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Vena cava filter as anticoagulation add-on did not reduce symptomatic recurrent pulmonary embolism
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The risk for symptomatic recurrent pulmonary embolism does not appear to diminish among patients hospitalized for a life-threatening blood clot in the lung when a retrievable inferior vena cava filter is added to anticoagulation, according to researchers.
“The availability of retrievable inferior vena cava filters has probably contributed to the increasing use of filters for managing acute venous thromboembolism, including their use in addition to full-dose anticoagulant therapy in patients with pulmonary embolism, a large clot burden, a poor cardiopulmonary reserve, or a suspected increased risk for recurrence, as advocated by several guidelines,” the researchers wrote. “The results of the present study do not support such a strategy.”
In the randomized, open-label PREPIC2 trial, Patrick Mismetti, MD, PhD, of the University Hospital of Saint-Etienne, France and colleagues looked at patients aged at least 18 years who were hospitalized for acute, symptomatic pulmonary embolism linked with lower-limb vein thrombosis and had at least one of the defined severity criteria.
Patients from 17 French centers were assigned to either a retrievable inferior vena cava filter implant plus anticoagulation (n = 200) or anticoagulation alone (n = 199). The study had a 6-month ambulatory follow-up and blinded end point; filter retrieval was planned for 3 months after placement.
The investigators primarily looked at symptomatic recurrent pulmonary embolism at 3 months; with recurrent pulmonary embolism at 6 months, symptomatic deep vein thrombosis, major bleeding and death at 3 and 6 months; and filter complications as secondary outcomes.
Filters were successfully implanted in 193 patients. Retrieval was attempted in 164 patients and went as planned in 153 patients.
At 3 months, recurrent pulmonary embolism had occurred in six patients (3%; all fatal) with a filter and three patients (1.5%; 2 fatal) with anticoagulation alone (RR with filter = 2; 95% CI, 0.51-7.89). Similar results were seen at 6 months.
For the secondary outcomes, no difference was observed between groups at 3 or 6 months. Filter thrombosis occurred in three patients.
Observational studies have demonstrated a surge in the placement of inferior vena cava filters over the past 3 decades, including as adjunct to anticoagulant in patients presenting with a blood clot, but the ratio of benefit to risk has to-date remained uncertain, according to the researchers.
“These findings do not support the use of this type of filter in patients who can be treated with anticoagulation,” the researchers wrote. – by Allegra Tiver
Disclosure: Mismetti reports receiving research grants from Bayer and fees for board memberships from Bayer, Bristol-Myers Squibb/Pfizer, and Daiichi Sankyo; for lectures from Bayer, Boehringer Ingelheim, Bristol-Myers Squibb/Pfizer, Daiichi Sankyo, and Sanofi-Aventis; and for development of educational presentations from Bayer and Bristol-Myers Squibb/Pfizer. Please see the full study for a list of all other authors’ relevant financial disclosures.
Perspective
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Nigel Key, MB, CHB, FRCP
Anticoagulation, when done properly, is a highly effective treatment in preventing recurrent pulmonary embolism and deep venous thrombosis, as the researchers show. Therefore, it is challenging to design a study comparing a new or additional intervention to a treatment that is so effective.
This issue has applied to studies that have aimed to show novel anticoagulants are superior to the traditional standard, as well as studies such as this, using adjunctive therapies like inferior vena cava (IVC) filters.
That said, this is a well-conducted randomized clinical trial; the researchers did make an effort to look at patients who would be considered at higher risk of pulmonary embolism recurrence, such as those with cancer or impaired cardiac or pulmonary reserve.
However, why the researchers chose this particular design is not entirely clear to me, since the up-front insertion of IVC filters in patients being treated with full intensity anticoagulation does not reflect the standard of care, at least in the U.S. It is possible the study design is more reflective of practice in France.
There are very few randomized clinical trials of IVC filters, and we definitely need more because they are being used everywhere for all types of indications, as the researchers point out.
References:
Decousus H, et al. N Engl J Med. 1998;338(7):409-415.
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