Clinical outcomes of isolated distal deep vein thrombosis versus proximal venous thromboembolism in cancer patients: The Cleveland Clinic experience

Clinical Presentation and Outcomes of Patients With Cancer-Associated Isolated Distal Deep Vein Thrombosis

PURPOSE

Patients with isolated distal deep vein thrombosis (DVT) have lower rates of adverse outcomes (death, venous thromboembolism [VTE] recurrence or major bleeding) than those with proximal DVT. It is uncertain if such findings are also observed in patients with cancer.

METHODS

Using data from the international Registro Informatizado de la Enfermedad TromboEmbolica venosa registry, we compared the risks of adverse outcomes at 90 days (adjusted odds ratio [aOR]; 95% CI) and 1 year (adjusted hazard ratio [aHR; 95% CI]) in 886 patients with cancer-associated distal DVT versus 5,196 patients with cancer-associated proximal DVT and 5,974 patients with non-cancer-associated distal DVT.

RESULTS

More than 90% of patients in each group were treated with anticoagulants for at least 90 days. At 90 days, the adjusted risks of death, VTE recurrence, or major bleeding were lower in patients with non-cancer-associated distal DVT than in patients with cancer-associated distal DVT (reference): aOR = 0.16 (0.11-0.22), aOR = 0.34 (0.22-0.54), and aOR = 0.47 (0.27-0.80), respectively. The results were similar at 1-year follow-up: aHR = 0.12 (0.09-0.15), aHR = 0.39 (0.28-0.55), and aHR = 0.51 (0.32-0.82), respectively. Risks of death, VTE recurrence, and major bleeding were not statistically different between patients with cancer-associated proximal versus distal DVT, both at 90 days: aOR = 1.11 (0.91-1.36), aOR = 1.10 (0.76-1.62), and aOR = 1.18 (0.76-1.83), respectively, and 1 year: aHR = 1.01 (0.89-1.15), aHR = 1.02 (0.76-1.35), and aHR = 1.10 (0.76-1.61), respectively. However, more patients with cancer-associated proximal DVT, compared with cancer-associated distal DVT, developed fatal pulmonary embolism (PE) during follow-up: The risk difference was 0.40% (95% CI, 0.23 to 0.58).

CONCLUSION

Cancer-associated distal DVT has serious and relatively comparable outcomes compared with cancer-associated proximal DVT. The lower risk of fatal PE from cancer-associated distal DVT needs further investigation.

Edoxaban for 12 Months Versus 3 Months in Patients With Cancer With Isolated Distal Deep Vein Thrombosis (ONCO DVT Study): An Open-Label, Multicenter, Randomized Clinical Trial

BACKGROUND

The optimal duration of anticoagulation therapy for isolated distal deep vein thrombosis in patients with cancer is clinically relevant, but the evidence is lacking. The prolonged anticoagulation therapy could have a potential benefit for prevention of thrombotic events; however, it could also increase the risk of bleeding.

METHODS

In a multicenter, open-label, adjudicator-blinded, randomized clinical trial at 60 institutions in Japan, we randomly assigned patients with cancer with isolated distal deep vein thrombosis, in a 1-to-1 ratio, to receive either a 12-month or 3-month edoxaban treatment. The primary end point was a composite of a symptomatic recurrent venous thromboembolism (VTE) or VTE-related death at 12 months. The major secondary end point was major bleeding at 12 months, according to the criteria of the International Society on Thrombosis and Haemostasis. The primary hypothesis was that a 12-month edoxaban treatment was superior to a 3-month edoxaban treatment with respect to the primary end point.

RESULTS

From April 2019 through June 2022, 604 patients were randomized, and after excluding 3 patients who withdrew consent, 601 patients were included in the intention-to-treat population: 296 patients in the 12-month edoxaban group and 305 patients in the 3-month edoxaban group. The mean age was 70.8 years, 28% of the patients were men, and 20% of the patients had symptoms of deep vein thrombosis at baseline. The primary end point of a symptomatic recurrent VTE event or VTE-related death occurred in 3 of the 296 patients (1.0%) in the 12-month edoxaban group and in 22 of the 305 patients (7.2%) in the 3-month edoxaban group (odds ratio, 0.13; 95% CI, 0.03-0.44). The major secondary end point of major bleeding occurred in 28 of the 296 patients (9.5%) in the 12-month edoxaban group and in 22 of the 305 patients (7.2%) in the 3-month edoxaban group (odds ratio, 1.34; 95% CI, 0.75-2.41). The prespecified subgroups did not affect the estimates on the primary end point.

