Randomized controlled trial of tissue plasminogen activator in proximal deep venous thrombosis

Citrullinated fibrinogen forms densely packed clots with decreased permeability

BACKGROUND

Fibrin, the main scaffold of thrombi, is susceptible to citrullination by PAD (peptidyl arginine deiminase) 4, secreted from neutrophils during the formation of neutrophil extracellular traps. Citrullinated fibrinogen (citFg) has been detected in human plasma as well as in murine venous thrombi, and it decreases the lysability and mechanical resistance of fibrin clots.

OBJECTIVE

To investigate the effect of fibrinogen citrullination on the structure of fibrin clots.

METHODS

Fibrinogen was citrullinated with PAD4 and clotted with thrombin. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to measure fiber thickness, fiber height/width ratio, and fiber persistence length in clots containing citFg. Fiber density was measured with laser scanning microscopy (LSM) and permeability measurements were carried out to estimate the porosity of the clots. The intra-fiber structure of fibrin was analyzed with small-angle X-ray scattering (SAXS).

RESULTS

SEM images revealed a decrease in the median fiber diameter that correlated with the fraction of citFg in the clot, while the fiber width/length ratio remained unchanged according to AFM. With SAXS we observed that citrullination resulted in the formation of denser clots in line with increased fiber density shown by LSM. The permeability constant of citrullinated fibrin decreased more than 3-fold indicating significantly decreased porosity. SAXS also showed largely preserved periodicity in the longitudinal assembly of fibrin monomers.

CONCLUSION

The current observations of thin fibers combined with dense packing and low porosity in the presence of citFg can provide a structural framework for the mechanical fragility and lytic resistance of citrullinated fibrin.

Breaking the fibrinolytic speed limit with microwheel co-delivery of tissue plasminogen activator and plasminogen

BACKGROUND

To reestablish blood flow in vessels occluded by clots, tissue plasminogen activator (tPA) can be used; however, its efficacy is limited by transport to and into a clot and by the depletion of its substrate, plasminogen.

OBJECTIVES

To overcome these rate limitations, a platform was designed to co-deliver tPA and plasminogen based on microwheels (µwheels), wheel-like assemblies of superparamagnetic colloidal beads that roll along surfaces at high speeds.

METHODS

The biochemical speed limit was determined by measuring fibrinolysis of plasma clots at varying concentrations of tPA (10-800 nM) and plasminogen (1-6 µM). Biotinylated magnetic mesoporous silica nanoparticles were synthesized and bound to streptavidin-coated superparamagnetic beads to make studded beads. Studded beads were loaded with plasminogen and tPA was immobilized on their surface. Plasminogen release and tPA activity were measured on the studded beads. Studded beads were assembled into µwheels with rotating magnetic fields and fibrinolysis of plasma clots was measured in a microfluidic device.

RESULTS

The biochemical speed limit for plasma clots was ~15 µm/min. Plasminogen-loaded, tPA-immobilized µwheels lyse plasma clots at rates comparableto the biochemical speed limit. With the addition of a corkscrew motion, µwheels penetrate clots, thereby exceeding the biochemical speed limit (~20 µm/min) and achieving lysis rates 40-fold higher than 50 nM tPA.

CONCLUSIONS

Co-delivery of an immobilized enzyme and its substrate via a microbot capable of mechanical work has the potential to target and rapidly lyse clots that are inaccessible by mechanical thrombectomy devices or recalcitrant to systemic tPA delivery.

Shape anisotropic magnetic thrombolytic actuators: synthesis and systematic behavior study

Thrombosis-related diseases are undoubtedly the deadliest disorders. During the last decades, numerous attempts were made to reduce the overall death rate and severe complications caused by treatment delays. Significant progress has been made in the development of nanostructured thrombolytics, especially magnetically controlled. The emergence of thrombolytic magnetic actuators, which can deliver tPA to the occlusion zone and perform mechanical disruption of the fibrin network under the application of a rotating magnetic field (RMF), can be considered for the next generation of thrombolytic drugs. Thus, we propose a systematic study of magnetic-field mediated mechanically-assisted thrombolysis (MFMMAT) for the first time. Four types of magnetic particles with different morphology and dimensionality were utilized to assess their impact on model clot lysis under different RMF parameters. Chain-like 1D and sea urchins-like 3D structures were found to be the most effective, increasing thrombolysis efficacy to nearly 200%. The drastic difference was also observed during the dissolution of 3 days old blood clots. Pure plasminogen activator had almost no effect on clot structure during 30 minutes of treatment while applying MFMMAT led to the significant decrease of clot area, thus uncovering the possibility of deep venous thrombosis therapy.

Thrombolytics for venous thromboembolic events: a systematic review with meta-analysis

Thrombolytic therapy might reduce venous thromboembolism-related mortality and morbidity, but it could also increase the risk of major bleeding. We systematically reviewed the literature to evaluate the effectiveness and safety of thrombolytics in patients with pulmonary embolism (PE) and/or deep venous thrombosis (DVT). We searched Medline, Embase, and Cochrane databases for relevant randomized controlled trials up to February 2019. Multiple investigators independently screened and collected data. We included 45 studies (4740 participants). Pooled estimates of PE studies indicate probable reduction in mortality with thrombolysis (risk ratio [RR], 0.61; 95% confidence interval [CI], 0.40-0.94) (moderate certainty) and possible reduction in nonfatal PE recurrence (RR, 0.56; 95% CI, 0.35-0.89) (low certainty). Pooled estimates of DVT studies indicate the possible absence of effects on mortality (RR, 0.77; 95% CI, 0.26-2.28) (low certainty) and recurrent DVT (RR, 0.99; 95% CI, 0.56-1.76) (low certainty), but possible reduction in postthrombotic syndrome (PTS) with thrombolytics (RR, 0.70; 95% CI, 0.59-0.83) (low certainty). Pooled estimates of the complete body of evidence indicate increases in major bleeding (RR, 1.89; 95% CI, 1.46-2.46) (high certainty) and a probable increase in intracranial bleeding (RR, 3.17; 95% CI 1.19-8.41) (moderate certainty) with thrombolytics. Our findings indicate that thrombolytics probably reduce mortality in patients with submassive- or intermediate-risk PE and may reduce PTS in patients with proximal DVT at the expense of a significant increase in major bleeding. Because the balance between benefits and harms is profoundly influenced by the baseline risks of critical outcomes, stakeholders involved in decision making would need to weigh these effects to define which clinical scenarios merit the use of thrombolytics.

