An analysis of factors associated with increased fluoroscopy time or the need for complex techniques at IVC filter retrieval

To evaluate factors associated with increased fluoroscopy time or the need for complex techniques at IVC filter retrieval. This is a retrospective IRB-approved study of 187 consecutive patients who underwent IVC filter retrieval at our institution from 2006-2016. Factors previously investigated or hypothesized to impact filter retrieval fluoro time or complexity were studied. A complex retrieval was defined as one requiring more than standard sheath and snare technique. Correlations were made using Fisher’s exact, Wilcoxon rank sum, Kruskal-Wallis tests, and Spearman’s rank correlation coefficient, as appropriate. Filter tilt angle at placement correlated with hook apposition to the caval wall at time of removal (P = 0.01). Hook apposition was associated with complex retrieval and increased fluoro time (P<0.01). Larger tilt angle at placement was not associated with complex retrieval (P = 0.39), but a larger angle at filter removal was (P<0.01). There was a moderate correlation between the angle of filter at placement and removal (ρ = 0.56, 95% CI 0.44-0.66). Longer filter dwell time correlated with the need for complex retrieval (P<0.01). There was a trend towards complex retrieval when the indication was failure of anticoagulation (P = 0.08). Access vein during filter placement was not associated with the filter tilt angle at placement or removal (P = 0.61, 0.48). Neither the direction of the filter hook (right, left, en-face) nor its relationship to the filter tilt were associated with the need for complex retrieval or increased retrieval fluoro time (P = 0.23, 0.47, P = 0.22, 0.56). Filter-type, sex, and age were not associated with complex retrievals (P = 0.58, 0.99, 0.78). Contrary to previous hypotheses, access vein for filter placement did not affect filter tilting, and direction of filter hook-tilt relationship did not affect retrieval fluoro time or the need for complex retrieval techniques. Confirming previous studies, a larger angle at the time of filter placement was associated with a larger angle at removal and hook wall apposition, both of which were associated with increased retrieval fluoro time and retrieval complexity.