sinus rhythm. The vitamin K antagonist warfarin, available for over half a century, is highly effective in reducing the risk of stroke in patients with AF, but it is a difficult drug to use properly. As a result, it is challenging to keep the anticoagulant effect of warfarin in the desired range. Newer oral anticoagulants (NOACs) that directly inhibit Factor IIa (thrombin) or Factor Xa provide reliable anticoagulation when administer in fixed oral doses without routine coagulation monitoring. This manuscript will review in detail the pivotal trials of these NOACs that led to their approval as well as comment on the factors that should influence their selection.

Complications in skin grafts when continuing antithrombotic therapy prior to cutaneous surgery requiring skin grafting: A systematic review

The risk of postoperative bleeding and wound healing complications in skin grafts among anticoagulated patients undergoing cutaneous surgery has not been firmly established. The objective was to examine the literature and assess the risk of postoperative bleeding or wound healing complications in skin grafts among anticoagulated patients, compared with patients who discontinue or patients who are not receiving antithrombotic therapy prior to cutaneous surgery requiring skin grafting. A systematic review examining the effect of antithrombotic therapy on cutaneous surgery was performed according to the PRISMA-guidelines. PubMed and Embase databases were primarily searched for relevant literature in the period from the start date of each database to 2014. A total of eight studies representing 443 patients met criteria for inclusion. No randomised controlled trials were found; the included studies were of prospective and retrospective design. Most of the reviewed studies suggest that the use of antithrombotic therapy can increase the risk of bleeding complications in skin grafts. These complications are only wound threatening and not life threatening. Therefore, this is of concern mostly in terms of hemostasis by the surgeon and good pressure dressings. Care should be taken when operating on anticoagulated patients undergoing cutaneous surgery requiring skin grafting. However, graft failure is rare and, given the risk of thrombotic events, the reviewed studies recommend continuing all medically necessary antithrombotic therapy. The limitations of this study are the small sample sizes and the level of evidence; hence, more research is needed to substantiate these preliminary findings.

Insights into onco-cardiology: atrial fibrillation in cancer

Atrial fibrillation (AF) has been found to occur with an increased frequency in patients with malignancies, particularly in those undergoing cancer surgery. The occurrence of AF in cancer may be related to comorbid states or a direct tumor effect or may represent a complication of cancer surgical or medical therapy, whereas inflammation may be a common denominator for both conditions. Treating AF in patients with malignancies is a challenge, especially in terms of antithrombotic therapy, because cancer may result in an increased risk of either thrombosis or hemorrhage and an unpredictable anticoagulation response, whereas thromboembolic risk prediction scores such as CHADS2 (Cardiac Failure, Hypertension, Age, Diabetes, and Stroke [doubled]) may not be applicable. The general lack of evidence imposes an individualized approach to the management of AF in those patients, although some general recommendations based on current guidelines in noncancer patients and the existing evidence in cancer patients, where available, may be outlined.

Provider specialty and atrial fibrillation treatment strategies in United States community practice: findings from the ORBIT-AF registry

Background

The prevalence of atrial fibrillation (AF) continues to increase; however, there are limited data describing the division of care among practitioners in the community and whether care differs depending on provider specialty.

Methods and Results

Using the Outcomes Registry for Better Informed Treatment of AF (ORBIT‐AF) Registry, we described patient characteristics and AF management strategies in ambulatory clinic practice settings, including electrophysiology (EP), general cardiology, and primary care. A total of 10 097 patients were included; of these, 1544 (15.3%) were cared for by an EP provider, 6584 (65.2%) by a cardiology provider, and 1969 (19.5%) by an internal medicine/primary care provider. Compared with those patients who were cared for by cardiologists or internal medicine/primary care providers, patients cared for by EP providers were younger (median age, 73 years [interquartile range, IQR, 64, 80 years, Q1, Q3] versus 75 years [IQR, 67, 82 years] for cardiology and versus 76 years [IQR, 68, 82 years] for primary care). Compared with cardiology and internal medicine/primary care providers, EP providers used rhythm control (versus rate control) management more often (44.2% versus 29.7% and 28.8%, respectively, P<0.0001; adjusted odds ratio [OR] EP versus cardiology, 1.66 [95% confidence interval, CI, 1.05 to 2.61]; adjusted OR for internal medicine/primary care versus cardiology, 0.91 [95% CI, 0.65 to 1.26]). Use of oral anticoagulant therapy was high across all providers, although it was higher for cardiology and EP providers (overall, 76.1%; P=0.02 for difference between groups).

Conclusions

Our data demonstrate important differences between provider specialties, the demographics of the AF patient population treated, and treatment strategies—particularly for rhythm control and anticoagulation therapy.