CONCLUSIONS

In patients with cancer with isolated distal deep vein thrombosis, 12 months was superior to 3 months for an edoxaban treatment with respect to the composite outcome of a symptomatic recurrent VTE or VTE-related death.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03895502.

Incidence of recurrent venous thromboembolism and bleeding complications in patients with cancer and isolated distal deep vein thrombosis

BACKGROUND

Isolated distal deep vein thrombosis (IDDVT) is a common clinical presentation of DVT. The efficacy and safety of anticoagulant therapy for the management of IDDVT in patients with cancer are unclear. We sought to assess the incidence of recurrent venous thromboembolism (VTE) and major bleeding in this patient population.

METHODS

A systematic search of MEDLINE, EMBASE and PubMed, from inception to June 2, 2022 was performed. The primary efficacy outcome was recurrent VTE and the primary safety outcome was major bleeding. The secondary outcomes were clinically relevant non-major bleeding (CRNMB) and mortality. The incidence rates of thrombotic, bleeding, and mortality outcomes were pooled using random effects model and expressed as events per 100 patient-months with associated 95 % confidence intervals (CI).

RESULTS

Out of a total of 5234 articles, 10 observational studies including 8160 patients with cancer and IDDVT were included in the analysis. The incidence rate of recurrent VTE was 5.65 (95 % CI: 2.09-15.30) per 100 patient-years regardless of type and duration of anticoagulant therapy. The incidence rate of major bleeding was 4.08 (95 % CI: 2.52-6.61) per 100 patient-years. The incidence rates for CRNMB and mortality per 100 patient-years were 8.11 (95 % CI: 5.56-11.83) and 30.22 (95 % CI: 22.60-40.42.89), respectively.

CONCLUSION

Patients with cancer and IDDVT are at high risk of developing recurrent VTE and bleeding complications (both major bleeding and CRNMB). More studies are needed to define the optimal management for this high-risk population.

Thrombosis questions from the inpatient wards

The multifaceted pathophysiologic processes that comprise thrombosis and thromboembolic diseases take on a particular urgency in the hospitalized setting. In this review, we explore 3 cases of thrombosis from the inpatient wards: purpura fulminans, cancer-associated thrombosis with thrombocytopenia, and coronavirus disease 2019 (COVID-19) and the use of dose-escalated anticoagulation therapy and antiplatelet agents. We discuss the evaluation and management of purpura fulminans and the roles of plasma transfusion, protein C and antithrombin replacement, and anticoagulation in treating this disease. We present a framework for evaluating the etiologies of thrombocytopenia in cancer and review 2 strategies for anticoagulation management in patients with cancer-associated thrombosis and thrombocytopenia, including recent prospective data supporting the use of dose-modified anticoagulation based on platelet count. Last, we dissect the major clinical trials of therapeutic- and intermediate-dose anticoagulation and antiplatelet therapy in hospitalized patients with COVID-19, reviewing key recommendations from consensus guidelines while highlighting ways in which institutional and patient-tailored practices regarding antithrombotic therapies in COVID-19 may differ. Together, the cases highlight the diverse and dramatic presentations of macro- and microvascular thrombosis as encountered on the inpatient wards.

EHA Guidelines on Management of Antithrombotic Treatments in Thrombocytopenic Patients With Cancer

In cancer patients, thrombocytopenia can result from bone marrow infiltration or from anticancer medications and represents an important limitation for the use of antithrombotic treatments, including anticoagulant, antiplatelet, and fibrinolytic agents. These drugs are often required for prevention or treatment of cancer-associated thrombosis or for cardioembolic prevention in atrial fibrillation in an increasingly older cancer population. Data indicate that cancer remains an independent risk factor for thrombosis even in case of thrombocytopenia, since mild-to-moderate thrombocytopenia does not protect against arterial or venous thrombosis. In addition, cancer patients are at increased risk of antithrombotic drug-associated bleeding, further complicated by thrombocytopenia and acquired hemostatic defects. Furthermore, some anticancer treatments are associated with increased thrombotic risk and may generate interactions affecting the effectiveness or safety of antithrombotic drugs. In this complex scenario, the European Hematology Association in collaboration with the European Society of Cardiology has produced this scientific document to provide a clinical practice guideline to help clinicians in the management of patients with cancer and thrombocytopenia. The Guidelines focus on adult patients with active cancer and a clear indication for anticoagulation, single or dual antiplatelet therapy, their combination, or reperfusion therapy, who have concurrent thrombocytopenia because of either malignancy or anticancer medications. The level of evidence and the strength of the recommendations were discussed according to a Delphi procedure and graded according to the Oxford Centre for Evidence-Based Medicine.

