Certain types of filters inserted into the inferior vena cava to prevent pulmonary emboli appear to have a high risk of fracture and other adverse events — leading to life-threatening complications in some cases, according to a warning from the FDA and a new study.
In a safety alert, the FDA cautioned that it had received hundreds of reports of adverse events for retrievable inferior vena cava (IVC) filters since 2005 — including device migration, perforation of the vena cava, filter embolization, and filter fracture.
The agency expressed concern that physicians don’t always remove the IVC filters — intended only for short-term placement — once a patient’s risk for pulmonary embolism subsides.
The FDA recommended that physicians consider removing the IVC filter as soon as the pulmonary embolism risk subsides — since the risk of device migration and fracture appears related to the length of time the filter remains in the body.
A study of 80 patients treated at one Pennsylvania hospital who had an IVC filter remaining in place suggested a particularly high risk of fracture and embolization for two popular devices made by Bard. The study was released online the same day as the FDA warning.
According to William Nicholson, MD, of York Hospital in York, Penn., and colleagues, fragmentation and embolization occurred in 25% of patients treated with the Bard Recovery device (7 out of 28 patients) and in 12% treated with the second-generation Bard G2 device (6 of 52 patients).
The emboli ended up in the right ventricle in 5 of the 7 patients who received the Recovery device, Nicholson and co-authors reported online ahead of print in the Nov. 8 issue of the Archives of Internal Medicine.
An accompanying commentary extrapolated the results of the study, and determined that more than 7,000 Americans may likely be carrying a fractured G2 filter with the potential to embolize.
The report by Nicholson and colleagues provides a case study for why the FDA device approval process needs improvement, especially for high-risk devices such as IVC filters, commented Archives editor Rita F. Redberg, MD, MSc, of the University of California, San Francisco.
Bard did not respond to request for comment in time for publication.
Nicholson’s group attempted to assess all non-pregnant patients who had either type of IVC filter implanted from 2004 through 2009, using fluoroscopy to assess the integrity of the filters.
This period spanned the period before and after Bard replaced its Recovery device in 2005 with the second-generation filter designed to better resist fracture.
The Bard Recovery filter was developed as a device that could either be left in place permanently or retrieved as needed; it was commercially available from April 2003 to October 2005.
Of the 189 patients treated at York Hospital with either of the filters, only 10 had it recovered prophylactically before the study.
Overall, fluoroscopy on the 80 surviving patients who still had the device in place revealed a fracture in at least one of its nitinol arms or legs, seen in 13 patients (16%) at an average 37.8 months after implantation.
These fragments made their way through the venous system to an end organ in all cases associated with the Bard Recovery filter.
Two of these patients had symptoms of pleuritic chest pain with documented nonsustained ventricular tachycardia, one of whom died suddenly at home three months after completion of the study.
Another patient had hemorrhagic pericardial effusion with cardiac tamponade requiring emergency open-heart surgery with drainage and fragment removal.
For the G2 filter, the fragments ended up in a patient’s hepatic vein in one case, in a lung in another case, and remained near the device in the other four cases.
The design modifications may have reduced the ability of fragments to embolize distally, bu the potential for these fragments to move to other vital organs still exists, Nicholson’s group warned.
Furthermore, the G2 filters were examined after a shorter average duration in place in the vena cava compared with the first generation device, the researchers noted.
“Because nitinol metal fatigue may play a role in the filter fracture, it is reasonable to assume that the incidence of filter fracture would be directly proportional to the time that the filter is allowed to dwell in the patient after implantation,” they wrote in the paper — a comment that agreed with the FDA’s assessment.
The FDA said it has reviewed the literature and will provide a decision analysis model for physicians to weigh the shifting risks and benefits of leaving the filter in over time.
Meanwhile, physicians and patients need to be alert to pleuritic chest pain and other symptoms that should prompt immediate evaluation, Nicholson and colleagues recommended.
As a single-center study, corroboration with independent evaluation of devices at other centers and with other brands of IVC filters is needed to determine if the results are specific to the Bard devices or a flaw inherent in all brands, they wrote.
Primary source: Archives of Internal Medicine