Ultrasound-assisted versus conventional catheter-directed thrombolysis for acute iliofemoral deep vein thrombosis: 1-year follow-up data of a randomized-controlled trial

The background and role of catheter-directed thrombolysis evolving procedures for acute iliofemoral deep venous thrombosis

Minimal invasive treatment such as early endovenous thrombus removal for iliofemoral deep venous thrombosis (DVT) emerged in the end of last century. The principle is catheter-directed thrombolysis (CDT) using either plasminogen activating agents alone, as ultrasound-assisted CDT, or in combination with mechanical devices as pharmaco-mechanical CDT. The interest for this treatment modality is the high rate of post-thrombotic syndrome (PTS) with anticoagulation (AC) alone, especially after iliofemoral DVT. Recently published randomized controlled trials (RCTs) comparing early thrombus removal with AC alone, as well as non-randomized studies, have demonstrated favorable rates, or at least a decrease of moderate and severe PTS, in favor of these procedures. This article will summarize the background and evolution of the procedures in the last three decades and discuss fundamental criteria for inclusion and exclusion, focusing on the procedures regarding thrombus age and location, technical issues, complications and results including different outcome measures for PTS, for which iliac DVT involvement is a massive risk factor to be prevented.

Patient-Reported Outcomes in Venous Thromboembolism: A Systematic Review of the Literature, Current Challenges, and Ways Forward

BACKGROUND

Venous thromboembolism (VTE) affects >1.2 million Americans annually. Although the clinical outcomes and economic burdens of VTE have been well described, the impact of VTE on patients' health status has yet to be summarized. This systematic review summarizes how patient-reported outcome measures (PROMs) have been used in VTE to date.

METHODS AND RESULTS

PubMed/MEDLINE was queried for literature published through March 2023 using PROMs in a population of patients with VTE. Studies were excluded if the reference was an editorial, review, or case report, or if the study included patients with conditions other than VTE. Qualitative analyses were performed. After screening and exclusion, 136 references were identified; 5 described PROM development, 20 focused on PROM validation, and 111 used PROMs in outcomes research. The most used generic PROMs were the 36-item Short-Form Health Survey and EuroQol 5-dimensional questionnaire, and the most common disease-specific PROMs were the Venous Insufficiency Epidemiological and Economic Study-Quality of Life/Symptoms and the Pulmonary Embolism Quality of Life Questionnaire. PROMs were used to quantify the changes in health status after diagnosis, characterize the trajectory of subsequent improvement, and identify drivers of continued impairments in health status like postthrombotic syndrome and postpulmonary embolism syndrome. PROMs were also used to investigate the impact of novel treatment modalities on quality of life.

CONCLUSIONS

This review demonstrates the many benefits of PROM use, including quantifying changes in health status with treatment, capturing patients' experiences with the treatment itself, and identifying complications of VTE. Incorporating PROMs into VTE care will be an essential component of evaluating the effectiveness of novel therapies and should lead to improved shared decision-making for patients with VTE.

Antithrombotic management of patients with deep vein thrombosis and venous stents: an international registry

BACKGROUND

In patients with acute deep vein thrombosis (DVT) treated with catheter-based thrombolysis and venous stenting, poststenting anticoagulant management is uncertain.

OBJECTIVES

To determine the type and duration of antithrombotic therapy used in patients who have received venous stents for treatment of acute lower extremity DVT.

METHODS

We created an international registry of patients with leg DVT from 2005 to 2019 who received venous stents as part of their acute management. We collected data on baseline clinical characteristics and pre-venous and post-venous stent antithrombotic therapy.

RESULTS

We studied 173 patients with venous stents: 101 (58%) were aged ≤50 years, 105 (61%) were female, and 128 (74%) had risk factors for thrombotic disease. DVT was iliofemoral in 150 (87%) patients, and catheter-based treatment was given within 7 days of diagnosis in 92 (53%) patients. After venous stenting, 109 (63%) patients received anticoagulant-only therapy with a direct oral anticoagulant (29%), warfarin (22%), or low-molecular-weight heparin (10%), and 59 (34%) received anticoagulant-antiplatelet therapy. In patients taking anticoagulant-only therapy, 29% received indefinite treatment; in patients on anticoagulant-antiplatelet therapy, 19% received indefinite treatment. Factors associated with combined anticoagulant-antiplatelet therapy vs anticoagulant-only therapy were use of thrombolytic, thrombectomy, and aspiration interventions (odds ratio [OR], 5.11; 95% CI, 1.45-18.05); use of balloon angioplasty (OR, 2.62; 95% CI, 1.20-5.76); and immediate stent restenosis (OR, 7.2; 95% CI, 1.45-5.89).

CONCLUSION

Anticoagulant therapy without concomitant antiplatelet therapy appears to be the most common antithrombotic strategy in patients with DVT and venous stenting. More research is needed to determine outcomes of venous stenting in relation to antithrombotic therapy.

Interventional therapies for pulmonary embolism

Pulmonary embolism (PE) is the leading cause of in-hospital death and the third most frequent cause of cardiovascular death. The clinical presentation of PE is variable, and choosing the appropriate treatment for individual patients can be challenging. Traditionally, treatment of PE has involved a choice of anticoagulation, thrombolysis or surgery; however, a range of percutaneous interventional technologies have been developed that are under investigation in patients with intermediate-high-risk or high-risk PE. These interventional technologies include catheter-directed thrombolysis (with or without ultrasound assistance), aspiration thrombectomy and combinations of the aforementioned principles. These interventional treatment options might lead to a more rapid improvement in right ventricular function and pulmonary and/or systemic haemodynamics in particular patients. However, evidence from randomized controlled trials on the safety and efficacy of these interventions compared with conservative therapies is lacking. In this Review, we discuss the underlying pathophysiology of PE, provide assistance with decision-making on patient selection and critically appraise the available clinical evidence on interventional, catheter-based approaches for PE treatment. Finally, we discuss future perspectives and unmet needs.

Strain-gauge venous occlusion plethysmography: An objective and non-invasive approach to the evaluation of venous hemodynamics in patients with acute deep-vein thrombosis undergoing post-pharmacomechanical thrombolysis

OBJECTIVES

Strain-gauge venous occlusion plethysmography (SGVOP) is a means of acquiring hemodynamic data non-invasively, unlike other methods used routinely for the diagnosis and follow-up of venous diseases. The present study compares the plethysmographic data with early- and mid-term routine data of patients with acute deep-vein thrombosis (DVT) who underwent pharmacomechanical thrombolysis.

