Volume 14 Supplement 1

State of the Art 2016: Research and Review from the 9th Congress of the Asian-Pacific Society on Thrombosis and Hemostasis

Review
Open Access

Management of venous thromboembolism: an update

Thrombosis Journal201614(Suppl 1):23

https://doi.org/10.1186/s12959-016-0107-z

©  The Author(s). 2016

Published: 4 October 2016

Abstract

Venous thromboembolism (VTE), which constitutes pulmonary embolism and deep vein thrombosis, is a common disorder associated with significant morbidity and mortality. Landmark trials have shown that direct oral anticoagulants (DOACs) are as effective as conventional anticoagulation with vitamin K antagonists (VKA) in prevention of VTE recurrence and associated with less bleeding. This has paved the way for the recently published guidelines to change their recommendations in favor of DOACs in acute and long-term treatment of VTE in patients without cancer. The recommended treatment of VTE in cancer patients remains low-molecular-weight heparin. The initial management of pulmonary embolism (PE) should be directed based on established risk stratification scores. Thrombolysis is an available option for patients with hemodynamically significant PE. Recent data suggests that low-risk patients with acute PE can safely be treated as outpatients if home circumstances are adequate. There is lack of support for use of inferior vena cava filters in patients on anticoagulation. This review describes the acute, long-term, and extended treatment of VTE and recent evidence on the management of sub-segmental PE.

Keywords

Venous thromboembolism Anticoagulation Direct oral anticoagulants Vitamin K antagonists

Background

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is one of the most common cardiovascular diseases occurring for the first time in about 1 in 1000 people [1, 2]. Its incidence rises with increasing age, for example to about 5 per 1000 people among those over 70 years of age [3]. VTE is associated with significant morbidity and mortality with the 30-day mortality rate in the absence of treatment of about 3 % for DVT and 31 % for PE [4]. The long-term complications of VTE are post-thrombotic syndrome (PTS), which occurs in 20 to 50 % of patients with DVT [5], and chronic thromboembolic pulmonary hypertension (CTEPH), which occurs in 2 to 4 % of patients with PE [6]. Patients with CTEPH have progressive dyspnea and exercise intolerance and those with PTS have chronic leg pain and swelling, which in a minority of patients can progress to development of venous ulcers. These conditions can significantly reduce the patient’s quality of life. Furthermore, the management VTE is associated with substantial health care costs for not only the initial hospitalization but also for hospital re-admissions [7, 8]. Therefore, VTE is associated with significant morbidity and mortality.

Initial management

The initial management of patients with a PE should be based on risk stratification of the patient into low, intermediate, or high risk for 30-day mortality based on established risk scores such as pulmonary embolism severity index (PESI) or its simplified version (simplified PESI) [9, 10]. Low risk patients, who are hemodynamically stable, can be treated as outpatients if home circumstances are adequate [11, 12]. At the other extreme, patients with acute PE and hypotension or patients with DVT-associated phlegmasia of the lower leg should be considered for treatment with thrombolytic agents [13, 14].

Oral anticoagulants

Anticoagulants are the mainstay treatment of VTE and are given in three phases of acute, long-term (in the first 3 months), and extended treatment [14]. For many years initial treatment was started with a parenteral anticoagulant, for example low-molecular-weight heparin (LMWH), overlapping with a vitamin K antagonist (VKA), such as warfarin. The combination was continued for at least 5 days until the achievement of therapeutic anticoagulation with international normalized ratio of 2 to 3 [14]. Although conventional therapy with VKAs is effective and safe, it has some limitations including delayed onset, need for parental daily injections, and interactions with dietary vitamin K and numerous drugs. Over the past 5 years, 4 direct oral anticoagulants (DOACs) have been approved for acute and long-term treatment of VTE [15–20]. The DOACs were compared with conventional therapy and found to be as effective in prevention of VTE recurrence and associated with less bleeding. The recently published American College of Chest Physicians (ACCP) guidelines have changed their recommendations in favor of DOACs in acute and long-term treatment of VTE in patients without cancer [21]. In patients with cancer associated VTE, the recommended anticoagulation remains LMWH over VKA [21].

The aim of this review is to (1) describe the initial management of patients with acute PE including the role of thrombolytic agents in hemodynamically unstable patients and at the other extreme outpatient management of low risk patients, (2) summarize the evidence on acute, long-term, and extended treatment of VTE comparing DOACs versus VKA, and (3) review the recent data on the management of sub-segmental PE and the lack of support for use of inferior vena cava filters in patients on anticoagulation.

Review

Acute and long-term treatment of venous thromboembolism

Thrombolytic and interventional treatment for acute venous thromboembolism

Anticoagulant therapy alone is recommended over thrombolysis for most patients with an acute DVT with exception for those with extensive iliofemoral or proximal DVT at high risk of limb ischemia [14, 21]. Thrombolytic therapy (systemic or catheter-directed) increase clot lysis and reduce the incidence of PTS compared to anticoagulation alone [22, 23]. However, this is at the expense of higher rate of major bleeding and no difference in rate of recurrent VTE or mortality [22–24]. Massive proximal DVT or iliofemoral thrombosis associated with limb-threatening ischemia or severe symptomatic swelling may be treated with thrombolysis. Thrombolysis can be considered only after objective diagnosis of the DVT and in a patient with low bleeding risk. The CaVenT trial randomized 209 patients with iliofemoral DVT to catheter directed therapy (CDT) versus anticoagulation. They found that the patients treated with CDT had significantly less PTS at 2 years compared with those treated with anticoagulation (41 versus 56 %) [22]. Another study randomized 32 patients with iliofemoral DVT to receive either CDT or systemic thrombolysis, followed by anticoagulation [25]. The patients who were treated with CDT had less reflux in both the deep and superficial veins and more patients had venous valvular competence preserved compared with patients who underwent systemic thrombolysis. A large, multicenter trial (the ATTRACT trial) is currently underway that randomizes patients to receive pharmaco-mechanical catheter-directed thrombolysis (PCDT) plus standard therapy with anticoagulation versus standard therapy alone [26]. It will investigate whether PCDT should be routinely utilized to prevent PTS in patients with symptomatic proximal DVT [26].

