CHICAGO – Penetration of the inferior vena cava and adjacent organs occurred with 46% of IVC filters placed among 262 patients, an award-winning analysis shows.
Grade 2 or 3 penetration was significantly associated with filter type (49% temporary vs. 5.3% permanent; P = .0001) and length of time in place (18.2% less than 30 days vs. 57.3% 30 days or more; P less than .0001).
"The majority of filters were placed for prophylaxis or relative indications and were temporary," Dr. Michael Go said at the annual meeting of the Midwestern Vascular Surgical Society.
The filter penetrated the aorta in 12 cases; duodenum in 26; and spine, colon, or kidney in 6; and simultaneously penetrated two organs in 7. Another 100 filters had struts immediately adjacent to the external aspect of the IVC, possibly indicating tenting of the cava.
Patrice Wendling/IMNG Medical Media
Dr. Michael Go
Only 1.6% of temporary filters, however, were retrieved during the 3-year study period, he said.
A filter retrieval rate between 1.2% and 5.1% was cited in a recent Medicare data analysis, which reported an alarming 111% increase in the rate of IVC filter placement from 1999 through 2008 (J. Am. Coll. Radio. 2011;8:483-9).
"IVC filter placement is an epidemic because of the ever-increasing number of risk factors being identified for VTE [venous thromboembolism]," said Dr. Go, with the division of vascular diseases and surgery, Ohio State University Medical Center, Columbus.
Other culprits behind the explosive growth of IVC filters are that angiography suites and catheter labs are now commonplace, the skill needed to insert a filter is easily disseminated, and temporary filters have decreased the threshold for placement.
"Concern over filter complications is increasing, as are referrals for removal, but little long-term data exist," he remarked.
A total of 591 patients had an IVC filter placed at Ohio State University between January 2006 and December 2009, with an adequate postfilter computed tomography (CT) scan available in 262. CT findings were graded, based on a modified, previously published scale (J. Vasc. Interv. Radiol. 2011;22:70-4), ranging from 0 (struts confined entirely within the IVC) to 3 (strut interacts with aorta, duodenum, or other organs).
Indications for filter placement were prophylaxis in 16.4% and VTE in 83.6%. Among the filters placed for VTE, 44.7% were for absolute indications (inability/failure of anticoagulation) and 55.3% for relative indications.
Grade 0 penetration occurred in 42 filters, grade 1 in 100, grade 2 in 83, and grade 3 in 37, Dr. Go said.
Grade 2 or 3 penetration was present in 44.6% of Tulip filters, 74.4% of Celect, 5.3% of Greenfield, and 0% of Optease (P = .0000), according to the analysis, which won this year’s Pfeifer Venous Award from the society.
There was a trend toward increased grade 2 or 3 penetration with uniconical filters vs. biconical filters (46.7% vs. 0%; P = .0645).
In all, 32 patients sought clinical follow-up for abdominal or back pain, but none were conclusively tied to filter problems or penetration.
"It remains unclear if most penetrations caused clinically significant problems," he said. "Monitoring of penetrations with CT, or some other follow-up, may be important to understand the natural history of this condition."
Audience members remarked that the retrieval rate in the series was extremely low and asked whether efforts, such as percutaneous retrieval, were being undertaken.
"We have attempted to remove some of these filters, sometimes successfully, sometimes not," Dr. Go responded. "As far as our retrieval rate, I agree 1.6% is dismal. Vascular surgery put in 19% of the filters. We don’t have a specific protocol in place, other than hyperawareness amongst all of us partners about who has a filter in place and to bring them back when appropriate."
He also observed that even when retrieval is undertaken, technical failure rates are high at about 8.5% in the recent literature (Eur. J. Vasc. Endovasc. Surg. 2013;46:353-9).
Dr. Go and his coauthors reported no financial disclosures.