Prevention of Deep Vein Thrombosis after Major Knee Surgery - A Randomized, Double-Blind Trial Comparing a Low Molecular Weight Heparin Fragment (Enoxaparin) to Placebo

Venous Thromboembolism Prophylaxis in Major Orthopedic Surgeries and Factor XIa Inhibitors

Venous thromboembolism (VTE), comprising pulmonary embolism (PE) and deep vein thrombosis (DVT), poses a significant risk during and after hospitalization, particularly for surgical patients. Among various patient groups, those undergoing major orthopedic surgeries are considered to have a higher susceptibility to PE and DVT. Major lower-extremity orthopedic procedures carry a higher risk of symptomatic VTE compared to most other surgeries, with an estimated incidence of ~4%. The greatest risk period occurs within the first 7-14 days following surgery. Major bleeding is also more prevalent in these surgeries compared to others, with rates estimated between 2% and 4%. For patients undergoing major lower-extremity orthopedic surgery who have a low bleeding risk, it is recommended to use pharmacological thromboprophylaxis with or without mechanical devices. The choice of the initial agent depends on the specific surgery and patient comorbidities. First-line options include low-molecular-weight heparins (LMWHs), direct oral anticoagulants, and aspirin. Second-line options consist of unfractionated heparin (UFH), fondaparinux, and warfarin. For most patients undergoing knee or hip arthroplasty, the initial agents recommended for the early perioperative period are LMWHs (enoxaparin or dalteparin) or direct oral anticoagulants (rivaroxaban or apixaban). In the case of hip fracture surgery, LMWH is recommended as the preferred agent for the entire duration of prophylaxis. However, emerging factor XI(a) inhibitors, as revealed by a recent meta-analysis, have shown a substantial decrease in the occurrence of VTE and bleeding events among patients undergoing major orthopedic surgery. This discovery poses a challenge to the existing paradigm of anticoagulant therapy in this specific patient population and indicates that factor XI(a) inhibitors hold great promise as a potential strategy to be taken into serious consideration.

THE USE OF CHEMOPROPHYLAXIS OR NOT FOR DVT IN SPINE SURGERY: A SYSTEMATIC REVIEW

ABSTRACT Objective: To compare pharmacological and non-pharmacological prophylaxis in elective spine surgery to determine the risks of DVT, PTE, and epidural hematoma (EH) in both groups, as well as their respective treatment effectiveness. Methods: Systematic review and meta-analysis based on systematically searched articles, using combinations of MeSH terms related to chemoprophylaxis and non-chemoprophylaxis for prevention of deep vein thrombosis and pulmonary embolism in elective spine surgery. Adult patients were eligible for inclusion in the study, except for those with trauma, spinal cord injury, neoplasms, or those using vena cava filters. Results: Five studies were selected for this systematic review and meta-analysis: 3 retrospective studies, 1 prospective study, and 1 case series. Data analysis showed that 4.64% of patients treated with chemoprophylaxis had an unfavorable outcome regarding DVT, while this outcome occurred in 1.14% of patients not treated with chemoprophylaxis (p=0.001). Among patients using chemoprophylaxis, only 0.1% developed epidural hematoma and 0.38% developed PTE. Among those on non-pharmaceutical prophylaxis, 0.04% had EH (p=0.11) and 0.42% had PTE (p=0.45). Conclusions: No benefits were found for chemoprophylaxis as compared to non-chemoprophylaxis in preventing DVT in elective spine surgery, nor was there an increased risk of epidural hematoma or fatal thromboembolic events. Level of evidence III; Therapeutic studies; Investigation of treatment results.

Is chemoprophylaxis required after total knee and total hip arthroplasty in the Asian population? A systematic review and network meta-analysis

INTRODUCTION

Although chemoprophylaxis against venous thromboembolism (VTE) after Total Joint Arthroplasty (TJA) is commonly practiced, epidemiology studies have shown Asians have a much lower incidence of VTE. The authors aim to investigate if chemoprophylaxis is really necessary in the Asian population undergoing TJA.

MATERIAL AND METHODS

Literature searched was conducted for randomized controlled trials or quasi-experimental studies investigating efficacy and/or safety of chemoprophylaxis for TJA without language restrictions. Network meta-analysis, comparing the incidence of 'VTE to be treated', 'VTE not to be treated', 'Minor bleeding', and 'Major bleeding' amongst the different interventions was performed using multivariate meta-regression model.

RESULTS

38 studies (11,769 patients) were included. Total incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) were 14.2% and 0.73% respectively. For outcome on efficiency, edoxaban, low-molecular-weight-heparin (LMWH), fondaparinux, and enoxaparin showed significantly lower Risk Ratio (RR) for 'VTE to be treated' compared to Control/Placebo. Although no interventions showed increased incidence of major bleeding, LMWH and fondaparinux showed higher RR for minor bleeding. Enoxaparin displayed the best efficacy and safety profile. Total incidence of symptomatic DVT in studies involving enoxaparin was 1.98% (1.07% in patients who received enoxaparin, 2.92% in Control/Placebo). Total incidence of proximal DVT was 2.93% (2.67% in patients who received enoxaparin, 3.11% in Control/Placebo).

CONCLUSION

Asian population has a much lower incidence of VTE events after TJA compared to the Western population. Although Enoxaparin is still efficacious in reducing symptomatic and proximal DVT after TJA, its benefit-to-risk ratio is much lower than described in the Western literature.

Indirect comparison meta-analysis of two enoxaparin regimens in patients undergoing major orthopaedic surgery

Two enoxaparin dosage regimens are used as comparators to evaluate new anticoagulants for thromboprophylaxis in patients undergoing major orthopaedic surgery, but so far no satisfactory direct comparison between them has been published. Our objective was to compare the efficacy and safety of enoxaparin 3,000 anti-Xa IU twice daily and enoxaparin 4,000 anti-Xa IU once daily in this clinical setting by indirect comparison meta-analysis, using Bucher’s method. We selected randomised controlled trials comparing another anticoagulant, placebo (or no treatment) with either enoxaparin regimen for venous thromboembolism prophylaxis after hip or knee replacement or hip fracture surgery, provided that the second regimen was assessed elsewhere versus the same comparator. Two authors independently evaluated study eligibility, extracted the data, and assessed the risk of bias. The primary efficacy outcome was the incidence of venous thomboembolism. The main safety outcome was the incidence of major bleeding. Overall, 44 randomised comparisons in 56,423 patients were selected, 35 being double-blind (54,117 patients). Compared with enoxaparin 4,000 anti-Xa IU once daily, enoxaparin 3,000 anti-Xa IU twice daily was associated with a reduced risk of venous thromboembolism (relative risk [RR]: 0.53, 95% confidence interval [CI]: 0.40 to 0.69), but an increased risk of major bleeding (RR: 2.01, 95% CI: 1.23 to 3.29). In conclusion, when interpreting the benefit-risk ratio of new anticoagulant drugs versus enoxaparin for thromboprophylaxis after major orthopaedic surgery, the apparently greater efficacy but higher bleeding risk of the twice-daily 3,000 anti-Xa IU enoxaparin regimen compared to the once-daily 4,000 anti-Xa IU regimen should be taken into account.