Incidence and Outcomes Associated with 6841 Isolated Distal Deep Vein Thromboses in Patients with 13 Common Cancers

INTRODUCTION

The epidemiology of isolated distal deep venous thrombosis (iDDVT) among cancer patients is not well described, particularly the incidence of recurrent venous thromboembolism (rVTE) and effect on mortality by cancer type.

METHODS

The cumulative incidence (CI) of iDDVT was determined for patients with 13 common cancers between 2005-2017 using the California Cancer Registry linked to the California Patient Discharge and Emergency Department Utilization datasets. The CI of rVTE was calculated and association of incident CAT location with rVTE was determined using Cox proportional hazards regression models. The association of incident cancer-associated venous thrombosis (CAT) location with overall and cancer-specific mortality was determined using Cox models, stratified by cancer site, and adjusted for individual characteristics.

RESULTS

Among 942,109 cancer patients, CAT occurred in 62,003 (6.6%): of these, 6,841 (11.0%) were iDDVT. Compared to more proximal sites of CAT, iDDVT was associated with similar risk for rVTE. IDDVT was associated with increased mortality across all cancer types when compared to patients without CAT (HR 1.56-4.60). The effect of iDDVT on mortality was similar to that of proximal DVT (pDVT) for most cancers except lung, colorectal, bladder, uterine, brain, and myeloma, where iDDVT was associated with a lesser association with mortality.

CONCLUSION

iDDVT represented 11% of CAT. The risk of rVTE after iDDVT was similar to other sites of CAT and rVTE occurred in more proximal locations after an incident iDDVT. IDDVT was associated with increased mortality and this effect was similar to that of PE or pDVT for most cancer types.

Building a CAT clinic - real-world systems approaches to prevention and treatment

Cancer patients have an increased risk of developing venous thrombosis. The implementation of a cancer associated thrombosis clinic can be instrumental for the prevention, early recognition, and management of venous thromboembolism in this vulnerable population. Cancer thrombosis clinics rely on a multidisciplinary approach to care and require standardization along with a dedicated team of healthcare professionals. Cancer thrombosis clinics have the potential to improve patient outcomes and lower healthcare expenditure. Herein, we describe a successful model of a cancer thrombosis clinic and highlight the potential impact on clinical outcomes.

Significance and management of isolated distal deep vein thrombosis

PURPOSE OF REVIEW

Management of isolated distal deep vein thrombosis (IDDVT) remains controversial. We summarize recent studies regarding the natural history of IDDVT as well as pertinent therapeutic trials. We also provide our management approach.

RECENT FINDINGS

IDDVT is more commonly associated with transient risk factors and less often associated with permanent, unmodifiable risk factors than proximal DVT. IDDVT has a significantly lower risk of proximal extension and recurrence than proximal DVT. Cancer-associated IDDVT has a similar natural history to cancer-associated proximal DVT, with substantially less favourable outcomes than noncancer-associated IDDVT. Anticoagulant treatment reduces the risk of proximal extension and recurrence in IDDVT at the cost of increased bleeding risk. Intermediate dosing of anticoagulation may be effective for treating noncancer-associated IDDVT in patients without prior DVT.

SUMMARY

IDDVT with a transient risk factor can be treated for 6 weeks in patients without a prior DVT. Unprovoked IDDVT in patients without malignancy can be treated for 3 months. Outpatients without malignancy or a prior DVT can be left untreated and undergo surveillance compression ultrasound in one week to detect proximal extension, but few patients opt for this in practice. Cancer-associated IDDVT should be treated analogously to cancer-associated proximal DVT.

