Inferior Vena Cava Filters for Prevention of Pulmonary Embolism
from the ACCP Guidelines, 9th Ed.
Inferior vena cava filters should generally be placed in patients with acute pulmonary embolism (PE) or deep venous thrombosis (DVT) who have a contraindication to anticoagulation, according to the ACCP’s recommendations. The ACCP recommends against placing an IVC filter in patients with PE or DVT who are being treated with anticoagulants.
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, strong recommendation based on moderate strength evidence).
- 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)
The first recommendation above would seem to advise against the common practice of placing an IVC filter in certain patients with large DVTs who are felt to be high risk due to their “clot burden” and its potential for producing a life-threatening PE despite anticoagulation. However, the intention may be more that ACCP are trying to discourage physicians from routinely treating patients with “ordinary” PEs with both anticoagulation and IVC filters.
In support of this, the ACCP describes one observational study from an international registry that suggested IVC filter placement in patients with massive PE (i.e., with hypotension) was associated with a reduction in the combined endpoint of mortality and recurrent PE. At other points in the document they refer to the possibility of using IVC filters as an “adjunct to anticoagulation,” presumably in selected patients.
Which patients with deep venous thrombosis (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, strong recommendation with moderate quality evidence)
- If such a patient with acute proximal DVT has an IVC filter placed, but then her risk of bleeding declines (after surgery, for example), ACCP suggests starting anticoagulation therapy for the usual duration. (Grade 2B, suggestion from moderate evidence)
- 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 (non-removable) 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. (Not graded.)
Should patients with chronic thromboembolic pulmonary hypertension (CTPH) receive inferior vena cava filters prior to planned pulmonary thromboendarterectomy?
Placement of a permanent IVC filter in patients with chronic thromboembolic pulmonary hypertension (CTPH or CTEPH) is a common practice, as a precautionary measure prior to pulmonary endarterectomy. Such patients are also often treated with anticoagulation therapy for an indefinite period. The ACCP notes the lack of evidence for IVC filters in this area and doesn’t state an opinion on the matter.
Should patients with upper extremity DVT undergo placement of superior vena cava (SVC) filters?
The ACCP doesn’t make an explicit recommendation. However, they note that the complication rates after SVC filter placement seem higher than after IVC filter placement. Since there is potential to hurt patients with this procedure, and any benefits are not established, they mention that “their use should be confined to exceptional circumstances in specialized centers.”
Important Facts about IVC Filters for DVT or PE
- No prospective observational or randomized trial has examined IVC filter placement as a single therapy (without anticoagulation) in acute DVT.
- The 1998 PREPIC study and its 8 year follow-up suggested that IVC filters reduce the risk of PE, while increasing the risk of recurrent DVT, and do not reduce all-cause mortality; they also do not increase the risk of post-thrombotic syndrome. However, it’s essential to note that the patients in PREPIC were also prescribed anticoagulation, so comparing their outcomes to patients with IVC filters alone is unwise. This, along with the increased risk of DVT after IVC filter placement, contributed to ACCP’s weak recommendation to provide anticoagulation to patients with IVC filters if their bleeding risk declines.
- Most “retrievable” IVC filters are not removed, in real-world practice. Retrievable filters may have a higher complication rate over the long term than permanent IVC filters, and there’s no evidence their outcomes are better (removed or not).
Although DVT and PE are often considered together, that’s not because they’re the same; rather, it’s a tactic researchers use to reduce the necessary sample sizes to detect effects in clinical studies. The risk of death within one month, or from a later recurrent PE, is far higher after presenting with an initial PE than when presenting after DVT. Decisions about anticoagulation and IVC filter placement over the short and long term should be made with this distinction in mind.
Kearon C 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 (suppl 2): e419-e494S