Surveillance Study of Temporary IVC Filters placed in Patients with VTE and Contraindications for Full Dose Anticoagulant Therapy

Abstract

To study the circumstances surrounding the use of IVC filters in our institution we collected medical information from all patients with IVC filters placed between January 1, 2006 and December 31, 2007 in our institution. During this time, 247 IVC filters were placed and we are reporting preliminary data of 50 of those patients. Of these patients, 8 (16%) had permanent filters placed (Vena tech™) and 42 (84%) had retrievable filters (Gunther Tulip filters). In most of the cases, the indication for the IVC filter was the inability to use full dose of anticoagulants in patients with acute DVT secondary to active bleeding, requiring immediate surgery or very high risk of bleeding due to different circumstances (such a recent intracranial bleed or traumatic intra-abdominal hemorrhage). Most of the patients were trauma patients. Thus, 30 of the patients had neurosurgical injuries, 13 had orthopedic injuries requiring urgent surgery, 5 had intra-abdominal injuries and 2 were medical patients with DVT and contraindications for anticoagulant therapy. Of the filters deployed, 12 (24%) were inserted after developing thrombosis despite the use of prophylactic dose of anticoagulants. Once the filter was inserted, surveillance Doppler studies revealed propagation of the clots in 7 (14%) patients. Of these 7 patients 2(29%) of them were receiving low dose enoxaparin and 5 (71%) were receiving no anticoagulants at all. In addition, there were 12 patients with DVT and contraindication to full dose anticoagulation who were treated with prophylactic dose of enoxaparin. Of these 12 patients, 10(83%) had stability or resolution of the thrombus and 2(17%) showed propagation. Twenty patients were given no anticoagulation after diagnosis of DVT, of them, 15(75%) had resolution or stabilization of the clots and 5(25%) experienced propagation. Most of the patients were eventually treated with full dose enoxaparin followed by warfarin for a minimum of 3 months. All IVC filters were inserted by intervention radiologists at our institution. Deployment was done uneventfully in all cases. The retrieval of all filters was done between 4 and 8 weeks of the time of insertion. By then, most of the patients were taking warfarin. This drug was held 3 evenings before the procedure and restarted 8–12 hours after the procedure. Enoxaparin at a dose of 40 mg SQ daily was use for bridging before and after the retrieval of the IVC filters. Of all temporary filters, only 11 (26%) were retrieved. IVC filter could not be retrieved despite attempting it in 1 (2%) of patients. The reason for this was that the filter had embedded in the intima of the IVC. Additionally, 1(2%) patient required two attempts to successfully remove the filter IVC filters as there was residual thrombus at the filter site the first time. IVC retrievable filters were effective in preventing pulmonary embolism in 49 (98%) of patients. The only patient with a pulmonary embolism was a neurosurgical patient that was not treated with anticoagulants and the clot extended to the filter. Excessive bleeding occurred in 2(4%) of all patients resulting in discontinuation of anticoagulants. IVC filters are safe and constitute a reasonable intervention to prevent pulmonary embolism in patients with contraindications for anticoagulation. Although, many temporary filters are placed they are often not retrieved. Low dose enoxaparin in patients with IVC filter and contraindication for full dose anticoagulants is associated to low risk of bleeding and seems to prevent proximal propagation of the clots. We expect to have all data from the 247 patients collected by the time of the Meeting.