Long-term treatment of deep-vein thrombosis with low-molecular-weight heparin: an update of the evidence

TILE pilot trial study protocol: Tinzaparin Lead-in to Prevent the Post-Thrombotic syndrome study protocol

INTRODUCTION

The post-thrombotic syndrome (PTS) is a form of chronic venous insufficiency due to a prior ipsilateral deep venous thrombosis (DVT). This is a frequent complication that develops in 20%-50% of patients after a proximal DVT and is associated with significant healthcare, economic and societal consequences. In the absence of effective and well-tolerated treatment options for established PTS, effective preventative measures are needed. Anticoagulation itself reduces the risk of PTS, and low-molecular-weight heparin may reduce this further through anti-inflammatory properties targeting the initial acute inflammatory phase of DVT.

METHODS AND ANALYSIS

The Tinzaparin Lead-In to Prevent the Post-Thrombotic syndrome pilot trial is an investigator-initiated, multicentre, open-label assessor-blinded trial that will randomise patients with first acute symptomatic common femoral or iliac DVT to receive either a 3-week lead-in course of tinzaparin, followed by rivaroxaban (experimental arm) or rivaroxaban alone (control arm). Its primary objectives are to assess: (1) proportion of PTS at 6 months using the Villalta scale and (2) study feasibility, which consists of (a) the proportion of screened patients eligible for the study, (2) the proportion of eligible patients recruited and (c) the proportion of recruited patients adherent to treatment (defined as at least 80% of drug taken). This study will determine the feasibility of a subsequent larger definitive trial. Secondary outcomes include change of quality of life scores, PTS severity, global improvement, patient satisfaction, bleeding, recurrent venous thromboembolism, leg pain, death and lost to follow-up. Target recruitment will be a total of 60 participants, recruited at 5-6 centres.

ETHICS AND DISSEMINATION

Primary ethics approval was received from the Sunnybrook Health Sciences Center Research Ethics Board (approval ID 3315). Results of the study will be disseminated via peer-reviewed presentation at scientific conferences and open access publication.

TRIAL REGISTRATION NUMBER

NCT04794569.

Incidence and Risk Factors for Post-Thrombotic Syndrome in Patients With Deep Vein Thrombosis Following Total Knee and Hip Arthroplasty

BACKGROUND

Deep vein thrombosis (DVT) is common after total joint arthroplasty (TJA), and can cause the sequela of post-thrombotic syndrome (PTS), which is associated with decreased quality of life and increased treatment cost. The purpose of this study is to determine the incidence and risk factors for PTS in patients with DVT following primary unilateral total knee and hip arthroplasty.

METHODS

We conducted this follow-up study involving patients developing DVT after primary unilateral total knee arthroplasty or total hip arthroplasty at our institution between April 2010 and March 2017. Each patient received a follow-up clinical interview regarding PTS-related symptoms and signs. We introduced demographic, clinical, and surgical data into the analysis to identify the risk factors for PTS.

RESULTS

A total of 182 patients with postoperative DVT were enrolled with a mean follow-up time of 3.6 years. The incidence of PTS was 9.3% in patients developing DVT after TJA. Malignancy (P = .033), previous surgery in ipsilateral lower extremity (P = .013), and blood transfusion (P = .022) appeared to be the risk factors for PTS.

CONCLUSION

We determined the incidence and risk factors for PTS in patients with DVT following TJA. Preventive measures should be used for patients at high risk of PTS.

Thrombolysis for Venous Thromboembolism During Pregnancy: A Literature Review

BACKGROUND

Pregnancy is a hypercoagulable state, conferring an increased risk of venous thromboembolism (VTE). However, treatment algorithms for deep venous thrombosis and pulmonary embolism are based on studies of nonpregnant patients.

METHODS

A literature review of cases in which thrombolysis was used for the treatment of VTE during pregnancy was conducted using the PubMed (National Institutes of Health) database.

RESULTS

A PubMed database search of English language articles for reports of thrombolysis for the treatment of VTE in pregnancy identified 215 cases, including 183 cases of systemic thrombolysis, 19 cases of catheter-directed thrombolysis, and 13 cases of mechanical thrombectomy. For systemic thrombolysis, the maternal complication rate was 4.40% and the fetal complication rate was 1.65%. For catheter-directed thrombolysis, the maternal complication rate was 14.75% and the fetal complication rate was 5.2%. In cases of mechanical thrombectomy, there were no reported maternal or fetal complications.

