Analysis of an algorithm incorporating limited and whole-leg assessment of the deep venous system in symptomatic outpatients with suspected deep-vein thrombosis (PALLADIO): a prospective, multicentre, cohort study

Sex Differences in Clinical Presentation of Lower Extremity Deep Vein Thrombosis

Background: Differences between men and women in the clinical features and extent of lower limb deep vein thrombosis (DVT) may influence DVT diagnostic algorithms involving pretest clinical probability (PTP) assessment, D-dimer, and compression ultrasonography (CUS). Aims: To assess differences in DVT clinical presentation between men and women and their effect on PTP and D-dimer. Methods: We conducted a retrospective study in outpatients referred for suspected DVT of the lower limbs to our vascular emergency department from January 2005 to December 2019. Patients underwent PTP assessment with the Wells score, D-dimer testing, and CUS. Results: More women were referred for suspected DVT than men (M/F: 1,785/2,821; F: 61.4%; p < 0.0001). Women were older than men (median age: 71 vs. 67 years; p = 0.0001), DVT was diagnosed in 436 patients (9.4%) but in more men than women (M: 210 [11.8%] vs. F: 226 [8%]; p = 0.0002), with more proximal DVT in men than women (M: 131 7.3% vs. F: 124 [4.4%]; p = 0.00021). PTP was more likely in men (355 [19.9%]) than women (455 [16.2%]) (p = 0.0011); more men had swelling in the entire limb, increased calf circumference by >3 cm compared with the contralateral limb, and pitting edema, than women. D-dimer levels (available in 65% of patients) were more frequently positive in women with DVT than in men (94.6% vs. 85.7%; p = 0.016). However, a positive D-dimer and/or likely PTP was similarly frequent in men (92%) and women (96%) with DVT. Conclusions: More women than men are referred for suspected DVT, and men have a higher prevalence of proximal DVT. However, current algorithms for DVT diagnosis perform similarly in men and in women.

Rivaroxaban treatment for six weeks versus three months in patients with symptomatic isolated distal deep vein thrombosis: randomised controlled trial

OBJECTIVE

To compare two different treatment durations of rivaroxaban in patients with symptomatic isolated distal deep vein thrombosis (DVT).

DESIGN

Randomised, double blind, placebo controlled clinical trial.

SETTING

28 outpatient clinics specialising in venous thromboembolism.

PARTICIPANTS

402 adults (≥18 years) with symptomatic isolated distal DVT.

INTERVENTIONS

After receiving standard dose rivaroxaban for six weeks, participants were randomly assigned to receive rivaroxaban 20 mg or placebo once daily for an additional six weeks. Follow-up was for 24 months from study inclusion.

MAIN OUTCOMES MEASURES

The primary efficacy outcome was recurrent venous thromboembolism during follow-up after randomisation, defined as the composite of progression of isolated distal DVT, recurrent isolated distal DVT, proximal DVT, symptomatic pulmonary embolism, or fatal pulmonary embolism. The primary safety outcome was major bleeding after randomisation until two days from the last dose of rivaroxaban or placebo. An independent committee adjudicated the outcomes.

RESULTS

200 adults were randomised to receive additional rivaroxaban treatment and 202 to receive placebo. Isolated distal DVT was unprovoked in 81 (40%) and 86 (43%) patients, respectively. The primary efficacy outcome occurred in 23 (11%) patients in the rivaroxaban arm and 39 (19%) in the placebo arm (relative risk 0.59, 95% confidence interval 0.36 to 0.95; P=0.03, number needed to treat 13, 95% confidence interval 7 to 126). Recurrent isolated distal DVT occurred in 16 (8%) patients in the rivaroxaban arm and 31 (15%) in the placebo arm (P=0.02). Proximal DVT or pulmonary embolism occurred in seven (3%) patients in the rivaroxaban arm and eight (4%) in the placebo arm (P=0.80). No major bleeding events occurred.

