Inferior vena cava, or IVC filters, are usually implanted in patients who are at risk of blood clots (thrombosis) and unable to tolerate anticoagulant medications that would prevent the formation of such clots. A cage-like device resembling a cellar spider, the IVC filter is meant to trap blood clots and prevent them from reaching the heart or lungs.
The device, however, has been known to cause severe internal injuries. Due to a defective design, these devices can come loose and migrate. They even fracture, causing small metal shards to lodge in arterial walls as well as the heart and lungs. Although intended for short-term use only (it is recommended that IVC filters remain in the patient for no more than three months), they often remain in a patient’s body for years. The reason: IVC filters have proven to be extremely difficult to remove once implanted.
A recent study published in the journal Cardiology has found that an IVC filter can kill a patient within a month. Researchers studied over 126,000 records of patients. Averaging 67 years of age, these patients had been hospitalized for deep vein thrombosis and/or pulmonary embolism and were unable to take anticoagulant medications. Just over 36 percent of the patients had received an IVC filter. After adjusting for variables, the research team found that having an IVC filter could raise a patient’s risk of death within thirty days by over 18 percent.
It bears mentioning that the research was a retrospective observational study, which the authors note “…may be subject to various types of bias that persist despite various techniques to adjust for differences in baseline characteristics” – in other words, factors over which they had no direct control. They acknowledge that “results should be considered hypothesis generating only.” Lead author Tyson Turner M.D. and his colleagues believe that additional studies should be performed under laboratory conditions.
In an editorial commenting on Turner’s research, Dr. Robert Yeh praises the study for its “attempt to add to the current dearth of data for IVC filter use…the greatest value of the study is to call out how limited our current evidence base is to support such a commonly used device.”
This is indeed a serious issue. Although the use of IVC filters dates back over half a century, there has been relatively little clinical research done on their use and effectiveness. What research exists indicates that at best, IVC filters are often useless – and at worst, they can be deadly.