PATIENTS AND METHOD

Included in this retrospective study were 118 patients with acute DVT, who underwent pharmacomechanical thrombolysis between February 2018 and July 2019. Pre- and post-procedure follow-up data including CIVIQ-20 (quality of life), VCSS (Venous Clinical Severity Score), D-Dimer, Doppler USG results, venous capacity (VC), and venous outflow (VO) obtained by SGVOP were recorded and compared.

RESULTS

In all 118 (100%) patients who underwent the procedure, early- and mid-term patency was seen to have been provided on Doppler USG follow-up, and various degrees of venous insufficiency were identified. A statistically significant improvement was observed in VCSS, CIVIQ-20, D-Dimer, VO, and VC measurements, although when the discrepancies between CIVIQ-20 and plethysmographic measurements were examined individually during the 6-month follow-up, nine (13.1%) patients were identified with comorbidities.

CONCLUSIONS

Pharmacomechanical thrombolysis is an effective treatment approach for patients with acute DVT. Providing non-invasive objective data supporting the diagnosis and follow-up of venous diseases, the SGVOP approach offers significant benefits and should be considered more frequently as a viable therapy.

Society of Interventional Radiology Position Statement on the Endovascular Management of Acute Iliofemoral Deep Vein Thrombosis

PURPOSE

To establish the updated position of the Society of Interventional Radiology (SIR) on the endovascular management of acute iliofemoral deep vein thrombosis (DVT).

MATERIALS AND METHODS

A multidisciplinary writing group with expertise in treating venous diseases was convened by SIR. A comprehensive literature search was conducted to identify studies on the topic of interest. Recommendations were drafted and graded according to the updated SIR evidence grading system. A modified Delphi technique was used to achieve consensus agreement on the recommendation statements.

RESULTS

A total of 84 studies, including randomized trials, systematic reviews and meta-analyses, prospective single-arm studies, and retrospective studies were identified and included in the review. The expert writing group developed 17 recommendations that pertain to the care of patients with acute iliofemoral DVT with the use of endovascular venous interventions.

CONCLUSIONS

SIR considers endovascular thrombus removal to be an acceptable treatment option in selected patients with acute iliofemoral DVT. Careful individualized risk assessment, high-quality general DVT care, and close monitoring during and after procedures should be provided.

Developing and optimizing a machine learning predictive model for post-thrombotic syndrome in a longitudinal cohort of patients with proximal deep venous thrombosis

BACKGROUND

Post-thrombotic syndrome (PTS) is the most common chronic complication of deep venous thrombosis (DVT). Risk measurement and stratification of PTS are crucial for patients with DVT. This study aimed to develop predictive models of PTS using machine learning for patients with proximal DVT.

METHODS

Herein, hospital inpatients from a DVT registry electronic health record database were randomly divided into a derivation and a validation set, and four predictive models were constructed using logistic regression, simple decision tree, eXtreme Gradient Boosting (XGBoost), and random forest (RF) algorithms. The presence of PTS was defined according to the Villalta scale. The areas under the receiver operating characteristic curves, decision-curve analysis, and calibration curves were applied to evaluate the performance of these models. The Shapley Additive exPlanations analysis was performed to explain the predictive models.

RESULTS

Among the 300 patients, 126 developed a PTS at 6 months after DVT. The RF model exhibited the best performance among the four models, with an area under the receiver operating characteristic curves of 0.891. The RF model demonstrated that Villalta score at admission, age, body mass index, and pain on calf compression were significant predictors for PTS, with accurate prediction at the individual level. The Shapley Additive exPlanations analysis suggested a nonlinear correlation between age and PTS, with two peak ages of onset at 50 and 70 years.

CONCLUSIONS

The current predictive model identified significant predictors and accurately predicted PTS for patients with proximal DVT. Moreover, the model demonstrated a nonlinear correlation between age and PTS, which might be valuable in risk measurement and stratification of PTS in patients with proximal DVT.

Impact of concomitant popliteal vein thrombosis in patients with acute iliofemoral deep vein thrombosis treated with endovascular early thrombus removal

Summary: Background: Catheter-based thrombus removal (CBTR) reduces the risk of moderate to severe post-thrombotic syndrome (PTS) in patients with acute iliofemoral deep vein thrombosis (IF-DVT). However, the impact of concomitant popliteal DVT on clinical and duplex sonographic outcomes is unknown. Patients and methods: In this post-hoc analysis including the entire cohort of the randomized controlled BERNUTIFUL trial (48 patients), we compared clinical (incidence/severity of PTS assessed by Villalta score and revised venous clinical severity scores, rVCSS), disease-specific quality-of-life (QOL, CIVIQ-20 survey) and duplex sonographic outcomes (patency, reflux, post-thrombotic lesions) at 12 months follow-up between patients with IF-DVT with and without concomitant popliteal DVT treated by CBTR. Results: Overall, 48 IF-DVT patients were included (48% men, median age of 50 years), of whom 17 (35%) presented with popliteal DVT. At baseline, patients with popliteal DVT were older, had a higher body mass index and more important leg swelling. At 12 months, freedom from PTS (93% vs 87%, P=0.17), median total Villalta score (1 vs 1.5; P=0.46), rVCSS (2 vs 1.5, P=0.5) and disease-specific QOL (24 points vs 24 points, P=0.72) were similar between patient with and without popliteal DVT, respectively. Duplex sonographic outcomes were similar, except for more frequent popliteal post-thrombotic lesions and reflux (P=0.02) in patients with popliteal DVT. Conclusions: Relevant clinical outcomes 1 year after successful CBTR were favorable, regardless of the presence or absence of concomitant popliteal DVT. However, post-thrombotic popliteal vein lesions and reflux are more frequent in IF-DVT patients with popliteal involvement. Their impact on long-term outcomes remains to be investigated.

Acute Deep Vein Thrombosis Involving the Inferior Vena Cava: Interventional Perspectives

Extension of an iliofemoral thrombosis into the inferior vena cava (IVC), or from the IVC descending into the iliofemoral segments, can confer significant morbidity and mortality. Interventional management of acute deep vein thrombosis (DVT) has been controversial, but there is little doubt that certain subpopulations benefit, such as those with symptomatic IVC thrombosis. When considering an intervention, caval involvement introduces technical difficulties due to its larger diameter, high thrombus burden, bilateral limb clot extension and need for dual access. The frequent coexistence of an IVC filter increases the complexity even more. This review summarises the current indications and treatment modalities available for the management of acute DVT involving the vena cava.