Systemic thrombolysis is a widely accepted treatment for PE in patients with persistent hypotension (e.g., systolic blood pressure <90 mmHg for 15 min) and not at high risk of bleeding [14, 21]. The use of thrombolytic therapy in intermediate risk patients with acute PE associated with right ventricle (RV) dysfunction is controversial. The RV dysfunction is confirmed by echocardiogram or computed tomography and a positive troponin I/T. The potential indication for thrombolysis in this group is based on evidence that patients with severe RV dysfunction have worse prognosis than those without RV dysfunction [27]. Three recently published trials have examined the role of systemic thrombolysis in intermediate risk patients [28–30]. In the Moderate Pulmonary Embolism Treated Thrombolysis (MOPETT) trial, 121 patients were randomly assigned to receive heparin (unfractionated or LMWH) alone or the combination of tissue type plasminogen activator (tPA) plus heparin [28]. Compared to the heparin group, treatment with tPA resulted in lower rates of pulmonary hypertension and significantly lower pulmonary artery systolic pressures at 28 months. The rates of bleeding, recurrent PE, and mortality was similar in both groups [28]. In another trial comparing the combination of LMWH plus an intravenous bolus of tenecteplase versus LMWH alone in intermediate risk PE patients, those treated with tenecteplase had fewer adverse outcomes and better functional capacity at 90 days [29]. In a large multicenter randomized trial (PEITHO), 1005 intermediate risk patients with PE were randomized to tenecteplase and heparin or to heparin therapy alone [30]. Thrombolysis therapy led to reduction in the primary composite outcome of death or cardiovascular collapse at seven days after randomization although it increased major bleeding (including intracranial bleeding) with no overall gained benefit from thrombolysis [30]. A meta-analysis of 16 trials comprising 2115 intermediate risk patients reported that 59 patients would need to be treated with thrombolysis to prevent one death, while a major bleeding occurs with every 18 patients treated [13]. Further studies are needed to identify subgroups of intermediate risk patients who will benefit from systemic thrombolytic therapy.

CDT may be used in patients with acute PE at increased risk of bleeding as a lower dose of a thrombolytic agent is infused directly into the pulmonary artery via a catheter [31]. CDT is also effective in lowering pulmonary arterial pressure and improving RV function [32]. In a randomized controlled trial of 59 patients with acute intermediate risk PE, ultrasound-assisted catheter-directed thrombolysis followed by heparin was compared to treatment with heparin alone [33]. At 24 h, CDT improved the hemodynamics compared to anticoagulation. At 90 days of follow-up, there was no difference in mortality or major bleeding between the two groups [33]. Most of the evidence is limited by small sample size and of low quality compared to the available evidence for systemic thrombolysis. Systemic thrombolysis is therefore currently recommended over CDT in patients with acute PE who are candidates for thrombolysis [21].

Outpatient treatment of venous thromboembolism

Home therapy is commonly employed for patients with an acute DVT in clinical practice with a few exceptions. Several randomized controlled trials and meta-analyses, which have compared home therapy with LMWH versus inpatient therapy with intravenous unfractionated heparin, suggest that outpatient therapy is safe and feasible in most patients with acute DVT [34–36]. Outpatient therapy should not be selected for those with massive symptomatic DVT, high risk of bleeding, or hemodynamic instability due to concurrent symptomatic PE [37].

The outpatient treatment of acute PE is suggested with grade 2B evidence in the most recent ACCP guidelines in low-risk patients with adequate home circumstances [21]. The decision for outpatient management should take into account the patient’s clinical condition, bleeding risk, their preference, and the available home support. Risk stratification scores such as PESI or simplified PESI may be utilized to identify low-risk patients without RV dysfunction who are potential candidates for short in-hospital stay or entirely outpatient management [11, 12, 38]. With the recent changed recommendations in favor of DOACs for acute and long-term VTE treatment, future research should focus on the safety and efficacy of DOACs in outpatient management of acute VTE.

Vitamin K antagonists versus direct oral anticoagulants

Four DOACs including dabigatran, rivaroxaban, apixaban, and edoxaban were compared with conventional therapy in the RE-COVER I and II, EINSTEIN-DVT and PE, AMPLIFY, and Hokusai-VTE trials, respectively [15–20]. The study design was double-blinded in all trials except for the ENSTEIN trials, which used a prospective, randomized, open-label, blinded end point evaluation design. The study designs and treat protocols are compared in Table 1. The study populations were similar in these trials. In the dabigatran and edoxaban trials, parental anticoagulation was added to both DOAC and conventional therapy arms, and after at least 5 days patients were switched to the DOAC. Therefore, in clinical practice, patients should be initiated on parenteral anticoagulation and either switched to dabigatran or edoxaban after 5 days or it should be overlapped with a vitamin K antagonist. In contrast, in the rivaroxaban and apixaban trials DOACs were started without the need for initial parental anticoagulation. The primary efficacy outcome was recurrent VTE or VTE-related mortality in all 6 trials. The primary safety outcome was either major bleeding or a composite of major and clinically relevant non-major bleeding (CRNMB). The efficacy and safety outcomes of these trials are listed in Table 2. All of the trials excluded patients with severe renal dysfunction, those with active bleeding or at high risk of bleeding, and patients already on therapeutic anticoagulation. A recent pooled analysis of these 6 trials reported that DOACs have similar efficacy as VKA in treatment of acute VTE and significantly lower risk of major bleeding than VKA [39]. Recurrent VTE occurred in 2 % of those given DOAC versus 2.2 % in patients that received VKA (relative risk [RR] 0.90; 95 % confidence interval [CI], 0.77 – 1.06) [39]. A 39 % reduction in risk of major bleeding was reported in DOAC recipients compared to those who received VKA therapy (RR 0.61; 95 % CI, 0.45 – 0.83). Compared with recipients of VKA therapy, intracranial bleeding, fatal bleeding, and CRNMB were significantly reduced in the DOAC group [39]. Given the better safety profile of DOACs with less major bleeding, similar efficacy in prevention of recurrent VTE, and the convenience of administration of DOACs, the recent ACCP guidelines suggested DOACs over VKA for the acute and long-term treatment of VTE in patients without cancer [21].
Table 1

Comparison of study design and treatment protocols of trials on DOACs Versus VKA for treatment of acute VTE

Trial name

RE-COVER

RE-COVER II

EINSTEIN-DVT

EINSTEIN-PE

AMPLIFY

Hokusai-VTE

Year of Publication [Ref]

2009 [15]

2014 [16]

2010 [17]

2012 [18]

2013 [19]

2013 [20]