Venous thromboembolism in Asia – an unrecognised and under-treated problem?

Venous thromboembolism (VTE) has been perceived for a long time to be less common in Asian populations, particularly in the Far East, than in Western populations. Generally, thromboprophylaxis is not implemented as frequently as it should be in high-risk patients. However, recent prospective studies undertaken in Asian countries have demonstrated higher rates of VTE after major surgery and in medical wards, approaching those observed in Western populations. Risk factors for VTE are not different in Asian patients from those of Western patients with the exception of thrombophilic mutations. Deficiencies of the natural anticoagulants (protein S, protein C, and antithrombin) are the predominant thrombophilias in Asia whereas factor V Leiden and prothrombin G20210A gene mutation are not found or rarely reported. Further large well-designed clinical studies are needed to evaluate the magnitude of the risk of VTE and the appropriate use of thromboprophylaxis in different clinical situations.

Prospective, multicenter study of postoperative deep-vein thrombosis in patients with haemophilia undergoing major orthopaedic surgery

Perioperative clotting factor replacement is administered to reverse the inherent haemostatic defect in persons with haemophilia (PWH), potentially increasing their risk for developing venous thromboembolism (VTE) postoperatively. It was our objective to determine the prevalence of VTE in PWH undergoing total hip or knee arthroplasty (THA, TKA). Patients with haemophilia A or B who underwent THA or TKA were enrolled in this prospective, multicentre observational cohort study. Lower extremity venous duplex ultrasound was performed prior to surgery and 4–6 weeks after surgery. Eleven centres enrolled 51 subjects, 46 of whom completed the study. Six subjects (13.0 %) were treated with bypass agents perioperatively; the remaining 40 subjects received factor VIII or IX replacement. Intermittent pneumatic compression devices were utilised postoperatively in 23 subjects (50 %), and four subjects (8.7 %) also received low-molecular-weight heparin prophylaxis. One subject (2.2 %) with moderate haemophilia A was diagnosed with symptomatic distal deep-vein thrombosis (DVT) on day 6 following TKA. One subject (2.2 %) with severe haemophilia A was diagnosed with pulmonary embolism on day 9 following bilateral TKA. No subjects had asymptomatic DVT. Eighteen subjects (39.1 %) had major bleeding, and three subjects (6.5 %) experienced minor bleeding. The observed prevalence of ultrasound-detectable, asymptomatic DVT in PWH following TKA or THA in this study was low, but the incidence of symptomatic VTE (4.3 %, 95 % CI, 0.5–14.8 %) appeared similar to the estimated incidence in the general population without thromboprophylaxis.

Low-Molecular-Weight Heparin and the Relative Risk of Surgical Site Bleeding Complications: Results of a Systematic Review and Meta-Analysis of Randomized Controlled Trials of Venous Thromboprophylaxis in Patients After Total Joint Arthroplasty

BACKGROUND

Venous thromboembolism causes significant morbidity and mortality in patients after total joint arthroplasty. Although network meta-analyses have demonstrated a benefit of various thromboprophylactic agents, there remains a concern in the surgical community regarding the resulting wound complications. There is currently no systematic review of the surgical site bleeding complications of thromboprophylactic agents. The aim of this study was to systematically review the surgical site bleeding outcomes of venous thromboembolism prophylaxis in this population.

METHODS

A systematic review and meta-analysis was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Randomized controlled trials comparing more than one of low-molecular-weight heparin (LMWH), warfarin, rivaroxaban, apixaban, dabigatran, aspirin, or no pharmacologic treatment in patients after total hip or knee arthroplasty were selected for inclusion. Five meta-analyses were performed to compare LMWH with control, warfarin, apixaban, rivaroxaban, and dabigatran.

RESULTS

Forty-five randomized controlled trials of 56,730 patients were included. LMWH had a significantly increased relative risk of surgical site bleeding in comparison with control (relative risk, 2.32; 95% confidence interval, 1.40-3.85) and warfarin (1.54; 1.23-1.94). The relative risk of LMWH trended higher than apixaban (1.27; 1.00-1.63) and was similar to rivaroxaban (0.95; 0.74-1.23). Only 1 study reported the risk of surgical site bleeding in LMWH vs dabigatran (5.97; 2.08-17.11).

CONCLUSION

LMWH increased the risk of surgical site bleeding compared with control, warfarin. and dabigatran and trended toward an increased risk compared with apixaban. The risk of surgical site bleeding was similar with LMWH and rivaroxaban.

Cost implications of low molecular weight heparins as prophylaxis following total hip and knee replacement

Deep venous thrombosis (DVT) and pulmonary embolism (PE) are serious and costly complications of total hip and knee replacement surgery. The risk of these complications is significantly reduced by prophylaxis. Low molecular weight heparins (LMWH) are being used for this indication with increased frequency. The objective of this study was to assess the cost implications of LMWH for the prevention of symptomatic DVT and PE complications following total hip and knee replacement surgery. The study design was cost analysis based on utilization and the costs of medical resources for prophylaxis and treatment of DVT/PE. A retrospective hospital data set was used to assess symptomatic DVT/PE complication rates and medical resource utilization in patients receiving warfarin, other, and no prophylaxis. The results of a clinical trial were used to estimate relative reductions in risk of symptomatic DVT/PE due to prophylaxis with LMWH. The 7721 total hip and knee replacement patients analyzed were admitted in 1992 in 57 acute-care non-federal hospitals. The measurements were of incremental costs or charges expected to be saved as a result of using LMWH prophylaxis instead of warfarin prophylaxis. Prophylaxis using LMWH rather than warfarin reduces the expected total costs (charges) of treatment by $50 ($193), not including the pharmaceutical costs associated with prophylaxis. The cost reduction in favor of LMWH was sensitive to several factors, including blood monitoring costs and DVT/PE complication rates. Where a reduction of one day in hospital stay could be realized from LMWH's early onset of action, the cost (charges) reduction increased to $226 ($624). In conclusion, LMWH has the potential to offer several short- and long-term cost advantages compared with warfarin, mostly due to lower test costs associated with prophylaxis and reduced complication rates.

