Each year, approximately 900,000 people in the US are affected by pulmonary embolism (PE) and/or deep vein thrombosis, according to the American Lung Association.¹ PE is a serious and potentially life-threatening condition that can result from blood clot formation in the legs, known as deep vein thrombosis (DVT). These clots can travel to the lungs and can lead to serious health consequences. Inferior vena cava (IVC) filters may be indicated for the prevention of recurrent PE when anticoagulant therapy is contraindicated; anticoagulant therapy has failed in thromboembolic diseases; emergency treatment following massive PE where anticipated benefits of conventional therapy are reduced; and chronic, recurrent PE where anticoagulant therapy has failed or is contraindicated.

Primary effectiveness endpoint:

Rate of technical placement success and 12-month freedom from new symptomatic PE while a filter was indwelling²

Primary safety endpoint:

Rate of 12-month freedom from MAEs (clinical perforation, clinical migration, clinical fracture, embolization of the filter or filter fragments to the heart or lungs, IVC thrombotic occlusion, new symptomatic DVT while the filter was indwelling, access site complications with clinical sequelae, procedure- or device-related death)²

Secondary endpoints:

Rate of technical placement success and 12-month freedom from new symptomatic PE while a filter was indwelling; rate of 12-month freedom from MAEs; rate of 12-month freedom from grade 2 or grade 3 filter leg interaction with the IVC; filter migration; filter fracture; and filter embolization (assessed for the overall cohort and for each stratum)²

• Grade 2 indicates a filter leg outside the IVC, within the retroperitoneum; grade 3 indicates a filter leg in contact with another organ (see glossary).

Secondary measures:

PE, DVT (symptomatic and total), IVC thrombotic occlusion, and postplacement filter outcomes including fracture, embolization, significant migration, filter leg interaction with the IVC wall, clinical perforation, filter retrieval measures, access site adverse events with clinical sequelae, and procedure- or device-related death (assessed for the overall cohort and for each stratum)²

thrombus in the deep veins, usually of the lower extremities or pelvis; documented by contrast venography, duplex ultrasound CT, or MR venography

postplacement movement of the filter or its components to a distant anatomical site completely out of the target zone (e.g., heart or lungs); documented by imaging or at autopsy

any loss of structural integrity (breakage or separation) of the filter; documented by imaging or at autopsy

• Grade 0: normal; filter strut confined entirely within the IVC
• Grade 1: filter strut immediately adjacent to the external aspect of the IVC wall (likely reflecting tenting of the IVC wall)
• Grade 2: filter strut entirely outside of the IVC lumen and within the retroperitoneum as evidenced by a “halo” of retroperitoneal fat around axially viewed strut
• Grade 3: filter strut touching, impressing, or perforating another organ (e.g., liver, bowel, aorta, psoas muscle, vertebral body, or lymph nodes)

change in filter position compared with its deployed position (cranial or caudal); classified as significant (>20 mm) or insignificant (<20 mm); documented by plain radiography, CT, or venography

• Access site adverse events with clinical sequelae: arteriovenous fistula, hematoma, or bleeding requiring transfusion (≥2 units), hospitalization (either admission or extended stay), or further treatment
• Clinical fracture: loss of structural integrity (breakage or separation) of a filter identified by imaging and associated with clinical sequelae and/or requiring intervention; confirmed by core laboratory
• Clinical migration: caudal or cranial movement of a filter resulting in surgical or endovascular intervention; confirmed by core laboratory
• Clinical perforation: protrusion of filter legs through the wall of the IVC causing hemorrhage or hematoma or touching, impressing, or perforating another organ (e.g., liver, bowel, aorta, psoas muscle, vertebral body, or lymph nodes); documented using CT and confirmed by core laboratory
• Embolization of a filter or filter fragments to the heart or lungs: postplacement movement of the filter or its components to the heart or lungs; documented by imaging or at autopsy and confirmed by core laboratory
• IVC thrombotic occlusion: presence of an occluding thrombus in the IVC occurring after filter placement (may be symptomatic or asymptomatic); documented by appropriate imaging or at autopsy and confirmed by core laboratory
• New symptomatic DVT while a filter is indwelling: documented by appropriate imaging and confirmed by core laboratory
• Procedure- or device-related death: death directly attributable to a filter or filter placement or the retrieval procedure itself; documented by clinical findings, imaging, or at autopsy, or as adjudicated by a clinical events committee (CEC)

Emboli to lungs via the pulmonary artery, which can arise from DVT in the lower extremities or pelvis; documented using pulmonary arteriography, cross-sectional imaging, significant change in ventilation or perfusion lung scan, or at autopsy

deployment of a filter in a location suitable to provide sufficient mechanical protection against PE with no filter deformation, fracture, premature release, or clinical migration