Invasive and Pharmacological Treatment of Deep Vein Thrombosis: a Scoping Review

The annual occurrence of venous thromboembolism (VTE) is 300,000-600,000 cases in the United States and 700,000 in Europe. VTE includes deep venous thrombosis (DVT) of upper or lower extremities, superior and inferior vena cava thrombosis, and pulmonary embolism (PE) as well. The primary treatment of DVT includes oral anticoagulation to prevent the progression of the thrombus and decrease the risk of pulmonary embolism. Depending on the symptoms, more invasive treatments can be applied to target the iliofemoral thrombus and its removal. However, less emphasis is given to acute symptomatology, early recovery of function, quality of life improvement, and the individualized likelihood of developing post-thrombotic syndrome. While invasive therapy has been used to enhance the acute management of iliofemoral DVT, our knowledge about the overall outcomes associated with the invasive treatment of VTE is still limited. In this review, we illustrate the available data on pharmacological and endovascular management of iliofemoral VTE, including therapies such as catheter-directed thrombolysis (CDT), mechanical thrombectomy (PMT), and pharmacomechanical catheter-directed thrombolysis (PCDT).

High-Pressure Low-Frequency Lateral Mode Phased-Array Transducer System for the Treatment of Deep Vein Thrombosis: An In Vitro Study

Deep vein thrombosis (DVT) can lead to a fatal disease known as pulmonary embolism. Application of high-power ultrasound has been successful in studies to mechanically fragment the clots. Single-element ultrasound transducers were used in most of the studies. Challenges associated with phased arrays, such as high electrical impedance and element breakdown at high voltages, were addressed in the previous study, and a high-power 64-element transducer module was designed and fabricated. In this study, a cylindrical array of 16 modules with the frequency of 260 kHz was modeled and constructed for DVT thrombolysis. The maximum pressure, focal size, and steering ability of the array were examined. In vitro experiments were conducted to assess the performance of the array. The simulated pressure amplitude of 34 MPa at the depth of 55 mm (average femoral vein (FV) distance from the inner surface of the thigh) was in consistent with the experiments and satisfied the purpose of this study. Moreover, the employed module distribution resulted in a focal spot dimension of 2.4×2.8×7.3 mm³ (at the 75% pressure amplitude level) that can be confined in a human FV with the average diameter of 12 mm. In vitro experiments manifested a partial and complete clot breakdown at 11.5- and 15-MPa pressure at the focus. The design and engineering of the array system was succeeded in maintaining the desired pressure and focal size even when steered. The results presented in this study suggest the potential of the designed array system for clinical applications.

Efficacy of ultrasound assisted catheter-directed thrombolysis compared to catheter-directed thrombolysis in vitro

BACKGROUND

Catheter-directed thrombolysis (CDT) is an effective and safe endovascular method used in critical limb ischemia and many other thromboembolic events. Ultrasound-assisted catheter-directed thrombolysis (US-CDT) is an emerging technique considered to accelerate thrombolysis and therefore is supposed to improve outcome.

PURPOSE

To evaluate the efficacy of US-CDT in comparison to standard CDT in vitro.

MATERIAL AND METHODS

A total of 69 sets of human venous blood were evaluated, each comprising a tube just treated with CDT, a tube treated with US-CDT, and a control tube. All tubes were kept under physiological conditions. Except for the controls, in all tubes 5 mg of tissue-type plasminogen activator was administered over the predetermined treatment interval. Thrombus mass was weighted at the end of the lysis intervals at 6 h or 24 h, respectively.

RESULTS

CDT led to a mean thrombus reduction of 32% and ultrasound-assisted lysis led to a mean thrombus reduction of 41% (P < 0.001 for both). Thrombus reduction was significantly higher after US-CDT compared to CDT (P = 0.001). The better efficacy of US-CDT was mostly already apparent at early phases during thrombolysis and did further mildly increase over time (r = 0.24; P = 0.047).

CONCLUSION

In vitro US-CDT is significantly superior to standard CDT; this effect is apparent at an early timepoint of lysis and slightly further increases over time.

A Systematic Review and Meta-Analysis of 12-Month Patency After Intervention for Iliofemoral Obstruction Using Dedicated or Non-Dedicated Venous Stents

BACKGROUND

Endovascular stenting of the deep venous system has been proposed as a method to treat patients with symptomatic iliofemoral outflow obstruction. The purpose of this systematic review and meta-analysis was to compare the effectiveness of this treatment at 1-year following the development of dedicated venous stents.

METHOD AND RESULTS

We searched MEDLINE and EMBASE for studies evaluating the effectiveness of venous stent placement. Data were extracted by disease pathogenesis: non-thrombotic iliac vein lesions (NIVL), acute thrombotic (DVT), or post-thrombotic syndrome (PTS). Main outcomes included technical success, stent patency at 1 year and symptom relief. A total of 49 studies reporting outcomes in 5154 patients (NIVL, 1431; DVT, 950; PTS, 2773) were included in the meta-analysis. Technical success rates were comparable among groups (97%-100%). There were no periprocedural deaths. Minor bleeding was reported in up to 5% of patients and major bleeding in 0.5% upon intervention. Transient back pain was noted in 55% of PTS patients following intervention. There was significant heterogeneity between studies reporting outcomes in PTS patients. Primary and cumulative patency at 1 year was: NIVL-96% and 100%; DVT-91% and 97%; PTS (stents above the ligament)-77% and 94%, and; PTS (stents across the ligament)-78% and 94%. There were insufficient data to compare patency outcomes of dedicated and nondedicated venous stents in patients with acute DVT. In NIVL and PTS patients, stent patency was comparable at 1 year. There was inconsistency in the use of validated tools for the measurement of symptoms before and after intervention. When reported, venous claudication, improved in 83% of PTS patients and 90% of NIVL patients, and ulcer healing occurred in 80% of PTS patients and 32% of NIVL patients.

CONCLUSIONS

The first generation of dedicated venous stents perform comparably in terms of patency and clinical outcomes to non-dedicated technologies at 1 year for the treatment of patients with NIVL and PTS. However, significant heterogeneity exists between studies and standardized criteria are urgently needed to report outcomes in patients undergoing deep venous stenting.