Design

Double-blinded

Double-blinded

PROBE

PROBE

Double-blinded

Double-blinded

Number of Patients

2539

2589

3449

4832

5395

8292

Indication for Anticoagulation

Acute VTE

Acute VTE

Acute DVT

Acute PE

Acute VTE

Acute VTE

DOAC Treatment Protocol

Dabigatran 150 mg twice daily

Dabigatran 150 mg twice daily

Rivaroxaban 15 mg twice daily for 3 weeks; then 20 mg once daily

Rivaroxaban 15 mg twice daily for 3 weeks; then 20 mg once daily

Apixaban 10 mg twice daily for days; then 5 mg twice daily

Edoxaban 60 once daily; patients with CrCl 30–50 mL/min, body weight ≤60 kg, or receiving strong P-glycoprotein inhibitors: edoxaban 30 mg once daily

Non-inferiority Margin for Hazard Ratio

2.75

2.75

2.0

2.0

1.8

1.5

Need for initial Parenteral Anticoagulation

Yes

Yes

No

No

No

Yes

Duration of Therapy (months)

6

6

3, 6, or 12

3, 6, or 12

6

≤12

TTR (%)

60

57

58

63

61

64

DOAC direct oral anticoagulant, DVT deep vein thrombosis, PE pulmonary embolism, PROBE prospective, randomized, open-label, blinded end point, TTR time in therapeutic range for warfarin, VKA vitamin K antagonists, VTE venous thromboembolism, CrCl creatinine clearance

Table 2

Efficacy and safety outcomes for treatment of acute VTE: DOACs versus VKA

Trial Name [Ref]

RE-COVER [15]

RE-COVER II [16]

EINSTEIN-DVT [17]

EINSTEIN-PE [18]

AMPLIFY [19]

Hokusai-VTE [20]

Primary Efficacy Outcome DOAC vs VKA (%)

Recurrent symptomatic VTE or related death: 2.4 vs 2.1a

Recurrent symptomatic VTE or related mortality: 2.3 vs 2.2a

Recurrent symptomatic VTE: 2.1 vs 3.0a

Recurrent symptomatic VTE: 2.1 vs 1.8a

Recurrent symptomatic VTE or related mortality: 2.3 vs 2.7a

Recurrent symptomatic VTE or related mortality: 3.2 vs 3.5a

Primary Safety Outcome(s)

Major bleeding; Major or CRNM bleeding: Any bleeding

Major bleeding Major or CRNM bleeding: Any bleeding

Major or CRNM bleeding

Major or CRNM bleeding

Major bleeding

Major or CRNM bleeding

Major Bleeding DOAC vs VKA (%)

1.6 vs 1.9

1.2 vs 1.7

0.8 vs 1.2

1.1a vs 2.2

0.6a vs 1.8

1.4 vs 1.6

Major or CRNM Bleeding DOAC vs VKA (%)

5.6 vs 8.8

5.0 vs 7.9

8.1 vs 8.1

10.3 vs 11.4

4.3a vs 9.7

8.5a vs 10.3

DOAC direct oral anticoagulant, CRNM clinically relevant non-major, DOAC direct oral anticoagulants, VKA vitamin K antagonists, VTE venous thromboembolism

aStatistically significant difference between the two groups

Management of VTE in patients with cancer

The major society guidelines including the ACCP, American Society of Clinical Oncology, and the National Comprehensive Cancer Network recommend use of LMWH for treatment of VTE in cancer patients [21, 40, 41]. Treatment with LMWH is continued for the duration of active cancer given that the risk of recurrent VTE can reach an annual risk of 20 % [42]. Five randomized trials have compared therapy with LMWH versus warfarin in cancer patients [43–47]. The details of these trials are outlined in Table 3. Two trials showed a reduction in the rates of recurrent VTE using LMWH with no effect on mortality or bleeding [44, 45], two showed no difference in any outcome [43, 46], and the recently published CATCH trial demonstrated a non-significant reduction in the rate of recurrent VTE and lower risk of CRNMB in those who received LMWH [47].
Table 3

Comparison of trials on LMWH versus VKA for treatment of VTE in cancer patients

Trial Name

CANTHANOX

CLOT

MAIN-LITE

ONCENOX

CATCH

Year of Publication [Ref]

2002 [43]

2003 [44]

2006 [45]

2006 [46]

2015 [47]

Design

Open-label

Open-label

Open-label

Open-label

Open-label

Number of Patients

146

676

200

122

900

Treatment Protocol

Enoxaparin 1.5 mg/kg daily

Dalteparin 200 IU/kg once daily for the first month then 150 IU/kg for 5 months

Tinzaparin 175 IU/kg once daily

Enoxaparin 1 mg/kg every 12 h for 5 days then enoxaparin 1 mg/kg or 1.5 mg/kg daily

Tinzaparin 175 IU/kg once daily

Duration of Therapy (months)

3

6

3

6

6

Primary Efficacy Outcome LMWH vs VKA (%)

Combination of major bleeding or recurrent VTE: 10.5 vs 21.1

Recurrent symptomatic VTE: 9a vs 17

Recurrent symptomatic VTE: 7 vs 10

Recurrent symptomatic VTE: enoxaparin 1 mg vs. 1.5 mg vs VKA 6.8 vs 6.3 vs 10.0

Composite of recurrent symptomatic VTE, fatal PE, or incidental VTE: 7.2 vs 10.5

Safety Bleeding Outcomes LMWH vs VKA (%)

Major bleeding: 7 vs 16;

Fatal bleeding: 0 vs 8a

Major bleeding: 6 vs 4;

Any bleeding 14 vs 19

Major bleeding: 7 vs 7;

Any bleeding: 27 vs 24

Major bleeding: enoxaparin 1 mg vs. 1.5 mg vs VKA : 6.5 vs 11.1 vs 2.9

Major bleeding: 2.7 vs 2.4 CRNM bleeding: 10.9a vs 15.3

CRNM clinically relevant non-major, DOAC direct oral anticoagulants, LMWH low-molecular weight heparin, PE pulmonary embolism, VKA vitamin K antagonists, VTE venous thromboembolism

aStatistically significant difference between the two groups

There are no published randomized trials that a priori have compared DOACs with VKA or LMWH for treatment of VTE in cancer patients. A meta-analysis of the subsets with DVT and cancer totaling 1132 patients in the six trials that compared DOACs versus VKA [15–20] has been published [48]. They found similar rates of VTE recurrence (3.9 versus 6 %; odds ratio [OR] 0.63; 95 % CI, 0.37 – 1.10) and major bleeding (3.2 versus 4.2%; OR 0.77; 95 % CI, 0.41-1.44). Although these trials included cancer patients [15–20], they were typically not receiving active chemotherapy or radiation. The cancer patients included in these trials had usually completed treatment or had a previous history of cancer and are not a true representative of all cancer patients. The Hokusai VTE-cancer randomized open label trial is currently underway and will examine whether edoxaban is non-inferior to LMWH for treatment of VTE in cancer patients [49].