CONCLUSIONS

Although conservative strategies are preferred in pregnancy, thrombolysis is an adjunct for limb or life-threatening VTE. Review of past reports suggests low rates of maternal and fetal complications following systemic thrombolysis and mechanical thrombectomy but higher rates of complications after catheter-directed thrombolysis in the treatment of VTE during pregnancy.

3-O sulfation of heparin leads to hepatotropism and longer circulatory half-life

INTRODUCTION

Heparins are common blood anticoagulants that are critical for many surgical and biomedical procedures used in modern medicine. In contrast to natural heparin derived from porcine gut mucosa, synthetic heparins are homogenous by mass, polymer length, and chemistry.

MATERIALS & METHODS

Stable cell lines expressing the human and mouse Stabilin receptors were used to evaluate endocytosis of natural and synthetic heparin. We chemoenzymatically produced synthetic heparin consisting of 12 sugars (dodecamers) containing 14 sulfate groups resulting in a non-3-O sulfated structure (n12mer). Half of the n12mer was modified with a 3-O sulfate on a single GlcNS sugar producing the 3-O sulfated heparin (12mer). Wildtype (WT), Stabilin-1 knock-out (KO), and Stabilin-2 KO C57BL/6 mice were developed and used for metabolic studies and provided as a source for primary liver sinusoidal endothelial cells.

RESULTS & CONCLUSIONS

Human and mouse Stabilin-2 receptors had very similar endocytosis rates of both the 12mer and n12mer, suggesting that they are functionally similar in primary cells. Subcutaneous injections of the n12mer and 12mer revealed that the 12mer had a much longer half-life in circulation and a higher accumulation in liver. The n12mer never accumulated in circulation and was readily excreted by the kidneys before liver accumulation could occur. Liver sinusoidal endothelial cells from the Stabilin-2 KO mice had lower uptake rates for both dodecamers, whereas, the Stabilin-1 KO mice had lower endocytosis rates for the 12mer than the n12mer. 3-O sulfation of heparin is correlated to both a longer circulatory half-life and hepatotropism which is largely performed by the Stabilin receptors.

Combined pharmacotherapy for osteonecrosis of the femoral head after severe acute respiratory syndrome and interstitial pneumonia: two and a half to fourteen year follow-up

PURPOSE

The purpose of this study was to retrospectively analyze the clinical, functional, and radiological outcomes of combined pharmacotherapy to ONFH after high-dose corticosteroid therapy.

METHOD

From August 2003 to June 2015, five patients (ten hips) of ONFH in ARCO stage I, after SARS and Interstitial pneumonia, were treated by combined pharmacotherapy. Lipo-prostaglandin E₁ 10 μg iv Bid × 28 days, enoxaparin 6000 iu H QD × 12 weeks, alendronate sodium tablet 10 mg QD × 1 year. The patients were fully weight-bearing following completion of the follow-up.

RESULT

For these five patients (ten hips), Harris score was 100 from the diagnosis to final follow-up time. Radiologic findings show no signs of collapse, necrotic focus was repaired, and ARCO stages were changed from I_C into II_B.

CONCLUSION

This combined pharmacotherapy has promising treatment results for delaying or preventing collapse of ONFH in ARCO stage I.

Postthrombotic syndrome: a 2014 update

PURPOSE OF REVIEW

Postthrombotic syndrome (PTS) is the most frequent complication of deep vein thrombosis. Its pathophysiology is incompletely understood and therapeutic options are limited. This review aims to present and discuss recently published studies that have improved our knowledge related to PTS.

RECENT FINDINGS

From a prognostic point of view, some polymorphisms of plasminogen activator inhibitor-1 and platelet endothelial cell adhesion molecule 1 influence the degree of thrombus resolution after deep vein thrombosis and the subsequent rate of PTS, and could help in predicting the risk of PTS. From a therapeutic point of view, the results of a large multicenter placebo-controlled trial suggest an absence of effectiveness of elastic compression stockings to prevent PTS. In addition, although the Cavent trial of catheter-directed thrombolysis to treat ilio-femoral deep vein thrombosis showed significant reduction in the incidence of PTS that was cost-effective, secondary analyses did not show dramatic improvements in quality of life associated with use of catheter-directed thrombolysis.

SUMMARY

Choice of anticoagulant to treat deep vein thrombosis may represent a new cornerstone of PTS therapeutic management. Studies are needed to assess the impact of new oral anticoagulants and the benefit of extended courses of low molecular weight heparins on the risk of PTS.

