IVC (Caval) filters current knowledge and uncertainties

IVC Filters in preventing pulmonary embolism: Current knowledge and uncertainties

Roshan Gunathilake MD

John Hunter Hospital, Newcastle

Australia

Objectives

1. Describe the rationale for the use of vena caval filters

2. Examine the available evidence of caval filter efficacy

3. Discuss common complications of IVC filters

4. Review the existing guidelines for filter placement

Anticoagulation decreases recurrence of PE and related mortality

Barritt and Jordan, 1960• 35 clinically diagnosed PE (severe end of

spectrum)• 14 days follow up • with or without anticoagulation

o↓Recurrent PE (0/16 vs. 10/19)o↓Mortality (1/16 vs. 5/19)

Lancet 1309-12, 1960

In patients with VTE treated with VKA, initial parenteral anticoagulation was superior to placebo

Brandjes et al., NEJM 1992; 327: 1485-9

Heparin+ VKA (n=60)

Placebo+ VKA (n=60)

VTE symptomatic extension / recurrence

6.7% 20% P=0.058

VTE asymptomatic extension

8.2% 39.6% p=<0.001

Major bleeding 3% 5% NS

Extended anticoagulation beyond 3 months after idiopathic VTE ↓recurrent events but is associated with ↑risk of bleeding

Kearon et al., N Engl J Med 1999;340:901-7

Balancing risks vs. benefits

Risk of recurrent VTE/PE• Unprovoked VTE or

persistent risk factor: ≈10% recurrence in the first year

• Case fatality 10% for recurrent VTE, 30% for PE

Risk of bleeding• Risk of major bleeding

≈2% per year• Absolute increase 1-1.5%• Case fatality rate 10%• = 0.2% annual rate of

fatal bleeding

Circulation.2004; 110: I10-18

We have robust data to justify using anticoagulation to prevent VTE

Carrier et al., Ann Intern Med 2010;152:578-589

• Based on current evidence, anticoagulation remains the primary treatment for VTE

In selected patient populations the risk of bleeding outweigh the benefits of anticoagulation

Contraindications to anticoagulation

Haemorrhagic stroke

Recent major trauma or surgery

Bleeding complicating anticoagulation

Thrombocytopenia <50,000/mm3

CNS neoplasm, aneurysm or AVM

Thrombocytopenia <50,000/mm3

• When anticoagulation is contraindicated or there are additional risk factors, caval interruption is an important alternative or add-on treatment strategy to be considered

Caval interruption: Historical Background

• 1846 - Rudolph Virchow – Pulmonary emboli originate in the leg veins

• 1868 - Armand Trousseau – Suggested a physical barrier to migration of emboli

• 1874 - John Hunter - Femoral vein ligation - modified by John Homans in 1930s

• 1940s – Ochner and DeBakey - IVC ligation• 1960s - Approaches to filter rather than occlude

the IVC• 1973 - Stainless steel Greenfield filter

Where is the evidence?

IVC Filter Efficacy: Prevention du Risque d’Embolie Pulmonaire par Interruption Cave (PREPIC) study

• 400 patients with acute proximal DVT at high risk of PE• Randomized to IVC filter or no filter• Heparin/enoxaparin, and warfarin for 3 months• V/Q scans and/or pulmonary angiography:

– Baseline, day 12, and if symptoms developed• Followed up for 8 years• Filters used:

– Greenfield, Bird’s nest, VenaTech, Cardial

Decousus et al., NEJM 1998;338:409-15

PREPIC study : IVC filters reduce the early risk of PE in high risk patients receiving anticoagulation


PREPIC study :Initial beneficial effect was counterbalanced by an excess of recurrent DVT


PREPIC study : At 8 years, filters reduced the risk of PE but increased the risk of recurrent DVT

57/20035.7%

41/20027.5%

24/20015.1%

9/2006.2%

PREPIC study : At 8 years filters conferred no survival benefit

PREPIC study : findings in a nut-shell

• In addition to anticoagulation, the use of permanent filters reduces the occurrence of PE, without changing either immediate or long term-mortality

• Permanent filters lose their initial benefit in preventing PE by increasing the morbidity of long term recurrence of DVT

• No randomized trials or prospective cohort studies have evaluated IVC filters as sole therapy for acute PE

• Retrospective population-based observational study

• 1547 patients with documented VTE• 203 (13%) received IVC filter• Median duration of follow up ≈ 926 days

.