Extended treatment of venous thromboembolism

Extended anticoagulation can be employed in patients with unprovoked VTE to reduce the risk of recurrent VTE if the benefit/risk ratio favors continuation of anticoagulation while taking into account patient’s risk of bleeding. All DOACs except for edoxaban have been compared with placebo in randomized trials for extended secondary VTE prevention beyond the initial three months of anticoagulation [17, 50, 51]. The details of these trials are compared in Table 4. All trials showed marked superiority of the DOACs over placebo for the prevention of recurrent VTE without significant increase in major bleeding [17,50, 51]. However, compared to the placebo arms, all DOACs had higher rate of CRNMB [17, 50, 51]. Duration of extended anticoagulation was 6 to 12 months in the EINSTEIN [17] and AMPLIFY-Extension [50] studies and 6 months in the RE-SONATE trial [51]. Two doses of apixaban were evaluated in the AMPLIFY-Extension trial and the rate of bleeding was lower for apixaban 2.5 mg twice daily than 5 mg twice daily [50]. A single regimen of rivaroxban (20 mg once daily) and dabigatran (150 mg twice daily) was used in the EINSTEIN and RE-SONATE studies.
Table 4

Comparison of extended duration DOAC trials

Trial Name

EINSTEIN-EXTENSION

AMPLIFY-EXT

RE-MEDY

RE-SONATE

Year of Publication [Ref]

2010 [17]

2013 [50]

2013 [51]

2013 [51]

Design

Double-blinded

Double-blinded

Double-blinded

Double-blinded

Comparison Arm

Placebo

Placebo

Warfarin

Placebo

Number of Patients

1197

2486

2866

1353

Treatment Protocol

Rivaroxaban 20 mg once daily

Apixaban 5 mg or 2.5 twice daily

Dabigatran 150 mg twice daily

Dabigatran 150 mg twice daily

Duration of Therapy (months)

6 to12

12

6 to 36

6

Primary Efficacy Outcome DOAC vs VKA or Placebo (%)

Recurrent symptomatic VTE: 1.3a vs 7.1

Recurrent symptomatic VTE or all-cause mortality: 3.8a vs 4.2a vs 11.6

Recurrent symptomatic VTE or related mortality: 1.8a vs 1.3

Recurrent symptomatic VTE or related mortality: 0.4a vs 5.6

Major Bleeding DOAC vs VKA or Placebo (%)

0.7 vs 0

0.2 vs 0.1 vs 0.5

0.9 vs 1.8

0.3 vs 0

Major and CRNM Bleeding DOAC vs VKA or Placebo (%)

6.0a vs 1.2

3.2 vs 4.3 vs 2.7

5.6a vs 10.2

5.3a vs 1.8

DOAC direct oral anticoagulant, CRNM clinically relevant non-major, DOAC direct oral anticoagulants, VKA vitamin K antagonists, VTE venous thromboembolism

aStatistically significant difference between the two groups

Dabigatran is the only DOAC that has been compared with warfarin for extended VTE prevention in the RE-MEDY trial [51]. Dabigatran was non-inferior to warfarin in prevention of recurrent VTE (1.8 versus 1.3 %, hazard ratio [HR] 1.44; 95 % CI, 0.78–2.64) and had a significantly lower rate of major bleeding or CRNMB (HR 0.54; 95 % CI, 0.41–0.71). These results demonstrated that DOACs are effective in secondary VTE prevention with no significant increase in major bleeding. The ACCP guidelines recommend no change in the choice of anticoagulant agent in patients who need extended anticoagulation after the first 3 months of therapy [21]. Given the observed lower bleeding risk, the dose of apixaban may be reduced to 2.5 mg twice daily after the initial treatment.

Aspirin has been also evaluated in secondary VTE prevention in patients with first unprovoked VTE who have completed anticoagulant treatment. In this setting, randomized trials and a meta-analysis reported a 30 % reduction in rates of recurrent VTE compared to placebo or observation [52–55]. The ACCP guidelines suggest that aspirin is an available option in patients with unprovoked VTE that are stopping anticoagulant therapy if there are no contraindications to use of aspirin [21]. However, aspirin is not recommended as an alternative to anticoagulant therapy [21].

Treatment of VTE in special situations

Management of sub-segmental pulmonary embolism

The increase in utilization of a highly sensitive computed tomography pulmonary angiography (CTPA) has led to detection of incidental asymptomatic PE or small sub-segmental PE [56]. Whether or not patients with sub-segmental pulmonary embolism (SSPE) should be anticoagulated is controversial. It is unclear whether the SSPE detected by CTPA are artifacts and therefore false positive [57]. Furthermore, an isolated SSPE likely does not have the same risk of progression or VTE recurrence as a single segmental or lobar PE [57]. There are currently no published randomized trials for treatment of patients with SSPE. Retrospective studies have reported VTE recurrence in only a small number of patients with SSPE and without DVT, who were not anticoagulated. [57, 58]. Details of these retrospective studies are summarized in Table 5 [59–65]. However, another retrospective study showed that patients with SSPE have similar rate of VTE recurrence as patients with larger PE during 3 months of anticoagulation [66]. The ACCP guidelines suggest performing bilateral ultrasounds to exclude proximal DVT before a decision is made not to treat a patient with SSPE [21]. If a DVT is detected then the patient should receive anticoagulation. However, if no proximal DVT is detected the guidelines suggest that the clinician assesses risk factors for VTE recurrence or progression and considers anticoagulation for those with high risk of VTE recurrence (e.g., recent surgery, immobilization, active cancer, previous history of VTE) [21]. Future prospective studies are needed to determine the optimal management strategy for patients with SSPE and no detected proximal DVT.
Table 5

Summary of retrospective studies on 3-month follow-up of patients with sub-segmental pulmonary embolism

Study

Musset et al.

Eyer et al.

Donato et al.

Pena et al.

Mehta et al.

Goy et al.

Ghazvinian et al.