Proposing a molecular classification associated with hypercoagulation in ovarian clear cell carcinoma

BACKGROUND

Although ovarian clear cell carcinoma (CCC) is associated with high incidence of thromboembolism, the clinicopathological and biological significance of hypercoagulable status in CCC remains unclear.

MATERIALS AND METHODS

We retrospectively analyzed pretreatment D-dimer levels, thromboembolic status, and clinical outcome of 125 CCCs in the discovery set and 143 CCCs in two other independent validation sets. Next, we performed RNA sequencing of 93 CCCs and compared coagulation-related gene profiles with 2492 pan-cancer data. We investigated differences in molecular characteristics of CCC subclasses based on coagulation status.

RESULTS

In the discovery dataset, D-dimer elevation above the normal range was significantly associated with shorter progression-free and overall survival, irrespective to thromboembolic status. Multivariate analysis identified D-dimer elevation and clinical stage as an independent prognostic factors. We confirmed the prognostic significance of D-dimer elevation in the validation sets. Tissue factor and IL6, which are considered key elements of cancer-induced hypercoagulation, were highly expressed in CCC than in other cancers regardless of D-dimer level. Higher activity of various oncogenic pathways was observed in CCC with compared to without D-dimer elevation. Moreover, hierarchical cluster analysis divided 57 CCCs with D-dimer elevation into immunologically hot and cold tumor subtypes. Hot tumors were characterized by enrichment of T-cell inflamed phenotype, inflammation, the epithelial-mesenchymal transition, and high serum levels of CRP, and cold tumors by enrichment of cell cycle and MYC pathways.

CONCLUSIONS

CCC represents hypercoagulable disease and elevate D-dimer is a prognostic factor for decreased survival in CCC. D-dimer high CCC has distinct molecular characteristics into the inflammatory-driven pathway (hot tumor) and the immune-suppressive pathway (cold tumor). Treatment implication of our proposed molecular classification merits further investigation.

Treatment of venous thromboembolism in cancer patients: The dark side of the moon

Venous thromboembolism (VTE) is a common complication in patients with cancer. The risk of emergent VTE is four- to seven-fold higher in cancer patients compared to non-cancer patients. Although the therapeutic armamentarium for cancer-associated VTE has been recently implemented, anticoagulant treatment remains challenging because of the increased risk of recurrent VTE and bleeding. Several international societies and expert panels released clinical practice guidelines on VTE treatment which are mostly focused on the general cancer population. Nevertheless, recommendations for the management of VTE in patients with peculiar clinical presentations are inconsistent and remain elusive due to the lack of pertinent evidence. The challenging clinical scenarios include, among others, patients with thrombocytopenia, renal impairment, gastrointestinal cancer, primary or metastatic brain cancer, distal thrombosis of the lower extremities, catheter-related VTE, splanchnic thrombosis, incidental VTE, extreme body weight, recurrent VTE during treatment, as well as the optimal duration of anticoagulant treatment in patients with active disease who have received 3 to 6 months of anticoagulation. Herein, we present a critical overview on VTE management in these challenging clinical settings, discuss potential approaches, and include some calls to action for future clinical research.

Calf vein thrombosis outcomes comparing patients with and without cancer

Distal or calf deep vein thrombosis (DVT) are said to have low rates of propagation, embolization, and recurrence. The objective of this study was to determine outcomes among cancer patients with calf DVT compared to those without cancer. Consecutive patients with ultrasound confirmed acute calf DVT (3/1/2013-8/10/2019) were assessed for venous thromboembolism (VTE) recurrence and bleeding outcomes compared by cancer status. There were 830 patients with isolated calf DVT; 243 with cancer and 587 without cancer. Cancer patients were older (65.9 ± 11.4 vs. 62.0 ± 15.9 years; p = 0.006), with less frequent recent hospitalization (31.7% vs. 48.0%; p < 0.001), surgery (30.0% vs. 38.0%; p = 0.03), or trauma (3.7% vs. 19.9%; p < 0.001). The four most common cancers included hematologic malignancies (20.6%), lung (11.5%), gastrointestinal (10.3%), and ovarian/GYN (9.1%). Nearly half of patients had metastatic disease (43.8%) and 57% were receiving chemotherapy. VTE recurrence rates were similar for patients with (7.1%) and without cancer (4.0%; p = 0.105). Major bleeding (6.3% vs. 2.3%; p = 0.007) were greater for cancer patients while clinical relevant non major bleeding rates did not differ (7.1% vs. 4.6%; p = 0.159). In this retrospective analysis, cancer patients with calf DVT have similar rates of VTE recurrence but higher major bleeding outcomes compared to patients without cancer.

