Duplex imaging of residual venous obstruction to guide duration of therapy for lower extremity deep venous thrombosis

The clinical application of venous ultrasound in diagnosis and follow-up of lower extremity deep vein thrombosis (DVT): a case-based discussion

Current clinical practice guidelines lack explicit guidance on the indications and appropriate timing of venous ultrasound (US) in lower extremity deep vein thrombosis (DVT) follow-up. Moreover, abnormal findings reported on venous US in DVT follow-up or suspected recurrent DVT may be difficult for clinicians to interpret, which carries risk of harm from inappropriate use of anti- coagulation and increased healthcare resource utilization. Due to the above factors, over-use of ultrasound in diagnosis and follow-up of lower extremity DVT has been reported in western health systems. We have undertaken a case-based discussion and a scoping review of existing guidelines on the use of venousUS following prior diagnosis of DVT, to guide appropriate interpretation of commonly reported US abnormalities and provide our suggestions in the light of best available evidence on appropriate timing to perform follow-up US in management of lower extremity DVT.

American Society of Hematology 2020 guidelines for management of venous thromboembolism: treatment of deep vein thrombosis and pulmonary embolism

BACKGROUND

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), occurs in ∼1 to 2 individuals per 1000 each year, corresponding to ∼300 000 to 600 000 events in the United States annually.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support patients, clinicians, and others in decisions about treatment of VTE.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and adult patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 28 recommendations for the initial management of VTE, primary treatment, secondary prevention, and treatment of recurrent VTE events.

CONCLUSIONS

Strong recommendations include the use of thrombolytic therapy for patients with PE and hemodynamic compromise, use of an international normalized ratio (INR) range of 2.0 to 3.0 over a lower INR range for patients with VTE who use a vitamin K antagonist (VKA) for secondary prevention, and use of indefinite anticoagulation for patients with recurrent unprovoked VTE. Conditional recommendations include the preference for home treatment over hospital-based treatment for uncomplicated DVT and PE at low risk for complications and a preference for direct oral anticoagulants over VKA for primary treatment of VTE.

D-dimer and high-sensitivity C-reactive protein levels to predict venous thromboembolism recurrence after discontinuation of anticoagulation for cancer-associated thrombosis

Background

Optimal duration of anticoagulation for cancer-associated thrombosis (CAT) remains unclear. This study assessed D-dimer (DD) and high-sensitivity C-reactive protein (hs-CRP) levels after the withdrawal of anticoagulation treatment to predict the risk of venous thromboembolism (VTE) recurrence among patients with CAT.

Methods

Prospective, multicentre study to evaluate CAT with ≥3 months of anticoagulation that was subsequently discontinued. Blood samples were taken when patients stopped the anticoagulation and 21 days later to determine the DD and hs-CRP levels. All patients were followed up for 6 months to detect VTE recurrence.

Results

Between 2013 and 2015, 325 patients were evaluated and 114 patients were ultimately enrolled in the study. The mean age was 62 ± 14 years and nearly 40% had metastasis. Ten patients developed VTE recurrence within 6 months (8.8%, 95% confidence interval [CI]: 4.3–15.5%). The DD and hs-CRP levels after 21 days were associated with VTE recurrence. The subdistribution hazard ratios were 9.82 for hs-CRP (95% CI: 19–52) and 5.81 for DD (95% CI: 1.1–31.7).

Conclusions

This study identified that hs-CRP and DD were potential biomarkers of VTE recurrence after discontinuation of anticoagulation in CAT. A risk-adapted strategy could identify low-risk patients who may benefit from discontinuation of anticoagulation.

Preliminary Investigations Showing Venous Thromboembolism Recurrence in Patients with Residual Venous Obstruction in Singaporean Population

This study aims to determine the association of residual venous obstruction (RVO) with recurrent venous thromboembolism (VTE). A retrospective cohort study was conducted determining if RVO on ultrasonography is associated with recurrent VTE in a Singaporean population. The subjects were identified from the Vascular Diagnostic Laboratory patients' record of Tan Tock Seng Hospital (TTSH), Singapore between 2008 and 2013. All the patients included had RVO after 3 months of anticoagulation. Data such as age, gender, race, thrombus location, etiology, history of malignancy, thrombophilia screen, treatment duration, and follow-up were recorded for analysis. Statistical analysis was performed using Stata/SE 13.1 (StataCorp LLC). The study was approved by the National Healthcare Group Domain Specific Review Board (DSRB), Singapore. Out of the 34 patients who had RVO, 6 (17.6%) developed VTE recurrence. Patients were treated with anticoagulation for a mean time of 24.5 months. The mean follow-up time for VTE recurrence was 25.4 months. Out of the six patients who had VTE recurrence, one had common iliac vein involvement, four had superficial femoral vein and common femoral vein involvement, zero had popliteal vein involvement, and one had calf veins involvement. There was a significant association between thrombophilia ( p  = 0.0195) and malignancy ( p  = 0.020) at inclusion with the risk of recurrent VTE. The presence of RVO after 3 months of anticoagulation is likely to increase the risk of VTE recurrence. Larger studies with RVO are needed to evaluate if there is an increased risk of VTE recurrence in the Asian population.

A Test in Context: D-Dimer

D-dimer is a soluble fibrin degradation product that results from ordered breakdown of thrombi by the fibrinolytic system. Numerous studies have shown that D-dimer serves as a valuable marker of activation of coagulation and fibrinolysis. Consequently, D-dimer has been extensively investigated for the diagnosis of venous thromboembolism (VTE) and is used routinely for this indication. In addition, D-dimer has been evaluated for determining the optimal duration of anticoagulation in VTE patients, for diagnosing and monitoring disseminated intravascular coagulation, and as an aid in the identification of medical patients at high risk for VTE. Thus, quantification of D-dimer levels serves an important role in guiding therapy. This review: 1) describes how D-dimer is generated; 2) reviews the assays used for its detection; and 3) discusses the role of D-dimer determination in these various conditions.

Thrombosis, Hypercoagulable States, and Anticoagulants

Patients with derangements of secondary hemostasis resulting from inherited or acquired thrombophilias are at increased risk of venous thromboemboli (VTE). Evaluation of a patient with suspected VTE proceeds via evidence-based algorithms that involve computing a pretest probability based on the history and physical examination; this guides subsequent work-up, which can include D dimer and/or imaging. Testing for hypercoagulable disorders should be pursued only in patients with VTE with an increased risk for an underlying thrombophilia. Direct oral anticoagulants are first-line VTE therapies, but they should be avoided in patients who are pregnant, have active cancer, antiphospholipid antibody syndrome, severe renal insufficiency, or prosthetic heart valves.