Year of Publication [Ref]

2002 [59]

2005 [60]

2010 [61]

2012 [62]

2014 [63]

2015 [64]

2016 [65]

Method of Detection

SDCT

MDCT

MDCT

MDCT

MDCT

MDCT

V/P SPECT

Number of Patient with Positive CTPA

360

499

1463

724

NAb

550

NAb

Number of Patients with SSPE n/N (%)

12 (3.3)

67 (13.4)

93 (6.4)

70 (9.6)

32 (100)

82 (15)

54 (100)

Number of Untreated SSPE (%)

9 (75)

25 (37.3)

22 (22.9)

18 (25.7)

12 (37.5)

39 (47.6)

54 (100)

VTE (%)

0

0

0

0

0

0

4a

CTPA computed tomography pulmonary angiography, NA not applicable, MDCT multi-detector computed tomography pulmonary angiography, SDCT single-detector computed tomography pulmonary angiography, SSPE sub-segmental pulmonary embolism, V/P SPECT ventilation/perfusion singe photon emission computed tomography, VTE venous thromboembolism

aTwo patients were diagnosed with a DVT

bOnly examined patients with SSPE

Role of inferior vena cava filter in management of acute venous thromboembolism

Inferior vena cava (IVC) filters are typically used in patients with an acute VTE and an absolute contraindication to anticoagulation (e.g., concurrent active bleeding) [67]. The IVC filter is removed once the bleeding risk is low and anticoagulation is given [14]. In patients with acute VTE already on anticoagulation with no absolute contraindications, studies suggest that there is lack of benefit to use of IVC filters in addition to anticoagulation [68–72]. In the PREPIC 1 trial, 400 patients with proximal DVT were randomized to either anticoagulation alone or anticoagulation plus IVC filter placement [68]. The initial 2-year PREPIC 1 study and a subsequently published 8-year follow-up reported that IVC filter insertion was associated with a reduction in the initial rate of PE, increase in the rate of DVT, and no difference in mortality [68, 69]. The PREPIC 2 trial examined the adjuvant role of IVC filters in patients with PE who received either anticoagulation alone or anticoagulation plus an IVC filter [70]. The filter was removed at 3 months. There was no difference in the rates of recurrent VTE or mortality between the two groups [70]. In addition to lack of benefit, IVC filters are associated with complications including IVC filter thrombosis, DVT, and guide wire entrapment [71, 72]. The ACCP guidelines recommend against the use of IVC filters in patients on anticoagulation for acute VTE [21].

Conclusions

VTE is a major cause of morbidity and mortality. DOACs are suggested over VKA for acute and long-term treatment of VTE in patients without cancer, as they have been shown to be as effective as VKA in reducing VTE recurrence and associated with significantly less major bleeding. Future studies are needed to assess their safety and efficacy in outpatient treatment of acute VTE. LMWH is the current standard of care for treatment of VTE in cancer patients. Randomized trials are ongoing to examine the non-inferiority of DOACs versus LMWH in cancer patients. Lastly, it is currently unclear whether or not to treat patients with SSPE and no proximal DVT; future prospective studies are needed to examine different management strategies in this patient group.

Abbreviations

ACCP: 

American College of Chest Physicians

CI: 

Confidence interval

CRNM: 

Clinically relevant non-major

CTEPH: 

Chronic thromboembolic pulmonary hypertension

CTPA: 

Computed tomography of the pulmonary angiography

DOAC: 

Direct oral anticoagulant

DVT: 

Deep vein thrombosis

IVC: 

Inferior vena cava

LMWH: 

Low-molecular weight heparin

PE: 

Pulmonary embolism

PESI: 

Pulmonary embolism severity index

SSPE: 

Sub-segmental pulmonary embolism

VKA: 

Vitamin K antagonists

VTE: 

Venous thromboembolism

Declarations

Acknowledgements

None.

Declaration

Publication fees for this article have been funded by APSTH 2016.

This article has been published as part of Thrombosis Journal Volume 14 Supplement 1, 2016. The full contents of the supplement are available at https://thrombosisjournal.biomedcentral.com/articles/supplements/volume-14-supplement-1.

Availability of data and material

Not applicable.

Authors’ contributions

SP and SS are responsible for writing and editing of the manuscript. Both authors read and approved the final manuscript.

Competing interests

Siavash Piran–nothing to disclose; Sam Schulman reports receiving consulting fees from Boehringer Ingelheim, Bristol-Myer-Squibb, Bayer and Daichii and grant support from Boehringer Ingelheim, Baxter and Octapharma.

Consent for publication

The authors consent to publication. No other consents are applicable.

Ethics approval and consent to participate

Not applicable.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
Department of Medicine, Division of Hematology and Thromboembolism, and Thrombosis and Atherosclerosis Research Institute, McMaster University