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.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Prevention and Management of the Post-Thrombotic Syndrome

The post-thrombotic syndrome (PTS) is a form of chronic venous insufficiency secondary to prior deep vein thrombosis (DVT). It affects up to 50% of patients after proximal DVT. There is no effective treatment of established PTS and its management lies in its prevention after DVT. Optimal anticoagulation is key for PTS prevention. Among anticoagulants, low-molecular-weight heparins have anti-inflammatory properties, and have a particularly attractive profile. Elastic compression stockings (ECS) may be helpful for treating acute DVT symptoms but their benefits for PTS prevention are debated. Catheter-directed techniques reduce acute DVT symptoms and might reduce the risk of moderate-severe PTS in the long term in patients with ilio-femoral DVT at low risk of bleeding. Statins may decrease the risk of PTS, but current evidence is lacking. Treatment of PTS is based on the use of ECS and lifestyle measures such as leg elevation, weight loss and exercise. Venoactive medications may be helpful and research is ongoing. Interventional techniques to treat PTS should be reserved for highly selected patients with chronic iliac obstruction or greater saphenous vein reflux, but have not yet been assessed by robust clinical trials.

Acute Thrombolysis-Resistant Occlusive Left Femoral and Iliac Venous Thrombosis Treated with Mechanical Thrombectomy via the ClotTriever Device

BACKGROUND

Deep vein thrombosis (DVT) is frequently treated by anticoagulation, which helps to prevent new thrombus formation, but to restore venous flow, additional efforts might be needed. Thrombolytic agents can help clear acute thrombus, but increased bleeding risk is a concern; frequent contraindications are another. One lesser discussed potential limitation is thrombus age, which can affect efficiency of treatment.

CASE

A 62-year-old female patient with extensive DVT affecting the inferior vena cava (IVC) through the left femoral vein was initially treated with EKOS catheter directed thrombolysis (CDT) for 24 hr. Subsequent venogram revealed persistent, occlusive femoral and iliac thrombus. We decided on mechanical thrombectomy via the ClotTriever catheter (Inari Medical, Irvine, California), a nitinol coring element with an attached collection bag that can remove wall-adherent thrombus. We performed three passes with the device and removed large amounts of organized thrombus. Subsequent venography showed complete resolution of the occlusion. Finally, an underlying compression was treated via stenting.

CONCLUSIONS

ClotTriever was effective in removing subacute and chronic thrombus, as demonstrated in this case with persistent extensive thrombus after 24 h of CDT. The ClotTriever System adds a valuable option for vascular interventionalists to treat DVT.

Analysis of recanalization of deep venous thrombosis: a comparative study of patients treated with warfarin vs. rivaroxaban

BACKGROUND

Deep venous thrombosis (DVT) strikes around ten million people worldwide every year and is associated with major complications including pulmonary embolism and post-thrombotic syndrome. Anticoagulation is the standard treatment, with administration of heparins, vitamin K antagonists, fondaparinux, or, more recently, direct oral anticoagulants (DOACs). Anticoagulants reduce thrombus progression and facilitate natural thrombolytic mechanisms, leading to a phenomenon known as recanalization, which can occur in varying degrees and over variable periods of time, under influence from many different factors, including the type of anticoagulation employed.

OBJECTIVES

To evaluate the degree of recanalization and the time taken, by analysis of color Doppler ultrasonography (CDU) reports from patients with DVT treated with DOACs or with heparin + warfarin.

METHODS

A retrospective analysis was conducted of demographic data and CDU reports from patients with DVT who had been treated from January 2009 to December 2016. These patients were classified into two groups, according to the treatment given: Group I (heparin + warfarin): 26 patients; or Group II (rivaroxaban): 51 patients. The primary outcomes assessed were degree of recanalization and time taken.

RESULTS

Recanalization rates at 30, 90, and 180 days were 10%, 52.5%, and 78.9%, respectively, in Group I, and 55.3%, 83.5%, and 92.4%, respectively, in Group II, with statistically significant difference (p = 0.041).

CONCLUSIONS

Both treatments led to recanalization. Recanalization occurred earlier among patients treated with rivaroxaban.

Clinical outcomes after direct and indirect surgical venous thrombectomy for inferior vena cava thrombosis

OBJECTIVE

Inferior vena cava thrombosis is rare, but patients are at high risk for development of a post-thrombotic syndrome (PTS) in the long term. Surgical approaches include indirect transfemoral venous thrombectomy (iTFVT) and direct open venous thrombectomy (dOVT). This study reports patient outcomes after iTFVT and dOVT for inferior vena cava thrombosis covering a 25-year follow-up period.

METHODS

The study period was from January 1, 1982, to December 31, 2013. Data were retrieved from archived medical records, and patients were invited for a detailed phlebologic follow-up examination (DPFE). Health-related quality of life was assessed with the 36-Item Short Form Health Survey questionnaire. Patient survival, patency rates, and freedom from PTS were calculated using Kaplan-Meier estimation with log-rank testing. The χ² test with Yates continuity correction and logistic regression analysis were applied to identify associations between risk factors or coagulation disorders, mortality, and PTS.

RESULTS

Complete medical records were available for 152 patients. Patients' 5-year survival was 91% ± 3%, and 5-year primary and secondary patency rates were 80% ± 3% and 94% ± 2%. Freedom from PTS after 25 years was 84% ± 6%. No differences for patient survival, patency rates, or freedom from PTS were identified between iTFVT, dOVT, and a combination of both procedures. Antithrombin III deficiency was the most common coagulation disorder, and patients' physical function and social function were impaired compared with those found in German normative data (P < .05). No risk factor or coagulation disorder was associated with survival or PTS.

CONCLUSIONS

Open surgical venous thrombectomy is safe and delivers satisfying short- and long-term outcomes compared with endovascular approaches. It remains valuable for patients who are not eligible for other interventional therapies.

A systematic review of paediatric deep venous thrombolysis

Objectives

The aim was to assess the effectiveness and safety of catheter-directed thrombolysis in children with deep venous thrombosis and to evaluate its long-term effect.

Method and results

EMBASE, Medline and Cochrane databases were searched to identify studies in which paediatric acute deep venous thrombosis patients received thrombolysis. Following title and abstract screening, seven cohort studies with a total of 183 patients were identified. Technical success was 82% and superior in regional rather than systemic thrombolysis (p < 0.00001). One cohort study identified significant difference in thrombus resolution at one year between thrombolytic and anticoagulant groups (p = 0.01). The complication rate was low, with incidence rates of major bleeding, pulmonary embolism and others at 2.8%, 1.8% and 8.4%, respectively. The overall post-thrombotic syndrome rate was 12.7%. The incidence of re-thrombosis ranged from 12.3% to 27%.

Conclusion

Thrombolysis for paediatric deep venous thrombosis is an effective and relatively safe therapeutic option, lowering the incidence of post-thrombotic syndrome and deep venous thrombosis recurrence.