Catheter-directed thrombolysis for deep vein thrombosis: 2021 update

Catheter-directed thrombolysis (CDT) has been utilized as an adjunct to anticoagulant therapy in selected patients with deep vein thrombosis (DVT) for approximately 30 years. CDT used to be limited to patients with DVT causing acute limb threat and those exhibiting failure of initial anticoagulation, but has expanded over time. Randomized trials evaluating the first-line use of CDT for proximal DVT have demonstrated that CDT does not produce a major reduction in the occurrence of post-thrombotic syndrome (PTS) and that it is poorly suited for elderly patients and those with limited thrombus extent or major risk factors for bleeding. However, CDT does offer selected patients with acute iliofemoral DVT improvement in reducing early DVT symptoms, in achieving reduction in PTS severity, and in producing an improvement in health-related quality of life (QOL). Clinical practice guidelines from medical and surgical societies are now largely aligned with the randomized trial results. This review offers the reader an update on the results of recently completed clinical trials, and additional guidance on appropriate selection of patients with DVT for catheter-directed thrombolytic therapy.

Clinical Outcomes of a Pharmacomechanical Catheter-Directed Venous Thrombolysis Strategy that Included Rheolytic Thrombectomy in a Multicenter Randomized Trial

PURPOSE

To describe the clinical outcomes of a pharmacomechanical catheter-directed venous thrombolysis (PCDT) strategy that included AngioJet rheolytic thrombectomy.

METHODS

In the Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis multicenter randomized trial, physicians at 33 sites designated AngioJet as their preferred device for PCDT. In these sites, 364 patients with acute proximal lower-extremity deep vein thrombosis (DVT) were randomized to a strategy of PCDT that incorporated either AngioJet along with anticoagulation or anticoagulation alone. Relief from presenting DVT symptoms was evaluated over 30 days of follow-up. Postthrombotic syndrome (PTS), quality of life (QOL), recurrent venous thromboembolism (VTE), and safety were evaluated over 24 months of follow-up.

RESULTS

Within 30 days, AngioJet-PCDT led to a greater improvement in leg swelling (mean difference calf circumference 0.55 cm, P = .009), venous QOL (mean difference 6.5 Venous Insufficiency Epidemiologic and Economic Study [VEINES]-QOL points, P = .0073), and venous symptoms (mean difference 5.6 VEINES-symptoms points, P = .0134) than control, with differences most apparent in iliofemoral DVT. AngioJet-PCDT reduced PTS at 6 months (24% with AngioJet-PCDT vs 40% with control, P = .003) but did not influence PTS or QOL between 12 and 24 months. Major bleeding, pulmonary embolism, renal failure, and bradycardia were infrequent with AngioJet-PCDT (<2% each), but 24-month VTE recurrence may have been more frequent (13.9% with AngioJet-PCDT vs 6.8% with control, P = .03) CONCLUSIONS: In patients with acute proximal DVT, a treatment strategy that included first-line AngioJet-PCDT was reasonably safe and led to an improved symptom status and venous QOL at 1 month and reduced PTS at 6 months compared with anticoagulation alone. However, AngioJet-PCDT did not influence PTS or the QOL beyond 6 months and may have increased recurrent VTE.

Comparison of ultrasound-accelerated versus conventional catheter-directed thrombolysis for deep vein thrombosis: A systematic review and meta-analysis

BACKGROUND

Recent in vitro and clinical studies have shown that ultrasound-accelerated catheter-directed thrombolysis (USACDT) can accelerate thrombolysis. Therefore, in this meta-analysis, we aimed to compare the efficacy and safety of USACDT with conventional catheter-directed thrombolysis in patients with deep vein thrombosis.

METHODS

A systematic search of the following electronic databases was performed from their dates of inception to 20 June 2020: MEDLINE, Scopus, Google Scholar, CINAHL, Cochrane Library, and EMBASE. All randomized controlled trials that directly compared the complications and efficacy of USACDT and conventional catheter-directed thrombolysis in patients with deep vein thrombosis were identified. The statistical analysis was performed using comprehensive meta-analysis software.

RESULTS

Finally, 18 studies with a total of 597 participants were included in our meta-analysis according to the eligibility criteria. Pooled proportion of USACDT success in patients with deep vein thrombosis was 87.8% (18 studies; 95% CI: 83.1-91.3). Success rate was significantly higher in USACDT treatment than in conventional catheter-directed thrombolysis treatment (seven studies; OR: 2.96; 95% CI: 1.69-5.16; P < 0.01)). Although the mean infusion time was higher in catheter-directed thrombolysis treatment compared to USACDT treatment, this difference was not statistically significant (three studies; MD: -1.46; 95% CI: -3.25-0.32; P = 0.10). Moreover, pooled rate of complications was lower in USACDT than catheter-directed thrombolysis which was not statistically significant (seven studies; OR: 0.49; 95% CI: 0.13-1.76; P = 0.27).

CONCLUSION

This meta-analysis revealed that USACDT significantly increased the success rate of thrombolysis compared to conventional catheter-directed thrombolysis. Furthermore, USACDT was associated with lower rate of complication and infusion time. Taken together, these findings confirm the superiority of this novel intervention over conventional catheter-directed thrombolysis in treatment of patients with deep vein thrombosis.

Thrombolytic strategies versus standard anticoagulation for acute deep vein thrombosis of the lower limb

BACKGROUND

Standard treatment for deep vein thrombosis (DVT) aims to reduce immediate complications. Use of thrombolytic clot removal strategies (i.e. thrombolysis (clot dissolving drugs), with or without additional endovascular techniques), could reduce the long-term complications of post-thrombotic syndrome (PTS) including pain, swelling, skin discolouration, or venous ulceration in the affected leg. This is the fourth update of a Cochrane Review first published in 2004.

OBJECTIVES

To assess the effects of thrombolytic clot removal strategies and anticoagulation compared to anticoagulation alone for the management of people with acute deep vein thrombosis (DVT) of the lower limb.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL and AMED and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registries to 21 April 2020. We also checked the references of relevant articles to identify additional studies.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) examining thrombolysis (with or without adjunctive clot removal strategies) and anticoagulation versus anticoagulation alone for acute DVT.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as recommended by Cochrane. We assessed the risk of bias in included trials with the Cochrane 'Risk of bias' tool. Certainty of the evidence was evaluated using GRADE. For dichotomous outcomes, we calculated the risk ratio (RR) with the corresponding 95% confidence interval (CI). We pooled data using a fixed-effect model, unless we identified heterogeneity, in which case we used a random-effects model. The primary outcomes of interest were clot lysis, bleeding and post thrombotic syndrome.

