The treatment of venous thromboembolism with low-molecular-weight heparins

AHPBA guidelines for managing VTE prophylaxis and anticoagulation for pancreatic surgery

BACKGROUND

Major abdominal surgery and malignancy lead to a hypercoagulable state, with a risk of venous thromboembolism (VTE) of approximately 3% after pancreatic surgery. No guidelines exist to assist surgeons in managing VTE prophylaxis or anticoagulation in patients undergoing elective pancreatic surgery for malignancy or premalignant lesions. A systematic review specific to VTE prophylaxis and anticoagulation after resectional pancreatic surgery is herein provided.

METHODS

Six topic areas are reviewed: pre- and perioperative VTE prophylaxis, early postoperative VTE prophylaxis, extended outpatient VTE prophylaxis, management of chronic anticoagulation, anti-coagulation after vascular reconstruction, and treatment of VTE. A Medline and PubMED search was completed with systematic medical literature review for each topic. Level of evidence was graded and strength of recommendation ranked according to the GRADE (Grades of Recommendation Assessment, Development and Evaluation) system for practice guidelines.

RESULTS

Levels of evidence and strength of recommendations are presented.

DISCUSSION

While strong data exist to guide management of chronic anticoagulation and treatment of VTE, data for anticoagulation after reconstruction is inconclusive and support for perioperative chemoprophylaxis with pancreatic surgery is similarly limited. The risk of post-pancreatectomy hemorrhage often exceeds that of thrombosis. The role of universal chemoprophylaxis must therefore be examined critically, particularly in the preoperative setting.

Interpretation of endpoints in a network meta-analysis of new oral anticoagulants following total hip or total knee replacement surgery

New oral anticoagulant (NOAC) regimens [dabigatran 150 mg (D150) and 220 mg (D220), rivaroxaban 10 mg (R20), and apixaban 2.5 mg bid (A5)] were effective and safe compared to enoxaparin for the prevention of venous thromboembolism (VTE) following elective total knee (TKR) or hip replacement (THR) surgery. First a cluster analysis was used to identify homogeneous studies for the trial programs of each NOAC. Second, only studies reporting VTE and VTE-related death, major bleeding, and mortality were included. The odds ratio (OR) and 95% confidence interval (CI) were calculated for each NOAC regimen versus the comparator. Third, these data were used for the indirect comparison between NOACs. Cluster analysis identified duration of treatment (10 ± 5 and 34 ± 5 days) as the only homogeneous parameter across all NOAC programs (p>0.05) except for A5 and VTE over 10 ± 5 days (analysis not performed). The results of the calculated OR and 95% CI of the four NOAC regimens over 10 ± 5 and 34 ± 5 days showed inferiority of D150 and D220 compared to R10 for VTE (p<0.01, p<0.001). Comparisons of major bleeding and mortality were not different for all indirect comparisons. Despite the lack of standard definitions for VTE and bleeding outcomes, cluster analysis seems to be an appropriate tool to identify homogeneity across trial programs and to perform an indirect comparison for NOACs for prevention of VTE following TKR and THR surgery.

The safety of low-molecular-weight heparins in the prevention of venous thromboembolism in surgically-treated cancer patients: results of a multicentre observational study

Aim of the study

Despite widespread use of pharmacological prophylaxis, venous thromboembolism (VTE) still constitutes a common complication in cancer patients. The aim of the study was to analyse the safety of low-molecular-weight heparins (LMWH) in the prevention of VTE in surgically-treated cancer patients.

Material and methods

A total of 5207 cancer patients (44.5% men and 55.5% women) aged 16–97 years participated in a prospective observational study conducted in 13 Polish cancer centres in 2005–2008. This cohort included 4782 subjects who were treated surgically and received LMWH as a pharmacological prophylaxis for VTE prior to or after the surgery. The incidence of haemorrhagic complications and thrombocytopaenia was analysed in this cohort, along with intra-hospital mortality.

Results

Mean duration of LMWH administration was 9.4 ±7.8 days. Haemorrhagic complications: heavy (n = 15) or light bleeding (n = 299), were observed in 314 patients (6.5%). A total of 314 patients (6.5%) presented with haemorrhagic complications: heavy (n = 15, 0.3%) or light bleeding (n = 299, 6.3%). Four cases of heavy bleeding: gastrointestinal bleeding (n = 2), retroperitoneal bleeding (n = 1), and central nervous system bleeding (n = 1), were classified as definitely related to LMWH. No significant association was found between the incidence of haemorrhagic complications and the type of administered LWMH (p = 0.523). No cases of thrombocytopaenia or deaths related to administration of LMWH were reported.

Conclusions

LMWH seems to be a safe form of pharmacological prophylaxis for VTE in surgically-treated cancer patients.

Venous Thromboembolism and Pulmonary Embolism Response Teams: An Overview

Venous thromboembolism is a common disease with a wide array of signs and symptoms. It has been cited as the third leading cause of cardiovascular death, and if left untreated, it leads to death in 1 in 4 patients. Sophisticated diagnostic tools have allowed physician to become more accurate in diagnosing pulmonary embolism and deep vein thrombosis. The advent of new oral anticoagulants, the emergence of pulmonary embolism response teams, and protocols demonstrate recent achievements in the management of venous thromboembolism. The focus of this article is to discuss the treatment of venous thromboembolism.