Catheter-directed thrombolysis of deep vein thrombosis: literature review and practice considerations

Deep vein thrombosis (DVT) is a major health problem worldwide. The risk of pulmonary embolism following DVT is well established, but the long-term vascular sequelae of DVT are often underappreciated, costly to manage, and can have extremely detrimental effects on quality of life. Treatment of DVT classically involves oral anticoagulation, which reduces the risk of pulmonary embolism but does not remove the clot. Anticoagulation therefore does little to prevent the venous damage and scarring that occurs following DVT, leaving the patient at risk for permanent venous insufficiency and development of post-thrombotic syndrome (PTS). Catheter-directed thrombolysis (CDT) is a minimally invasive endovascular treatment that is used as an adjunct to anticoagulation. CDT lowers the risk of PTS by reducing clot burden and protecting against valvular damage. A catheter is advanced directly to the site of thrombosis under fluoroscopy followed by a slow, prolonged infusion of a relatively low dose of thrombolytic agent. CDT restores venous patency faster than anticoagulation, which hastens the relief of acute symptoms. Adjunctive CDT modalities have become increasingly popular among interventional radiologists, allowing for additional mechanical thrombectomy or ultrasound-enhanced thrombolysis at the time of catheter placement. These pharmacomechanical CDT (PCDT) techniques have the potential to reduce treatment time and associated healthcare costs. Numerous observational and retrospective studies have consistently shown a benefit of CDT plus anticoagulation over anticoagulation alone for prevention of PTS. Patients with long life expectancy and acute thrombosis involving the iliac and proximal femoral veins (iliofemoral DVT) have the greatest benefit from CDT, which may decrease the risk of PTS and/or decrease the severity of PTS symptoms if they do occur. Randomized controlled trials remain limited but generally support the observational data. CDT also plays an important role in those with acute limb-threatening venous occlusion or severe symptoms from DVT. Although adverse outcomes are rare, a potential devastating outcome is intracranial bleeding. While the available literature suggests the risk of serious morbidity from bleeding is quite rare, the absolute risk of bleeding is not clear and will require outcomes data from randomized trials. Future studies should also examine the cost-effectiveness of CDT for PTS prevention, particularly with respect to quality-adjusted life years, and compare the effectiveness of available PCDT devices.

Evaluation of thrombolysis using tissue plasminogen activator in lower extremity deep venous thrombosis with concomitant femoral-popliteal venous segment involvement

OBJECTIVE

Current guidelines recommend thrombolytic therapy for iliofemoral deep venous thrombosis (DVT). Anticoagulation is the standard treatment for femoral-popliteal and tibial-level DVT. The objective of this study was to evaluate the efficacy of catheter-directed thrombolysis (CDT) using tissue plasminogen activator vs standard anticoagulation alone in patients with lower extremity DVT involving the femoral-popliteal segment.

METHODS

A retrospective review was performed of patients referred to the vascular surgery service with lower extremity DVT from 2006 to 2015. Patients who had DVT involving the femoral-popliteal segment were identified, including some patients who had concomitant involvement of iliofemoral and tibial veins. Patients with pure iliofemoral and tibial vein DVT were excluded from this analysis. Review of medical records, follow-up ultrasound studies, hypercoagulable panel, and venography were performed. Comparison of outcomes between patients who received thrombolytic therapy using tissue plasminogen activator and patients who received standard anticoagulation alone was performed. The primary outcomes measured were restoration of patency of the femoral-popliteal segment at 3 months, incidence of post-thrombotic syndrome (PTS), and valvular dysfunction. Secondary outcomes were incidence of bleeding, in-hospital mortality, and pulmonary embolism.

RESULTS

The study cohort was composed of 191 patients (CDT, n = 89; anticoagulation alone, n = 102) who met inclusion criteria. Most patients with thrombus involving the femoral-popliteal segment also had proximal venous segment involvement, with 93% of the patient cohort having proximal iliofemoral DVT. Patients who did not receive CDT were older (mean age of 64 years vs 51 years; P < .001) and had more associated comorbidities, such as diabetes, immobility, and cancer. A significant number of patients who received CDT had a positive family history for DVT (21.3% vs 8.8%; P = .023), and it was more likely to be their first episode of DVT (73.0% vs 55.9%; P = .016). Patients who received CDT were more likely to have restoration of patency (74.7% vs 11.1%; P < .001) and lower incidence of PTS (21.3% vs 73.4%; P < .001) and valvular dysfunction (23.0% vs 66.7%; P < .001) compared with patients who were treated with anticoagulation alone. Incidence of bleeding was significantly more for patients treated with anticoagulation alone (14.7% vs 5.6%; P = .018) compared with patients who received CDT. On multivariate analysis, age was the predominant risk factor for bleeding. There was no significant difference in mortality and pulmonary embolism.

CONCLUSIONS

In patients with acute proximal DVT and concomitant femoral-popliteal venous segment involvement, CDT resulted in superior patency at 3 months and less PTS and valvular reflux. This was achieved without increase in bleeding complications compared with anticoagulation alone. Age was the major factor predictive of bleeding in either group. The results of this study may not be applicable to patients with pure femoral-popliteal venous segment DVT because only 3% of patients had this finding.

Thrombolysis for acute deep vein thrombosis

BACKGROUND

Standard treatment for deep vein thrombosis aims to reduce immediate complications. Use of thrombolysis or clot dissolving drugs 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 third update of a review first published in 2004.

OBJECTIVES

To assess the effects of thrombolytic therapy and anticoagulation compared to anticoagulation alone for the management of people with acute deep vein thrombosis (DVT) of the lower limb as determined by the effects on pulmonary embolism, recurrent venous thromboembolism, major bleeding, post-thrombotic complications, venous patency and venous function.

SEARCH METHODS

For this update the Cochrane Vascular Information Specialist (CIS) searched the Specialised Register (February 2016). In addition the CIS searched the Cochrane Register of Studies (CENTRAL (2016, Issue 1)). Trial registries were searched for details of ongoing or unpublished studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) examining thrombolysis and anticoagulation versus anticoagulation for acute DVT were considered.

DATA COLLECTION AND ANALYSIS

For this update (2016), LW and CB selected trials, extracted data independently, and sought advice from MPA where necessary. We assessed study quality with the Cochrane risk of bias tool. For dichotomous outcomes, we calculated the risk ratio (RR) and corresponding 95% confidence interval (CI). Data were pooled using a fixed-effect model unless significant heterogeneity was identified in which case a random-effects model was used. GRADE was used to assess the overall quality of the evidence supporting the outcomes assessed in this review.