MAIN RESULTS

Two new studies were added for this update. Therefore, the review now includes a total of 19 RCTs, with 1943 participants. These studies differed with respect to the thrombolytic agent, the doses of the agent and the techniques used to deliver the agent. Systemic, loco-regional and catheter-directed thrombolysis (CDT) strategies were all included. For this update, CDT interventions also included those involving pharmacomechanical thrombolysis. Three of the 19 included studies reported one or more domain at high risk of bias. We combined the results as any (all) thrombolysis interventions compared to standard anticoagulation. Complete clot lysis occurred more frequently in the thrombolysis group at early follow-up (RR 4.75; 95% CI 1.83 to 12.33; 592 participants; eight studies) and at intermediate follow-up (RR 2.42; 95% CI 1.42 to 4.12; 654 participants; seven studies; moderate-certainty evidence). Two studies reported on clot lysis at late follow-up with no clear benefit from thrombolysis seen at this time point (RR 3.25, 95% CI 0.17 to 62.63; two studies). No differences between strategies (e.g. systemic, loco-regional and CDT) were detected by subgroup analysis at any of these time points (tests for subgroup differences: P = 0.41, P = 0.37 and P = 0.06 respectively). Those receiving thrombolysis had increased bleeding complications (6.7% versus 2.2%) (RR 2.45, 95% CI 1.58 to 3.78; 1943 participants, 19 studies; moderate-certainty evidence). No differences between strategies were detected by subgroup analysis (P = 0.25). Up to five years after treatment, slightly fewer cases of PTS occurred in those receiving thrombolysis; 50% compared with 53% in the standard anticoagulation (RR 0.78, 95% CI 0.66 to 0.93; 1393 participants, six studies; moderate-certainty evidence). This was still observed at late follow-up (beyond five years) in two studies (RR 0.56, 95% CI 0.43 to 0.73; 211 participants; moderate-certainty evidence). We used subgroup analysis to investigate if the level of DVT (iliofemoral, femoropopliteal or non-specified) had an effect on the incidence of PTS. No benefit of thrombolysis was seen for either iliofemoral or femoropopliteal DVT (six studies; test for subgroup differences: P = 0.29). Systemic thrombolysis and CDT had similar levels of effectiveness. Studies of CDT included four trials in femoral and iliofemoral DVT, and results from these are consistent with those from trials of systemic thrombolysis in DVT at other levels of occlusion.

AUTHORS' CONCLUSIONS

Complete clot lysis occurred more frequently after thrombolysis (with or without additional clot removal strategies) and PTS incidence was slightly reduced. Bleeding complications also increased with thrombolysis, but this risk has decreased over time with the use of stricter exclusion criteria of studies. Evidence suggests that systemic administration of thrombolytics and CDT have similar effectiveness. Using GRADE, we judged the evidence to be of moderate-certainty, due to many trials having small numbers of participants or events, or both. Future studies are needed to investigate treatment regimes in terms of agent, dose and adjunctive clot removal methods; prioritising patient-important outcomes, including PTS and quality of life, to aid clinical decision making.

Can we predict and prevent the postthrombotic syndrome?

Postthrombotic syndrome (PTS) remains one of the major late complications of deep vein thrombosis (DVT) with a reported prevalence from 10 to 50%. Many factors were found to be related with the development and severity of PTS such as ipsilateral recurrent DVT, advanced age, obesity, ilio-femoral DVT and primary chronic venous disease presence. Some PTS prediction models have been proposed based on risk factor weight. However, it is still difficult to predict which patient with DVT will develop PTS and thus, the clinical application of these models remains limited. Among the identified problems the heterogeneity of the DVT patient population together with the variety of PTS clinical presentations and difficulties concerning PTS severity assessment should be mentioned. Difficulties on the implementation of the specific and objective PTS identification method have also the significant influence on the research focusing on PTS prevention modalities including risk factor modification, compression treatment, anticoagulation and invasive DVT treatment. In this review, the current approach and knowledge on PTS prediction and prevention are presented, including the conservative and invasive DVT treatment possibilities.

Endovascular mechanical thrombectomy versus thrombolysis in patients with iliofemoral deep vein thrombosis – a systematic review and meta-analysis

Summary: Background: This study sought to compare effectiveness and safety of percutaneous mechanical thrombectomy (PMT) and thrombolysis alone (THR) in patients with acute or subacute iliofemoral deep vein thrombosis (IfDVT). Patients and methods: Observational and randomized trials, published between January 2001 to February 2019 were identified by searching MEDLINE. Studies on deep venous thrombosis (DVT) treated with either THR or PMT adjunctive to conventional anticoagulation and compressive intervention were included. Meta-analysis of proportions was conducted to assess effectiveness outcomes of successful lysis and primary patency, post-thrombotic syndrome (PTS), valvular reflux, recurrent DVT, as well as safety outcomes of major bleeding, hematuria, and pulmonary embolism. Results: Of 77 identified records, 17 studies including 1417 patients were eligible. Pooled proportion of successful lysis was similar between groups (THR: 95 % [I2 = 68.4 %], PMT 96 %, [I2 = 0 %]; Qbet [Cochran’s Q between groups] 0.3, p = 0.61). However, pooled proportion of 6-month primary patency was lower after THR than after PMT (68 % [I2 = 15.6 %] versus 94 %; Qbet 26.4, p < 0.001). Considerable heterogeneity within groups did not allow for between-group comparison of PTS and recurrent DVT. Major bleeding was more frequent after THR than after PMT (6.0 % [I2 = 0 %] versus 1.0 % [I2 = 0 %]; Qbet 12.3, p < 0.001). Incidence of hematuria was lower after THR as compared to PMT (2 % [I2 = 56 %] versus 91.3 % [I2 = 91.7 %]; Qbet 714, p < 0.001). Incidences of valvular reflux and pulmonary embolism were similar across groups (THR: 61 % versus PMT: 53 %; Qbet 0.7, p = 0.39 and THR: 2 % versus PMT: 1 %; Qbet 1.1, p = 0.30, respectively). Conclusions: In patients with iliofemoral DVT, percutaneous mechanical thrombectomy was associated with a higher cumulative 6-month primary patency and a lower incidence of major bleeding compared to thrombolysis alone. Risk of hemolysis from mechanical thrombectomy needs further consideration.