CONCLUSIONS

Rivaroxaban administered for six additional weeks in patients with isolated distal DVT who had an uneventful six week treatment course reduces the risk of recurrent venous thromboembolism, mainly recurrent isolated distal DVT, over a two year follow-up without increasing the risk of haemorrhage.

TRIAL REGISTRATION

EudraCT 2016-000958-36; ClinicalTrials.gov NCT02722447.

Diagnostic accuracy of D-dimer in patients at high-risk for splanchnic vein thrombosis: A systematic review and meta-analysis

BACKGROUND

D-dimer is included in the diagnostic algorithm for deep vein thrombosis and pulmonary embolism. However, its role in the diagnosis of splanchnic vein thrombosis (SVT) is still controversial. The aim of this study was to evaluate the diagnostic accuracy of D-dimer for SVT.

METHODS

We performed a systematic review of the literature with meta-analysis (PROSPERO protocol registration number: CRD42020184300). The electronic databases MEDLINE, EMBASE, and CENTRAL were searched from inception to March 2021 week 4. Studies which evaluated D-dimer accuracy for SVT in any category of patients were selected. The index test was any D-dimer assay; the reference standard was any radiological imaging. The QUADAS-2 checklist was used for the risk of bias assessment. A bivariate random-effects regression model was used to calculate summary estimates of sensitivity and specificity.

RESULTS

12 studies (with a total of 1298 patients) evaluating the accuracy of D-dimer in patients at high risk of SVT (surgical patients, patients with liver cirrhosis or hepatocellular carcinoma) were included. None of the included studies was at low risk of bias. The weighted mean prevalence of SVT was 33.4% (95% CI, 22.5-45.2%, I2 = 94.8%). D-dimer accuracy was expressed by sensitivity 96% (95% CI, 72-100%); specificity 25% (95% CI, 5-67%); positive likelihood ratio 1.3 (95% CI, 0.9-1.9); negative likelihood ratio 0.16 (95% CI, 0.03-0.84); area under the ROC curve 0.80 (95% CI, 0.76-0.83).

CONCLUSIONS

D-dimer seems to have high sensitivity in the diagnosis of patients at high-risk for SVT. However, there is a strong need for more robust evidence on this topic.

Isolated calf deep venous thrombosis: frequency on venous ultrasound and clinical characteristics

Background

It remains controversial whether to include calf veins in the initial ultrasound evaluation of suspected deep venous thrombosis (DVT). We sought to investigate the frequency and clinical characteristics of isolated calf DVT.

Materials and methods

In this retrospective analysis, we investigated a cohort of 596 patients (median age 69 years, 52.3% women) who had been imaged with complete lower extremity venous duplex ultrasound for suspected acute DVT. Radiology reports were analyzed for the presence and localization of DVT. Clinical information was collected from patients’ electronic charts.

Results

DVT was found in 157 patients (26.3%), of which 74 patients (47.1%) had isolated calf DVT. Isolated calf DVTs were located in the posterior tibial veins (22 patients, 29.7%), peroneal veins (41 patients, 55.4%) and muscle veins (19 patients, 25.7%). There were no differences in age or sex between patients with isolated calf DVT and patients with proximal DVT. Isolated calf DVT was more commonly associated with leg pain (52.7% vs. 33.7%, p = 0.0234) and less commonly associated with subjective leg swelling (35.1% vs. 55.4%, p = 0.0158) and objectively measured difference in leg circumference (23% vs. 39.8%, p = 0.0268). D-Dimers were significantly lower in patients with isolated lower leg DVT (median 2.3 vs. 6.8 mg/L, p < 0.0001) compared to patients with proximal DVT.

Conclusions

Isolated calf DVT represents approximately half of DVT cases and has different clinical characteristics than proximal DVT.

Comparing lung ultrasound: extensive versus short in COVID-19 (CLUES): a multicentre, observational study at the emergency department

BACKGROUND

Bedside lung ultrasound (LUS) is an affordable diagnostic tool that could contribute to identifying COVID-19 pneumonia. Different LUS protocols are currently used at the emergency department (ED) and there is a need to know their diagnostic accuracy.