Management of isolated distal deep-vein thrombosis with direct oral anticoagulants in the RIETE registry

Isolated distal deep-vein thrombosis (DVT, infra-popliteal DVT without pulmonary embolism) is a common presentation of venous thromboembolism (VTE), but was an exclusion criterion from the pivotal trials that validated the use of direct oral anticoagulants (DOACs) for VTE management. Using data from the international RIETE registry, we analyzed and compared trends in DOACs prescription between January 2011 and June 2019 in patients with distal vs. proximal DVT. We also assessed DOACs' prescriptions and compared the outcomes (VTE recurrence, bleeding and death) of distal DVT patients treated with DOACs vs. those on vitamin K antagonists (VKAs). 2308 patients with distal DVT and 11,364 patients with proximal DVT were included in the current analysis. DOACs were more frequently prescribed in patients with distal than proximal DVT (25% vs. 16%, p < 0.001). DOACs use increased sharply during the observation period (P < 0.001 for trend). In 2018, 56% of patients with distal DVT received DOACs. Distal DVT patients treated with rivaroxaban or edoxaban received the dose recommended for VTE management in most (> 85%) cases. Patients treated with apixaban were older, more likely to have underlying conditions than patients treated with rivaroxaban and, in most cases (> 75%), did not receive the recommended 1-week loading dose for acute VTE management. Outcomes between distal DVT patients treated with VKAs or DOACs appeared to be similar. In patients with distal DVT, DOACs have become the most common anticoagulant regimen. Specific trials are needed to determine the optimal DOACs dose regimen for treatment of distal DVT.

Incidence of Upper Extremity Deep Vein Thrombosis in Acute Leukemia and Effect on Mortality

The cumulative incidence, risk factors, rate of subsequent venous thromboembolism (VTE) and bleeding and impact on mortality of isolated upper extremity deep vein thrombosis (UE DVT) in acute leukemia are not well-described. The California Cancer Registry, used to identify treated patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) diagnosed between 2009 and 2014, was linked with the statewide hospitalization database to determine cumulative incidences of UE DVT and subsequent VTE and bleeding after UE DVT diagnosis. Cox proportional hazards regression models were used to assess the association of UE DVT on the risk of subsequent pulmonary embolism (PE) or lower extremity deep vein thrombosis (LE DVT) and subsequent bleeding, and the impact of UE DVT on mortality. There were 5,072 patients identified: 3,252 had AML and 1,820 had ALL. Three- and 12-month cumulative incidences of UE DVT were 4.8% (95% confidence interval [CI]: 4.1–5.6) and 6.6% (95% CI: 5.8–7.5) for AML and 4.1% (95% CI: 3.2–5.1) and 5.9% (95% CI: 4.9–7.1) for ALL, respectively. Twelve-month cumulative incidences of subsequent VTE after an incident UE DVT diagnosis were 5.3% for AML and 12.2% for ALL. Twelve-month cumulative incidences of subsequent bleeding after an incident UE DVT diagnosis were 15.4% for AML and 21.1% for ALL. UE DVT was associated with an increased risk of subsequent bleeding for both AML (hazard ratio [HR]: 2.07; 95% CI: 1.60–2.68) and ALL (HR: 1.62; 95% CI: 1.02–2.57) but was not an independent risk factor for subsequent PE or LE DVT for either leukemia subtype. Isolated incident UE DVT was associated with increased leukemia-specific mortality for AML (HR: 1.42; 95% CI: 1.16–1.73) and ALL (HR: 1.80; 95% CI: 1.31–2.47). UE DVT is a relatively common complication among patients with AML and ALL and has a significant impact on bleeding and mortality. Further research is needed to determine appropriate therapy for this high-risk population.

