ODEN Trial: Option vs. Denali IVC Filters

Overview

This research study is a prospective randomized trial evaluating the relative safety of two inferior vena cava (IVC) filters used to prevent the migration of potentially dangerous deadly blood clots from the legs to the lung in patients who cannot take blood thinners. All eligible patients will have been ordered to have a IVC filter placed by their primary medical team and filters will be placed in these patients whether or not they wish to participate in this trial as part of standard of care. The investigators will follow up with patients 30 days after IVC filter placement and ask them to come back for filter removal if medically appropriate. If removal is not medically appropriate in 30 days, the investigators will attempt to schedule removal every 30 days after initial placement. Primary outcome measures will be IVC filter complications such as filter penetration through the IVC wall and into other organs, filter tilt, filter migration, filter fracture and clots formed within the filter. All of these are reported complications of all IVC filters. The research also aims to improve the standard of care for IVC filter patient follow up as the FDA and Society of Interventional Radiology recommend that IVC filters be removed as soon as it is safe to do so. Hypothesis: The investigators hypothesize that there is no significant difference in efficacy and complication rate between the Option and the Denali filter.

This is a prospective, randomized trial comparing two FDA-approved inferior vena cava filters, the Denali retrievable IVC filter (Bard Peripheral Vascular Inc., Tempe, AZ) and the Option Elite (Argon Medical, Athens, Texas). Patients scheduled for IVC filter placement at UCSF Department of Interventional Radiology (IR) will be asked by the IR physician performing the procedure at either UCSF Mt. Zion or Moffitt hospital if they wish to participate in this prospective, randomized study. Recruitment will be conducted by the physicians performing the IR procedures only. No additional recruitment calls, emails, posters or web pages are necessary. All procedures and the randomization to one of the two experimental groups will be carefully explained before obtaining signed written consent. Screening: Screening will be conducted by the IR physician prior to the placement of the IVC filters. Since this is a standard of care study, patients who are recommended for IVC filter placement and are scheduled for the procedure are generally eligible. The screening procedures are part of routine care before IVC filter placement and would be done even if patients did not join the study. The study doctor will review the results of most recent routine care imaging scans (CT or MRI) of the abdomen and pelvis. This is done to confirm that the diameter of IVC is no wider than 2.8cm. Both filters are FDA-approved to be placed in an IVC with maximal diameter of 2.8cm. The study doctor will also review ultrasound of the lower extremity, when available, to confirm that a blood clot was in fact present prior to performing the study. This ensures that patients who present for IVC filter placement are screened properly. The following screening procedures should be done within 12 days before the IVC filter placement procedure as part of the standard of care. * A complete physical exam * The study doctor will ask about medical history and how well patient is able to do daily activities * Routine care blood tests (about 2 tablespoons) o This is to ensure that the INR and platelet count of the patient is within the safe limits to perform an invasive procedure. After Enrollment: If the screening procedures show that the patient is eligible and consents to take part in the study, IVC filter placement will occur after randomization. After enrollment, the following procedures will be done during the study: Just as with screening, all of these procedures are part of regular IVC filter placement care. Randomization: Randomization will occur on the day of procedure or prior clinic visit with IR physician to either the Denali or Option IVC filter. All IR attending physicians on the protocol are familiar with placement of either filter type. Prior to opening study to accrual, 75 sealed security envelopes with the word Denali printed on a card inside and 75 sealed security envelopes with the word Option will be assembled by IR staff not involved in the research. The envelopes will be mixed up and placed in a bag. Computerized randomization programs and tables were considered but we feel the envelopes will work best as there may be limited time after patient is consented and procedure begins. This is especially true as some filters are placed emergently. Previous IR studies have used this randomization technique with great success. Filter Placement: Placement of an IVC filter involves the insertion of a plastic tube (catheter) into a vein in the neck. Some numbing medicine (Lidocaine) will be injected in the skin over the vein before the catheter is inserted. Intravenous medications will be given to induce moderate sedation (Fentanyl for analgesic and Versed for moderate sedation). Once the catheter has been placed into the vein, it will be advanced into the IVC. Once in correct position, x-ray contrast material (x-ray dye-Omnipaque 350) will be injected through the catheter and x-ray pictures taken. A series of x-ray pictures will be obtained of the IVC. These pictures are taken as part of standard of care to determine the position of the renal veins with respect to the IVC. The top of the filter must sit below the renal veins so it does not cause obstruction of the renal veins. In addition, pictures of the IVC are taken to serve as another tool in measuring the diameter of the IVC to make sure the diameter of the IVC is less than 2.8cm. This is particularly important in situations when a CT or MRI of the abdomen and pelvis is not available to have reviewed prior to the procedure. Once pictures are obtained and it is made certain that the IVC diameter is less than 2.8cm, the filter will be inserted through the catheter, and placed below the renal veins. During the placement procedure, positioning of the filter will be monitored with x-ray pictures. At the completion of the procedure the catheter will be removed and pressure will be applied to the insertion site until the bleeding has stopped. All of this is part of routine standard of care for placement of the filter. The doctor performing the procedure will be asked to complete a short questionnaire after IVC filter placement which will be attached to "Study Documents". Follow-Up: After the IVC filter placement procedure patient status will be followed by the interventional radiology doctors. Per standard of care after IVC filter placement, patient will be monitored in the hospital for up to 1 hour after the procedure. If patient is in stable condition and sedation has resolved, they will return home the same day or returned to their hospital rooms. A tentative appointment for follow up and filter retrieval will be ordered by IR physician at time of filter placement in APEX. This will ensure that scheduling and study staff will be aware that further patient and primary care follow-up is required. Patient primary care physician and/or relevant medical staff will be telephoned one month after IVC filter placement to determine if patient is medically stable and suitable for IVC filter removal. If IR and other doctors agree that IVC filter removal is recommended, patient will be scheduled to return for follow-up imaging and filter retrieval. If patient is not medically stable or still at high risk for blood clots, we will attempt to schedule a follow up one month later. Close contact with primary physician and patient will be maintained to ensure that filter is removed as soon as possible. APEX scheduling will be used to make sure follow up is performed at regular intervals. At follow-up appointment these routine tests per standard of care before IVC filter removal will be performed: * A physical exam * The study doctor will ask about medical history, how well patient is able to do daily activities, and if they are experiencing any possible symptoms related to the IVC filter placement such as abdominal or back pain. * A rotation CT focused to the site of the filter will be performed as part of routine practice of filter removal. This is done to ensure the filter has not migrated or that the filter has not penetrated through the walls of the IVC such that filter retrieval would be unsafe. * IR physician will determine if patient status is stable and safe for IVC filter removal. If not, physician will discuss with primary care doctor if filter needs to remain permanently in patient or if later retrieval should be considered at subsequent follow up visits. * IVC filter retrieval will be performed under moderate sedation. This procedure is very similar in nature to the filter placement procedure. The IVC filter is removed via a similar process to the way in which it was placed. X-ray dye (contrast) will be injected around the filter to assure that the filter and the area beneath the filter are free of blood clots and that it is safe to proceed with removal. A catheter-based snare will be used to engage the hook at the end of the filter and the filter will then be enveloped by a removal sheath and removed from the body.