DESIGN

A multicentre, prospective, observational study, to compare the diagnostic accuracy of three commonly used LUS protocols in identifying COVID-19 pneumonia at the ED.

SETTING/PATIENTS

Adult patients with suspected COVID-19 at the ED, in whom we prospectively performed 12-zone LUS and SARS-CoV-2 reverse transcription PCR.

MEASUREMENTS

We assessed diagnostic accuracy for three different ultrasound protocols using both PCR and final diagnosis as a reference standard.

RESULTS

Between 19 March 2020 and 4 May 2020, 202 patients were included. Sensitivity, specificity and negative predictive value compared with PCR for 12-zone LUS were 91.4% (95% CI 84.4 to 96.0), 83.5% (95% CI 74.6 to 90.3) and 90.0% (95% CI 82.7 to 94.4). For 8-zone and 6-zone protocols, these results were 79.7 (95% CI 69.9 to 87.6), 69.0% (95% CI 59.6 to 77.4) and 81.3% (95% CI 73.8 to 87.0) versus 89.9% (95% CI 81.7 to 95.3), 57.5% (95% CI 47.9 to 66.8) and 87.8% (95% CI 79.2 to 93.2). Negative likelihood ratios for 12, 8 and 6 zones were 0.1, 0.3 and 0.2, respectively. Compared with the final diagnosis specificity increased to 83.5% (95% CI 74.6 to 90.3), 78.4% (95% CI 68.8 to 86.1) and 65.0% (95% CI 54.6 to 74.4), respectively, while the negative likelihood ratios were 0.1, 0.2 and 0.16.

CONCLUSION

Identifying COVID-19 pneumonia at the ED can be aided by bedside LUS. The more efficient 6-zone protocol is an excellent screening tool, while the 12-zone protocol is more specific and gives a general impression on lung involvement.

TRIAL REGISTRATION NUMBER

NL8497.

Venous thromboembolism

Venous thromboembolism, comprising both deep vein thrombosis and pulmonary embolism, is a chronic illness that affects nearly 10 million people every year worldwide. Strong provoking risk factors for venous thromboembolism include major surgery and active cancer, but most events are unprovoked. Diagnosis requires a sequential work-up that combines assessment of clinical pretest probability for venous thromboembolism using a clinical score (eg, Wells score), D-dimer testing, and imaging. Venous thromboembolism can be considered excluded in patients with both a non-high clinical pretest probability and normal D-dimer concentrations. When required, ultrasonography should be done for a suspected deep vein thrombosis and CT or ventilation-perfusion scintigraphy for a suspected pulmonary embolism. Direct oral anticoagulants (DOACs) are the first-line treatment for almost all patients with venous thromboembolism (including those with cancer). After completing 3-6 months of initial treatment, anticoagulation can be discontinued in patients with venous thromboembolism provoked by a major transient risk factor. Patients whose long-term risk of recurrent venous thromboembolism outweighs the long-term risk of major bleeding, such as those with active cancer or men with unprovoked venous thromboembolism, should receive indefinite anticoagulant treatment. Pharmacological venous thromboembolism prophylaxis is generally warranted in patients undergoing major orthopaedic or cancer surgery. Ongoing research is focused on improving diagnostic strategies for suspected deep vein thrombosis, comparing different DOACs, developing safer anticoagulants, and further individualising approaches for the prevention and management of venous thromboembolism.

Teaching limited compression ultrasound to general practitioners reduces referrals of suspected DVT to a hospital: a retrospective cross-sectional study

BACKGROUND

The aim of this study was to retrospectively determine whether teaching limited compression ultrasound (LCUS) to general practitioners (GP) would reduce the number of patients with a suspected lower extremity DVT referred to a hospital for ultrasound (US) examination. According to the current literature, an LCUS protocol is a safe way to diagnose or exclude lower extremity deep venous thrombosis (DVT) and a good option to radiologist-performed whole-leg ultrasound (US), especially in remote health care units where there may be a limited availability of radiological services.

