Vena cava filters might fracture, embolize

When patients have retrievable inferior vena cava (IVC) filters implanted but not removed, there is a risk of serious cardiac events, a new study and a communication from the FDA warn.

Physicians at York Hospital in Pennsylvania conducted a retrospective study of all of their patients who had received a Bard Recovery or Bard G2 filter between April 2004 and January 2009, after one patient required open-heart surgery to retrieve a fractured filter. Patients who had died or had filters removed were eliminated, leaving 80 patients in the trial.

The patients underwent fluoroscopy to assess the integrity of their filters. The testing revealed strut fractures in 13 (or 16%) of the patients. Of the 28 Bard Recovery filters studied, seven (or 25%) had fractured, and fragments had embolized to the heart in five of those seven patients. Three patients experienced ventricular tachycardia and/or tamponade, including one case of sudden death during the study. There were 52 of the newer Bard G2 filters in the study, and 6 (or 12%) fractured, resulting in two cases of asymptomatic end-organ fragmentation.

Although the results would appear to indicate that the Bard G2 is associated with less fracture risk, the study authors cautioned against that interpretation, because the Bard Recovery filters had been implanted earlier. If the prevalence of fractures observed with the Bard G2 was extrapolated to the 50 months that the Bard Recovery was observed, the rate would be the same, the authors noted.

The authors also expressed concerns about the difficulty of removing the filters after local fibrosis, and noted that implantation of these specific devices has been halted at their institution. They urged other physicians and medical centers to evaluate patients who have received the filters, warning that the symptoms of perforation of the heart resulting from filter fracture are similar to those of pulmonary embolism (PE), and could be misdiagnosed as a recurrence.

An accompanying commentary called for closer and more public scrutiny of such devices during the FDA approval process. The article and commentary were published online by Archives on Internal Medicine on Aug. 9.

The same day, the FDA issued an initial communication about retrievable IVC filters, recommending that removal of the filters be considered as soon as protection from PE is no longer needed. Since 2005, the agency has received 921 adverse event reports about IVC filters, of which 328 involved device migration, 146 involved embolizations, 70 involved perforation of the IVC, and 56 involved filter fracture.