MAIN RESULTS

Seventeen RCTs with 1103 participants were included. These studies differed in the both thrombolytic agent used and in the technique used to deliver it. Systemic, loco-regional and catheter-directed thrombolysis (CDT) were all included. Fourteen studies were rated as low risk of bias and three studies were rated as high risk of bias. We combined the results as any (all) thrombolysis compared to standard anticoagulation. Complete clot lysis occurred significantly more often in the treatment group at early follow-up (RR 4.91; 95% CI 1.66 to 14.53, P = 0.004) and at intermediate follow-up (RR 2.44; 95% CI 1.40 to 4.27, P = 0.002; moderate quality evidence). A similar effect was seen for any degree of improvement in venous patency. Up to five years after treatment significantly less PTS occurred in those receiving thrombolysis (RR 0.66, 95% CI 0.53 to 0.81; P < 0.0001; moderate quality evidence). This reduction in PTS was still observed at late follow-up (beyond five years), in two studies (RR 0.58, 95% CI 0.45 to 0.77; P < 0.0001; moderate quality evidence). Leg ulceration was reduced although the data were limited by small numbers (RR 0.87; 95% CI 0.16 to 4.73, P = 0.87). Those receiving thrombolysis had increased bleeding complications (RR 2.23; 95% CI 1.41 to 3.52, P = 0.0006; moderate quality evidence). Three strokes occurred in the treatment group, all in trials conducted pre-1990, and none in the control group. There was no significant effect on mortality detected at either early or intermediate follow-up. Data on the occurrence of pulmonary embolism (PE) and recurrent DVT were inconclusive. Systemic thrombolysis and CDT had similar levels of effectiveness. Studies of CDT included two 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

Thrombolysis increases the patency of veins and reduces the incidence of PTS following proximal DVT by a third. Evidence suggests that systemic administration and CDT have similar effectiveness. Strict eligibility criteria appears to improve safety in recent studies and may be necessary to reduce the risk of bleeding complications. This may limit the applicability of this treatment. In those who are treated there is a small increased risk of bleeding. Using GRADE assessment, the evidence was judged to be of moderate quality due to many trials having low numbers of participants. However, the results across studies were consistent and we have reasonable confidence in these results.

Diagnosis and Treatment of Lower Extremity Deep Vein Thrombosis: Korean Practice Guidelines

Lower extremity deep vein thrombosis is a serious medical condition that can result in death or major disability due to pulmonary embolism or post-thrombotic syndrome. Appropriate diagnosis and treatment are required to improve symptoms and salvage the affected limb. Early thrombus clearance rapidly resolves symptoms related to venous obstruction, restores valve function and reduces the incidence of post-thrombotic syndrome. Recently, endovascular treatment has been established as a standard method for early thrombus removal. However, there are a variety of views regarding the indications and procedures among medical institutions and operators. Therefore, we intend to provide evidence-based guidelines for diagnosis and treatment of lower extremity deep vein thrombosis by multidisciplinary consensus. These guidelines are the result of a close collaboration between interventional radiologists and vascular surgeons. The goals of these guidelines are to improve treatment, to serve as a guide to the clinician, and consequently to contribute to public health care.

Multimodal Therapy for Acute and Chronic Venous Thrombotic and Occlusive Disease

Critical deep venous thrombosis and occlusion constitutes a small percentage of patients with venous disease. However, these patients exhibit severe symptomatology including pain and extensive edema that may progress to limb-or life-threatening complications such as phlegmasia cerulea dolens and superior vena cava syndrome. This paper reviews the different multimodal percutaneous interventions currently available for the treatment of complex critical venous thrombotic and occlusive disease.

Histotripsy Thrombolysis on Retracted Clots

Retracted blood clots have been previously recognized to be more resistant to drug-based thrombolysis methods, even with ultrasound and microbubble enhancements. Microtripsy, a new histotripsy approach, has been investigated as a non-invasive, drug-free and image-guided method that uses ultrasound to break up clots with improved treatment accuracy and a lower risk of vessel damage compared with the traditional histotripsy thrombolysis approach. Unlike drug-mediated thrombolysis, which is dependent on the permeation of the thrombolytic agents into the clot, microtripsy controls acoustic cavitation to fractionate clots. We hypothesize that microtripsy thrombolysis is effective on retracted clots and that the treatment efficacy can be enhanced using strategies incorporating electronic focal steering. To test our hypothesis, retracted clots were prepared in vitro and the mechanical properties were quantitatively characterized. Microtripsy thrombolysis was applied on the retracted clots in an in vitro flow model using three different strategies: single-focus, electronically-steered multi-focus and dual-pass multi-focus. Results show that microtripsy was used to successfully generate a flow channel through the retracted clot and the flow was restored. The multi-focus and the dual-pass treatments incorporating the electronic focal steering significantly increased the recanalized flow channel size compared to the single-focus treatments. The dual-pass treatments achieved a restored flow rate up to 324 mL/min without cavitation contacting the vessel wall. The clot debris particles generated from microtripsy thrombolysis remained within the safe range. The results of this study show the potential of microtripsy thrombolysis for retracted clot recanalization with the enhancement of electronic focal steering.

Endovascular Interventions for Acute and Chronic Lower Extremity Deep Venous Disease: State of the Art

The societal and individual burden caused by acute and chronic lower extremity venous disease is considerable. In the past several decades, minimally invasive endovascular interventions have been developed to reduce thrombus burden in the setting of acute deep venous thrombosis to prevent both short- and long-term morbidity and to recanalize chronically occluded or stenosed postthrombotic or nonthrombotic veins in symptomatic patients. This state-of-the-art review provides an overview of the techniques and challenges, rationale, patient selection criteria, complications, postinterventional care, and outcomes data for endovascular intervention in the setting of acute and chronic lower extremity deep venous disease. Online supplemental material is available for this article.

Remarkable regression of massive deep vein thrombosis in response to intensive oral rivaroxaban treatment

Deep vein thrombosis (DVT) is a common disease and is associated with pulmonary embolism (PE). Proximal iliofemoral DVT may lead to severe PE and chronic venous insufficiency. The standard therapy for DVT is anticoagulant therapy using heparin and a vitamin K antagonist, but a recent clinical study showed that rivaroxaban, an oral Xa inhibitor, was comparable to standard therapy and had less bleeding complications. Intensive high-dose anticoagulation is recommended during the initial 3 weeks of DVT treatment. The present report describes a case of a 77-year-old male showing a remarkable regression of DVT in response to rivaroxaban treatment within the initial 3 weeks of therapy and who did not experience any adverse events. His DVT was massive and was accompanied by proximal iliofemoral vein thrombus and iliac vein compression syndrome. Rivaroxaban, especially in intensive high-dose treatment, might be a safe and effective therapeutic choice for massive DVT.