Postoperative Versus Preoperative Initiation of Deep-Vein Thrombosis Prophylaxis with a Low-Molecular-Weight Heparin (Nadroparin) in Elective Hip Replacement

The aim of this multicenter, randomized, dou ble-blind study performed in patients undergoing elective hip surgery was to compare the efficacy and safety of prophylaxis with low-molecular-weight heparin (LMWH) (Nadroparin, 7,500 anti-Xa IC units for the first 3 days and 10,000 from the fourth day on, s.c. o.i.d.) begun in one group shortly after surgery and in the other 12 h before operation, as is usually recommended. Preopera tive administration (drug or placebo) was the only differ ence between the two groups. Deep vein thrombosis (DVT) was detected by bilateral venography 10-15 days after surgery. The study investigated 179 patients (55 men), 40-80 years old, in seven Italian orthopedic cen ters. In 131 patients efficacy analysis was possible be cause of adequate bilateral venography. All 179 patients were evaluated for bleeding complications. The preva lence of thrombotic complications was similar in the two groups. Proximal DVT was found in 8.4% of patients (10.8% and 6.1% in the preop and postop groups, respec tively ; difference not statistically significant). Distal DVT was recorded in 30.5% of patients (30.8% and 30.3% in the pre- and postop groups, respectively). DVTs were more common in patients ≥65 years old (54.2% versus 28.4%, p < 0.05); no significant differences were detected in terms of other characteristics. No significant differ ences were recorded in the number or type of bleeding complications: major (nonfatal) bleeding episodes were reported in five patients (2.8%, two and three in the pre- and postop groups); minor bleeding was noted in 25 (13.9%, 14 and 11 in the pre- and postop groups). In con clusion, the present study suggests that a LMWH regi men started postoperatively is no less effective in pre venting DVT in elective hip replacement than the classi cal regimen started preoperatively. Surprisingly, postoperative commencement offered no significant ad vantage in terms of bleeding complications.

State-of-the-Art Review: Usefulness of Laboratory Techniques for Evaluating Antithrombotic Efficacy of New Therapeutic Strategies

New drugs and new therapeutic strategies are being introduced for the prevention and the management of cardiovascular and thromboembolic disorders. Extensive clinical studies and large-scale epidemiological investigations are conducted to demonstrate the efficacy of these therapeutic approaches. Laboratory assays are invaluable tools for this exploration. We discuss how the new understanding concerning the regulation of the coagulolytic equilibrium offers novel investigation tools. Parameters reflecting the activities of new drugs targeted to their impact site and presenting few side effects are available. In addition to global clotting methods and chromogenic substrate-based assays, introduction of immunoassays has allowed measurement of most of the molecular markers of hemostatic activation. We recommend use of a panel of markers exploring the endothelial damage, the blood cell involvement, the early coagulant pathways' activation (XIIa and VIIa), the thrombin-formation pathways, the fibrin formation, and the evaluation of the global fibrinolytic capacity. When related to the clinical end points, all these laboratory assays offer useful and reliable monitoring of new drugs. They contribute to the establishment of new therapeutic strategies. Key Words: Hemostasis—Activation—Antithrombotic—Therapy— Laboratory monitoring.

Risk of and Prophylaxis for Venous Thromboembolism in Hospital Patients

Objective:

To review the published clinical data on prophylaxis for thromboembolism in order to develop general guidelines to encourage the establishment of local protocols for management.

Data sources:

Published papers on thromboembolism over the period 1991–1997 were identified by Medline search and/or from the authors' personal literature collections and reviewed.

Study selection:

A total of 981 studies were identified. Only those papers reporting randomized studies with clearly defined diagnostic methods and clear end-points were included in this review.

Data extraction:

The available evidence for each specialty was summarized and reviewed by the authors responsible for each specialty, prior to presentation and discussion of their findings within the group. Where a consensus opinion was achieved in a speciality, general guidelines for thromboprophylaxis were summarized. Where a consensus could not be agreed, recommendations for further work were made.

Data synthesis:

There is evidence to support the preferred use of low-molecular-weight heparins (LMWHs) over unfractionated heparin (UFH) in orthopaedic surgery, major trauma and general surgery. However, the ideal duration of thromboprophylaxis has yet to be defined. The use of once daily subcutaneous administration of LMWH offers major practical advantages and may have significant cost saving implications. Further work is required to investigate the use of thromboprophylaxis in minimal access surgery, trauma, elective lower limb surgery, hip fracture and pregnancy; to compare the efficacy of LMWH and mechanical prophylaxis; and to investigate extended prophylaxis after discharge.

Conclusions:

There is overwhelming evidence that thromboembolic prophylaxis reduces the incidence of postoperative deep vein thrombosis and pulmonary embolism. Recommendations concerning the management of these patients when stratified into low, moderate and high risk are made with the suggestion that hospitals develop their own guidelines for the treatment of these patients.

PROPHYLAXIS OF VENOUS THROMBOEMBOLISM IN ORTHOPAEDIC SURGERY

The relevance of prophylaxis of venous thromboembolism and its complications in orthopedic surgery is increasingly significant. This review discusses the pathophysiology of thrombus formation in general and orthopedic surgery, its incidence, predisposing factors and complications. It also presents an updated presentation and critique of prophylaxis currently available in our environment.

Incidence of venous thromboembolism following major surgery in Korea: from the Health Insurance Review and Assessment Service database

BACKGROUND

Data on the incidence of venous thromboembolism (VTE) following major surgery in Asian populations are limited.

METHODS

Using the Korean Health Insurance Review and Assessment Service database, we performed a nationwide population-based epidemiologic study to estimate the incidence of VTE after major orthopedic, cancer, and benign surgeries. VTE cases were identified from all patients undergoing major surgery between 2007 and 2011 using both diagnostic and drug codes as treatment evidence of VTE within 5 weeks of surgery. We also calculated the relative risk of VTE in major orthopedic and cancer surgery compared to benign surgery.

RESULTS

The overall rates of postoperative VTE were 1.24%, 0.67%, and 0.05% for major orthopedic, cancer, and benign surgeries, respectively. Hip fracture (1.60%) and colorectal cancer surgeries (1.67%) were associated with the highest rates of VTE, and the rates steadily increased during the study period. Advanced age, female sex, and general anesthesia were independent risk factors for VTE. Patients undergoing surgery for colorectal, pancreatic, ovarian, and esophageal cancer, and major orthopedic surgery had a > 20-fold higher risk of VTE than those undergoing benign surgery.

CONCLUSIONS

This is the largest epidemiologic study to investigate the incidence of VTE after major surgery in Asia, demonstrating that the rates of postoperative VTE are lower than in Caucasian populations. This study contributes to a better understanding of the differences in postoperative VTE development between Korean and Caucasian populations; the data also suggest that perioperative prophylactic strategies in Asians should be based on studies of such populations.

