Researchers report that inferior vena cava (IVC) filter placement position relative to the level of the most inferior renal vein was not associated with differences in IVC thrombosis in a recent single-centre cohort study.
Additional key findings from the study include a low incidence of other filter-related complications, including migration, fracture, and caval wall penetration, and no occurrence of device-related mortality. These conclusions were recently shared online in the Journal of Vascular Surgery: Venous and Lymphatic Disorders (JVS-VL).
Authors Scott Grubman (Yale University School of Medicine, New Haven, USA) and colleagues write that indwelling IVC filters can cause complications, including penetration into surrounding structures, migration, and thrombosis of the vena cava. They add that, while computational fluid dynamics suggest juxtarenal placement of IVC filters decreases the risk of thrombosis, this has not been explored clinically.
Against this background, Grubman et al communicate that it was their aim in the present study to examine the effect of filter placement position on long-term device complications with an emphasis on IVC thrombosis. “We hypothesised that IVC filters placed further caudal to the renal veins were more likely to develop long-term thrombosis,” they write.
In order to investigate their hypothesis, the researchers document that they conducted a retrospective review of the medical records of patients receiving IVC filters at a single tertiary centre between 2008 and 2016. They note that they excluded patients missing follow-up or procedural imaging data.
“The placement procedure venograms were reviewed, and the distance from the filter apex to the more inferior renal vein was measured using reported IVC filter lengths for calibration,” Grubman and colleagues detail in JVS-VL, sharing their study methods. They add that they patients were divided into three groups according to the tip position relative to the more inferior renal vein: group A (at or superior), group B (1–20mm inferior), and group C (>20mm inferior). The researchers then compared patient and procedural characteristics and outcomes between the three groups, with the primary endpoints being IVC thrombosis and device-related mortality.
Grubman et al state in the results section of their paper that, of the 1,497 eligible patients, 267 (17.8%) were excluded from the present study. They write that the most common placement position was group B (64%), and that the mean age was lowest in group C (59.5 years), followed by groups A (64.6 years) and B (62.6 years), with a p value of 0.003. The team convey that no statistically significant differences were found in the distribution of sex or the measured comorbidities.
The authors continue that group C was the most likely to receive jugular access (group C, 71.7%; group A, 48.3%; group B, 62.4%; p<0.001) and received more first-generation filters (group C, 58.5%; group A, 46.6%l group B, 52.5%; p=0.045).
Sharing their key findings from the study, Grubman and colleagues report: “The short-term (<30-day) and long-term (≥30-day) outcomes, including access site haematoma, deep vein thrombosis, and pulmonary embolism, were uncommon, with no differences between the groups.” They add that cases of symptomatic filter penetration, migration, and fracture were rare (one, one, and three cases, respectively).
The authors further highlight that, although a pattern of increasing thrombosis with more inferior placement was found, the difference between groups was not statistically significant (group A, 1.5%; group B, 1.8%; group C, 2.5%; p=0.638).
Grubman et al also relay that no cases of device-related mortality occurred, and that all-cause mortality after a mean follow-up of 2.6±2.3 years was 41.3% and did not vary significantly between the groups (p=0.051).
Finally, the authors state that multivariate logistic regression revealed that placement position did not predict for short- or long-term deep vein thrombosis, pulmonary embolism, IVC thrombosis, or all-cause mortality after adjustment for the baseline patient characteristics.
In their conclusion, Grubman and colleagues summarise: “IVC filters have low rates of short- and long-term complications, including IVC thrombosis. The placement position did not affect the occurrence of device complications in this study.”
The authors acknowledge some limitations of their study, including those “common to a retrospective medical record review”, such as inconsistent information entry into the medical records, missing or incomplete records or procedural imaging studies, potential bias from loss to follow-up, and the potential for uncaptured, non-randomised confounding variables.
In addition, Grubman et al recognise that the study “likely lacked a sufficient sample size to limit type II errors when comparing the rates of the more uncommon complications between groups” and note that “larger studies would be helpful to further elucidate the relationship between filter position and the occurrence of rare adverse events”.
