Symptomatic inferior vena cava filter thrombosis: clinical study of 30 consecutive cases.

Inferior vena cava (IVC) filter thrombosis has not been described as a clinical entity. Thirty patients with IVC percutaneous filter thrombosis were assessed by cavography, computed tomographic (CT) scan and/or duplex ultrasonography. All patients had proximal venous thrombosis when the filter was placed, and the indication for filter placement was a contraindication to anticoagulant therapy in eight patients (27%). Filter thrombosis occurred within 6 months following filter placement in 15 patients (early filter thrombosis group). Among these patients, 10 were not treated with oral anticoagulant, and none of the other five received adjusted anticoagulation. No patients with late filter thrombosis received anticoagulant at the time of the diagnosis. Early filter thrombosis was mainly associated with LGM filters (12 of the 15 cases). Occlusion was revealed by recurrent venous thrombosis in 18 cases. A thrombus above the filter and pulmonary embolism was found in 10 patients (33%). Thrombolytic therapy failed in 5 out of 7 cases, and all but two patients were treated with anticoagulant therapy. In conclusion, early filter thrombosis appears to be due to intracaval extension of deep vein thrombosis, and this emphasizes the need for appropriate anticoagulation. In the case of temporary contraindication to anticoagulation at the time of the filter placement, anticoagulant should be reassessed later.