Evidence-base for aspirin as venous thromboembolic prophylaxis following joint replacement

The National Institute for Health and Clinical Excellence (NICE) has thus far relied on historical data and predominantly industry-sponsored trials to provide evidence for venous thromboembolic (VTE) prophylaxis in joint replacement patients. We argue that the NICE guidelines may be reliant on assumptions that are in need of revision. Following the publication of large scale, independent observational studies showing little difference between low-molecular-weight heparins and aspirin, and recent changes to the guidance provided by other international bodies, should NICE reconsider their recommendations?

Cite this article: Bone Joint Res 2014;3:146–9.

Rivaroxaban is as efficient and safe as bemiparin as thromboprophylaxis in knee arthroscopy

PURPOSE

The aim of this study is to compare effectiveness and safety profile of rivaroxaban with bemiparin in 3-week extended prophylaxis after knee arthroscopy.

METHODS

Four hundred and sixty-seven patients were included in this review divided in two groups. One followed prophylaxis with rivaroxaban and the other one with bemiparin. All patients were interviewed and explored at 1 and 3 months postoperatively, looking for symptomatic signs of deep-vein thrombosis (DVT). In case of suspicion, diagnostic tests were performed. Collected data were age, sex, gender, diagnosis, time with ischemia, body mass index, concomitant diseases, concomitant therapy, DVT signs, treatment satisfaction, minor and major complications, treatment adherence and tolerability.

RESULTS

No thromboembolic events were observed in any of the groups. In one case treated with rivaroxaban, the drug had to be withdrawn due to epistaxis.

CONCLUSIONS

Our study showed that extended prophylaxis with 10 mg of rivaroxaban once daily for 3 weeks resulted as effective as bemiparin in knee arthroscopy thromboprophylaxis.

Intermittent pneumatic compression for venous thromboembolism prophylaxis in total knee arthroplasty

Venous thromboembolism (VTE) prophylaxis in total knee arthroplasty (TKA) is controversial. The purpose of this study was to evaluate the efficacy of bilateral intra- and postoperative intermittent pneumatic compression without major anticoagulation as prophylaxis for VTE in TKA.This retrospective study involved 157 consecutive patients undergoing TKA performed by 1 surgeon who were treated with bilateral intra- and postoperative intermittent pneumatic compression stockings. All patients were followed for at least 6 weeks postoperatively. Postoperative color duplex ultrasound imaging with compression by certified vascular technologists was obtained for 120 patients 2 to 3 days postoperatively. During hospitalization, 2 (1.7%) patients had acute deep vein thrombosis (DVT) diagnosed, 2 (1.7%) had DVT of indeterminate age, and 4 (3.3%) had chronic DVT. During follow-up, 1 (0.8%) patient had an acute DVT diagnosed at 5 weeks postoperatively and 1 (0.8%) had a superficial phlebitis and subsequently had a nonfatal pulmonary embolism 23 days postoperatively. The predominant chemoprophylaxis used was aspirin alone in 107 (89.2%) patients. Epidural anesthesia was used in the majority (n=96; 80%) of patients.The results of this study support the use of a multimodal approach to VTE prophylaxis in TKA, using bilateral intra- and postoperative intermittent pneumatic compression, epidural anesthesia, early mobilization, and postoperative aspirin without the use of major anticoagulation as an effective, safe VTE prophylactic protocol for patients undergoing elective TKA. The study suggests that the protocol is highly effective, has low morbidity, and is cost effective.

Prevention of VTE in orthopedic surgery patients: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

VTE is a serious, but decreasing complication following major orthopedic surgery. This guideline focuses on optimal prophylaxis to reduce postoperative pulmonary embolism and DVT.

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

In patients undergoing major orthopedic surgery, we recommend the use of one of the following rather than no antithrombotic prophylaxis: low-molecular-weight heparin; fondaparinux; dabigatran, apixaban, rivaroxaban (total hip arthroplasty or total knee arthroplasty but not hip fracture surgery); low-dose unfractionated heparin; adjusted-dose vitamin K antagonist; aspirin (all Grade 1B); or an intermittent pneumatic compression device (IPCD) (Grade 1C) for a minimum of 10 to 14 days. We suggest the use of low-molecular-weight heparin in preference to the other agents we have recommended as alternatives (Grade 2C/2B), and in patients receiving pharmacologic prophylaxis, we suggest adding an IPCD during the hospital stay (Grade 2C). We suggest extending thromboprophylaxis for up to 35 days (Grade 2B). In patients at increased bleeding risk, we suggest an IPCD or no prophylaxis (Grade 2C). In patients who decline injections, we recommend using apixaban or dabigatran (all Grade 1B). We suggest against using inferior vena cava filter placement for primary prevention in patients with contraindications to both pharmacologic and mechanical thromboprophylaxis (Grade 2C). We recommend against Doppler (or duplex) ultrasonography screening before hospital discharge (Grade 1B). For patients with isolated lower-extremity injuries requiring leg immobilization, we suggest no thromboprophylaxis (Grade 2B). For patients undergoing knee arthroscopy without a history of VTE, we suggest no thromboprophylaxis (Grade 2B).

CONCLUSIONS

Optimal strategies for thromboprophylaxis after major orthopedic surgery include pharmacologic and mechanical approaches.

The Efficacy and Safety of Pharmacological Prophylaxis of Venous Thromboembolism Following Elective Knee or Hip Replacement

The present systematic review was conducted to assess the efficacy and safety of apixaban versus other anticoagulants, for the prevention of venous thromboembolism (VTE) following total hip replacement (THR) and total knee replacement (TKR) surgery. Electronic databases were interrogated to identify relevant randomized controlled trials. A series of direct/indirect comparisons and a network meta-analysis were conducted. Indirect comparisons found that the odds ratio of “all VTE and all-cause death” were significantly higher for dabigatran than for apixaban in patients with THR (odds ratio [OR], 2.51; 95% confidence interval [CI], 1.50-4.21) and TKR (OR, 1.72; 95% CI, 1.22-2.42). Rivaroxaban showed similar efficacy to apixaban in patients with THR and TKR (OR, 0.69; 95% CI, 0.38-1.25 and OR, 0.83; 95% CI, 0.57-1.19, respectively). No significant differences were observed in bleeding outcomes between treatments. The novel anticoagulants apixaban, rivaroxaban, and dabigatran demonstrated similar or improved efficacy and similar safety compared with current therapies in this indication.

