Letters to the Editor
Don’t Fear the Filter
December 2015 issue
To the Editor: As an interventional radiologist who specializes
in acute and chronic deep-vein thrombosis (DVT), superficial
venous disease, and complex filter removal, I applaud Joseph M.
Stavas, MD, and Anita Rajasekhar, MD, for discussing a topic
that is not well understood by many physicians, including those
who actually insert inferior vena cava (IVC) filters (“Drawing
First Blood: Should IVC Filters Still Be Inserted into Thrombosis
Management Guidelines?” December 2015).
Since the introduction of the first Mobin–Uddin IVC filter in
19671, the concept of a device that could capture and prevent
large, potentially fatal DVT from traveling to the lungs made
sense – at least in theory. Even with the advent of retrievable
IVC filters and the knowledge that we have gained about filters
in the past 10 years, the IVC filter still makes sense from a very
simple perspective.
Drs. Stavas and Rajasekhar point out that there are discrepancies between the various societal guidelines, some of which
are broader in their indications for filter placement than others.
From my perspective, there are only two absolute indications for
an IVC filter:
1. A patient with acute proximal DVT that cannot be anticoagulated.
2. A patient with recurrent DVT/pulmonary embolism (PE)
despite being therapeutically anticoagulated.
There are myriad other relative indications for IVC filters. While
there are no data to support these indications, there is something else much more powerful. That something is fear.
Whether or not we physicians admit it, fear is a very real
driver for many of us who practice medicine in both the private
practice and academic sectors. Fears such as “What if I don’t
place a filter and this patient dies of a PE?” or “What if the patient has a bad outcome and I get sued?” or “I know this patient
has a weak heart and the smallest clot could tip them over the
edge …” run rampant in our minds. While the latter fear was addressed by the PREPIC 2 trial2, the vast majority of these fears
are often the drivers for so many unnecessary filter placements.
As is true of any other physician, I too am often faced with
clinical scenarios in which I am asked to place an IVC filter in a
patient who has only a relative indication for a filter. Most of the
time I find that, with a little education, I can convince the referring physician or service of why a filter is not indicated.
Or can I?
While I am uncertain of what happens after I hang up the
phone, I do know that my evidence-based logic sometimes goes
unheeded and is no match for the power of fear. For if one specialty attempts to practice evidence-based medicine in regard
to IVC filter placement, there is always another specialty that is
more than willing to place the filter whether it be for economic
reasons, lack of knowledge of the potential risks, or a perception
that they are truly helping the patient.
So, what can we do about fear? Knowledge is the only
real guardian of fear. As physicians, we must be united in our
message to patients and other physicians about the benefits
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and risks of these devices. We should not be fearful of educating our colleagues – the majority of whom are truly concerned
about their patient’s well-being – about the current evidence
on IVC filters. There is no doubt that further studies are needed
to help answer these questions. In the meantime, with studies
showing filter retrieval rates ranging from a paltry 3.7 percent to
a less than stellar 40 percent3, institutions that place IVC filters
should take it upon themselves to develop their own IVC filter
retrieval program that tracks each and every filter placed within
the institution and works closely with the patient’s primary
medical doctor to monitor the patient for filter removal when
there is no further clinical indication for the filter. While there
will always be patients lost to follow-up, this kind of monitoring
program is a step toward reducing future complications and the
downstream costs that Drs. Stavas and Rajasekhar mentioned.
Finally, the PRESERVE trial, which is jointly sponsored by the
Society of Interventional Radiology and the Society of Vascular
Surgery and supported by the U.S. Food and Drug Administration, is the first large-scale, multi-specialty, prospective trial
that aims to evaluate the safety and effectiveness of IVC filters
and the long term follow-up. The trial will help us define the
true role and indications for IVC filters and be a major step in
answering the question, “Do IVC filters still have a role in managing thrombosis?”
—Deepak Sudheendra, MD, RPVI
Assistant Professor of Clinical Radiology & Surgery
Hospital of the University of Pennsylvania – Perelman School of
Medicine
REFERENCES
1. Mobin-Uddin K, Smith PE, Martinez LO, et al. A vena caval filter for the prevention of pulm