by By Harjit Bhogal, MD, Shaker Eid, MD, Melinda Kantsiper, MD, Division of Hospital Medicine, Johns Hopkins Bayview Medical Center, Baltimore
A 67-year-old man with a history of hypertension presents with a swollen right lower extremity. An ultrasound reveals a DVT, and he is commenced on low-molecular-weight heparin and warfarin. Two days later, he develops slurred speech and right-sided weakness. A head CT reveals an intracranial hemorrhage. When should an inferior vena cava (IVC) filter be utilized for treatment of DVT?
It is estimated that 350,000 to 600,000 Americans develop a VTE each year.1 Patients with a DVT are at high risk of developing a pulmonary embolism (PE). In a multicenter study, nearly 40% of patients admitted with a DVT had evidence of a PE on ventilation perfusion scan.2 Treatment of a DVT is aimed at preventing the extension of the DVT and embolization.3 The American College of Chest Physicians (ACCP) recommends anticoagulation as the primary DVT treatment (Grade 1A).4 However, IVC filters might be considered when anticoagulation is contraindicated.
In 1868, Trousseau created the conceptual model of surgical interruption of the IVC to prevent PE. However, it wasn’t until 1959 by Bottini that the surgical interruption was successfully performed.5 The Mobin-Uddin filter was introduced in 1967 as the first mechanical IVC filter.6 IVC filters mechanically trap the DVT, preventing emboli from traveling into the pulmonary vasculature.7
There are two classes of IVC filters: permanent filters and removable filters. Removable filters include both temporary filters and retrievable filters. Temporary filters are attached to a catheter that exits the skin and therefore must be removed due to the risk of infection and embolization.7 Retrievable filters are similar in design to permanent filters but are designed to be removed. However, this must be done with caution, as neointimal hyperplasia can prevent removal or cause vessel wall damage upon removal.8
IVC filters are inserted into the vena cava percutaneously via the femoral or jugular approach under fluoroscopy or ultrasound guidance (see Figure 1, p. 16). The filters typically are placed infrarenally, unless there is an indication for a suprarenal filter (e.g., renal vein thrombosis or IVC thrombus extending above the renal veins).7 Complete IVC thrombosis is an absolute contraindication to IVC filter placement, and the relative contraindications include significant coagulopathy and bacteremia.9
The incidence of complications related to IVC filter placement is 4% to 11%. Complications include:
A review of the National Hospital Discharge Survey database for trends in IVC filter use in the U.S. found a dramatic increase in the use of IVC filters from 1979 to 1999—to 49,000 patients from 2,000 patients with IVC filters in place. The indications for IVC filter use vary such that it is imperative there are well-designed trials and guidelines to guide appropriate use.11
The 2008 ACCP guidelines on VTE management follow a grading system that classifies recommendations as Grade 1 (strong) or Grade 2 (weak), and classifies the quality of evidence as A (high), B (moderate), or C (low).12 The ACCP guidelines’ recommended first-line treatment for a confirmed DVT is anticoagulation with subcutaneous low-molecular-weight heparin, intravenous unfractionated heparin, monitored subcutaneous heparin, fixed-dose subcutaneous unfractionated heparin, or subcutaneous fondaparinux (all Grade 1A recommendations). The ACCP recommends against the routine use of an IVC filter in addition to anticoagulants (Grade 1A). However, for patients with acute proximal DVT, if anticoagulant therapy is not possible because of the risk of bleeding, IVC filter placement is recommended (Grade 1C). If a patient requires an IVC filter for treatment of an acute DVT as an alternative to anticoagulation, it is recommended to start anticoagulant therapy once the risk of bleeding resolves (Grade 1C).4
The 2008 ACCP guidelines for IVC filter use have a few important changes from the 2004 version. First, the IVC filter placement recommendation for patients with contraindications to anticoagulation was strengthened from Grade 2C to Grade 1C. Second, the 2008 guidelines omitted the early recommendation of IVC filter use for recurrent VTE, despite adequate anticoagulation (Grade 2C).13
Only one randomized study has evaluated the efficacy of IVC filters. All other studies of IVC filters are retrospective or prospective case series.