Direct thrombin inhibitors versus vitamin K antagonists or low molecular weight heparins for prevention of venous thromboembolism following total hip or knee replacement

BACKGROUND

Patients who have undergone total hip or knee replacement (THR, TKR) have a high risk of developing venous thromboembolism (VTE) following surgery, despite appropriate anticoagulation with warfarin or low molecular weight heparin (LMWH). New anticoagulants are under investigation.

OBJECTIVES

To examine the efficacy and safety of prophylactic anticoagulation with direct thrombin inhibitors (DTIs) versus LMWH or vitamin K antagonists in the prevention of VTE in patients undergoing THR or TKR.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Disease Group searched their Specialized Register (last searched 12 March 2010) and CENTRAL (last searched 2010, Issue 2).

SELECTION CRITERIA

Randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Three reviewers independently assessed methodological quality and extracted data in pre-designed tables. The reported follow-up events were included

MAIN RESULTS

We included 14 studies included involving 21,642 patients evaluated for efficacy and 27,360 for safety. No difference was observed in major VTE in DTIs compared with LMWH in both types of operations (odds ratio (OR) 0.91; 95% confidence interval (CI) 0.69 to 1.19), with high heterogeneity (I(2) 71%). No difference was observed with warfarin (OR 0.85; 95% CI 0.63 to 1.15) in TKR, with no heterogeneity (I(2) 0%).More total bleeding events were observed in the DTI group (in ximelagatran and dabigatran but not in desirudin) in patients subjected to THR (OR 1.40; 95% CI 1.06, 1.85; I(2) 41%) compared with LMWH. No difference was observed with warfarin in TKR (OR 1.76; 95% CI 0.91 to 3.38; I(2) 0%). All-cause mortality was higher in the DTI group when the reported follow-up events were included (OR 2.06; 95% CI 1.10 to 3.87).Studies that initiated anticoagulation before surgery showed less VTE events; those that began anticoagulation after surgery showed more VTE events in comparison with LMWH. Therefore, the effect of the DTIs compared with LMWH appears to be influenced by the time of initiation of coagulation more than the effect of the drug itself.The results obtained from sensitivity analysis, did not differ from the analysed results; this strengthens the value of the results.

AUTHORS' CONCLUSIONS

Direct thrombin inhibitors are as effective in the prevention of major venous thromboembolism in THR or TKR as LMWH and vitamin K antagonists. However, they show higher mortality and cause more bleeding than LMWH. No severe hepatic complications were reported in the analysed studies. Use of ximelagatran is not recommended for VTE prevention in patients who have undergone orthopedic surgery. More studies are necessary regarding dabigatran.

Is a tourniquet beneficial in total knee replacement surgery? A meta-analysis and systematic review

Proponents of tourniquets postulate that they optimise intra-operative visibility and reduce blood loss. This study compared the outcomes of tourniquet assisted to non-tourniquet assisted total knee replacement (TKR). A systematic review was undertaken of the electronic databases Medline, CINAHL, AMED and EMBASE, in addition to a review of unpublished material and a hand search of pertinent orthopaedic journals. The evidence-base was critically appraised using a tool from the Cochrane Bone, Joint and Muscle Trauma Group. Fifteen studies were identified evaluating 16 outcome measures and parameters of 1040 TKRs in 991 patients. There was a significantly greater intra-operative blood loss in non-tourniquet compared to tourniquet assisted surgery (p=0.004). There was no significant difference between the groups for total blood loss or transfusion rate (p=0.22; p=0.48). There was a trend for greater complications in tourniquet compared to non-tourniquet patients. There was no difference between the groups for any other outcome measure assessed. In conclusion, this systematic review has found that there is no advantage to using a tourniquet in knee replacement surgery for reduction of transfusion requirements.

EVALUATION OF HEPATIC FUNCTION AMONG PATIENTS UNDERGOING TOTAL HIP ARTHROPLASTY USING ENOXAPARIN

Objective: To evaluate hepatic changes resulting from the use of enoxaparin for prophylaxis of deep vein thrombosis among patients undergoing total hip arthroplasty. Methods: Thirty-two patients underwent elective total hip arthroplasty, using enoxaparin, and were followed up for 65 days with serial hepatic enzyme assays. Results: Changes in laboratory parameters were found in up to 75% of the patients during the study, but the parameters normalized after suspension of the treatment. No clinical evidence of hepatic lesions was found. Conclusion: The hepatic enzyme levels increase in most patients using enoxaparin, but without clinical correlation, and the levels normalize after suspension of the treatment.

Efficacy and safety of enoxaparin in Japanese patients undergoing curative abdominal or pelvic cancer surgery: results from a multicenter, randomized, open-label study

BACKGROUND

Enoxaparin sodium (enoxaparin) is used worldwide for the prevention of venous thromboembolism (VTE). Registration trials of enoxaparin have been conducted primarily in Caucasian populations, and its preventive use in Japanese patients has yet to be established. To address this, we evaluated the efficacy and safety of postoperative enoxaparin in Japanese patients undergoing surgery for abdominal cancer.

METHODS

This multicenter, open-label study randomized 151 Japanese patients undergoing curative surgery for abdominal cancer to enoxaparin 20mg twice daily for 14 days, started 24-36 hours after surgery (n=113) or intermittent pneumatic compression (IPC) as a reference (n=38). IPC was performed at least once in both groups between randomization and surgery. The primary efficacy endpoint was the incidence of VTE in the modified intention-to-treat (mITT) population. The primary safety outcome was the incidence of any bleeding during treatment and follow-up.

RESULTS

Incidence of VTE was 1.2% (95% CI, 0.03-6.53%) (1/83 patients) in the enoxaparin group and 19.4% (95% CI, 7.45-37.47%) (6/31 patients) in the IPC group. In the safety population, 10/109 patients in the enoxaparin group (9.2%; 95% CI, 4.49-16.23%) and 3/38 patients in the IPC group (7.9%; 95% CI, 1.66-21.38%) experienced a bleeding event. There were no cases of fatal bleeding or bleeding into any critical organ.

CONCLUSIONS

These favorable efficacy and safety data support the use of enoxaparin (20mg twice daily for 14 days started 24-36 hours after surgery) in Japanese patients undergoing abdominal or pelvic cancer surgery.

Overview of current venous thromboembolism protocols in hip reconstruction

Venous thromboembolic disease continues to be a serious complication of total-hip arthroplasty. The use of anticoagulant drugs for preventing this complication has repeatedly been proven to be useful. This article reviews the current evidence-based recommendations for anticoagulant prophylaxis after total-hip arthroplasty and provides insight into the current areas of active research and controversy.