High incidence of venous thromboembolism and major bleeding in patients with primary CNS lymphoma

Venous thromboembolism (VTE) and major bleeding in primary central nervous system lymphoma (PCNSL) patients are not well described. We identified 992 PCNSL patients using the California Cancer Registry (2005-2014). The cumulative incidence of VTE and major bleeding was determined using California hospitalization data. The 12-month cumulative incidence of VTE was 13.6% (95% confidence interval (CI) 11.5-15.8%); chemotherapy and radiation therapy were associated with increased risk of VTE (hazard ratio (HR) 2.41, CI 1.31-4.46 and HR 1.56, CI 1.08-2.25, respectively). The 12-month cumulative incidence of major bleeding was 12.4% (CI 10.1-14.6%). Pulmonary embolism (PE) and proximal deep vein thrombosis were associated with increased risk of major bleeding, likely due to anticoagulation. PE (HR 1.61, CI 1.11-2.33, p=.011) and major bleeding (HR 2.36, CI 1.82-3.06, p<.0001) were associated with increased mortality. This study highlights the high incidence of both VTE and major bleeding and the significant impact on survival for PCNSL patients.

Dose-adjusted enoxaparin thromboprophylaxis in hospitalized cancer patients: a randomized, double-blinded multicenter phase 2 trial

Hospitalized patients with cancer are at an increased risk of developing venous thromboembolism (VTE). The recommendation for routine pharmacologic thromboprophylaxis in hospitalized patients with cancer to prevent VTE is based on extrapolation of results from noncancer cohorts. There are limited data to support the efficacy and safety of fixed-dose low-molecular-weight heparin (LMWH) regimens in high-risk hospitalized patients with cancer. We conducted a randomized, double-blinded, phase 2 trial in hospitalized patients with active cancer at high risk of developing VTE based on Padua risk score. Patients were randomly assigned to fixed-dose enoxaparin (40 mg daily) vs weight-adjusted enoxaparin (1 mg/kg daily) during hospitalization. The primary objectives were to evaluate the safety of dose-adjusted enoxaparin and evaluate the incidence of VTE with fixed-dose enoxaparin. Blinded clinical assessments were performed at day 14, and patients randomly assigned to fixed-dose enoxaparin subsequently underwent a bilateral lower extremity ultrasound. A total of 50 patients were enrolled and randomized. The median weight of patients enrolled in weight-adjusted enoxaparin arm was 76 kg (range, 60.9-124.5 kg). There were no major hemorrhages or symptomatic VTE in either arm. At time of completion of the blinded clinical assessment, there was only 1 incidentally identified pulmonary embolus that occurred in the weight-adjusted arm. In the group randomly assigned to fixed-dose enoxaparin who subsequently underwent surveillance ultrasound, the cumulative incidence of DVT was 22% (90% binomial confidence interval, 0%-51.3%). This phase 2 trial confirms a high incidence of asymptomatic VTE among high-risk hospitalized patients with cancer and that weight-adjusted LMWH thromboprophylaxis is feasible and well-tolerated. This trial was registered at www.clinicaltrials.gov as #NCT02706249.

Experience of a 40-day (6 week) LMWH treatment for isolated distal deep vein thrombosis

Clinical significance of distal deep vein thrombosis (DVT) is important as it can potentially result in pulmonary embolism (PE), DVT extension, DVT recurrence and post-thrombotic syndrome (PTS). Controversy remains about the necessity and modalities of anticoagulation in all distal DVT. Evaluation of the efficiency of a 40-day weight-based low molecular weight heparin (LMWH) treatment in a cohort of 119 consecutive patients with distal DVT. Compression ultrasonography of the lower limb was performed initially for diagnosis as well as at the end of the treatment to identify persistence or resolution of the blood clot. A 3-month follow-up estimated the rates of PE, DVT recurrence, DVT extension, PTS and bleeding. Risk factors for DVT were considered to evaluate a possible correlation between them and the outcomes. In 71.4% of the patients the blood clot was totally dissolved and thrombus persistence was statistically associated with the number of initially involved veins. DVT recurrence occurred in 5% of patients and was also associated with the number of initial clotted veins. DVT extension and PTS rates were present in 1.7% and 3.4% respectively and no patient was diagnosed with PE or bleeding. This retrospective study including a limited number of patients and no control group supports that a 40-day weight-based LMWH treatment after distal DVT seems to be efficient when one single vein is initially affected whereas for multiple vein distal DVT and to avoid potential DVT recurrence, longer than 6 weeks of anticoagulant treatment is required. Our results support safety of the treatment, its potential to prevent DVT extension and the occurrence of PE.