The PREPIC study randomized 400 patients with proximal DVT considered to be at high risk for PE to receive either an IVC filter or no IVC filter. Additionally, patients were randomized to receive enoxaparin or unfractionated heparin as a bridge to warfarin therapy, which was continued for at least three months. The primary endpoints were recurrent DVT, PE, major bleeding, or death. The patients were followed up at day 12, two years, and then annually up to eight years following randomization.14 At day 12, there were fewer PEs in the group that received filters (OR 0.22, 95% CI, 0.05-0.90). However, at year two, there was no significant difference in PE development in the filter group compared with the no-filter group (OR 0.50, 95% CI, 0.19-1.33).
Additionally, at year two, the filter group was more likely to develop recurrent DVT (OR 1.87, 95% CI, 1.10-3.20). At year eight, there was a significant reduction in the number of PEs in the filter group versus the no-filter group (6.2% vs.15.1%, P=0.008). However, at eight-year followup, IVC filter use was associated with increased DVT (35.7% vs. 27.5%, P=0.042). There was no difference in mortality between the two groups.
In summary, the use of IVC filters was associated with decreased incidence of PE at eight years, offset by higher rates of recurrent DVT and no overall mortality benefit.14,15 Importantly, the indications for IVC filter use in this study differ from the current ACCP guidelines; all patients were given concomitant anticoagulation for at least three months, which might not be possible in patients for whom the ACCP recommends IVC filters.
There are no randomized studies to compare the efficacy of permanent IVC filters and retrievable filters for PE prevention. A retrospective study comparing the clinical effectiveness of the two filter types reported no difference in the rates of symptomatic PE (permanent filter 4% vs. retrievable filter 4.7%, P=0.67) or DVT (11.3% vs. 12.6%, P=0.59). In addition, the frequency of symptomatic IVC thrombosis was similar (1.1% vs. 0.5%, p=0.39).16 A paper reviewing the efficacy of IVC filters reported that permanent filters were associated with a 0%-6.2% rate of PE versus a 0%-1.9% rate with retrievable filters.7 Notably, these studies were not randomized controlled trials—rather, case series—and the indications for IVC filters were not necessarily those currently recommended by the ACCP.
Due to the long-term complications of permanent IVC filters, it is suggested that a retrievable IVC filter be used for patients with temporary contraindications to anticoagulation.17 Comerata et al created a clinical decision-making tool for picking the type of filter to employ. If the duration of contraindication to anticoagulation is short or uncertain, a retrievable filter is recommended.18 Table 1 (p. 15) outlines the recommendations for IVC filter placement.
There are no randomized controlled trials to guide the use of concomitant anticoagulation after filter insertion, although this intervention may be beneficial to prevent DVT propagation, recurrence, or IVC filter thrombosis.5 A meta-analysis of 14 studies evaluating the rates of VTE after IVC filter placement demonstrated a non-statistically significant trend toward fewer VTE events in the patients with an IVC filter and concomitant anticoagulation in comparison with those who solely had an IVC filter (OR 0.64, 95% CI, 0.35-1.2). The duration and degree of anticoagulation was not presented in all of the studies in the meta-analysis, therefore limiting the analysis.19
In addition to the ACCP guidelines, there have been other proposed indications for IVC filter use, including recurrent VTE despite anticoagulation, chronic recurrent PE with pulmonary hypertension, extensive free-floating iliofemoral thrombus, and thrombolysis of ilio-caval thrombus.20 The ACCP guidelines do not specifically address these individual indications, and at this time there are no randomized controlled trials to guide IVC filter use in these cases.
Our patient developed a significant complication from anticoagulation. Current ACCP guidelines recommend an IVC filter if anticoagulant therapy is contraindicated (Grade 1C). The anticoagulation was discontinued and a retrievable IVC filter was placed. Once a patient no longer has a contraindication for anticoagulation, the ACCP recommends restarting a conventional course of anticoagulation. Thus, once the patient can tolerate anticoagulation, consideration will be given to removal of the retrievable filter.
An IVC filter should be considered in patients with a DVT who have a contraindication to anticoagulation. Other indications for IVC filter use are not supported by the current literature. TH
Drs. Bhogal and Eid are hospitalist fellows and instructors at Johns Hopkins Bayview Medical Center in Baltimore. Dr. Kantsiper is a hospitalist and assistant professor at Bayview Medical Center.
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