Oral thrombin inhibitor dabigatran etexilate vs North American enoxaparin regimen for prevention of venous thromboembolism after knee arthroplasty surgery

Dabigatran, an oral once-daily unmonitored thrombin inhibitor, has been tested elsewhere using enoxaparin 40 mg once daily. We used the North American enoxaparin 30 mg BID regimen as the comparator. This was a double-blind, centrally randomized trial. Unilateral total knee arthroplasty patients were randomized to receive oral dabigatran etexilate 220 or 150 mg once daily, or enoxaparin 30 mg SC BID after surgery, blinded. Dosing stopped at contrast venography, 12 to 15 days after surgery. Among 1896 patients, dabigatran 220 and 110 mg showed inferior efficacy to enoxaparin (venous thromboembolism rates of 31% [P = .02 vs enoxaparin], 34% [P < .001 vs enoxaparin], and 25%, respectively). Bleeding rates were similar, and no drug-related hepatic illness was recognized. Dabigatran, effective compared to once-daily enoxaparin, showed inferior efficacy to the twice-daily North American enoxaparin regimen, probably because of the latter's more intense and prolonged dosing.

Portable compression device and low-molecular-weight heparin compared with low-molecular-weight heparin for thromboprophylaxis after total joint arthroplasty

This preliminary prospective study to determine the rate of deep venous thrombosis (DVT) examined 277 patients undergoing total knee or total hip arthroplasty (TKA or THA) who were randomized to use a portable, continuous enhanced circulation therapy (CECT) compression device and low-molecular-weight heparin (LMWH) or to receive LMWH alone. Patients were screened for DVT using duplex ultrasound at hospital discharge and followed clinically for 3 months. In TKA, 5 DVTs (6.6%) occurred in the CECT + LMWH group compared with one pulmonary embolism and 14 DVTs (19.5%) in the LMWH group (P = .018). In THA, 1 DVT (1.5%) occurred in the CECT + LMWH group and 2 DVTs (3.4%) occurred in the LMWH group. This preliminary study demonstrated significant reduction in rate of DVT after TKA when the CECT device was combined with LMWH.

Prevention of postoperative venous thromboembolism in Japanese patients undergoing total hip or knee arthroplasty: two randomized, double-blind, placebo-controlled studies with three dosage regimens of enoxaparin

BACKGROUND

Enoxaparin is a low-molecular-weight heparin indicated in Europe and North America for the prevention of venous thromboembolism (VTE) in patients undergoing major orthopedic surgery. Registration trials of enoxaparin have been conducted primarily in Caucasian populations, and the efficacy and safety of enoxaparin in Japanese patients have not been demonstrated. We evaluated three dosage regimens of postoperative enoxaparin in Japanese patients undergoing elective total hip or knee arthroplasty.

METHODS

Two multicenter, randomized, double-blind studies enrolled 436 and 396 Japanese adults undergoing total hip or knee arthroplasty, respectively. The dosage regimens of enoxaparin were 20 mg once daily (qd), 40 mg qd, 20 mg twice daily (bid), or placebo for 14 consecutive days. The primary efficacy endpoint was the incidence of VTE in the modified intention-to-treat (mITT) population up to 15 days after surgery. VTE was defined as a composite of deep vein thrombosis (determined by venography) and symptomatic pulmonary embolism (confirmed by appropriate objective methods). Patients were also followed up at 90 days for VTE events. The primary safety outcome was the incidence of any bleeding during treatment and the follow-up period.

RESULTS

In the mITT populations, the incidence of VTE was 41.9% and 60.8% in the placebo groups after hip or knee arthroplasty, respectively, 25.9% and 44.9% in the enoxaparin 20 mg qd groups, 33.8% and 35.1% in the enoxaparin 40 mg qd groups, and 20.0% and 29.8% in the enoxaparin 20 mg bid groups. Only enoxaparin 20 mg bid significantly lowered the risk of VTE relative to placebo (by 52.2% and 51.0% after hip and knee arthroplasty, respectively). At the 90-day follow-up, no further cases of VTE were reported. In both the hip and knee studies, the four treatment groups did not differ significantly regarding the incidence of patients with any bleeding.

CONCLUSIONS

Our findings support the use of enoxaparin (20 mg bid daily, commencing 24-36 h postoperatively) in Japanese patients undergoing total hip or knee arthroplasty.

Ninety-day mortality after elective total hip replacement

Thromboprophylaxis after elective orthopaedic surgery remains controversial. Recent guidelines from the National Institute for Clinical Excellence (NICE) have suggested that low molecular weight heparin should be given to all patients undergoing total hip replacement. The British Orthopaedic Association is currently debating this guideline with NICE, as it is not clear whether published evidence supports this view. We present the early mortality in our unit after total hip replacement using aspirin as chemical thromboprophylaxis. The 30-day and 90-day mortality after primary total hip arthroplasty was zero. We compare this with that reported previously from our unit without using chemical thromboprophylaxis. With the introduction of routine aspirin thromboprophylaxis, deaths from cardiovascular causes have dropped from 0.75% to zero.

These results demonstrate that there is a strong argument for the routine administration of aspirin after elective total hip replacement.

Oral dabigatran etexilate vs. subcutaneous enoxaparin for the prevention of venous thromboembolism after total knee replacement: the RE-MODEL randomized trial

BACKGROUND

Oral anticoagulants, such as dabigatran etexilate, an oral, direct thrombin inhibitor, that do not require monitoring or dose adjustment offer potential for prophylaxis against venous thromboembolism (VTE) after total knee replacement surgery.

METHODS

In this randomized, double-blind study, 2076 patients undergoing total knee replacement received dabigatran etexilate, 150 mg or 220 mg once-daily, starting with a half-dose 1-4 hours after surgery, or subcutaneous enoxaparin 40 mg once-daily, starting the evening before surgery, for 6-10 days. Patients were followed-up for 3 months. The primary efficacy outcome was a composite of total VTE (venographic or symptomatic) and mortality during treatment, and the primary safety outcome was the incidence of bleeding events.

RESULTS

The primary efficacy outcome occurred in 37.7% (193 of 512) of the enoxaparin group versus 36.4% (183 of 503) of the dabigatran etexilate 220 mg group (absolute difference, -1.3%; 95% CI, -7.3 to 4.6) and 40.5% (213 of 526) of the 150 mg group (2.8%; 95% CI, -3.1 to 8.7). Both doses were noninferior to enoxaparin based on the pre-specified noninferiority criterion. The incidence of major bleeding did not differ significantly between the three groups (1.3% versus 1.5% and 1.3% respectively). No significant differences in the incidences of liver enzyme elevation and acute coronary events were observed during treatment or follow-up.

CONCLUSIONS

Dabigatran etexilate (220 mg or 150 mg) was at least as effective and with a similar safety profile as enoxaparin for prevention of VTE after total knee-replacement surgery.

