Up to Half of All IVC Filter Implants May Be Unnecessary: Study

According to the findings of a new study, nearly half of all surgeries to implant patients with inferior vena cava (IVC) filters, which are devices designed to catch blood clots and prevent a pulmonary embolism, may be unnecessary or at least questionable. 

In the study, published in the September 13 edition of the Archives of Internal Medicine, doctors could only agree that it was necessary to perform 51% of procedures to implant IVC filters that they reviewed. The research comes on the heels of an FDA warning about the high rate of IVC filter fractures, which can send debris from the devices into the heart or lung, with sometimes lethal consequences.

Inferior vena cava filters are an alternative treatment for patients at risk for a pulmonary embolism. They are often used when an anticoagulant is contraindicated or if such medications have not been effective. They contain a number of legs or struts that extend out like a spider to catch blood clots that may break free elsewhere in the body, such as the deep veins of the legs. However, if there is an IVC filter strut fracture, small pieces of the filter may travel to other parts of the body, such as the heart or lungs.

In the new study, which was headed by Dr. Frederick A. Spencer with the McMaster University Divisions of Cardiology and Hematology/Thrombosis in Ontario, researchers looked at 1,547 people from Worcester, Massachusetts who had been diagnosed with acute venous thromboembolism (VTE); blood clots that could travel to the heart or lungs. The researchers found that 203 of those people, or about 13%, received IVC filters.

Doctors and researchers determined that about 51% of the cases represented an appropriate use of an IVC filter, but determined that the devices were not necessary in at least 26% of those cases, and were unable to reach a consensus on the remaining 23% of the cases.

They also found that the patients with an IVC filter had a much higher in-hospital mortality rate than those who did not have an IVC filter implanted. Patients with an IVC filter died at almost double the rate of those who did not; 9.9% compared to 5.1%. However, the researchers pointed out that patients who received the filters were more likely to be older and more likely to have suffered recent bleeding problems and repeat hospitalizations.

The researchers said that the findings indicate that better, clearer guidelines need to be given to be provided to the medical community on the appropriate use of IVC filters. They said that more studies need to be done, as the rate of implantations may vary in different medical communities and populations.

According to an alert issued by the FDA on August 9, the federal regulatory agency has received 921 reports of problems with IVC filters, with 328 of those cases involving an IVC filter that migrated through the body, 146 involved components breaking loose, 70 involved the IVC being perforated and 56 reports involved an IVC filter fracture. As a result of the problems, the FDA recommended that physicians remove the filters, which are often designed to be retrievable, once the threat of a pulmonary embolism has passed.

In a different study released on the same day as the FDA warning, two Bard IVC filters were found to have a particularly high rate of problems. Researchers who examined 80 patients who had either a Bard Recovery IVC filter or Bard G2 IVC filter were found to have at least one of the IVC filter struts fracture in 16% and 12% of all cases, respectively.

A number of Bard IVC filter lawsuits have been filed against C.R. Bard over the last year alleging that serious injuries or deaths were caused by design defects associated with these filters. In addition, as Bard IVC filter lawyers continue to review potential lawsuits for individuals with a vena cava filter implanted since 2003, it is likely that the IVC filter litigation will grow.

According to the most recent report in The Archives of Internal Medicine, researchers concluded that additional studies are clearly needed to better define the indications and efficacy of IVC filter placement given the increasing use of the devices.