Analysis of disease patterns and cost of treatments for prevention of deep venous thrombosis after total knee or hip replacement: results from the Practice Analysis of THromboprophylaxis after Orthopaedic Surgery (PATHOS) study

Introduction

Venous thromboembolism (VTE) is a well-known complication of total hip replacement (THR) and total knee replacement (TKR). Various drugs have been introduced in an attempt to reduce the mortality as well as the short-term and long-term morbidity associated with the development of VTE. The aim of this study was to analyze drug utilization for thromboprophylaxis and the cost of illness in real clinical practice in patients with THR or TKR.

Materials and methods

A multicenter, retrospective, observational cohort study based on local health unit administrative databases was conducted. All patients (≥18 years old) discharged for THR/TKR procedures between January 1, 2007 and December 31, 2008 were included in the study. The date of first hospital discharge was the index date; patients were followed up for a period of 12 months.

Results

A total of 10,389 patients were included: 3516 males (33.8%, 69.4 ± 10.4 years) and 6873 females (66.2%, 71.7 ± 9.0 years), of which 5483 (52.8%) were discharged for THR and 4906 (47.2%) for TKR. First antithrombotic treatments after discharge were enoxaparin (3937, 37.9%), heparin (3752, 36.1%), antiplatelet agents (658, 6.3%), vitamin K antagonists (276, 2.7%), fondaparinux (136, 1.3%), combinations (185, 1.8%), and no therapy (1445, 13.9%). Overall, we observed 2347 (22.6%) treatment changes; median duration of antithrombotic treatment was 23 days (range 11–47) for THR and 22 days (range 11–46) for TKR. During the follow-up period, we observed 129 cases of VTE (120 per 10,000 patients), five post-thrombotic syndrome (4.8 per 10,000 patients), and three heparin-induced thrombocytopenia (2.9 per 10,000 patients). Median cost for both THR and TKR was €9052.00 (range €8063.00–€9084.96), with a median length of stay of 9.0 days (range 6.0–12.0).

Monocyte chemotactic protein-1 as a potential biomarker for early anti-thrombotic therapy after ischemic stroke

Inflammation following ischemic brain injury is correlated with adverse outcome. Preclinical studies indicate that treatment with acetylsalicylic acid + extended-release dipyridamole (ASA + ER-DP) has anti-inflammatory and thereby neuroprotective effects by inhibition of monocyte chemotactic protein-1 (MCP-1) expression. We hypothesized that early treatment with ASA + ER-DP will reduce levels of MCP-1 also in patients with ischemic stroke. The EARLY trial randomized patients with ischemic stroke or TIA to either ASA + ER-DP treatment or ASA monotherapy within 24 h following the event. After 7 days, all patients were treated for up to 90 days with ASA + ER-DP. MCP-1 was determined from blood samples taken from 425 patients on admission and day 8. The change in MCP-1 from admission to day 8 did not differ between patients treated with ASA + ER-DP and ASA monotherapy (p > 0.05). Comparisons within MCP-1 baseline quartiles indicated that patients in the highest quartile (>217–973 pg/mL) showed improved outcome at 90 days if treated with ASA + ER-DP in comparison to treatment with ASA alone (p = 0.004). Our data does not provide any evidence that treatment with ASA + ER-DP lowers MCP-1 in acute stroke patients. However, MCP-1 may be a useful biomarker for deciding on early stroke therapy, as patients with high MCP-1 at baseline appear to benefit from early treatment with ASA + ER-DP.

Comprehensive risk reduction in patients with atrial fibrillation: emerging diagnostic and therapeutic options--a report from the 3rd Atrial Fibrillation Competence NETwork/European Heart Rhythm Association consensus conference

While management of atrial fibrillation (AF) patients is improved by guideline-conform application of anticoagulant therapy, rate control, rhythm control, and therapy of accompanying heart disease, the morbidity and mortality associated with AF remain unacceptably high. This paper describes the proceedings of the 3rd Atrial Fibrillation NETwork (AFNET)/European Heart Rhythm Association (EHRA) consensus conference that convened over 60 scientists and representatives from industry to jointly discuss emerging therapeutic and diagnostic improvements to achieve better management of AF patients. The paper covers four chapters: (i) risk factors and risk markers for AF; (ii) pathophysiological classification of AF; (iii) relevance of monitored AF duration for AF-related outcomes; and (iv) perspectives and needs for implementing better antithrombotic therapy. Relevant published literature for each section is covered, and suggestions for the improvement of management in each area are put forward. Combined, the propositions formulate a perspective to implement comprehensive management in AF.