Insufficient duration of venous thromboembolism prophylaxis after total hip or knee replacement when compared with the time course of thromboembolic events: findings from the Global Orthopaedic Registry

Patients who have undergone total hip or knee replacement (THR and TKR, respectively) are at high risk of venous thromboembolism. We aimed to determine the time courses of both the incidence of venous thromboembolism and effective prophylaxis. Patients with elective primary THR and TKR were enrolled in the multi-national Global Orthopaedic Registry. Data on the incidence of venous thromboembolism and prophylaxis were collected from 6639 THR and 8326 TKR patients. The cumulative incidence of venous thromboembolism within three months of surgery was 1.7% in the THR and 2.3% in the TKR patients. The mean times to venous thromboembolism were 21.5 days (sd 22.5) for THR, and 9.7 days (sd 14.1) for TKR. It occurred after the median time to discharge in 75% of the THR and 57% of the TKA patients who developed venous thromboembolism. Of those who received recommended forms of prophylaxis, approximately one-quarter (26% of THR and 27% of TKR patients) were not receiving it seven days after surgery, the minimum duration recommended at the time of the study. The risk of venous thromboembolism extends beyond the usual period of hospitalisation, while the duration of prophylaxis is often shorter than this. Practices should be re-assessed to ensure that patients receive appropriate durations of prophylaxis.

Altered regulation of in-vivo coagulation in orthopedic patients prior to knee or hip replacement surgery

Up to 20% of patients develop venographically proven deep-vein thrombosis after elective orthopedic surgery even under the cover of heparin or low molecular weight heparin. The extent to which the chronic inflammation of osteoarthritis requiring elective orthopedic surgery alters in-vivo coagulation and whether any specific alteration influences the development of postoperative thrombosis are unknown. This study compared the concentrations of activated factor VII (FVIIa), tissue factor pathway inhibitor (TFPI), activated factor X (FXa)-TFPI, thrombin-antithrombin, and prothrombin fragment 1+2 (F1+2) in plasmas of 535 healthy individuals (ages 17-76) with those in the preoperative plasmas of 306 arthritis patients (ages 30-92) scheduled for elective knee or hip replacement surgery. C-reactive protein was also measured in the plasmas of approximately 15% of the participants. Age-adjusted concentrations of FVIIa, F1+2, and C-reactive protein were higher in patients than controls, while the concentrations of thrombin-antithrombin, TFPI and FXa-TFPI were similar. Chronic inflammation in the patients was thus associated with increased coagulation in vivo. Without compensatory increases in the concentrations of TFPI (natural inhibitor of prothrombinase), the elevated concentrations of FVIIa in the preoperative plasmas and the trauma associated with surgery may enhance the risk for developing postoperative deep-vein thrombosis.

Rationale for low-molecular-weight heparin prophylaxis after total knee arthroplasty

Low-molecular-weight heparin has been studied extensively in total knee arthroplasty (TKA) and provides highly effective and safe prophylaxis against deep venous thrombosis (DVT). Low-molecular-weight heparin received the highest rating (A1) in the American College of Chest Physicians recommendations for DVT prophylaxis after elective TKA. Prevalence of DVT with low-molecular-weight heparin prophylaxis was 33% in TKA data pooled from six randomized studies, with a proximal DVT rate of 7.1%. A metaanalysis reported a 2.4% rate of major bleeding with low-molecular-weight heparin. Low-molecular-weight heparin, given by subcutaneous injection, can be started before surgery or after surgery. A synthetic pentasaccharide (fondaparinux), which received an A1 rating in the American College of Chest Physicians recommendations, also is available. As with all treatments, the benefit must be considered against the risk when using these anticoagulants.

Opening wedge high tibial osteotomy: an operative technique and rehabilitation program to decrease complications and promote early union and function

BACKGROUND

High tibial osteotomy has been associated with significant complications, including delayed union or nonunion, loss of correction, arthrofibrosis, and patella infera.

HYPOTHESES

A technique for opening wedge osteotomy that incorporates an autogenous iliac crest bone graft will prevent delayed union or nonunion, allow early rehabilitation and weightbearing, and prevent knee arthrofibrosis and patella infera. Secondly, the authors' methods for calculating the desired correction of valgus alignment prevent undesired alterations in tibial slope.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 55 consecutive patients who underwent high tibial osteotomy were observed at a mean of 20 months postoperatively. Preoperative and postoperative measurements of radiographs were conducted by independent examiners for bony union, tibial slope, and patellar height. The osteotomy opening size ranged from 5 to 17.5 mm; 35 knees (64%) had openings < or =10 mm, and 20 knees (36%) had openings >11 mm.

RESULTS

The osteotomy united in all patients. Three patients had a delay in union, which resolved by 6 to 8 months postoperatively. A loss of fixation occurred in 1 patient, who admitted to full weightbearing immediately after surgery; the osteotomy required revision. The iliac crest graft site healed without complications, and there were no infections, loss of knee motion, nerve or arterial injuries, alterations in tibial slope, or cases of patellar infera postoperatively. Full weightbearing was achieved at a mean of 8 weeks (range, 4-11 weeks) postoperatively.

CONCLUSIONS

The operative technique including use of an autologous iliac crest bone graft in addition to a progressive rehabilitation program successfully prevented nonunion, change in tibial slope, and knee arthrofibrosis in this study.

Clinical and economic consequences of bleeding following major orthopedic surgery

BACKGROUND

Major orthopedic surgery patients who receive antithrombotics as prophylaxis against VTE may be at higher risk of bleeding. The clinical and economic consequences of this complication may be relevant to therapeutic decision-making.

OBJECTIVE

To assess the impact of major bleeding following major orthopedic surgery on length of stay (LOS) and inpatient charges.

METHODS

Using a database with information on approximately 750,000 admissions annually to 100+ US acute-care hospitals, we identified all patients who underwent major orthopedic surgery between January 1, 1998 and December 13, 2000. Patients were stratified according to whether or not they experienced major postoperative bleeding prior to hospital discharge, defined as (a) fatal bleeding; (b) nonfatal bleeding at critical site; (c) re-operation due to bleeding; and (d) overt bleeding with bleeding index (BI)>or=2, where BI=number of blood units transfused plus pre-bleeding minus post-bleeding hemoglobin (g/dL) values. LOS and total inpatient charges were compared between patients with and without major bleeding.

