The ALN inferior vena cava filter has been available in the European market for over a decade. Following US FDA approval a few centres in the USA have gained extensive experience with this filter. A retrospective study reporting intermediate-term experience from the University of Texas Medical was presented at CIRSE 2014 (12–17 September, Glasgow, UK).
“In our experience, ALN filters have demonstrated good deployment success and a relative ease of retrieval even up to 24 months. The safety profile so far appears acceptable. Longer follow-up and multicentre data for a larger pool of patients are required to validate our current experience,” Rodrick C Zvavanjanja, Diagnostic and Interventional Imaging, University of Texas Medical School at Houston, USA told delegates.
The study, carried out from August 2010 to January 2014 and assessed the deployment, safety, and retrievability of the filter. The researchers evaluated the data obtained from electronic medical records and the picture archiving and communication systems for filter safety, deployment success, and tilt angle. The data on filter retrieval was assessed for dwelling time, tilt angle, fluoroscopy time, and associated complications. The results were also presented at the Society of Interventional Radiology’s annual scientific meeting in March.
Zvavanjanja presented that 170 ALN filters were placed in 170 patients (10 using intravascular ultrasound and 160 fluoroscopically). A majority (120/170 patients) were deployed via the femoral access and the remainder using the jugular approach.
There was 100% deployment success. The median tilt angle at the time of placement was 11.6 degrees (range 0–27 degrees). Eighteen (10.6%) retrieval attempts were made with 100% success. The mean time between placement and retrieval was 7.7 months (range 1–24 months). During retrieval, median filter tilt angle was 10.5 degrees (range 2.5–27 degrees) and median fluoroscopy time was 5.9 minutes (range 1.4–20.6 minutes). Only one filter demonstrated significant penetration (into the duodenum), incidentally diagnosed on CT and this was retrieved uneventfully, Zvavanjanja noted. Among the retrieved filters, there was no evidence of filter fractures.