Medical treatment and long-term outcome of chronic atrial fibrillation in the aged with chest distress: a retrospective analysis versus sinus rhythm

Although "chest distress" is the most frequent complication in the aged with chronic atrial frbrillation (AF) in clinical practice, there are few data on the association between chronic AF and coronary artery disease (CAD) in the aged in terms of medical treatment and long-term outcome. We assessed coronary artery lesions in such patients and evaluated the efficacy of medical treatment in long-term follow-ups. Of 315 elderly patients (mean age: 77.39 ± 6.33 years) who had undergone coronary angiography for chest distress, 297 exhibited sinus rhythm (SR), whereas 18 patients exhibited chronic AF. Patients with AF were followed for 4.22 ± 2.21 years. Average diastolic blood pressure (DBP) of AF patients was observed to be markedly less than that of patients with SR (57.33 ± 6.87 mmHg vs 71.08 ± 10.54 mmHg, t-test: P < 0.01). Compared with SR patients, severe stenosis of the coronary artery in AF patients was reduced (73.06% vs 44.44%, Chi-square test: P < 0.01). AF patients with chest distress had high CHADS2 score (3.72 ± 1.27), but only 33.3% patients received oral anticoagulants, and such patients had a significantly lower rate of revascularization (21.43% vs 55.63%, Chi-square test: P < 0.01), and higher rate of all-cause death (22.22% vs 4.38%, Chi-square test: P < 0.01) and thromboembolism (16.67% vs 1.68%, Chi-square test: P < 0.01) in the long-term follow-ups compared with SR patients. Chest distress in the aged with AF was related to insufficient coronary blood supply that was primarily due to a reduced DBP rather than to occult CAD. Adequate and safe medical therapy was difficult to achieve in these patients. Such patients typically have a poor prognosis, and optimal therapeutic strategies to treat them are urgently needed.

Antithrombotic therapy in very elderly patients with atrial fibrillation: is it enough to assess thromboembolic risk?

Although attention has been given to thromboprophylaxis for atrial fibrillation (AF) in present treatment guidelines, practical, clinical antithrombotic therapy is poorly developed for very elderly patients. We reviewed the records of 105 consecutive patients with AF of mean age 85 years, to determine how the greatest benefits from antithrombotic therapy could be obtained in this group. The mean CHADS2 score in these patients was 3.1 ± 1.5. Before antithrombotic therapy, 21.0% of the patients had diseases with a risk of hemorrhage, 26.7% had diseases with a risk of thrombosis, and 8.6% had diseases with a risk of both hemorrhage and thrombosis. Moreover, 89 patients (84.8%) were receiving a single antiplatelet drug, 10 (9.5%) used aspirin plus clopidogrel, and six (5.7%) were taking an oral anticoagulant (OAC). Additionally, dual antiplatelet therapy was more commonly given to patients with permanent AF (paroxysmal and persistent versus permanent, 6.3% and 12.5% versus 30%, respectively, Chi-square = 8.4, P = 0.010). The incidence of adverse events was 25.7%, with thromboembolic events in 20.0% and hemorrhage in 5.7% of patients. There were no thromboembolic events in those patients taking OACs, but 33% of patients who took OACs had bleeding complications. It is difficult to choose appropriate antithrombotic strategies in very elderly patients. Both the thrombotic risk and the bleeding risk should be considered for helping such patients derive optimal benefit from thromboprophylaxis for AF.

New anticoagulants for the prevention of venous thromboembolism

Anticoagulant drugs have an essential role in the prevention and treatment of thromboembolic diseases. Currently available anticoagulants substantially reduce the incidence of thromboembolic events in a number of clinical conditions. However, these agents have limitations that strengthen the case for the development of new anticoagulants. An ideal anticoagulant should be at least as effective as those currently in use, as well as safe, simple to use, and widely applicable.The majority of new anticoagulants currently under investigation are small molecules with a selective and direct anti-Xa or antithrombin action, allowing oral administration in fixed doses. These new agents are in different phases of clinical development. The anti-Xa agent rivaroxaban and the antithrombin agent dabigatran are already available for the prophylaxis of venous thromboembolism in some countries. Apixaban is in an advanced phase of clinical development and several anti-Xa agents are currently approaching phase III clinical trials. Promising results in terms of efficacy and safety profiles have been obtained with these agents in different clinical conditions. Differences in pharmacokinetics and pharmacodynamics could offer the potential for individualized anticoagulant therapies in the near future.