Catheter Interventions for Acute Deep Venous Thrombosis: Who, When and How

Deep venous thrombosis (DVT) is common and can be a source of morbidity by way of pulmonary embolism and post-thrombotic syndrome. Recent trials have demonstrated both early and late symptomatic benefit in venous thrombolysis and early recanalisation of the iliocaval system of selected patients. Based on the emerging evidence, national societies have published guidelines that recommend early thrombus removal in iliofemoral DVT in patients with low bleeding risk and good life expectancy. In light of these recommendations, endovenous thrombolysis and/or thrombectomy have become more popular among vein specialists. As more venous technology becomes available, surgeons and interventionalists should take pause and ensure their patient selection and treatment algorithms parallel that of existing and emerging evidence. This article summarises current evidence, technology, and the approach used at a high-volume academic centre in treating iliofemoral DVT.

Factors associated with the development of post-thrombotic syndrome in patients with iliofemoral deep venous thrombosis who underwent catheter-directed thrombolysis

OBJECTIVE

To identify predictors of post-thrombotic syndrome in patients with iliofemoral deep venous thrombosis who underwent catheter-directed thrombolysis.

METHODS

Fifty-two consecutive patients who underwent catheter-directed thrombolysis were included in this retrospective study. In addition to catheter-directed thrombolysis, aspiration thrombectomy or stent placement was performed if needed. At six months, duplex ultrasound was performed to assess iliofemoral patency and deep venous reflux. Post-thrombotic syndrome was assessed using the clinical, etiologic, anatomic, and pathophysiologic classification (post-thrombotic syndrome present ≥3 on a scale from 0 to 6). Univariate analysis and multivariate logistic regression were used to identify predictors of post-thrombotic syndrome.

RESULTS

Median follow-up was 52 months and post-thrombotic syndrome developed in nine patients (17.3%). In univariate analysis, stent placement (odds ratio 0.16, p = 0.022) was negatively associated with post-thrombotic syndrome, whereas iliofemoral venous obstruction with reflux at six months (OR 6.08, p = 0.037) was positively associated with post-thrombotic syndrome. Multivariate analysis indicated that stent placement was associated with reduced risk of post-thrombotic syndrome (OR 0.17, p = 0.043), and iliofemoral obstruction with reflux was associated with increased risk (OR 6.67, p = 0.046).

CONCLUSION

Stent placement and iliofemoral venous obstruction with reflux, respectively, were important protective and risk factors for post-thrombotic syndrome in patients who underwent catheter-directed thrombolysis.

Interventional Therapies in Acute Pulmonary Embolism

Treatment of acute pulmonary embolism (PE) historically included anticoagulation and systemic thrombolytic therapy. More recently, catheter guided interventions provided promise of mitigating bleeding risks usually associated with systemic thrombolysis in intermediate to high risk PE patients. Catheter based interventions can broadly be divided into catheter directed thrombolysis and catheter based embolectomy. Both modalities are currently undergoing active research and each has their respective risks and benefits. The decision to administer these advanced therapies for acute PE can be challenging but can be accomplished via a multi-disciplinary PE response team.

Endovascular Thrombus Removal for Acute Iliofemoral Deep Vein Thrombosis

BACKGROUND

The ATTRACT trial (Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis) previously reported that pharmacomechanical catheter-directed thrombolysis (PCDT) did not prevent postthrombotic syndrome (PTS) in patients with acute proximal deep vein thrombosis. In the current analysis, we examine the effect of PCDT in ATTRACT patients with iliofemoral deep vein thrombosis.

METHODS

Within a large multicenter randomized trial, 391 patients with acute deep vein thrombosis involving the iliac or common femoral veins were randomized to PCDT with anticoagulation versus anticoagulation alone (No-PCDT) and were followed for 24 months to compare short-term and long-term outcomes.

RESULTS

Between 6 and 24 months, there was no difference in the occurrence of PTS (Villalta scale ≥5 or ulcer: 49% PCDT versus 51% No-PCDT; risk ratio, 0.95; 95% CI, 0.78-1.15; P=0.59). PCDT led to reduced PTS severity as shown by lower mean Villalta and Venous Clinical Severity Scores ( P<0.01 for comparisons at 6, 12, 18, and 24 months), and fewer patients with moderate-or-severe PTS (Villalta scale ≥10 or ulcer: 18% versus 28%; risk ratio, 0.65; 95% CI, 0.45-0.94; P=0.021) or severe PTS (Villalta scale ≥15 or ulcer: 8.7% versus 15%; risk ratio, 0.57; 95% CI, 0.32-1.01; P=0.048; and Venous Clinical Severity Score ≥8: 6.6% versus 14%; risk ratio, 0.46; 95% CI, 0.24-0.87; P=0.013). From baseline, PCDT led to greater reduction in leg pain and swelling ( P<0.01 for comparisons at 10 and 30 days) and greater improvement in venous disease-specific quality of life (Venous Insufficiency Epidemiological and Economic Study Quality of Life unit difference 5.6 through 24 months, P=0.029), but no difference in generic quality of life ( P>0.2 for comparisons of SF-36 mental and physical component summary scores through 24 months). In patients having PCDT versus No-PCDT, major bleeding within 10 days occurred in 1.5% versus 0.5% ( P=0.32), and recurrent venous thromboembolism over 24 months was observed in 13% versus 9.2% ( P=0.21).

CONCLUSIONS

In patients with acute iliofemoral deep vein thrombosis, PCDT did not influence the occurrence of PTS or recurrent venous thromboembolism. However, PCDT significantly reduced early leg symptoms and, over 24 months, reduced PTS severity scores, reduced the proportion of patients who developed moderate-or-severe PTS, and resulted in greater improvement in venous disease-specific quality of life.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier: NCT00790335.

Evaluation of Percutaneous Mechanical Thrombectomy via the AngioJet System Combined with Catheter-Directed Thrombolysis for the Treatment of Symptomatic Lower Extremity Deep Venous Thrombosis

BACKGROUND

Current methods of treating lower extremity deep venous thrombosis (LEDVT), such as catheter-directed thrombolysis (CDT) alone, or percutaneous mechanical thrombectomy (PMT) alone, are accompanied by unacceptably high risks of complications. This preliminary retrospective study evaluated the efficacy of CDT combined with PMT (via the AngioJet system), relative to CDT alone, in treating LEDVT.