References

  1. White RH. The epidemiology of venous thromboembolism. Circulation. 2003;107(23 Suppl 1):14–8.Google Scholar
  2. Martinez C, Cohen AT, Bamber L, Rietbrock S. Epidemiology of first and recurrent venous thromboembolism: a population-based cohort study in patients without active cancer. Thromb Haemost. 2014;112:255–63.PubMedView ArticleGoogle Scholar
  3. ISTH Steering Committee for World Thrombosis Day. Thrombosis: a major contributor to global disease burden. Thromb Res. 2014;134:931–8.View ArticleGoogle Scholar
  4. Søgaard KK, Schmidt M, Pedersen L, Horváth-Puhó E, Sørensen HT. 30-year mortality after venous thromboembolism: a population-based cohort study. Circulation. 2014;130:829–36.PubMedView ArticleGoogle Scholar
  5. Prandoni P, Lensing AW, Cogo A, Cuppini S, Villalta S, Carta M, et al. The long-term clinical course of acute deep venous thrombosis. Ann Intern Med. 1996;125:1–7.PubMedView ArticleGoogle Scholar
  6. Pengo V, Lensing AW, Prins MH, Marchiori A, Davidson BL, Tiozzo F, et al. Incidence of chronic thromboembolic pulmonary hypertension after pulmonary embolism. N Engl J Med. 2004;350:2257–64.PubMedView ArticleGoogle Scholar
  7. LaMori JC, Shohieber O, Mody SH, Bookhart BK. Inpatient resource use and cost burden of deep vein thrombosis and pulmonary embolism in the United States. Clin Ther. 2015;37:62–70.PubMedView ArticleGoogle Scholar
  8. Spyropoulos AC, Lin J. Direct medical costs of venous thromboembolism and subsequent hospital readmission rates: an administrative claims analysis from 30 managed care organizations. J Manag Care Pharm. 2007;13:475–86.PubMedGoogle Scholar
  9. Donzé J, Le Gal G, Fine MJ, Roy PM, Sanchez O, Verschuren F, et al. Prospective validation of the Pulmonary Embolism Severity Index. A clinical prognostic model for pulmonary embolism. Thromb Haemost. 2008;100:943–8.PubMedGoogle Scholar
  10. Jiménez D, Aujesky D, Moores L, Gómez V, Lobo JL, Uresandi F, et al. Simplification of the pulmonary embolism severity index for prognostication in patients with acute symptomatic pulmonary embolism. Arch Intern Med. 2010;170:1383–9.PubMedView ArticleGoogle Scholar
  11. Zondag W, Kooiman J, Klok FA, Dekkers OM, Huisman MV. Outpatient versus inpatient treatment in patients with pulmonary embolism: a meta-analysis. Eur Respir J. 2013;42:134–44.PubMedView ArticleGoogle Scholar
  12. Piran S, Le Gal G, Wells PS, Gandara E, Righini M, Rodger MA, et al. Outpatient treatment of symptomatic pulmonary embolism: a systematic review and meta-analysis. Thromb Res. 2013;132:515–9.PubMedView ArticleGoogle Scholar
  13. Chatterjee S, Chakraborty A, Weinberg I, Kadakia M, Wilensky RL, Sardar P, et al. Thrombolysis for pulmonary embolism and risk of all-cause mortality, major bleeding, and intracranial hemorrhage: a meta-analysis. JAMA. 2014;311:2414–21.PubMedView ArticleGoogle Scholar
  14. Kearon C, Akl EA, Comerota AJ, Prandoni P, Bounameaux H, Goldhaber SZ, et al. Antithrombotic therapy for VTE disease: Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(2 Suppl):e419S–94.PubMedPubMed CentralView ArticleGoogle Scholar
  15. Schulman S, Kearon C, Kakkar AK, Mismetti P, Schellong S, Eriksson H, et al. Dabigatran versus warfarin in the treatment of acute venous thromboembolism. N Engl J Med. 2009;361:2342–52.PubMedView ArticleGoogle Scholar
  16. Schulman S, Kakkar AK, Goldhaber SZ, Schellong S, Eriksson H, Mismetti P, et al. Treatment of acute venous thromboembolism with dabigatran or warfarin and pooled analysis. Circulation. 2014;129:764–72.PubMedView ArticleGoogle Scholar
  17. EINSTEIN Investigators, Bauersachs R, Berkowitz SD, Brenner B, Buller HR, Decousus H, et al. Oral rivaroxaban for symptomatic venous thromboembolism. N Engl J Med. 2010;363:2499–510.View ArticleGoogle Scholar
  18. EINSTEIN-PE Investigators, Büller HR, Prins MH, Lensin AW, Decousus H, Jacobson BF, et al. Oral rivaroxaban for the treatment of symptomatic pulmonary embolism. N Engl J Med. 2012;366:1287–97.View ArticleGoogle Scholar
  19. Agnelli G, Buller HR, Cohen A, Curto M, Gallus AS, Johnson M, et al. Oral apixaban for the treatment of acute venous thromboembolism. N Engl J Med. 2013;369:799–808.PubMedView ArticleGoogle Scholar
  20. Hokusai-VTE Investigators, Büller HR, Décousus H, Grosso MA, Mercuri M, Middeldorp S, et al. Edoxaban versus warfarin for the treatment of symptomatic venous thromboembolism. N Engl J Med. 2013;369:1406–15.View ArticleGoogle Scholar
  21. Kearon C, Akl EA, Ornelas J, Blaivas A, Jimenez D, Bounameaux H, et al. Antithrombotic therapy for VTE disease: CHEST guideline and expert panel Report. Chest. 2016;149:315–52.PubMedView ArticleGoogle Scholar
  22. Enden T, Haig Y, Kløw NE, Slagsvold CE, Sandvik L, Ghanima W, et al. Long-term outcome after additional catheter-directed thrombolysis versus standard treatment for acute iliofemoral deep vein thrombosis (the CaVenT study): a randomised controlled trial. Lancet. 2012;379:31–8.PubMedView ArticleGoogle Scholar
  23. Watson L, Broderick C, Armon MP. Thrombolysis for acute deep vein thrombosis. Cochrane Database Syst Rev. 2014;1, CD002783.PubMedGoogle Scholar
  24. Bashir R, Zack CJ, Zhao H, Comerota AJ, Bove AA. Comparative outcomes of catheter-directed thrombolysis plus anticoagulation vs anticoagulation alone to treat lower-extremity proximal deep vein thrombosis. JAMA Intern Med. 2014;174:1494.PubMedView ArticleGoogle Scholar
  25. Laiho MK, Oinonen A, Sugano N, Harjola VP, Lehtola AL, Roth WD, et al. Preservation of venous valve function after catheter-directed and systemic thrombolysis for deep venous thrombosis. Eur J Vasc Endovasc Surg. 2004;28:391.PubMedView ArticleGoogle Scholar
  26. Vedantham S, Goldhaber SZ, Kahn SR, Julian J, Magnuson E, Jaff MR, et al. Rationale and design of the ATTRACT Study: a multicenter randomized trial to evaluate pharmacomechanical catheter-directed thrombolysis for the prevention of postthrombotic syndrome in patients with proximal deep vein thrombosis. Am Heart J. 2013;165:523–30.e3.PubMedPubMed CentralView ArticleGoogle Scholar
