In an article published in the International Journal of Cardiology in 2014, Drs. Mohamad Alkhouli and Riyaz Bashir question the efficacy of the inferior vena cava (IVC) filter as a device for routine use and raise cautions about the apparent lack of retrieval of these temporary filters, particularly in U.S. patients. There is little doubt that in some cases, the IVC filter is a necessary device; however, the article’s authors expressed concern over “prophylactic” use of IVC filters in certain patient populations.
The IVC filter is a device designed to reduce the possibility of recurrent pulmonary embolism or PE, (blood clots reaching the heart and lungs) as well as fatalities caused by PE. The filters are manufactured by eleven companies and, when called for, are implanted in the inferior vena cava, the largest vein in the human body. The article’s authors state there is “only one randomized-controlled trial” that examined the efficacy of the IVC filter in accomplishing its primary purpose. This study, called PREPIC (Prevention du Risque d’Embolie Pulmonaire par Interruption Cave), showed that, while there was a reduction in PE occurrence, there was no impact on short- or long-term mortality. Worse, PREPIC showed a significant increase in the occurrence of deep-vein thrombosis (DVT). DVT is a condition in which a blood clot (thrombus) forms in one of the deeper veins, typically in the legs. If DVT occurs and the clot breaks loose, PE is a likely result and can be fatal.
Though there is a definite lack of data strongly supporting IVC filter use, Drs. Alkhouli and Bashir found that the use of IVC filters in the U.S. is on the rise. At the time of their writing, IVC filters were being used in 12% – 17% of patients with venous thromboembolism (VTE), a condition involving both DVT and PE, but used in over 40% of patients with a high risk of bleeding. One of the items the doctors found most intriguing was the fact that the implantation rates in patients with a high risk of bleeding was 25 times greater in the U.S. than in Europe. This is likely due to a lack of commonality among guidelines for IVC filter use.
The indications (or conditions calling for use) for IVC filters vary widely, even in the U.S. There are two types of indications: therapeutic and prophylactic. The most common indications are therapeutic and include:
- DVT or PE and contraindication of anticoagulation therapies (reasons blood thinners should not be used)
- Anticoagulation therapy failure
- Massive PE
- Severe cardiopulmonary (heart and lung) disease complicated by DVT.
Among the more controversial prophylactic uses of IVC filters are:
- Preventing PE in patients having high-risk surgeries, such as bariatric or spinal procedures
- Trauma victims without VTE
The problem, according to the authors, is that over half of IVC filter placements fall into the prophylactic category, despite one population-based study of 213 IVC filter patients. That study, conducted by a panel of thrombosis experts, showed that only 51% of those studied actually needed the IVC filter. The other 49% didn’t meet the requisite indications for such therapy. Further, there is a marked lack of agreed-upon definition of “contraindication to anticoagulation” therapy, as well as evidence that several patients who were implanted with an IVC filter due to contraindication to anticoagulation were, in face, on anticoagulation protocols.
One paper, referencing the RIETE registry (registry of patients with venous thromboembolism), stated that 60% of patients studied who were implanted with an IVC filter due to “relative or absolute contraindication to anticoagulation” were on some form of anticoagulant therapy. This further underscores the question of “true contraindications to anticoagulation.”
Perhaps the worst issue with IVC filters is the possibility of serious short- and long-term health complications due to their use. Such complications include:
Migration of the IVC filter, including to another blood vessel (called embolization)
Fracture of the filter
Penetration of the inferior vena cava by the filter
IVC perforation of the inferior vena cava
IVC thrombosis (a clot forming around the filter)
The main reason for these complications is late retrieval of the IVC filters. These devices were not meant to be permanent; rather, they are intended for use only until the risk of PE passes and then they are supposed to be removed. Drs. Alkhouli and Bashir cite research that shows “late filter-related thrombosis” occurred in 8% – 30% of cases studied.
The major problem with IVC filters in the U.S. is the poor rates of retrieval. At the time the authors wrote their article, the highest removal rate reported in the U.S. was 34%, compared to 81% in U.K. They found that some IVC filters aren’t removed for good reasons, such as a tilted filter or a trapped clot.
However, the most common reason they found for lack of removal was poor follow-up by implanting doctors. In the meantime, the IVC filters that remain in the body longer than recommended continue to put patients at risk of very serious health complications. This, even after the FDA issued two safety warnings (2010 & 2014) stating that implanting doctors should remove the IVC filters as soon as the risk of PE has passed.