According to a new study published in Helio, an online medical journal, inferior vena cava (IVC) filters that have remained in the body longer than seven months are less likely to come out easily using standard retrieval techniques.
The study scrutinized 762 IVC filter retrieval procedures performed from the dates of January 2009 to April 2015. The success rate was 98 percent, and standard retrieval methods were effectively used in 82 percent of the procedures. More invasive, advanced methods were necessary in 18 percent of them.
The only thing that changed results was the dwell time of the filter. Over the course of the research, data consistently confirmed that if a filter stays in place longer than seven months, the retrieval rate significantly drops.
“Based on our data, we have defined prolonged dwell time as seven months, where there is significant risk of standard technique failure, thereby requiring advanced techniques to maintain a high rate of technical success,” the researchers concluded. “Knowledge of this inflection point may be particularly useful in guiding referral of patients to centers with expertise in advanced retrieval techniques, where [retrievable inferior vena cava filters] with extended implantation times can be safely removed. As data on the potential risks of prolonged dwell [retrievable inferior vena cava filters] continue to mount, it is important to optimize opportunities to remove [inferior vena cava filters] that are no longer indicated.”
At seven months exactly, the retrieval failure rate jumped to 40.9 percent and spiked with each additional week.
Kush R. Desai, MD, from the department of radiology, Northwestern University Feinberg School of Medicine, and associates noted, “Devices that have been in place for extended periods of time potentially encounter prolonged exposure to multivector respiration-based caval biomechanics, resulting in metal fatigue, thereby increasing the risk of fracture and en bloc or component migration/embolization.”