Vena cava filter occlusion and venous thromboembolism risk in persistently anticoagulated patients: a prospective, observational cohort study.

Background: Inferior vena cava (IVC) filter placement may be life-saving, but after contraindications to anticoagulation remit, patient management is uncertain.

Methods: We followed patients who had venous thromboembolism, followed by treatment with permanent IVC filter placement, and were anticoagulated long-term as soon as safety allowed. We conducted annual physical examinations and ultrasound surveillance of the lower extremity deep veins and of the IVC filter site. Clot detected at the filter site was treated with graded intensities of anticoagulation, depending on the clot burden.

Results: Symptomatic DVT occurred in 24 of 121 patients (20%; 95% CI, 14%-28%); symptomatic pulmonary embolism (one fatal) was diagnosed in six patients (5%; 95% CI, 2%-10%). There were 45 episodes of filter clot in 36 patients (30%; 95% CI, 22%-38%). The rate of major bleeding (6.6%) was similar to that of a concurrent persistently anticoagulated cohort without IVC filters (5.8%).

Conclusions: If therapeutic anticoagulation can be safely begun in patients with IVC filters inserted after venous thromboembolism, further management with clinical surveillance, including ultrasound examination of the IVC filter and graded degrees of anticoagulation therapy if filter clot is detected, has a favorable prognosis. This approach appears valid for patients with current IVC filter and can serve as a comparison standard in subsequent clinical trials to optimize clinical management of these patients.