Iftikhar Ahmad MD, Presenter: Nothing to Disclose

Kalpana Yeddula MBBS, Abstract Co-Author: Nothing to Disclose

Stephan Wicky MD, Abstract Co-Author: Consultant, Johnson & Johnson

Sanjeeva Prasad Kalva MD, Abstract Co-Author: Research grant, AngioDynamics, Inc Speakers Bureau, Johnson & Johnson

To assess the longterm clinical sequelae of IVC filter thrombus and the effect of anticoagulation on filter thrombus

Of 1718 patients who had IVC filters during 2001-08, 598(34.8%) had followup abdominal CT. Filter thrombus was seen in 111/598 (18.6%). There were 44 men (39.6%). The mean age at filter placement was 64y. The medical diseases included cancer in 64, trauma in 15, stroke in 12 and others in 20. The frequency of filter thrombus on CT and asymptomatic filter thrombus on CT was calculated. The frequency of PE in patients with filter thrombus was calculated. The frequency of thrombus progression or regression (on CT, available in 56) was calculated. The effect of anticoagulation on filter thrombus regression/progression was evaluated using Fischer Exact Test by comparing the group of patients who received anticoagulants versus those who did not. A p value of <0.05 was considered significant.

The overall frequency of filter thrombus was 18.6%. Total occlusion of the IVC filter was seen in 12/598 (2%). The filter thrombus was asymptomatic in 110(18.3%). Filter thrombus was detected after a median of 35 days (range 0-2082) following filter placement. Thrombus extended above the filter in 4(3.6%). IVC thrombus below the filter was seen in 35(31.5%).Thrombus in the filter occluded <25% of filter volume in 58(52.3%), 25%-50% in 21(18.9%) and 50%-75% in 20(18%). Total IVC occlusion was seen in 12(10.8%). 83 patients received anticoagulation. 16 patients developed symptoms of PE. PE was confirmed on CT in 3/15(2.7%). On followup, filter thrombus regressed completely in 19(33.9%) after a median of 6 months. Filter thrombus decreased in size in 13(23.2%) and it progressed without IVC occlusion in 7(12.6%). In one (1.7%), filter thrombus progressed to IVC occlusion. Filter thrombus remained stable in 16(28.6%). There was no significant difference in thrombus regression or progression rates whether or not the patients received anticoagulation for filter thrombus.

Asymptomatic thrombus in the filter is common and it rarely progresses to complete caval occlusion. Anticoagulation has little effect on the resolution of filter thrombosis and future occurrence of PE.

Asymptomatic caval occlusion occurs ten times more often than symptomatic caval occlusion following filter placement. Regression/progression rate of filter thrombus is not affected by anticoagulation.

Ahmad, I, Yeddula, K, Wicky, S, Kalva, S, Clinical Sequelae of Thrombus in an Inferior Vena Cava Filter.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8011843.html