  27. Grifoni S, Olivotto I, Cecchini P, Pieralli F, Camaiti A, Santoro G, et al. Short-term clinical outcome of patients with acute pulmonary embolism, normal blood pressure, and echocardiographic right ventricular dysfunction. Circulation. 2000;101:2817–22.PubMedView ArticleGoogle Scholar
  28. Sharifi M, Bay C, Skrocki L, Rahimi F, Mehdipour M. Moderate pulmonary embolism treated With thrombolysis (from the “MOPETT” Trial). Am J Cardiol. 2013;111:273–7.PubMedView ArticleGoogle Scholar
  29. Kline JA, Nordenholz KE, Courtney DM, Kabrhel C, Jones AE, Rondina MT, et al. Treatment of submassive pulmonary embolism with tenecteplase or placebo: cardiopulmonary outcomes at 3 months: multicenter double-blind, placebo-controlled randomized trial. J Thromb Haemost. 2014;12:459–68.PubMedView ArticleGoogle Scholar
  30. Meyer G, Vicaut E, Danays T, Agnelli G, Becattini C, Beyer-Westendorf J, et al. Fibrinolysis for patients with intermediate-risk pulmonary embolism. N Engl J Med. 2014;370:1402–11.PubMedView ArticleGoogle Scholar
  31. McCabe JM, Huang PH, Riedl L, Eisenhauer AC, Sobieszczyk P. Usefulness and safety of ultrasound-assisted catheter-directed thrombolysis for submassive pulmonary emboli. Am J Cardiol. 2015;115:821–4.PubMedView ArticleGoogle Scholar
  32. Kuo WT, Banerjee A, Kim PS, DeMarco Jr FJ, Levy JR, Facchini FR, et al. Pulmonary embolism response to fragmentation, embolectomy, and catheter thrombolysis (PERFECT): initial results from a prospective multicenter registry. Chest. 2015;148:667–73.PubMedView ArticleGoogle Scholar
  33. Kucher N, Boekstegers P, Müller OJ, Kupatt C, Beyer-Westendorf J, Heitzer T, et al. Randomized, controlled trial of ultrasound-assisted catheter-directed thrombolysis for acute intermediate-risk pulmonary embolism. Circulation. 2014;129:479–86.PubMedView ArticleGoogle Scholar
  34. Koopman MM, Prandoni P, Piovella F, Ockelford PA, Brandjes DP, van der Meer J, et al. Treatment of venous thrombosis with intravenous unfractionated heparin administered in the hospital as compared with subcutaneous low-molecular-weight heparin administered at home. The Tasman Study Group. N Engl J Med. 1996;334:682–7.PubMedView ArticleGoogle Scholar
  35. Levine M, Gent M, Hirsh J, Leclerc J, Anderson D, Weitz J, et al. Comparison of low-molecular-weight heparin administered primarily at home with unfractionated heparin administered in the hospital for proximal deep-vein thrombosis. N Engl J Med. 1996;334:677–81.PubMedView ArticleGoogle Scholar
  36. Segal JB, Bolger DT, Jenckes MW, Krishnan JA, Streiff MB, Eng J, et al. Outpatient therapy with low molecular weight heparin for the treatment of venous thromboembolism: a review of efficacy, safety, and costs. Am J Med. 2003;115:298–308.PubMedView ArticleGoogle Scholar
  37. Douketis JD. Treatment of deep vein thrombosis: what factors determine appropriate treatment? Can Fam Physician. 2005;51:217–23.PubMedPubMed CentralGoogle Scholar
  38. Aujesky D, Roy PM, Verschuren F, Righini M, Osterwalder J, Egloff M, et al. Outpatient versus inpatient treatment for patients with acute pulmonary embolism: an international, open-label, randomised, non-inferiority trial. Lancet. 2011;378:41–8.PubMedView ArticleGoogle Scholar
  39. van Es N, Coppens M, Schulman S, Middeldorp S, Büller HR. Direct oral anticoagulants compared with vitamin K antagonists for acute venous thromboembolism: evidence from phase 3 trials. Blood. 2014;124:1968–75.PubMedView ArticleGoogle Scholar
  40. Lyman GH, Khorana AA, Kuderer NM, Lee AY, Arcelus JI, Balaban EP, et al. Venous thromboembolism prophylaxis and treatment in patients with cancer: American Society of Clinical Oncology clinical practice guideline update. J Clin Oncol. 2013;31:2189–204.PubMedView ArticleGoogle Scholar
  41. Engman CA, Zacharski LR. Low molecular weight heparins as extended prophylaxis against recurrent thrombosis in cancer patients. J Natl Compr Canc Netw. 2008;6:637–45.PubMedGoogle Scholar
  42. Prandoni P, Lensing AW, Piccioli A, Bernardi E, Simioni P, Girolami B, et al. Recurrent venous thromboembolism and bleeding complications during anticoagulant treatment in patients with cancer and venous thrombosis. Blood. 2002;100:3484–8.PubMedView ArticleGoogle Scholar
  43. Meyer G, Marjanovic Z, Valcke J, Lorcerie B, Gruel Y, Solal-Celigny P, et al. Comparison of low-molecular-weight heparin and warfarin for the secondary prevention of venous thromboembolism in patients with cancer: a randomized controlled study. Arch Intern Med. 2002;162:1729–35.PubMedView ArticleGoogle Scholar
  44. Lee AY, Levine MN, Baker RI, Bowden C, Kakkar AK, Prins M, et al. Low-molecular-weight heparin versus a coumarin for the prevention of recurrent venous thromboembolism in patients with cancer. N Engl J Med. 2003;349:146–53.PubMedView ArticleGoogle Scholar
  45. Hull RD, Pineo GF, Brant RF, Mah AF, Burke N, Dear R, et al. Long-term low-molecular-weight heparin versus usual care in proximal-vein thrombosis patients with cancer. Am J Med. 2006;119:1062–72.PubMedView ArticleGoogle Scholar
  46. Deitcher SR, Kessler CM, Merli G, Rigas JR, Lyons RM, Fareed J, et al. Secondary prevention of venous thromboembolic events in patients with active cancer: enoxaparin alone versus initial enoxaparin followed by warfarin for a 180-day period. Clin Appl Thromb Hemost. 2006;12:389–96.PubMedView ArticleGoogle Scholar
  47. Lee AY, Kamphuisen PW, Meyer G, Bauersachs R, Janas MS, Jarner MF, et al. Tinzaparin vs warfarin for treatment of acute venous thromboembolism in patients with active cancer: A randomized clinical trial. JAMA. 2015;314:677–86.PubMedView ArticleGoogle Scholar