Vitamin K antagonists versus low-molecular-weight heparin for the long term treatment of symptomatic venous thromboembolism

BACKGROUND

People with venous thromboembolism (VTE) generally are treated for five days with intravenous unfractionated heparin or subcutaneous low-molecular-weight heparin (LMWH), followed by three months of vitamin K antagonists (VKAs). Treatment with VKAs requires regular laboratory measurements and carries risk of bleeding; some patients have contraindications to such treatment. Treatment with LMWH has been proposed to minimise the risk of bleeding complications. This is the second update of a review first published in 2001.

OBJECTIVES

The purpose of this review was to evaluate the efficacy and safety of long term treatment (three months) with LMWH versus long term treatment (three months) with VKAs for symptomatic VTE.

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Specialised Register (last searched November 2016) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 10), The Cochrane Vascular Information Specialistalso searched clinical trials registries for ongoing studies.

SELECTION CRITERIA

Randomised controlled trials comparing LMWH versus VKA for long treatment (three months) of symptomatic VTE. Two review authors independently evaluated trials for inclusion and methodological quality.

DATA COLLECTION AND ANALYSIS

Review authors independently extracted data and assessed risk of bias. We resolved disagreements by discussion and performed meta-analysis using fixed-effect models with Peto odds ratios (Peto ORs) and 95% confidence intervals (CIs). Outcomes of interest were recurrent VTE, major bleeding, and mortality. We used GRADE to assess the overall quality of evidence supporting these outcomes.

MAIN RESULTS

Sixteen trials, with a combined total of 3299 participants fulfilled our inclusion criteria. According to GRADE, the quality of evidence was moderate for recurrent VTE, low for major bleeding, and moderate for mortality. We downgraded the quality of the evidence for imprecision (recurrent VTE, mortality) and for risk of bias and inconsistency (major bleeding).We found no clear differences in recurrent VTE between LMWH and VKA (Peto OR 0.83, 95% confidence interval (CI) 0.60 to 1.15; P = 0.27; 3299 participants; 16 studies; moderate-quality evidence). We found less bleeding with LMWH than with VKA (Peto OR 0.51, 95% CI 0.32 to 0.80; P = 0.004; 3299 participants; 16 studies; low-quality evidence). However, when comparing only high-quality studies for bleeding, we observed no clear differences between LMWH and VKA (Peto OR 0.62, 95% CI 0.36 to 1.07; P = 0.08; 1872 participants; seven studies). We found no clear differences between LMWH and VKA in terms of mortality (Peto OR 1.08, 95% CI 0.75 to 1.56; P = 0.68; 3299 participants; 16 studies; moderate-quality evidence).

AUTHORS' CONCLUSIONS

Moderate-quality evidence shows no clear differences between LMWH and VKA in preventing symptomatic VTE and death after an episode of symptomatic DVT. Low-quality evidence suggests fewer cases of major bleeding with LMWH than with VKA. However, comparison of only high-quality studies for bleeding shows no clear differences between LMWH and VKA. LMWH may represent an alternative for some patients, for example, those residing in geographically inaccessible areas, those who are unable or reluctant to visit the thrombosis service regularly, and those with contraindications to VKA.

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.

Detection and characterization of plasminogen receptors on clinical isolates of Trichosporon asahii

Trichosporon asahii is the major causative agent of deep-seated trichosporonosis. The virulence factors of this yeast pathogen remain uncharacterized. To investigate the pathogenicity of T. asahii, we focused on the interactions between surface molecules of the yeast and host biomolecules. We examined the ability of surface molecules to bind human plasminogen using clinical isolates of T. asahii. Living T. asahii cells accelerated the conversion of plasminogen to plasmin in a dose-dependent manner in the presence of tissue plasminogen activator. Extracts from cells using lithium chloride contained plasminogen-binding molecules based on surface plasmon resonance (SPR) analyses. In all strains tested, several of the fractions obtained using DEAE column chromatography bound and accelerated the conversion of plasminogen to plasmin. Based on far-Western blotting analyses, a common protein was identified within the four strains, which was identified as a hypothetical protein from genome analyses of T. asahii. blast searches suggested the protein might be heparinase, and heparinase activity was detected in the T. asahii extract. Furthermore, affinity chromatography using plasminogen as a ligand detected one protein band by SDS-PAGE, which was identified as thioredoxin-dependent peroxide reductase.SPR analyses suggested the presence of molecules on T. asahii cells that could bind plasminogen with differing affinities.