Low-molecular-weight heparins and cancer: focus on antitumoral effect

A close relationship between cancer and thrombosis does exist, documented by the fact that an overall 7-fold increased risk of venous thromboembolism (VTE) has been reported in patients with malignancy compared to non-malignancy. The potential impact of antithrombotic agents in cancer-associated VTE has long been recognized, and, in particular, several clinical trials in the last 20 years have reported the safety and efficacy of low-molecular-weight heparins (LMWHs) for treatment and prophylaxis of VTE in patients with various types of cancer. More recently, a number of preclinical and clinical studies have suggested that LMWHs may improve survival in cancer patients with mechanisms that are different from its antithrombotic effect but are linked to the ability of influencing directly the tumor biology. This paper reviews the evidence around the potential survival benefits of LMWHs by analyzing the suggested mechanisms and the available clinical data.

Statins improve the resolution of established murine venous thrombosis: reductions in thrombus burden and vein wall scarring

Despite anticoagulation therapy, up to one-half of patients with deep vein thrombosis (DVT) will develop the post-thrombotic syndrome (PTS). Improving the long-term outcome of DVT patients at risk for PTS will therefore require new approaches. Here we investigate the effects of statins—lipid-lowering agents with anti-thrombotic and anti-inflammatory properties—in decreasing thrombus burden and decreasing vein wall injury, mediators of PTS, in established murine stasis and non-stasis chemical-induced venous thrombosis (N = 282 mice). Treatment of mice with daily atorvastatin or rosuvastatin significantly reduced stasis venous thrombus burden by 25% without affecting lipid levels, blood coagulation parameters, or blood cell counts. Statin-driven reductions in VT burden (thrombus mass for stasis thrombi, intravital microscopy thrombus area for non-stasis thrombi) compared similarly to the therapeutic anticoagulant effects of low molecular weight heparin. Blood from statin-treated mice showed significant reductions in platelet aggregation and clot stability. Statins additionally reduced thrombus plasminogen activator inhibitor-1 (PAI-1), tissue factor, neutrophils, myeloperoxidase, neutrophil extracellular traps (NETs), and macrophages, and these effects were most notable in the earlier timepoints after DVT formation. In addition, statins reduced DVT-induced vein wall scarring by 50% durably up to day 21 in stasis VT, as shown by polarized light microscopy of picrosirius red-stained vein wall collagen. The overall results demonstrate that statins improve VT resolution via profibrinolytic, anticoagulant, antiplatelet, and anti-vein wall scarring effects. Statins may therefore offer a new pharmacotherapeutic approach to improve DVT resolution and to reduce the post-thrombotic syndrome, particularly in subjects who are ineligible for anticoagulation therapy.

The current landscape of treatment options for venous thromboembolism: a focus on novel oral anticoagulants

BACKGROUND

Venous thromboembolism (VTE), comprising deep vein thrombosis (DVT) and pulmonary embolism (PE), is a major cause of morbidity, mortality, and healthcare expenditure. Anticoagulant therapy is recommended for at least 3 months in patients with acute VTE to prevent recurrence. Conventional anticoagulants are associated with inherent limitations including route of administration, required monitoring and dose adjustments, potential for food-drug and drug-drug interactions, unpredictable pharmacokinetics and pharmacodynamics, and possible severe adverse events.

SCOPE

This manuscript reviews the pharmacology of the novel oral anticoagulants (NOACs), and analyzes the differences in phase 3 clinical trial designs, outcomes, and specific patient populations investigated for the treatment of acute and prevention of secondary VTE.

METHODS

A literature search was performed in PubMed using the key words dabigatran, apixaban, rivaroxaban, edoxaban, and venous thromboembolism in PubMed. The search included all years, English language, and peer-reviewed articles relating to phase 3 clinical trials, subanalyses, and meta-analyses of these NOACs for the treatment of acute VTE and secondary prevention.

FINDINGS

NOACs have demonstrated comparable efficacy and comparable or superior safety in large, randomized clinical trials in the treatment and prevention of VTE compared with conventional therapy. New oral anticoagulants, including the direct thrombin (dabigatran etexilate) and direct factor Xa inhibitors (rivaroxaban, apixaban, and edoxaban), have advantages over conventional agents such as oral administration at fixed doses, predictable pharmacokinetics and pharmacodynamics, minimal potential for food-drug and drug-drug interactions, and lack of required monitoring.

CONCLUSIONS

NOACs offer additional oral anticoagulation treatment options for patients with VTE.