Thrombolysis for acute deep vein thrombosis

BACKGROUND

Standard treatment for deep vein thrombosis aims to reduce immediate complications. Use of thrombolysis or clot dissolving drugs could reduce the long-term complications of post-thrombotic syndrome (PTS) (pain, swelling, skin discolouration, or venous ulceration) in the affected leg. This is the second update of a review first published in 2004.

OBJECTIVES

To assess the effects of thrombolytic therapy and anticoagulation versus anticoagulation in the management of people with acute deep vein thrombosis (DVT) of the lower limb as determined by the effects on pulmonary embolism, recurrent venous thromboembolism, major bleeding, post-thrombotic complications, venous patency and venous function.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched April 2013) and CENTRAL (2013, Issue 4).

SELECTION CRITERIA

Randomised controlled trials (RCTs) examining thrombolysis and anticoagulation versus anticoagulation for acute DVT were considered.

DATA COLLECTION AND ANALYSIS

In the previous review of 2010, one review author (LW) selected trials, extracted data and assessed study quality, with checking at all stages by the other review author (MPA). If necessary, we sought additional information from trialists. For this update (2013), LW and CB selected trials, extracted data independently, and sought advice from MPA where necessary. All studies, existing and new, required full risk of bias assessment in line with current Cochrane procedures. Two of LW, CB and MA independently assessed risk of bias with discussion with the third author where necessary.

MAIN RESULTS

Seventeen studies with 1103 participants were included. Complete clot lysis occurred significantly more often in the treatment group in early follow up (risk ratio (RR) 4.91; 95% confidence interval (CI) 1.66 to 14.53, P = 0.004) and at intermediate follow up (RR 2.37; 95% CI 1.48 to 3.80, P = 0.0004). A similar effect was seen for any degree of improvement in venous patency. Significantly less PTS occurred in those receiving thrombolysis, (RR 0.64; 95% CI 0.52 to 0.79, P < 0.0001). Leg ulceration was reduced although the data were limited by small numbers (RR 0.48; 95% CI 0.12 to 1.88, P = 0.29). Those receiving thrombolysis had significantly more bleeding complications (RR 2.23; 95% CI 1.41 to 3.52, P = 0.0006). Three strokes occurred in the treatment group, all in trials conducted pre-1990, and none in the control group. There was no significant effect on mortality detected at either early or intermediate follow up. Data on the occurrence of pulmonary embolism (PE) and recurrent DVT were inconclusive. Systemic thrombolysis is now not commonly used and catheter-directed thrombolysis (CDT) is the more favoured means of administration. This has been studied in iliofemoral DVT, and results from two trials are consistent with those from trials of systemic thrombolysis in DVT at other levels of occlusion.

AUTHORS' CONCLUSIONS

Thrombolysis increases the patency of veins and reduces the incidence of PTS following proximal DVT by a third. Strict eligibility criteria are necessary to reduce the risk of bleeding complications and this limits the applicability of this treatment. In those who are treated there is a small increased risk of bleeding. In recent years CDT is the most studied route of administration, and results appear to be similar to systemic administration.

Antithrombotic therapies: anticoagulation and thrombolysis

Pediatric deep vein thrombosis is an increasingly recognized phenomenon, especially with advances in treatment and supportive care of critically ill children and with better diagnostic capabilities. High-quality evidence and uniform management guidelines for antithrombotic treatment, particularly thrombolytic therapy, remain limited. Optimal dosing, intensity and duration strategies for anticoagulation as well as thrombolytic regimens that maximize efficacy and safety need to be determined through well-designed clinical trials using use of a risk-stratified approach.

Post-thrombotic syndrome: a clinical review

Up to half of patients with proximal deep vein thrombosis (DVT) will develop post-thrombotic syndrome (PTS) despite optimal anticoagulant therapy. PTS significantly impacts upon quality of life and has major health-economic implications. This narrative review describes the pathophysiology, risk factors, and diagnosis, prevention and treatment of PTS, to improve our understanding of the disease and guide treatment. Relevant articles were identified through systematic searches of the PubMed, EMBASE and Cochrane databases between 1966 and November 2011. Studies were included for detailed assessment if they met the following criteria: published in English, human study participants, study population aged > 18 years, and lower limb post-thrombotic syndrome. All non-systematic reviews and single patient case reports were excluded. Recurrent thrombosis, thrombus location and obesity are major risk factors, whereas the importance of gender and age remain uncertain. The diagnosis of PTS is based on clinical findings in patients with a known history of DVT. Several clinical scales have been described, with the Villalta Score gaining increasing popularity. Adequate anticoagulation and use of elastic compression stockings (ECS) following DVT can reduce the incidence of PTS. Catheter-directed thrombolysis and mechanical thrombectomy of acute DVT may preserve valvular function. Studies to date of these techniques are encouraging, and have reported improved hemodynamics and a reduced incidence of PTS. The management of established PTS is challenging. Compression therapy, aimed at reducing the underling venous hypertension, remains the mainstay of treatment. This is despite a paucity of high-quality evidence to support its use. Pharmacologic and surgical treatments have also been described, with a number of studies citing symptomatic improvement.

Antithrombotic therapy for VTE disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

This article addresses the treatment of VTE disease.

METHODS

We generated strong (Grade 1) and weak (Grade 2) recommendations based on high-quality (Grade A), moderate-quality (Grade B), and low-quality (Grade C) evidence.

RESULTS

For acute DVT or pulmonary embolism (PE), we recommend initial parenteral anticoagulant therapy (Grade 1B) or anticoagulation with rivaroxaban. We suggest low-molecular-weight heparin (LMWH) or fondaparinux over IV unfractionated heparin (Grade 2C) or subcutaneous unfractionated heparin (Grade 2B). We suggest thrombolytic therapy for PE with hypotension (Grade 2C). For proximal DVT or PE, we recommend treatment of 3 months over shorter periods (Grade 1B). For a first proximal DVT or PE that is provoked by surgery or by a nonsurgical transient risk factor, we recommend 3 months of therapy (Grade 1B; Grade 2B if provoked by a nonsurgical risk factor and low or moderate bleeding risk); that is unprovoked, we suggest extended therapy if bleeding risk is low or moderate (Grade 2B) and recommend 3 months of therapy if bleeding risk is high (Grade 1B); and that is associated with active cancer, we recommend extended therapy (Grade 1B; Grade 2B if high bleeding risk) and suggest LMWH over vitamin K antagonists (Grade 2B). We suggest vitamin K antagonists or LMWH over dabigatran or rivaroxaban (Grade 2B). We suggest compression stockings to prevent the postthrombotic syndrome (Grade 2B). For extensive superficial vein thrombosis, we suggest prophylactic-dose fondaparinux or LMWH over no anticoagulation (Grade 2B), and suggest fondaparinux over LMWH (Grade 2C).