METHODS

Between 2015 and 2016, altogether 13 GPs working in the same primary care unit were trained in LCUS for DVT diagnostics. The number of annual referrals due to a suspected DVT from Saarikka primary care unit to the closest hospital was evaluated before and after training. The incidence of DVT was considered to be constant. Thus, the reduction of referrals was attributed to the fact that these patients were diagnosed and treated in primary health care. Incidence rate ratio of hospital referrals was calculated. As a measure of safety, all patients diagnosed with a pulmonary embolism in the nearest hospital were evaluated to determine if they had undergone LCUS by a GP in primary care.

RESULTS

Before training in 2014, there were 60 annual referrals due to a suspected DVT; in 2017, after training, the number was reduced to 16, i.e., a 73.3% decrease. The incidence of referrals decreased from 3.21 to 0.89 per 1000 person-years. (IRR 3.58, 95% CI 2.04-6.66, p < 0.001). No patient with a pulmonary embolism diagnosis had LCUS performed previously, indicating that there were no false negatives, resulting in pulmonary embolism.

CONCLUSIONS

Teaching LCUS to GPs can safely reduce the number of patients with a suspected DVT referred to a hospital substantially.

Current Challenges in Diagnosis of Venous Thromboembolism

In patients with suspected venous thromboembolism, the goal is to accurately and rapidly identify those with and without thrombosis. Failure to diagnose venous thromboembolism (VTE) can lead to fatal pulmonary embolism (PE), and unnecessary anticoagulation can cause avoidable bleeding. The adoption of a structured approach to VTE diagnosis, that includes clinical prediction rules, D-dimer testing and non-invasive imaging modalities, has enabled rapid, cost-effective and accurate VTE diagnosis, but problems still persist. First, with increased reliance on imaging and widespread use of sensitive multidetector computed tomography (CT) scanners, there is a potential for overdiagnosis of VTE. Second, the optimal strategy for diagnosing recurrent leg deep venous thrombosis remains unclear as is that for venous thrombosis at unusual sites. Third, the conventional diagnostic approach is inefficient in that it is unable to exclude VTE in high-risk patients. In this review, we outline pragmatic approaches for the clinician faced with difficult VTE diagnostic cases. In addition to discussing the principles of the current diagnostic framework, we explore the diagnostic approach to recurrent VTE, isolated distal deep-vein thrombosis (DVT), pregnancy associated VTE, subsegmental PE, and VTE diagnosis in complex medical patients (including those with impaired renal function).

Direct-access to sonographic diagnosis of deep vein thrombosis in general practice: a descriptive cohort study

Background

Suspicion of deep vein thrombosis (DVT) is common and requires urgent and efficient investigation due to hazardous prognosis. The traditional diagnostic pathway can be complex and time-consuming, and innovative solutions may provide easy access to diagnostics and better use of healthcare resources. We aimed to describe use, clinical outcomes and time used when providing general practitioners (GPs) with a direct-access pathway to hospital-based, single whole-leg compression ultrasound (CUS) for patients with suspected DVT. Furthermore we aimed to describe the resources used in the new direct-access pathway and compare it with the previous pathway.

Methods

We conducted a 2-year descriptive cohort study (2016–2017) including 449 consecutively referred patients for diagnosis of DVT in a Danish regional hospital. The previous pathway included pre-test at the medical department, a proximal leg CUS if required based on the pre-test and a re-scan if the first CUS was negative. The new pathway included two strategies: 1) a ‘yes-no strategy’, where GPs referred patients directly to whole-leg CUS and if positive, treated at the medical department and if negative, discharged to the GP, 2) a ‘follow-up strategy’ where GPs could require that patients were seen at the medical department, irrespective of the CUS result. Data included extractions from the Radiology Information and Patient Administrative Systems, and mean salaries of healthcare professionals at Silkeborg Regional Hospital, Denmark. Descriptive statistics were used to describe prevalence, timelines and costs.