The use of oral anticoagulants for the treatment of venous thromboembolic events in an ED

Venous thromboembolism (VTE) is a disease spectrum that ranges from deep vein thrombosis (DVT) to pulmonary embolism (PE). Rapid diagnosis and treatment of VTE by emergency care providers are critical for decreasing patient mortality, morbidity, and the incidence of recurrent events. Recent American College of Chest Physicians guidelines recommend initial treatment with unfractionated heparin, low-molecular weight heparin, or fondaparinux overlapped with warfarin for a minimum of 5 days for the treatment of VTE in most cases. Warfarin monotherapy is thereafter continued for 3, 6, or 12 months. These guidelines were published before the approval of target-specific oral anticoagulants (TSOACs), and they have yet to be updated to reflect these new treatment options. For some patients, TSOACs, which act by directly inhibiting factor IIa or factor Xa, may provide safer, more convenient alternatives to warfarin. Their advantages include ease of use, reduced monitoring requirements, and lower bleeding risk than traditional therapy. Additionally, clinical trials have established noninferiority of TSOACs to warfarin for the prevention of recurrent VTE. These trials have demonstrated that TSOACs exhibit similar or lower bleeding rates, particularly intracranial bleeding rates compared with warfarin. Anticoagulation therapy with TSOACs may allow early discharge or outpatient management options for low-risk patients with DVT and PE. This review addresses the importance of early diagnosis and treatment of VTE, outcomes of VTE risk assessment, key efficacy and safety data from phase 3 clinical trials for the various TSOACs for the treatment of DVT and PE, and the corresponding considerations for clinical practice.

Tissue factor in tumor microenvironment: a systematic review

The aberrant hemostasis is a common manifestation of cancer, and venous thromboembolism (VTE) is the second leading cause of cancer patients’ mortality. Tissue factor (TF), comprising of a 47-kDa transmembrane protein that presents in subendothelial tissues and leukocytes and a soluble isoform, have distinct roles in the initiation of extrinsic coagulation cascade and thrombosis. Laboratory and clinical evidence showed the deviant expression of TF in several cancer systems and its tumor-promoting effects. TF contributes to myeloid cell recruitment in tumor stroma, thereby remodeling of tumor microenvironment. Additionally, the number of TF-positive-microparticles (TF⁺MP) from tumor origins correlates with the VTE rates in cancer patients. In this review, we summarize our current understanding of the TF regulation and roles in tumor progression and clinical complications.

The Efficacy of Sulodexide in the Prevention of Postthrombotic Syndrome

Aim:

The aim of this open, observational registry was to evaluate the effects of antithrombotic treatment on the development of postthrombotic syndrome (PTS): the effects of “standard management” (SM; according to International Union of Angiology guidelines) were compared to SM in association with sulodexide or aspirin.

Methods:

Postthrombotic syndrome occurrence was observed in 3 nonparallel groups after deep venous thrombosis (DVT); the registry started after the end of the anticoagulation period. The target was to observe the occurrence of PTS in 5 years. Three possible options were suggested to the patients, and the patients and their caregivers defined the type of management. A group of 167 patients was involved in the SM with reevaluation every 6 months; the sulodexide group included 124 patients and the aspirin group included 48 patients.

Results:

The 3 groups were clinically similar and comparable for age and sex distribution. Of the 167 patients in the SM group, 154 patients completed 60 months of follow-up. The percentage of patients with PTS in the SM group ranged from 14.9% (1 year after the end of anticoagulation) to 19.5% (60 months). In the nonparallel group using sulodexide (124 comparable patients at inclusion; 115 at 60 months), the percentage of PTS was variable from 8.8% (1 year after anticoagulants) to 12.17% at 60 months. These percentages are significantly lower than those observed with SM. In the nonparallel aspirin group (48 patients at inclusion and 34 at 54 months), there was a PTS incidence of 23.5% at 54 months (vs 12.17% in the sulodexide group and 18.23% in the SM group). The incidence of PTS was significantly higher in comparison with the other 2 groups. The incidence of PTS was lower in the sulodexide group in comparison with the 2 other groups.

Conclusions:

Sulodexide administration after DVT appears to be effective in preventing PTS in association with recommended management and a number of recurrent DVTs. Modalities of treatment, dosages, and timing of administration should be explored in more comprehensive and complete studies.

Intermediate doses of low-molecular-weight heparin for the long-term treatment of pregnancy thromboembolism. A systematic review

Note: The contact information for Drs. Gandara and Carrier is the same as for Dr. Rodger. Their e-mail addresses are egandara@ohri.ca and mcarrier@ohri.ca, respectively.