METHODS

Forty-two patients (43 limbs) with symptomatic deep venous thrombosis received either CDT alone (n = 12) or PMT combined with CDT (PMT + CDT) from May 2012 to December 2016. The groups were compared for clinical outcomes and demographics, LEDVT risk factors, and dosages of urokinase. Thrombus removal, by venographic evidence, was classified as grades I (<50%), II (50 to 99%), or III (>99%).

RESULTS

In the CDT (PMT + CDT) cohorts, grades I, II, and III thrombus removal was achieved by 8% (3%), 17% (10%), and 75% (87%) of patients, respectively. The urokinase dosage and hospitalization required by the CDT group (5.29 ± 0.45 million IU, 20.4 ± 4.6 days) were significantly greater than those required by the PMT + CDT group (4.08 ± 1.15 million IU, 16.0 ± 6.0 days; P = 0.001, 0.039). The clinical outcomes of the 2 groups were similar.

CONCLUSION

Combined PMT and CDT was effective and safe for LEDVT clinical therapy, and hospital stay, urokinase dosage, and complications were less compared with patients who received CDT only.

Interventional Therapies for Acute Pulmonary Embolism: Current Status and Principles for the Development of Novel Evidence: A Scientific Statement From the American Heart Association

Pulmonary embolism (PE) represents the third leading cause of cardiovascular mortality. The technological landscape for management of acute intermediate- and high-risk PE is rapidly evolving. Two interventional devices using pharmacomechanical means to recanalize the pulmonary arteries have recently been cleared by the US Food and Drug Administration for marketing, and several others are in various stages of development. The purpose of this document is to clarify the current state of endovascular interventional therapy for acute PE and to provide considerations for evidence development for new devices that will define which patients with PE would derive the greatest net benefit from their use in various clinical settings. First, definitions and limitations of commonly used risk stratification tools for PE are reviewed. An adjudication of risks and benefits of available interventional therapies for PE follows. Next, considerations for optimal future evidence development in this field are presented in the context of the current US regulatory framework. Finally, the document concludes with a discussion of the pros and cons of the rapidly expanding PE response team model of care delivery.

Comparison of Ultrasound-Accelerated Versus Multi-Hole Infusion Catheter-Directed Thrombolysis for the Treatment of Acute Limb Ischemia

Objective:

Thrombolytic therapy is widely used in the treatment of arterial occlusions causing acute limb ischemia (ALI); however, knowledge regarding the efficacy of the different catheter systems available is scarce. The objective of this study was to compare the safety and efficacy of 2 catheter-directed infusion systems for intra-arterial thrombolysis in the setting of ALI.

Methods:

A retrospective analysis was conducted to study all catheter-directed thrombolysis procedures performed over 32 months in patients diagnosed with ALI. Patients with thrombosis in both native arteries and bypass grafts were included. Patients with contraindications to thrombolysis, or those receiving thrombolysis for deep venous thrombosis, were excluded. The duration of thrombolysis, amount of thrombolytic agent, and technical success rate were recorded. Technical success was defined as complete or near-complete resolution of thrombus burden, allowing for further intervention. Data were stratified to include location of thrombus, procedural complications, mortality, and rates of limb loss.

Results:

Ninety-one patients met inclusion criteria. Among them, Uni-Fuse and EKOS catheters were used in 69 and 22 patients, respectively. The mean age of the population was 71 (standard deviation [SD]: ±1.5) for patients treated with the EKOS catheter and 70 years (SD: ±2.6) for patients receiving thrombolysis with Uni-Fuse. There was no significant difference in the mean infusion duration (1.65 vs 1.9 days), volume of tissue plasminogen activator (44.6 vs 48.2 mg), or technical success rate (72% vs 86%) between the Uni-Fuse and EKOS cohorts ( P > .3). Furthermore, there was no difference in major limb loss or compartment syndrome between each group ( P > .4). The overall complication rate was 14% in both groups, with a 30-day mortality rate of 4% when treated with either catheter system.

Conclusion:

This study suggests that a standard multi-hole infusion catheter demonstrates similar clinical safety and efficacy as the ultrasound-accelerated EKOS system in the treatment of ALI.

Cessation of anticoagulation therapy following endovascular thrombus removal and stent placement for acute iliofemoral deep vein thrombosis

Summary. Background: The optimal duration of anticoagulation therapy (AT) following catheter-based therapy of acute iliofemoral deep vein thrombosis (IFDVT) with stent placement is unknown. Theoretically, resolving the underlying obstructive iliac vein lesion by a stent may eliminate the main trigger for recurrence, the post-thrombotic syndrome (PTS), and the need for extended-duration AT. Patients and methods: From 113 patients with acute IFDVT who underwent endovascular thrombus removal and stent placement, we compared patency rates and clinical outcomes between 58 patients on limited-duration AT (3–12 month) and 55 patients on extended-duration AT (> 12 months). Results: Mean follow-up duration was 26 ± 18 (range 3–77) months; it was 24 ± 18 (range 3–69) months after cessation of AT in the limited-duration AT group. In comparison to patients with extended-duration AT, patients with limited-duration AT were younger (38 versus 54 years; p < 0.001), more often female (74 % versus 49 %; p = 0.01), and had less often prior venous thromboembolism (VTE) (9 % versus 35 %; p = 0.001). May-Thurner syndrome was more frequent in the limited-duration AT group (66 % versus 38 %; p = 0.004). Overall, primary and secondary patency rates at 24 months were 80 % (95 % CI, 70–87 %) and 95 % (95 % CI, 88–98 %), respectively, with no difference between the groups. Overall, 17 (15 %) patients developed recurrent VTE, of which 14 (82 %) events were thrombotic stent occlusions, and 13 (76 %) events occurred during AT. In the limited-duration AT group, 98 % patients were free from the PTS at two years with a VTE recurrence rate of 3.5 per 100 patient years after cessation of AT. Conclusions: In selected patients with acute IFDVT and patent venous stent, particularly in younger and otherwise healthy patients with May-Thurner syndrome, it appears to be safe to discontinue AT 3–12 months after endovascular treatment. Clinical Trial Registration: The study is registered on the National Institutes of Health website (ClinicalTrials.gov; identifier NCT02433054).