RESULTS

The incidence of major bleeding among 23,518 patients who underwent major orthopedic surgery was 2.6%. In multivariate analyses controlling for differences in baseline characteristics between patients with and without major bleeds, adjusted mean LOS was 1.8 days longer among those with major bleeding (95% CI: 1.5, 2.0) (6.1 days vs. 4.3 days for those without bleeds); adjusted mean total inpatient charges were 7,593 dollars higher (95% CI: 6,622 dollars, 8,646 dollars) (25,669 dollars vs. 18,076 dollars).

CONCLUSION

Bleeding following major orthopedic surgery may increase length of stay and total hospital charges and should be an important consideration in choice of VTE prophylaxis.

BAY 59-7939: an oral, direct factor Xa inhibitor for the prevention of venous thromboembolism in patients after total knee replacement. A phase II dose-ranging study

BACKGROUND

BAY 59-7939, a novel, oral, direct factor Xa inhibitor, is in clinical development for the prevention of venous thromboembolism (VTE), a frequent complication following orthopaedic surgery.

METHODS

In a multicenter, parallel-group, double-blind, double-dummy study, 621 patients undergoing elective total knee replacement were randomly assigned to oral BAY 59-7939 (2.5, 5, 10, 20, and 30 mg b.i.d., initiated 6-8 h postsurgery), or subcutaneous enoxaparin (30 mg b.i.d., initiated 12-24 h postsurgery). Treatment was continued until mandatory bilateral venography 5-9 days after surgery. The primary efficacy endpoint was a composite of any deep vein thrombosis (proximal and/or distal), confirmed non-fatal pulmonary embolism and all-cause mortality during treatment. The primary safety endpoint was major, postoperative bleeding during treatment.

RESULTS

Of the 613 patients treated, 366 (59.7%) were evaluable for the primary efficacy analysis. The primary efficacy endpoint occurred in 31.7%, 40.4%, 23.3%, 35.1%, and 25.4% of patients receiving 2.5, 5, 10, 20 and 30 mg b.i.d. doses of BAY 59-7939, respectively (test for trend, P = 0.29), compared with 44.3% in the enoxaparin group. The frequency of major, postoperative bleeding increased with increasing doses of BAY 59-7939 (test for trend, P = 0.0007), with no significant difference between any dose group compared with enoxaparin. Bleeding endpoints were lower for the 2.5-10 mg b.i.d. doses compared with higher doses of BAY 59-7939.

CONCLUSIONS

Oral administration of 2.5-10 mg b.i.d. of BAY 59-7939, early in the postoperative period, showed potential efficacy and an acceptable safety profile, similar to enoxaparin, for the prevention of VTE in patients undergoing elective total knee replacement.

The clinical challenge of bridging anticoagulation with low-molecular-weight heparin in patients with mechanical prosthetic heart valves: an evidence-based comparative review focusing on anticoagulation options in pregnant and nonpregnant patients

BACKGROUND

Recent labeling changes for enoxaparin, a low-molecular-weight heparin (LMWH), have prompted a reexamination of its role in patients with mechanical prosthetic heart valves (MPHVs). Healthcare providers are faced with the challenge of weighing favorable trial results with LMWHs and balancing their clinical experiences with these agents as a bridge to oral anticoagulation in patients with prosthetic heart valves. This review will provide evidence-based guidance on issues surrounding the use of LMWH that require bridging anticoagulant therapy in the setting of cardiac surgery (MPHVs), cardiovascular disease, and during temporary interruption of oral anticoagulants in patients requiring periprocedural bridging therapy.

METHODS

A Medline search was conducted of articles appearing in the medical literature published in English between 1992 and 2004. Approximately 120 clinical trials, case reports, editorials, and/or guideline statements were retrieved and reviewed by the authors as to their relevance for the subject under review, ie, bridging anticoagulation in patients with MPHVs. Approximately 80 of these publications were selected for detailed review, analysis, and discussion in a consensus format.

RESULTS

This review addresses the controversy surrounding the divergence between the new labeling recommending against the use of LMWH in patients with MPHVs as well as the ongoing clinical experience and evidence in the medical literature. The clinical challenges in the use of LMWH and unfractioned heparin (UFH) in pregnant patients with MPHVs are presented; the evidence for LMWHs in nonpregnant patients with prosthetic valves is described; and the role of LMWH for bridging immediately after mechanical valve surgery and its periprocedural and perioperative uses are discussed. Based on an expert consensus panel, clinical algorithms for the use of LMWH in pregnant and nonpregnant patients with MPHVs are also illustrated.

CONCLUSIONS

Based on the available data sets, clinical trials, reviews, and registry data, the evidence suggests that LMWH compared to UFH may be a safe and effective agent in patients with MPHVs. Future large-scale, randomized trials are warranted.

Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

This article discusses the prevention of venous thromboembolism (VTE) and is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following. We recommend against the use of aspirin alone as thromboprophylaxis for any patient group (Grade 1A). For moderate-risk general surgery patients, we recommend prophylaxis with low-dose unfractionated heparin (LDUH) (5,000 U bid) or low-molecular-weight heparin (LMWH) [< or = 3,400 U once daily] (both Grade 1A). For higher risk general surgery patients, we recommend thromboprophylaxis with LDUH (5,000 U tid) or LMWH (> 3,400 U daily) [both Grade 1A]. For high-risk general surgery patients with multiple risk factors, we recommend combining pharmacologic methods (LDUH three times daily or LMWH, > 3,400 U daily) with the use of graduated compression stockings and/or intermittent pneumatic compression devices (Grade 1C+). We recommend that thromboprophylaxis be used in all patients undergoing major gynecologic surgery (Grade 1A) or major, open urologic procedures, and we recommend prophylaxis with LDUH two times or three times daily (Grade 1A). For patients undergoing elective total hip or knee arthroplasty, we recommend one of the following three anticoagulant agents: LMWH, fondaparinux, or adjusted-dose vitamin K antagonist (VKA) [international normalized ratio (INR) target, 2.5; range, 2.0 to 3.0] (all Grade 1A). For patients undergoing hip fracture surgery (HFS), we recommend the routine use of fondaparinux (Grade 1A), LMWH (Grade 1C+), VKA (target INR, 2.5; range, 2.0 to 3.0) [Grade 2B], or LDUH (Grade 1B). We recommend that patients undergoing hip or knee arthroplasty, or HFS receive thromboprophylaxis for at least 10 days (Grade 1A). We recommend that all trauma patients with at least one risk factor for VTE receive thromboprophylaxis (Grade 1A). In acutely ill medical patients who have been admitted to the hospital with congestive heart failure or severe respiratory disease, or who are confined to bed and have one or more additional risk factors, we recommend prophylaxis with LDUH (Grade 1A) or LMWH (Grade 1A). We recommend, on admission to the intensive care unit, all patients be assessed for their risk of VTE. Accordingly, most patients should receive thromboprophylaxis (Grade 1A).