CONCLUSION

Strong recommendations apply to most patients, whereas weak recommendations are sensitive to differences among patients, including their preferences.

Low-dose, once-daily, intraclot injections of alteplase for treatment of acute deep venous thrombosis

PURPOSE

To evaluate the safety and efficacy of once-daily intraclot injections of low doses (≤ 10 mg) of tissue plasminogen activator (tPA) for thrombolysis of venous thrombosis.

MATERIALS AND METHODS

In prospective studies, 33 patients with subclavian, jugular, and central venous thrombosis (SJ-CVT) (all but two cases associated with central catheters) were treated once a day with ≤ 4 mg/day of tPA, and 30 patients with acute deep vein thrombosis of the lower extremity (DVT-LE) < 14 days old were treated once a day with ≤ 10 mg/leg/day of tPA by intraclot "lacing" of thrombus without continuous infusions of tPA.

RESULTS

Patency was restored in 26 (79%) of 33 patients with SJ-CVT using an average total dose of 7.1 mg of tPA/per patient and average of 2.1 treatments or days of therapy. Five patients received thrombolytic therapy for SJ-CVT as outpatients. Initial patency was restored in 29 (97%) of 30 patients with acute DVT-LE using an average total dose of 20 mg of tPA per patient over an average of 2.7 treatments/or days per patient. Follow-up imaging examinations at 6 months showed continued patency in 27 (96%)/of 28 patients. There were no major bleeding complications, and no patient required a blood transfusion.

CONCLUSIONS

Intraclot injection of low doses of alteplase is effective for acute venous thrombosis, and pharmacokinetic data suggest potentially greater safety.

The role of thrombolysis in the clinical management of deep vein thrombosis

The cornerstones of current management of deep vein thrombosis (DVT) are the routine use of anticoagulant therapy, graduated elastic compression stockings, and early ambulation. Thrombolytic therapy was previously reserved only for patients with life-, limb-, or organ-threatening complications. However, the postthrombotic syndrome has been increasingly recognized as a frequent and serious long-term complication of DVT. In parallel, endovascular thrombolytic methods have evolved considerably in recent years, prompting discussion and controversy as to whether they should be more liberally used. In some centers, pharmacomechanical catheter-directed thrombolysis is now routinely used in the treatment of acute iliofemoral DVT. Randomized trials are currently under way to determine when the use of pharmacomechanical catheter-directed thrombolysis is appropriate in patients presenting with acute proximal DVT.

Management of massive and submassive pulmonary embolism, iliofemoral deep vein thrombosis, and chronic thromboembolic pulmonary hypertension: a scientific statement from the American Heart Association

Venous thromboembolism (VTE) is responsible for the hospitalization of >250 000 Americans annually and represents a significant risk for morbidity and mortality. Despite the publication of evidence-based clinical practice guidelines to aid in the management of VTE in its acute and chronic forms, the clinician is frequently confronted with manifestations of VTE for which data are sparse and optimal management is unclear. In particular, the optimal use of advanced therapies for acute VTE, including thrombolysis and catheter-based therapies, remains uncertain. This report addresses the management of massive and submassive pulmonary embolism (PE), iliofemoral deep vein thrombosis (IFDVT),and chronic thromboembolic pulmonary hypertension (CTEPH). The goal is to provide practical advice to enable the busy clinician to optimize the management of patients with these severe manifestations of VTE. Although this document makes recommendations for management, optimal medical decisions must incorporate other factors, including patient wishes, quality of life, and life expectancy based on age and comorbidities. The appropriateness of these recommendations for a specific patient may vary depending on these factors and will be best judged by the bedside clinician.

A multimodal therapeutic approach to phlegmasia cerulea dolens in a pediatric patient

Phlegmasia cerulea dolens is a rare but serious complication of deep venous thrombosis, which can lead to arterial compromise, tissue ischemia, and gangrene. It typically presents in an elderly population often with coexistent malignancy. There have been no reported cases in the ambulatory pediatric population. The authors report a case of a 5-year-old girl who presented with acute, extensive left lower extremity deep venous thrombosis resulting in phlegmasia cerulea dolens. Pharmacologic and mechanical interventions as described in the adult population were utilized. This case demonstrates that an aggressive, multimodal approach to phlegmasia cerulea dolens can be employed in the pediatric population and result in successful limb salvage.

Low-dose systemic thrombolytic therapy for deep vein thrombosis in pediatric patients

Reduction of thrombus size and recanalization of vessels after deep vein thrombosis (DVT) are important goals to prevent recurrent thrombosis and development of postthrombotic syndrome. Thrombolysis is effective but concern for bleeding complications has limited its use in children. We retrospectively analyzed data for children with DVT treated with a low-dose systemic tissue plasminogen activator (tPA) regimen. Twenty-three pediatric patients (12 males and 11 females, median age 12 y) received low-dose systemic tPA, initiated at 0.03 to 0.06 mg/kg/h for a median of 24 hours (range 12 to 48 h). Of the 20 patients imaged within 24 hours of therapy, 6 (30%) showed partial to complete thrombus resolution. Eight patients subsequently received increased tPA at 0.12 mg/kg/h for an additional 24 hours (range 12 to 36 h). Six of these 8 (75%) patients responded to the increased dose. The overall response at the end of thrombolytic therapy was 59% (13/22). Two bleeding complications occurred without serious sequelae. Low-dose tPA administration leads to a substantial response rate although the risk of bleeding remains unclear. A prospective multicenter trial of low-dose thrombolytic therapy in children with acute DVT is warranted.

[Venous interventions--part 1: techniques and lower torso thromboses]

Venous thrombosis is one of the most common vascular diseases. Without treatment, pulmonary embolism is a potentially life-threatening complication. Long-term complications are chronic venous insufficiency and post-thrombotic syndrome. Medical anticoagulation is currently the standard therapy, since it prevents appositional thrombus growth although it usually can not prevent the development of post-thrombotic syndrome. The structure of the thrombotic material often leads to partial recanalisation with residual stenosis. Early and sufficient systemic thrombolysis with adequate concentration may achieve disintegration of the thrombus and preservation of venous valve function. Supplementary to conservative therapy, local catheter thrombolysis is possible even in cases with contraindications for a systemic thrombolysis therapy. Additional interventional techniques reduce the required concentration of the thrombolytic. Venous stenosis can be treated by balloon angioplasty and stent implantation. This article reviews the different percutaneous treatment options as well as their application and usefulness in thrombosis of the lower torso.