Cost effectiveness of venous thromboembolism pharmacological prophylaxis in total hip and knee replacement: a systematic review

Total hip and knee replacements (THR and TKR) are high-risk settings for venous thromboembolism (VTE). This review summarizes the cost effectiveness of VTE prophylaxis regimens for THR and TKR. We searched MEDLINE (January 1997 to October 2009), EMBASE (January 1997 to June 2009) and the UK NHS Economic Evaluation Database (1997 to October 2009). We analysed recent cost-effectiveness studies examining five categories of comparisons: (i) anticoagulants (warfarin, low-molecular-weight heparin [LMWH] or fondaparinux) versus acetylsalicylic acid (aspirin); (ii) LMWH versus warfarin; (iii) fondaparinux versus LMWH; (iv) comparisons with new oral anticoagulants; and (v) extended-duration (> or =3 weeks) versus short-duration (<3 weeks) prophylaxis. We abstracted information on cost and effectiveness for each prophylaxis regimen in order to calculate an incremental cost-effectiveness ratio. Because of variations in effectiveness units reported and horizon length analysed, we calculated two cost-effectiveness ratios, one for the number of symptomatic VTE events avoided at 90 days and the other for QALYs at the 1-year mark or beyond. Our search identified 33 studies with 67 comparisons. After standardization, comparisons between LMWH and warfarin were inconclusive, whereas fondaparinux dominated LMWH in nearly every comparison. The latter results were derived from radiographic VTE rates. Extended-duration prophylaxis after THR was generally cost effective. Small numbers prohibit conclusions about aspirin, new oral anticoagulants or extended-duration prophylaxis after TKR. Fondaparinux after both THR and TKR and extended-duration LMWH after THR appear to be cost-effective prophylaxis regimens. Small numbers for other comparisons and absence of trials reporting symptomatic endpoints prohibit comprehensive conclusions.

A critical review of clinical trials for low-molecular-weight heparin therapy in unstable coronary artery disease

Unstable angina and non-ST-segment elevation myocardial infarction (MI) are collectively referred to as unstable coronary artery disease (UCAD). They are conditions that share a common pathophysiology and represent frequently encountered, potentially life-threatening clinical manifestations of advanced atherosclerosis. Therefore, treatment of UCAD is a major focus for practicing clinicians, and although pharmacologic agents have been developed that impact on patient outcome, recent data suggest that a further reduction in ischemic complications is possible. Acute-phase treatment with aspirin is associated with a significant reduction in death and nonfatal MI in patients with UCAD. This benefit is enhanced by the addition of unfractionated heparin (UFH) to the treatment strategy; however, UFH requires careful monitoring and titration. In contrast, low-molecular-weight heparins (LMWHs), produced by chemical or enzymatic depolymerization of UFH, yield a predictable and consistent pharmacokinetic profile and anticoagulant response, making them an attractive treatment alternative to UFH in patients with UCAD. The optimal duration of treatment with LMWH is an important question influenced by the observation that reactivation of coagulation occurs following the early and abrupt discontinuation of heparin treatment. Early trials, such as FRISC and FRIC, demonstrated the benefit of acute therapy with dalteparin sodium; however, the results of extended treatment with dalteparin were inconclusive. The extended phase of these studies included relatively low-risk patients, and a once-daily, relatively low-dose strategy was employed. The findings derived from the FRISC II trial, which used a twice-daily dose of dalteparin, suggest a benefit for at least 60 days with extended treatment in high-risk patients with UCAD. Although an early-invasive treatment strategy is particularly beneficial, patients in whom early revascularization is not possible should be considered for extended treatment with dalteparin for up to 45 days, especially those awaiting percutaneous coronary intervention. Extended treatment with dalteparin therefore provides a protective "bridge" to enhance the outcome of patients with UCAD awaiting revascularization.

The safety and adequacy of antithrombotic therapy for atrial fibrillation: a regional cohort study

BACKGROUND

Atrial fibrillation is a common problem in older people. The evidence base for the safety of warfarin and aspirin in atrial fibrillation is largely derived from selective research studies and secondary care. Further assessment of the safety of warfarin in older people with atrial fibrillation in routine primary care is needed.

AIM

To measure the complication rates and adequacy of warfarin control in a cohort of patients with atrial fibrillation managed in primary care and compare them with published data from controlled trials and community patients with atrial fibrillation not receiving warfarin.

DESIGN OF STUDY

Retrospective review of regional cohort.

SETTING

Twenty-seven general practices in southwest Scotland.

METHOD

Case note review of 601 patients previously identified as having atrial fibrillation by GPs.

RESULTS

The average age of our cohort was 77 years at recruitment. Two hundred and sixty-four (44%) patients died within 5 years of follow up. Three hundred and nine of the 601 (51%) patients with atrial fibrillation took warfarin at some stage during this study. INR (international normalised ratio) was maintained between 2 and 3 for 68% of the time. Bleeding risk was higher in patients taking warfarin than in those on aspirin or no antithrombotic therapy (warfarin 9.0% per year versus aspirin 4.7% per year versus no therapy 4.6% per year). The annual risk of any bleeding complication on warfarin (9%) was similar to that recorded in randomised trials (9.2%) whereas the annual risk of severe bleeding was approximately double (2.6 versus 1.3%).

CONCLUSION

Adequacy of anticoagulant control was broadly comparable to that reported in clinical trials, whereas the risk of severe bleeding was higher, possibly reflecting the older age and the comorbidities of our unselected cohort.