Results

GPs referred 318 (71%) patients through the yes-no strategy and 131 (29%) via the follow-up strategy with DVT diagnosed in 48 (15%) and 51 (39%) patients, respectively (p < 0.001). For the 263 patients completed after CUS in the yes-no strategy, median pathway time was 24 min (IQI: 16–36), and for those with DVT (including both strategies) 202 min (IQI: 158–273). Direct-access pathway costs were €49.7 less per patient than the previous pathway.

Conclusion

Direct-access to CUS for suspected DVT was achievable, had short time intervals and required fewer resources. The difference in DVT prevalence indicates that GPs distinguish between patients with low and high risk of DVT.

Calf deep vein thrombosis – clinical relevance, diagnostic approaches and therapeutic options

Summary. Isolated distal deep vein thromboses (IDDVT) represent up to 50 % of legs deep vein thromboses (DVT). However, since their natural history is to date unknown, the need to diagnose and treat them is a matter of debate. The diagnostic strategy based on the assessment of pre-test probability and D-dimer demonstrated a scarse efficiency for IDDVT. The choice between a proximal and a complete ultrasonographic approach should be guided by the clinical context, the local expertise and the patient characteristics. Randomized and observational studies have analyzed the need of therapy and compared different regimens of anticoagulation, with conflicting results. Systematic reviews and meta-analyses tend to support the usefulness of an anticoagulant treatment, even if the optimal dose and duration are not still defined. A careful stratification of the patient’s profile, taking into account risk factors for proximal extension, recurrence and bleeding should address the therapeutic approach, which must always be discussed with an adequately informed patient. Further studies aimed to clarify the natural history of IDDVT, and to assess safety and efficacy of lower intensity and shorter duration protocols are urgently needed.

Diagnostic accuracy of three ultrasonography strategies for deep vein thrombosis of the lower extremity: A systematic review and meta-analysis

Background

Compression ultrasonography (CUS) is the first-line imaging test in the diagnostic management of suspected deep vein thrombosis (DVT) of the lower extremity. Three CUS strategies are used in clinical practice. However, their relative diagnostic accuracy is uncertain.

Objectives

This systematic review and meta-analysis aimed to summarize and compare the diagnostic accuracy of single limited, serial limited, and whole-leg CUS for DVT.

Methods

MEDLINE, Embase, and CENTRAL were searched from January 1^st, 1989 to July 23^rd, 2019 for studies assessing at least one of the CUS strategies in adults with suspected DVT of the lower extremity, using clinical follow-up for venous thromboembolism or contrast venography as the reference standard. Study selection, data extraction, and risk of bias assessment were performed in duplicate by independent authors. A bivariate random-effects model was used to compute diagnostic accuracy summary estimates.

Results

Forty studies (n = 21,250) were included. The venous thromboembolic event rate after a negative CUS (failure rate) of single limited (1.4%; 95% CI, 0.83–2.5), serial limited (1.9%; 95% CI, 1.4–2.5), and whole-leg CUS (1.0%; 95% CI, 0.6–1.6) did not differ significantly. The proportion of positive results was lower with single limited CUS, as was DVT prevalence in this group.

Conclusions

The failure rates of single limited, serial limited, and whole-leg CUS for DVT appeared to be quite comparable. The relative failure rate of single limited CUS remains uncertain, as the DVT prevalence was lower in these studies. Therefore, this CUS strategy may only be safe in a selected group of low-risk patients. Preference for one of the strategies may be based on pretest probability assessment, feasibility, expertise, and perceived clinical relevance of isolated distal DVT.