  48. Vedovati MC, Germini F, Agnelli G, Becattini C. Direct oral anticoagulants in patients with VTE and cancer: a systematic review and meta-analysis. Chest. 2015;147:475–83.PubMedView ArticleGoogle Scholar
  49. van Es N, Di Nisio M, Bleker SM, Segers A, Mercuri MF, Schwocho L, et al. Edoxaban for treatment of venous thromboembolism in patients with cancer. Rationale and design of the Hokusai VTE-cancer study. Thromb Haemost. 2015;114:1268–76.PubMedView ArticleGoogle Scholar
  50. Agnelli G, Buller HR, Cohen A, Curto M, Gallus AS, Johnson M, et al. Apixaban for extended treatment of venous thromboembolism. N Engl J Med. 2013;368:699–708.PubMedView ArticleGoogle Scholar
  51. Schulman S, Kearon C, Kakkar AK, Schellong S, Eriksson H, Baanstra D, et al. Extended use of dabigatran, warfarin, or placebo in venous thromboembolism. N Engl J Med. 2013;368:709–18.PubMedView ArticleGoogle Scholar
  52. Becattini C, Agnelli G, Schenone A, Eichinger S, Bucherini E, Silingardi M, et al. Aspirin for preventing the recurrence of venous thromboembolism. N Engl J Med. 2012;366:1959–67.PubMedView ArticleGoogle Scholar
  53. Brighton TA, Eikelboom JW, Mann K, Mister R, Gallus A, Ockelford P, et al. Low-dose aspirin for preventing recurrent venous thromboembolism. N Engl J Med. 2012;367:1979–87.PubMedView ArticleGoogle Scholar
  54. Simes J, Becattini C, Agnelli G, Eikelboom JW, Kirby AC, Mister R, et al. Aspirin for the prevention of recurrent venous thromboembolism: the INSPIRE collaboration. Circulation. 2014;130:1062–71.PubMedView ArticleGoogle Scholar
  55. Castellucci LA, Cameron C, Le Gal G, Rodger MA, Coyle D, Wells PS, et al. Efficacy and safety outcomes of oral anticoagulants and antiplatelet drugs in the secondary prevention of venous thromboembolism: systematic review and network meta-analysis. BMJ. 2013;347:f5133.PubMedPubMed CentralView ArticleGoogle Scholar
  56. Wiener RS, Schwartz LM, Woloshin S. When a test is too good: how CT pulmonary angiograms find pulmonary emboli that do not need to be found. BMJ. 2013;347:f3368.PubMedPubMed CentralView ArticleGoogle Scholar
  57. Carrier M, Righini M, Le Gal G. Symptomatic subsegmental pulmonary embolism: what is the next step? J Thromb Haemost. 2012;10:1486–90.PubMedView ArticleGoogle Scholar
  58. Stein PD, Goodman LR, Hull RD, Dalen JE, Matta F. Diagnosis and management of isolated subsegmental pulmonary embolism: review and assessment of the options. Clin Appl Thromb Hemost. 2012;18:20–6.PubMedView ArticleGoogle Scholar
  59. Musset D, Parent F, Meyer G, Maître S, Girard P, Leroyer C, et al. Diagnostic strategy for patients with suspected pulmonary embolism: a prospective multicentre outcome study. Lancet. 2002;360:1914–20.PubMedView ArticleGoogle Scholar
  60. Eyer BA, Goodman LR, Washington L. Clinicians' response to radiologists’ reports of isolated subsegmental pulmonary embolism or inconclusive interpretation of pulmonary embolism using MDCT. AJR Am J Roentgenol. 2005;184:623–8.PubMedView ArticleGoogle Scholar
  61. Donato AA, Khoche S, Santora J, Wagner B. Clinical outcomes in patients with isolated subsegmental pulmonary emboli diagnosed by multidetector CT pulmonary angiography. Thromb Res. 2010;126:e266–70.PubMedView ArticleGoogle Scholar
  62. Pena E, Kimpton M, Dennie C, Peterson R, LE Gal G, Carrier M. Difference in interpretation of computed tomography pulmonary angiography diagnosis of subsegmental thrombosis in patients with suspected pulmonary embolism. J Thromb Haemost. 2012;10:496–8.PubMedView ArticleGoogle Scholar
  63. Mehta D, Barnett M, Zhou L, Woulfe T, Rolfe-Vyson V, Rowland V, et al. Management and outcomes of single subsegmental pulmonary embolus: a retrospective audit at North Shore Hospital. New Zealand Intern Med J. 2014;44:872–6.PubMedGoogle Scholar
  64. Goy J, Lee J, Levine O, Chaudhry S, Crowther M. Sub-segmental pulmonary embolism in three academic teaching hospitals: a review of management and outcomes. J Thromb Haemost. 2015;13:214–8.PubMedView ArticleGoogle Scholar
  65. Ghazvinian R, Gottsäter A, Elf J. Is it safe to withhold long-term anticoagulation therapy in patients with small pulmonary emboli diagnosed by SPECT scintigraphy? Thromb J. 2016;14:12.PubMedPubMed CentralView ArticleGoogle Scholar
  66. den Exter PL, van Es J, Klok FA, Kroft LJ, Kruip MJ, Kamphuisen PW, et al. Risk profile and clinical outcome of symptomatic subsegmental acute pulmonary embolism. Blood. 2013;122:1144–9.View ArticleGoogle Scholar
  67. White RH, Brunson A, Romano PS, Li Z, Wun T. Outcomes after vena cava filter use in non-cancer patients with acute venous thromboembolism: A population-based study. Circulation. 2016;133:2018–29.PubMedView ArticleGoogle Scholar
  68. Decousus H, Leizorovicz A, Parent F, Page Y, Tardy B, Girard P, et al. A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep-vein thrombosis. Prévention du Risque d’Embolie Pulmonaire par Interruption Cave Study Group. N Engl J Med. 1998;338:409–15.PubMedView ArticleGoogle Scholar
  69. PREPIC Study Group. Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism: the PREPIC (Prevention du Risque d’Embolie Pulmonaire par Interruption Cave) randomized study. Circulation. 2005;112:416–22.View ArticleGoogle Scholar
  70. Mismetti P, Laporte S, Pellerin O, Ennezat PV, Couturaud F, Elias A, et al. Effect of a retrievable inferior vena cava filter plus anticoagulation vs anticoagulation alone on risk of recurrent pulmonary embolism: a randomized clinical trial. JAMA. 2015;313:1627–35.PubMedView ArticleGoogle Scholar
  71. Streiff MB. Vena caval filters: a comprehensive review. Blood. 2000;95:3669–77.PubMedGoogle Scholar
  72. Wu A, Helo N, Moon E, Tam M, Kapoor B, Wang W. Strategies for prevention of iatrogenic inferior vena cava filter entrapment and dislodgement during central venous catheter placement. J Vasc Surg. 2014;59:255–9.PubMedView ArticleGoogle Scholar

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