Antithrombotic therapy for venous thromboembolic disease: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This chapter about treatment for venous thromboembolic disease is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh risks, burden, and costs. Grade 2 suggests that individual patient values may lead to different choices (for a full understanding of the grading, see "Grades of Recommendation" chapter). Among the key recommendations in this chapter are the following: for patients with objectively confirmed deep vein thrombosis (DVT) or pulmonary embolism (PE), we recommend anticoagulant therapy with subcutaneous (SC) low-molecular-weight heparin (LMWH), monitored IV, or SC unfractionated heparin (UFH), unmonitored weight-based SC UFH, or SC fondaparinux (all Grade 1A). For patients with a high clinical suspicion of DVT or PE, we recommend treatment with anticoagulants while awaiting the outcome of diagnostic tests (Grade 1C). For patients with confirmed PE, we recommend early evaluation of the risks to benefits of thrombolytic therapy (Grade 1C); for those with hemodynamic compromise, we recommend short-course thrombolytic therapy (Grade 1B); and for those with nonmassive PE, we recommend against the use of thrombolytic therapy (Grade 1B). In acute DVT or PE, we recommend initial treatment with LMWH, UFH or fondaparinux for at least 5 days rather than a shorter period (Grade 1C); and initiation of vitamin K antagonists (VKAs) together with LMWH, UFH, or fondaparinux on the first treatment day, and discontinuation of these heparin preparations when the international normalized ratio (INR) is > or = 2.0 for at least 24 h (Grade 1A). For patients with DVT or PE secondary to a transient (reversible) risk factor, we recommend treatment with a VKA for 3 months over treatment for shorter periods (Grade 1A). For patients with unprovoked DVT or PE, we recommend treatment with a VKA for at least 3 months (Grade 1A), and that all patients are then evaluated for the risks to benefits of indefinite therapy (Grade 1C). We recommend indefinite anticoagulant therapy for patients with a first unprovoked proximal DVT or PE and a low risk of bleeding when this is consistent with the patient's preference (Grade 1A), and for most patients with a second unprovoked DVT (Grade 1A). We recommend that the dose of VKA be adjusted to maintain a target INR of 2.5 (INR range, 2.0 to 3.0) for all treatment durations (Grade 1A). We recommend at least 3 months of treatment with LMWH for patients with VTE and cancer (Grade 1A), followed by treatment with LMWH or VKA as long as the cancer is active (Grade 1C). For prevention of postthrombotic syndrome (PTS) after proximal DVT, we recommend use of an elastic compression stocking (Grade 1A). For DVT of the upper extremity, we recommend similar treatment as for DVT of the leg (Grade 1C). Selected patients with lower-extremity (Grade 2B) and upper-extremity (Grade 2C). DVT may be considered for thrombus removal, generally using catheter-based thrombolytic techniques. For extensive superficial vein thrombosis, we recommend treatment with prophylactic or intermediate doses of LMWH or intermediate doses of UFH for 4 weeks (Grade 1B).

Thromboembolic Therapies in Dogs and Cats: An Evidence-Based Approach

In veterinary medicine, we are forced to make use of less than ideal "evidence," such as extrapolation from experimental studies in dogs and cats without naturally occurring diseases and from clinical trials in other species (particularly human clinical trials), as well as limited information gained from veterinary clinical experience, small clinical trials, case studies, and anecdotal reports. In this article, specific treatment recommendations are made for each of the common thromboembolic conditions seen in dogs and cats. These recommendations are made with the important caveat that, to date, such suggested therapeutic approaches are based on limited evidence.

Catheter-directed thrombolysis (intrathrombus injection) in treatment of deep venous thrombosis: A systematic review

Methods of delivery of thrombolytic agents for massive or limb threatening deep venous thrombosis (DVT) include a systemic infusion, local-regional administration, and catheter-directed therapy (tip of catheter placed inside the thrombus). We evaluated the effectiveness of catheter-directed therapy and compared the results with randomized clinical trials of systemic and local-regional thrombolytic therapy. Many who used catheter-directed thrombolysis used balloon angioplasty, stents, or thrombectomy in addition. Pooled data showed higher rates of complete early opening of occluded veins with catheter-directed thrombolysis alone, 90%, or with catheter-directed thrombolysis often followed by adjunct therapy, 76%, than with a systemic infusion, 28%, or local-regional administration, 20%. The prevalence of postthrombotic syndrome was lower with catheter-directed combined with adjunct therapy, 26%, compared with 56% and 69%, respectively. Rates of any bleeding were higher with catheter-directed thrombolytic therapy, but bleeding was usually minor. In conclusion, the data suggest that catheter-directed thrombolytic therapy may be more beneficial than systemic or local regional administration. An advantage is that it lends itself to adjunct treatment following the administration of thrombolytic agents if the thrombolysis is inadequate.

The Post-thrombotic Syndrome: The Forgotten Morbidity of Deep Venous Thrombosis

The postthrombotic syndrome (PTS) is the most common complication of deep venous thrombosis (DVT) yet has received little attention from clinicians and researchers. Clinically, PTS is characterized by chronic pain, swelling, heaviness and other signs in the affected limb. In severe cases, venous ulcers may develop. PTS is burdensome and costly to patients and society because of its high prevalence, severity and chronicity. Preventing DVT with the use of effective thromboprophylaxis in high-risk patients and settings and minimizing the risk of ipsilateral DVT recurrence are likely to reduce the frequency of PTS. Compression stockings worn daily after DVT appear to reduce the incidence and severity of PTS but questions regarding their use and effectiveness remain. Future research should focus on identifying patients at high risk for PTS, assessing the role of thrombolysis in preventing PTS and evaluating the optimal use of compression stockings in preventing and treating PTS. In addition, new therapies to treat PTS should be sought and evaluated.

The Case for Thrombolysis for Iliofemoral Venous Thrombosis

Deep venous thrombosis and its consequences remain a significant clinical challenge despite advances in the current healthcare system. The use of thrombolytic therapy has played an important role in the management of both arterial and venous thrombotic conditions. In this article, relevant clinical evidence and rationale in support of thrombolytic therapy in ileofemoral deep venous thrombosis are discussed.

Temporary vena caval interruption and thrombolysis in the management of deep vein thrombosis

Temporary interruption of the inferior vena cava (IVC) with a retrievable filter should be considered in patients with objectively verified proximal deep vein thrombosis (DVT) of the legs who have a temporary contraindication to therapeutic anticoagulation, or in patients who experience severe complications from anticoagulation. The risk of the temporary filter being left in place permanently must be considered. Use of a retrievable filter in conjunction with therapeutic anticoagulation during the early phase of therapy for acute DVT in patients whose cardiopulmonary reserve is limited (ie, those with pre-existing pulmonary hypertension) may be a future indication for this intervention. Interruption of the superior vena cava with a retrievable filter has been performed in a small number of cases, but there are insufficient data to guide risk:benefit analysis for this procedure. Thrombolysis, either systemic or local, results in a higher rate of thrombus resolution than anticoagulation alone. However, the long-term benefit of thrombolysis in preventing or improving the post-thrombotic syndrome remains unproven. Due to the substantial risk and cost of thrombolytic therapy, it should not be performed in the routine treatment of DVT. Thrombolytic therapy, in the absence of contraindication, should be considered in highly symptomatic, massive iliofemoral DVT. Catheter-directed thrombolytic therapy has shown promise in case series, but its role remains to be elucidated in randomized trials.