The Prevalence of Concomitant Deep Vein Thrombosis, Symptomatic or Asymptomatic, Proximal or Distal, in Patients With Symptomatic Pulmonary Embolism

Patients with pulmonary embolism (PE) may have symptomatic or asymptomatic concomitant deep vein thrombosis (DVT). The reported prevalence of PE-associated DVT is variable, and thus, the utility of routine testing is controversial. The aim of our study was to analyze the prevalence of DVT and the factors associated with proximal DVT/whole-leg DVT in patients with symptomatic PE. In 428 consecutive patients (mean age: 59 ± 16.4 years; 52.3% men), we performed clinical examination and complete bilateral compression ultrasound and ascertained medical history and risk factors for DVT/PE. χ² and t tests were used. Deep vein thrombosis was found in 70.6%; proximal DVT in 49.5%. Sensitivity/specificity of DVT symptoms was 42.7%/93.7% for whole-leg DVT and 47.6%/83.3% for proximal DVT. Male gender significantly prevailed among those with whole-leg DVT and with proximal DVT (58.9% and 61.8%). Active malignancy was significantly more frequent in the patients with proximal DVT than without proximal DVT (10.4% vs 3.7%). In conclusion, the prevalence of PE-associated DVT is quite high but clinical diagnosis is unreliable. In our group, male gender and active malignancy were significantly associated with the presence of concomitant proximal DVT.

Ultrasound for Lower Extremity Deep Venous Thrombosis

Venous ultrasound is the standard imaging test for patients suspected of having acute deep venous thrombosis (DVT). There is variability and disagreement among authoritative groups regarding the necessary components of the test. Some protocols include scanning the entire lower extremity, whereas others recommend scans limited to the thigh and knee supplemented with serial testing. Some protocols use gray-scale ultrasound alone, whereas others include Doppler interrogation. Point-of-care ultrasound is recommended in some settings, and there is heterogeneity of these protocols as well. Heterogeneity of recommendations can lead to errors including incorrect application of guidelines, confusion among requesting physicians, and incorrect follow-up. In October 2016, the Society of Radiologists in Ultrasound convened a multidisciplinary panel of experts to evaluate the current evidence to develop recommendations regarding ultrasound protocols for DVT and the terminology used to communicate results to clinicians. Recommendations were made after open discussion and by unanimous consensus.

The panel recommends a comprehensive duplex ultrasound protocol from thigh to ankle with Doppler at selected sites rather than a limited or complete compression-only examination. This protocol is currently performed in many facilities and is achievable with standard ultrasound equipment and personnel. The use of these recommendations will increase the diagnosis of calf DVT and provide better data to explain the presenting symptoms. The panel recommends a single point-of-care protocol that minimizes underdiagnoses of proximal DVT.

The panel recommends the term chronic postthrombotic change to describe the residual material that persists after the acute presentation of DVT to avoid potential overtreatment of prior thrombus.

Adoption of a single standardized comprehensive duplex ultrasound and a single point-of-care examination will enhance patient safety and clinicians’ confidence.

Age-adjusted D-dimer to rule out deep vein thrombosis: findings from the PALLADIO algorithm

Essentials The accuracy of the age-adjusted D-dimer in suspected venous thromboembolism is still debated. We assessed the performance of age-adjusted D-dimer combined with the PALLADIO algorithm. The age-adjusted threshold can reduce the need for imaging tests compared to the fixed cut-off. The safety of this approach should be confirmed in large management studies.

SUMMARY

Background Age-adjusted D-dimer has been proposed to increase specificity for the diagnosis of venous thromboembolism (VTE). However, the accuracy of this threshold has been recently questioned. Objectives To assess the diagnostic performance of age-adjusted D-dimer combined with clinical pretest probability (PTP) in patients with suspected deep vein thrombosis (DVT). Methods PALLADIO (NCT01412242) was a multicenter management study that validated a new diagnostic algorithm, incorporating PTP, D-dimer (using the manufacturer's cut-off) and limited or extended compression ultrasonography (CUS) in outpatients with clinically suspected DVT. Patients with unlikely PTP and negative D-dimer had DVT ruled out without further testing (group 1); patients with likely PTP or positive D-dimer underwent limited CUS (group 2); patients with likely PTP and positive D-dimer underwent extended CUS (group 3). Patients with DVT ruled out at baseline had a 3-month follow-up. In this post-hoc analysis we evaluated age-adjusted D-dimer cut-off (defined as age times 10 μg L-1 , or age times 5 μg L-1 for D-dimers with a lower manufacturer's cut-off, in patients > 50 years). Results In total, 1162 patients were enrolled. At initial visit, DVT was detected in 4.0% of patients in group 2 and 53.0% in group 3. The age-adjusted D-dimer, compared with the fixed cut-off, resulted in 5.1% (95% CI, 4.0-6.5%) reduction of CUS. The incidence of symptomatic VTE during follow-up was: 0.24% (95% CI, 0.04-1.37) in group 1; 1.12% (95% CI, 0.44-2.85) in group 2; and 1.89% (95% CI, 0.64-5.40) in group 3. Conclusions The PALLADIO algorithm using age-adjusted D-dimer slightly decreased the number of required imaging tests, but this approach should be confirmed in large management studies.