Duration of anticoagulant therapy for deep vein thrombosis and pulmonary embolism

It takes about 3 months to complete “active treatment” of venous thromboembolism (VTE), with further treatment serving to prevent new episodes of thrombosis (“pure secondary prevention”). Consequently, VTE should generally be treated for either 3 months or indefinitely (exceptions will be described in the text). The decision to stop anticoagulants at 3 months or to treat indefinitely is dominated by the long-term risk of recurrence, and secondarily influenced by the risk of bleeding and by patient preference. VTE provoked by a reversible risk factor, or a first unprovoked isolated distal (calf) deep vein thrombosis (DVT), has a low risk of recurrence and is usually treated for 3 months. VTE associated with active cancer, or a second unprovoked VTE, has a high risk of recurrence and is usually treated indefinitely. The decision to stop anticoagulants at 3 months or to treat indefinitely is more finely balanced after a first unprovoked proximal DVT or pulmonary embolism (PE). Indefinite anticoagulation is often chosen if there is a low risk of bleeding, whereas anticoagulation is usually stopped at 3 months if there is a high risk of bleeding. The decision to continue anticoagulation indefinitely after a first unprovoked proximal DVT or PE is strengthened if the patient is male, the index event was PE rather than DVT, and/or d-dimer testing is positive 1 month after stopping anticoagulant therapy.

Rationale and methodology for a multicentre randomised trial of fibrinolysis for pulmonary embolism that includes quality of life outcomes

BACKGROUND

Submassive pulmonary embolism (PE) has a low mortality rate but can degrade functional capacity.

OBJECTIVE

The present study aims to provide rationale, methodology, and initial findings of a multicentre, randomised trial of fibrinolysis for PE that used a composite end-point, including quality of life measures.

METHODS

This investigator-initiated study was funded by a contract between a corporate partner and the investigator's hospital (the prime site). The investigator was the Food and Drug Administration (FDA) sponsor. The prime site subcontracted, indemnified, and trained consortia members. Consenting, normotensive patients with PE and right ventricular strain (by echocardiography or biomarkers) received low-molecular-weight heparin and random assignment to a single bolus of tenecteplase or placebo in double-blinded fashion. The outcomes were: (i) in-hospital rate of intubation, vasopressor support, and major haemorrhage, or (ii) at 90 days, death, recurrent PE, or composite that defined poor quality of life (echocardiography, 6 min walk test and surveys). The planned sample size was n = 200.

RESULTS

Eight sites enrolled 87 patients over 5 years. The ratio of patients screened for each enrolled was 7.4 to 1, equating to 11 h screening time per patient enrolled. Primary barrier to enrolment was the cost of screening. Two patients died (2.5%, 95%CI [0-8%]), one developed shock, but 18 (22%, 95%CI: [13-30%]) had a poor quality of life.

CONCLUSIONS

An investigator-initiated, FDA-regulated, multicentre trial of fibrinolysis for submassive PE was conducted, but was limited by screening costs and a low mortality rate. Quality of life measurements might represent a more important patient-centred end-point.

Vitamin K antagonists or low-molecular-weight heparin for the long term treatment of symptomatic venous thromboembolism

BACKGROUND

People with venous thromboembolism (VTE) are generally treated for five days with intravenous unfractionated heparin or subcutaneous low-molecular-weight heparin (LMWH) followed by three months of vitamin K antagonist treatment. Treatment with vitamin K antagonists requires regular laboratory measurements and some patients have contraindications to treatment. This is an update of a review first published in 2000 and updated in 2002.

OBJECTIVES

To evaluate the efficacy and safety of long term treatment of VTE with LMWH compared to vitamin K antagonists.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched their Specialised Register (last searched February 2012) and CENTRAL (2012, Issue 1).

SELECTION CRITERIA

Two authors evaluated trials independently for methodological quality.

DATA COLLECTION AND ANALYSIS

The review authors extracted data independently. Primary analysis included all trial participants randomised to the allocated treatment groups. Separate analyses were performed according to the quality of the trials and for subgroups such as trials initially using similar treatments in both trial arms and those that did not, trials concerning deep vein thrombosis (DVT) and pulmonary embolism (PE) and the different periods of follow-up.

MAIN RESULTS

All 15 trials, with a combined total of 3197 patients, fulfilling our criteria were combined in a meta-analysis. We found a non-statistically significant reduction in the risk of recurrent VTE between the two treatments (odds ratio (OR) 0.82, 95% CI 0.59 to 1.13). Analysis of pooled data for category I trials (those with a high methodological quality) showed a non-significant reduction in the odds of recurrent VTE favouring LMWH treatment (OR 0.80, 95% CI 0.54 to 1.18).For all trials combined, the difference in bleeding significantly favoured treatment with LMWH (OR 0.50, 95% CI 0.31 to 0.79). Considering only category I trials, a non-significant trend favouring LMWH remained (OR 0.62, 95% CI 0.36 to 1.07). No difference was observed in mortality (OR 1.06, 95% CI 0.74 to 1.54).

AUTHORS' CONCLUSIONS

LMWHs are possibly as effective as vitamin K antagonists in preventing symptomatic VTE after an episode of symptomatic deep venous thrombosis, but are much more expensive. Treatment with LMWH is significantly safer than treatment with vitamin K antagonists. LMWH may result in fewer episodes of bleeding and is possibly a safe alternative in some patients, especially those in geographically inaccessible areas, are reluctant to visit the thrombosis service regularly, or with contraindications to vitamin K antagonists. However, treatment with vitamin K antagonists remains the treatment of choice for the majority of patients.