Worcestor VTE study

Worcestor VTE study: IVC filter-treated patients tend to have a ↓cumulative incidence of PE and ↑DVTs

1.7%

5.3%

Spenser et al., Arch Intern med 2010; 170(16)1456-1462

Worcestor study: Filter–treated arm had higher all-cause mortality study:

Spenser et al., Arch Intern med 2010; 170(16)1456-1462

Retrievable filters

• Retrievable filters were developed to take advantage of short term PE prevention benefits, without the long-term disadvantages of increasing DVTs

Retrievable IVC filters: did they fix it all?

• Systematic review of 37 studies, 6834 patients• 11 prospective, none randomized • 3667 (58%) prophylactic, 2702 (42%)

therapeutic• Average follow up 10 months (range 2-25)

Angel et al., J Vasc Interv Radiol 2011; 22: 1522-1530

Benefits of retrievable filters in preventing PE are comparable to reported rates of PREPIC study


PREPIC study 1.1%Worcetor study 1.7%Carrier et al., Medical therapy 1.7%

Retrievable filters: Adverse outcomes

• Complication rates of retrievable filters are low, time-dependant (> 30 days), and possibly device-dependant (but no prospective data)


Long-term risks of vena cava filters include deep vein and caval thrombosis


The most common unanticipated complications are perforation, migration and fracture of filters


Most “retrievable” IVC filters are not removed, in real-world practice

• Retrieval rate 34% (range 12-45%)• Average time to retrieval 72 days• Mean follow up after filter placement 10 months (range2-

25 months)• Overall retrieval failure rate 5.5%, increased with time -

Most common causes were tilting (43%), adherence to the IVC wall (39%), and large clot burden (18%)

• Most common reasons for not removing filter were loss to follow up and continued risk


In 2010, FDA issued a warning about the risks of leaving behind retrievable filters

Physicians should remove the filters once the danger of PE has passed

“FDA recommends that implanting physicians and clinicians responsible for the ongoing care of patients with retrievable IVC filters consider removing the filter as soon as protection from PE is no longer needed.”

• Based on the evidence, it is not reasonable to withhold an IVC filter from a high risk patient who is not a candidate for anticoagulation.

• Using a caval filter in addition to anticoagulation probably carries a complication rate which may not be worth the small benefit.

Place for use of concomitant anticoagulation after filter insertion is uncertain

• Meta-analysis of 14 studies • Evaluated rates of VTE after IVC filter placement (with or

without concomitant anticoagulation)• Non-statistically significant trend toward fewer VTE

events with concomitant anticoagulation (OR 0.64, 95% CI 0.35-1.2)

Ray et al., Cardiovasc Intervent Radiol. 2008; 31(2):316-324.

Other indications for IVC filter use that are not supported by the current literature

• Prospective studies that address the prophylactic use of IVC filters are lacking

• There is currently insufficient data to support the use of IVC filters for such situations as:

• recurrent VTE on anticoagulation• chronic recurrent PE with pulmonary hypertension• extensive free-floating ilio-femoral thrombus, and • post-thrombolysis of ilio-caval thrombus

ACCP Guidelines: Which patients with acute pulmonary embolism should receive inferior vena cava filters?

• The ACCP recommends not placing IVC filters in patients with acute PE who are being treated with anticoagulant therapy (Grade 1B)

• They recommend placing IVC filters in patients with acute PE who have a contraindication to anticoagulation. (Grade 1B)

• In such patients, ACCP recommends starting anticoagulation for the usual treatment period (e.g., 6 months), if the patient’s risk of bleeding declines after IVC filter placement. (Grade 2B)

ACCP Guidelines: Which patients with DVT should receive inferior vena cava filters?

• The ACCP recommends placement of an IVC filter for patients with acute proximal DVT of the leg who have a contraindication to anticoagulation. (Grade 1B)

• They recommend against placing an IVC filter as an additional protective therapy in patients with acute DVT who are being treated with anticoagulants. (Grade 1B).

• For patients with permanent IVC filters, the ACCP does not feel long-term anticoagulation is required simply to prevent DVT or PE that might result from the IVC filter itself.

Summary

• VTE is associated with significant morbidity and mortality, and PE is its most severe manifestation

• Primary means of therapy and prophylaxis of VTE are pharmacologic

• Vena caval filters are a valuable second line of defense against PE when anticoagulation is contraindicated

• Limited data support the efficacy of vena caval filters

• Improvement in retrieval rate may help balance the risk-benefit profile of retrievable filters

Healthcare

IVC (Caval) filters current knowledge and uncertainties