Should we diagnose and treat distal deep vein thrombosis?

Ultrasound series report that isolated distal deep vein thrombosis (DVT), also known as calf DVT, represents up to 50% of all lower-limb DVTs and, therefore, is a frequent medical condition. Unlike proximal DVT and pulmonary embolism, which have been studied extensively and for which management is well standardized, much less is known about the optimal management of isolated calf DVT. Recent data arising from registries and nonrandomized studies have suggested that most distal DVTs do not extend to the proximal veins and have an uneventful follow-up when left untreated. These data had some impact on the international recommendations that recently stated that ultrasound surveillance instead of systematic therapeutic anticoagulation might be an option for selected low-risk patients. However, robust data from randomized studies are scarce. Only 5 randomized trials assessing the need for anticoagulation for calf DVT have been published. Many of these trials had an open-label design and were affected by methodological limitations. The only randomized placebo-controlled trial included low-risk patients (outpatients without cancer or previous venous thromboembolism [VTE]) and was hampered by limited statistical power. Nevertheless, data from this trial confirmed that the use of therapeutic anticoagulation in low-risk patients with symptomatic calf DVT is not superior to placebo in reducing VTE but is associated with a significantly higher risk of bleeding. Further randomized studies are needed to define the best therapy for high-risk patients (inpatients, patients with active cancer, or patients with previous VTE) and the optimal dose and duration of treatment.

Diagnosis of deep-vein thrombosis

The diagnostic approach to suspected symptomatic deep-vein thrombosis of the lower extremities is usually based on non-invasive methods, including the estimation of clinical probability, the measurement of D-dimer levels, and ultrasonography. The present review discusses the evidence available from the literature about the management of the first episode of suspected deep-vein-thrombosis.

Venous thromboembolism: Past, present and future

Venous thromboembolism (VTE), the third most frequent acute cardiovascular syndrome, is associated with a considerable disease burden which continues to grow along with the longer life expectancy of the population worldwide. In the past century, parenteral heparin prophylaxis was established for hospitalised patients at elevated risk of VTE. More recently, non-vitamin K antagonist oral anticoagulants (NOACs) with a direct inhibiting effect on factor Xa or thrombin, underwent extensive testing in clinical trials and have been approved for patients undergoing hip or knee replacement. Clinical investigation is ongoing in further areas of thromboprophylaxis, including medical prophylaxis in patients and high-risk situations in the outpatient setting. The diagnostic approach to suspected VTE is now based on advanced imaging techniques and robust diagnostic algorithms which ensure high sensitivity and specificity. Nevertheless, the role of clinical, or pre-test, probability assessment remains crucial to avoid overdiagnosis and treatment errors. Advances in reperfusion strategies, along progressive establishment of the NOACs as the new standard of anticoagulation treatment, have simplified the management of VTE, improving outcomes and particularly safety. While new molecular targets for anticoagulation are being investigated in the quest to further reduce bleeding risk, adjusting the initial regimen to the patient's risk and finding the optimal duration of anticoagulation after an index VTE event will be some of the top priorities in the years to come. Importantly, and in parallel to new drugs and technical advances in imaging, incentives such as hospital accreditation and funding based on evidence-based practice need to be implemented to increase guideline adherence.