Rivaroxaban or vitamin-K antagonists following early endovascular thrombus removal and stent placement for acute iliofemoral deep vein thrombosis

BACKGROUND

The optimal anticoagulant following catheter-based therapy of acute iliofemoral deep vein thrombosis (IFDVT) is unknown.

METHODS

From the Swiss Venous Stent registry, an ongoing prospective cohort study, we performed a subgroup analysis of patients with acute IFDVT who underwent catheter-based early thrombus removal followed by nitinol stent placement. Duplex ultrasound and Villalta scores were used to determine patency rates and incidence of the post-thrombotic syndrome (PTS) in patients treated with either rivaroxaban (n = 73) or a vitamin K-antagonist (VKA; n = 38) for a minimum duration of 3 months.

RESULTS

Mean follow-up duration was 24 ± 19 months (range 3 to 77 months). Anticoagulation therapy was time-limited (3 to 12 months) in 56% of patients (47% in the rivaroxaban group and 58% in the VKA group, p = 0.26), with shorter mean duration of anticoagulation in the rivaroxaban group (180 ± 98 days versus 284 ± 199 days, p = 0.01). Overall, primary and secondary patency rates at 24 months were 82% (95%CI, 71-89%) and 95% (95%CI, 87-98%), respectively, with no difference between the rivaroxaban (87% [95%CI, 76-94%] and 95% [95%CI, 85-98%]) and the VKA group (72% [95%CI, 52-86%] and 94% [95%CI, 78-99%]; p > 0.10 for both). Overall, 86 (86%) patients were free from PTS at latest follow-up, with no difference between the rivaroxaban and the VKA groups (57 [85%] versus 29 [88%]; p = 0.76). Two major bleeding complications (1 in each group) occurred in the peri-interventional period, without any major bleeding thereafter.

CONCLUSIONS

In patients with acute IFDVT treated with catheter-based early thrombus removal and venous stent placement, the effectiveness and safety of rivaroxaban and VKA appear to be similar.

CLINICAL TRIAL REGISTRATION

The study is registered on the National Institutes of Health website (ClinicalTrials.gov; identifier NCT02433054).

Is there a role for intervention radiology for the treatment of lower limb deep vein thrombosis in the era of direct oral anticoagulants? A comprehensive review

Despite recent advances in the treatment of Deep Vein Thrombosis (DVT) provided by Direct Oral Anticoagulants (DOAC), a substantial proportion of lower limb DVT patients will develop some degree of post-thrombotic syndrome (PTS) within 2 years. Systemic thrombolysis, although effective in reducing the risk of PTS and leg ulceration, is associated with a high risk of major bleeding, making it unsuitable for the vast majority of patients. A local approach, aimed at delivering the fibrinolytic drug directly into, or near to, the thrombus surface, is attractive because of the possibility of lowering of the administered drug dose, thus reducing the bleeding risks. However, even after the recent publication of the ATTRACT trial, only weak evidence is available about the efficacy and safety of Catheter Directed Thrombolysis (CDT), either alone (pharmacological technique) or in combination with additional endovascular approaches (pharmacomechanical technique, PMT) including percutaneous mechanical thrombectomy, angioplasty with or without stenting and ultrasound-assisted CDT. The present review is aimed at providing the physicians with a comprehensive evaluation of the current evidence about this relevant topic, in order to build a reliable conceptual framework for a more appropriate use of this resource.

Thrombectomy and thrombolysis for the prevention and treatment of postthrombotic syndrome

Postthrombotic syndrome (PTS) is a frequent complication of lower-extremity deep vein thrombosis (DVT), occurring in approximately 40% of patients despite the use of anticoagulant therapy. PTS causes significant impairment of patients' health-related quality of life, and no evidence-based therapies have been consistently effective. Catheter-directed thrombolysis and thrombectomy have been shown to remove acute thrombus, and it has been hypothesized they could prevent or reduce PTS. However, because these procedures can be associated with complications, mainly bleeding, randomized trial data are needed to determine when they should be used. In this article, I summarize the current status of thrombus removal procedures for DVT to provide contemporary guidance to clinicians seeking to individualize treatment decisions for their patients.

Can thrombus age guide thrombolytic therapy?

Venous thrombosis (VT) is a common yet complex clinical condition that has shown minimal alteration in clinical management for decades. It is well known that thrombus evolves structurally over time, with complex changes resulting from the interplay between coagulation factors, cytokines, leukocytes and a myriad of other factors. Our current treatment options are most effective in the acute thrombus, which is composed predominantly of a loose mesh of fibrin and red blood cells (RBCs), making current anticoagulation therapies and thrombolytics quite effective in treatment. Later stages of thrombus are more cellular containing leukocytes, and develop a fibrotic collagenous framework that is more resistant to our current treatments. Understanding the biology of an evolving thrombus will allow us to tailor our treatment and optimize outcomes, as well as focus on novel therapies for the treatment of chronic thrombus. Given the morbidity and mortality of both post thrombotic syndrome (PTS) in patients with deep VT, as well as chronic thromboembolic pulmonary hypertension (CTEPH) in patients with pulmonary embolism (PE), new and innovative therapies must continue to be explored to help prevent these potentially devastating conditions.

Catheter-directed thrombolysis to avoid late consequences of acute deep vein thrombosis

The application of catheter-based methods to treat acute deep vein thrombosis (DVT) has increased in recent years. Catheter-directed thrombolysis (CDT), introduced during the early 1990s, has shown the ability to rapidly eliminate thrombus and is used in many centers as a salvage therapy for DVT patients who exhibit a poor initial response to anticoagulant therapy. However, CDT has disadvantages in terms of safety and resource use. Although CDT methods have evolved substantially to try to address these issues, for most of the last 25years there was little high-quality data on CDT outcomes upon which to base patient care decisions. The paucity of evidence was particularly problematic for long-term outcomes such as recurrent venous thromboembolism (VTE) and the post-thrombotic syndrome (PTS). Fortunately, rigorous studies of CDT are now being completed. Accordingly, the purpose of this article is to: 1) state the known and unknown factors influencing risk and benefit with use of CDT and related methods to treat acute DVT; 2) summarize emerging evidence showing the patient outcomes that occur when CDT is used for first-line management of DVT; and 3) suggest clinical parameters for CDT utilization in light of the available evidence.