Thrombolytic Therapy: Current Clinical Practice

Thrombolytic therapy is an essential tool in the array of therapies designed to reopen arteries and veins occluded with thrombus. As the use of thrombolytic agents has entered mainstream practice, their application has expanded to include a wide variety of indications and settings. Thrombolytic agents are used in patients who have thrombosis of coronary arteries, precerebral and cerebral arteries, the aorta, iliac and mesenteric arteries, and peripheral arteries. The use of thrombolysis in venous thrombosis has included deep venous thrombosis of the upper and lower extremities and vena cava, mesenteric veins, cerebral veins, and central access catheters. Guidelines are available from the American College of Cardiology/American Heart Association regarding thrombolysis in myocardial infarction and from the American Stroke Association regarding thrombolysis in acute ischemic stroke.

Antithrombotic therapy for venous thromboembolic disease: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

This chapter about antithrombotic therapy for venous thromboembolic disease is part of the seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following: for patients with objectively confirmed deep vein thrombosis (DVT), we recommend short-term treatment with subcutaneous (SC) low molecular weight heparin (LMWH) or, alternatively, IV unfractionated heparin (UFH) [both Grade 1A]. For patients with a high clinical suspicion of DVT, we recommend treatment with anticoagulants while awaiting the outcome of diagnostic tests (Grade 1C+). In acute DVT, we recommend initial treatment with LMWH or UFH for at least 5 days (Grade 1C), initiation of vitamin K antagonist (VKA) together with LMWH or UFH on the first treatment day, and discontinuation of heparin when the international normalized ratio (INR) is stable and > 2.0 (Grade 1A). For the duration and intensity of treatment for acute DVT of the leg, the recommendations include the following: for patients with a first episode of DVT secondary to a transient (reversible) risk factor, we recommend long-term treatment with a VKA for 3 months over treatment for shorter periods (Grade 1A). For patients with a first episode of idiopathic DVT, we recommend treatment with a VKA for at least 6 to 12 months (Grade 1A). We recommend that the dose of VKA be adjusted to maintain a target INR of 2.5 (INR range, 2.0 to 3.0) for all treatment durations (Grade 1A). We recommend against high-intensity VKA therapy (INR range, 3.1 to 4.0) [Grade 1A] and against low-intensity therapy (INR range, 1.5 to 1.9) compared to INR range of 2.0 to 3.0 (Grade 1A). For the prevention of the postthrombotic syndrome, we recommend the use of an elastic compression stocking (Grade 1A). For patients with objectively confirmed nonmassive PE, we recommend acute treatment with SC LMWH or, alternatively, IV UFH (both Grade 1A). For most patients with pulmonary embolism (PE), we recommend clinicians not use systemic thrombolytic therapy (Grade 1A). For the duration and intensity of treatment for PE, the recommendations are similar to those for DVT.

Thrombolysis for acute deep vein thrombosis

BACKGROUND

Standard treatment for deep vein thrombosis (DVT) aims to reduce immediate complications. Use of thrombolysis or clot dissolving drugs could reduce the long-term complications of post-thrombotic syndrome (pain, swelling, skin discolouration, or venous ulceration) in the affected leg.

OBJECTIVES

To determine the efficacy and safety of thrombolysis for DVT.

SEARCH STRATEGY

Publications describing randomised controlled trials (RCTs) of thrombolysis versus anticoagulation for acute DVT were sought through electronic searches of the Cochrane Peripheral Vascular Diseases trials register (last searched April 2004) and the Cochrane Central Register of Controlled Trials (CENTRAL) (last searched The Cochrane Library Issue 2, 2004). Additional trials were identified by reviewing reference lists of papers. There were no restrictions for language.

SELECTION CRITERIA

RCTs examining thrombolysis versus anticoagulation for acute DVT and/or calf vein thrombosis were considered.

DATA COLLECTION AND ANALYSIS

One reviewer (LIW) selected trials, extracted data and assessed study quality, with checking at all stages by the other reviewer (MPA). Where required, additional information was sought from trialists.

MAIN RESULTS

Twelve studies were included. Complete clot lysis occurred significantly more often in the treatment group in early follow up, (relative risk (RR) 0.24; 95% confidence interval (CI) 0.07 to 0.82), and in late follow up, (RR 0.37; 95 % CI 0.25 to 0.54). A similar effect was also seen for any degree of improvement in venous patency. Significantly less post-thrombotic syndrome occurred in those receiving thrombolysis, (RR 0.66; 95 % CI 0.47 to 0.94). Leg ulceration was reduced although the data were limited by small numbers, (RR 0.53; 95 % CI 0.12 to 2.43). Venous function was improved at late follow up, but not significantly (RR 0.43; 95 % CI 0.06 to 3.17)Out of 668 patients, those receiving thrombolysis had significantly more bleeding complications, (RR 1.73; 95 % CI 1.04 to 2.88). Two strokes occurred in the treatment group (RR 1.70; 95 % CI 0.21 to 13.70). The incidence of bleeding appears to have reduced over time with the introduction of stricter selection criteria. There was no significant effect on mortality detected in either early or late follow up. Data on occurrence of pulmonary embolism (PE) and recurrent DVT were inconclusive.

REVIEWERS' CONCLUSIONS

Thrombolysis appears to offer advantages in terms of reducing post-thrombotic syndrome and maintaining venous patency after DVT. Use of strict eligibility criteria has improved the safety and acceptability of this treatment. The optimum drug, dose and route of administration have yet to be determined.

Endovascular management of venous thrombotic and occlusive diseases of the lower extremities

Acute complications of deep vein thrombosis (DVT) of the lower extremities include pulmonary embolism and venous ischemia. Delayed complications include a spectrum of debilitating symptoms referred to as postthrombotic syndrome (PST). Anticoagulation therapy is recognized as the mainstay of therapy in acute DVT. However, there are few data to suggest any major beneficial effect on PTS, which is thought to be mediated by valve damage and/or occlusive chronic thrombus and venous scarring. Endovascular catheter-directed thrombolysis techniques with pharmacologic thrombolytic agents, used alone or in combination with mechanical thrombectomy devices, have been proven highly effective in clearing acute DVT, which may allow the preservation of venous valve function and prevention of subsequent venous occlusive disease. Definitive management of underlying anatomic occlusive abnormalities can also be undertaken.