Treatment of Isolated Below the Knee Deep Vein Thrombosis

The natural history of isolated distal deep-vein thrombosis (IDDVT) is still uncertain, as well as the real clinical risks associated with the disease and the need for its diagnosis and treatment. While more and more IDDVTs are diagnosed in everyday clinical practice, their appropriate therapeutic management is, unfortunately, far from straightforward, and different recommendations on how patients with diagnosed IDDVT should be treated are present between expert professionals and even among international guidelines. The present article aims at briefly reviewing the issue of IDDVT therapy in general, particularly focusing on the different approaches to the treatment of the disease that have been suggested by recent guidelines, those that are currently adopted in clinical practice, and necessary future directions.

Deep vein thrombosis and pulmonary embolism

Deep vein thrombosis and pulmonary embolism, collectively referred to as venous thromboembolism, constitute a major global burden of disease. The diagnostic work-up of suspected deep vein thrombosis or pulmonary embolism includes the sequential application of a clinical decision rule and D-dimer testing. Imaging and anticoagulation can be safely withheld in patients who are unlikely to have venous thromboembolism and have a normal D-dimer. All other patients should undergo ultrasonography in case of suspected deep vein thrombosis and CT in case of suspected pulmonary embolism. Direct oral anticoagulants are first-line treatment options for venous thromboembolism because they are associated with a lower risk of bleeding than vitamin K antagonists and are easier to use. Use of thrombolysis should be limited to pulmonary embolism associated with haemodynamic instability. Anticoagulant treatment should be continued for at least 3 months to prevent early recurrences. When venous thromboembolism is unprovoked or secondary to persistent risk factors, extended treatment beyond this period should be considered when the risk of recurrence outweighs the risk of major bleeding.

Management of distal deep vein thrombosis

Isolated distal deep vein thrombosis (DVT), also known as calf DVT, represents up to 50% of all lower limb DVT in ultrasound series and is therefore a frequent medical condition. Unlike proximal DVT and pulmonary embolism (PE), which have been extensively studied and for which management is well standardized, much less is known on the optimal management of isolated calf DVT. Recent data arising from registries and non-randomized studies suggest that most distal DVTs do not extend to the proximal veins and have an uneventful follow-up when left untreated. This data had some impact on the international recommendations which recently stated that ultrasound surveillance instead of systematic therapeutic anticoagulation might be an option for selected low-risk patients. However, robust data arising from randomized studies are scarce. Indeed, only five randomized trials assessing the need for anticoagulation for calf DVT have been published. Many of these trials had an open-label design and were affected by methodological limitations. The only randomized placebo-controlled trial included low-risk patients (outpatients without cancer or previous venous thromboembolic events (VTE)) and was hampered by a limited statistical power. Nevertheless, data from this trial tend to confirm that the use of therapeutic anticoagulation in low-risk patients with symptomatic calf DVT is not superior to placebo in reducing VTE, but is associated with a significantly higher risk of bleeding. Further randomized studies are needed to define the best therapy for high-risk patients (inpatients, patients with active cancer or previous VTE), and the optimal dose and duration of treatment.

Controversies in venous thromboembolism: the unique case of isolated distal deep vein thrombosis

Venous thromboembolism (VTE) represents the third leading cause of cardiovascular mortality, and it is the main cause of preventable mortality in hospitalized patients. Among VTE, there is the unique case of isolated distal deep vein thrombosis (IDDVT), which still lacks an agreement in terms of optimal therapeutic strategy. Although most IDDVTs are self-limiting and associated with a very low risk of embolic complications, still not all IDDVTs can be safely identified as stable. Lack of strong scientific evidence, fear of thromboembolic complications, and risk of bleeding upon initiation of anticoagulant treatment result in very heterogeneous therapeutic strategies among physicians. Here, we provide a comprehensive review of the literature, highlight the many controversial issues regarding IDDVTs, and call for a consensus of experts aimed to shed new light on the gray areas of IDDVT management and therapy.