title: Mid- and long-term outcome of patients with permanent inferior vena cava filters: a single center review.
abstract: BACKGROUND
  Inferior vena cava (IVC) filters are used to prevent pulmonary embolism (PE), especially in patients with active contraindication to systemic anticoagulation. The aim of this study is to examine the outcomes of patients who received permanent IVC filters at our institution.
  
  
  METHODS
  This is a single-center retrospective observational study with review of a prospectively collected database for patients who had permanent IVC filters. Patient demographics, indications of filter placement, postprocedure clinical outcome and complications, as well as use of anticoagulant therapy were documented. Chi-squared test was used to test for statistically significant differences (IBM SPSS version 21; IBM Corp., Armonk, NY), while survival was calculated using Kaplan-Meier survival curves analysis.
  
  
  RESULTS
  Between February 1998 and December 2013, a total of 109 patients with a median age of 65 (47 men, range 19-97) years had IVC filters inserted at our institution. All of them had documented venous thromboembolism (VTE) before filter placement: 99 (90.8%) had lower extremity deep vein thrombosis (DVT) (including 34 iliac, 65 infrainguinal), 9 (8.3%) had massive PE without evidence of lower limb DVT, and 1 (0.9%) had isolated IVC thrombosis. Forty-seven (43.1%) patients had PE before filter insertion. There were 2 serious procedure-related complications: one access site thrombosis and one right ventricular perforation. With a mean follow-up of 36 ± 33 months, no patient had further symptomatic PE or paradoxical embolism. There were a total of 54 (49.5%) deaths, with a 30-day mortality of 8.3%; none of them was device or procedure related. Among the 92 patients followed up, 27 (29.3%) had further VTE-either DVT in the index or the contralateral lower limb (20 patients, 21.7%), or thrombus inside the filter or the IVC (14 patients, 15.2%). Forty-one (44.6%) patients reported post-thrombotic syndrome (PTS) symptoms. Anticoagulant therapy was given to 39 (42.4%) and 55 (59.8%) patients in the periprocedural period and at any time during the study period, respectively. It did not reduce the rate of postfilter VTE or PTS in both instances. None of the filters in this series was retrieved.
  
  
  CONCLUSIONS
  This observational study showed that IVC filters were effective in the prevention of PE, although symptomatic postfilter VTE and PTS were common, leading to significant morbidity. Patients who received permanent filters have high mortality on follow-up; however, none were procedure or device related.
authors.affiliation: Division of Vascular & Endovascular Surgery, Department of Surgery, University of Hong Kong Medical Centre, Queen Mary Hospital, Hong Kong.
authors.forename: Felix Che-Lok
authors.initials: FC
authors.lastname: Chow
authors.affiliation: Division of Vascular & Endovascular Surgery, Department of Surgery, University of Hong Kong Medical Centre, Queen Mary Hospital, Hong Kong. Electronic address: ycchan88@hkucc.hku.hk.
authors.forename: Yiu-Che
authors.initials: YC
authors.lastname: Chan
authors.affiliation: Division of Vascular & Endovascular Surgery, Department of Surgery, University of Hong Kong Medical Centre, Queen Mary Hospital, Hong Kong.
authors.forename: Grace Chung-Yan
authors.initials: GC
authors.lastname: Cheung
authors.affiliation: Division of Vascular & Endovascular Surgery, Department of Surgery, University of Hong Kong Medical Centre, Queen Mary Hospital, Hong Kong.
authors.forename: Stephen Wing-Keung
authors.initials: SW
authors.lastname: Cheng
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use; D016009:Chi-Square Distribution; D016208:Databases, Factual; D005260:Female; D006723:Hong Kong; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010690:Phlebography / Q000379:methods; D054070:Postthrombotic Syndrome / Q000209:etiology; D016016:Proportional Hazards Models; D011655:Pulmonary Embolism / Q000175:diagnosis / Q000209:etiology / Q000401:mortality / Q000517:prevention & control*; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D016306:Vena Cava Filters / Q000009:adverse effects; D020246:Venous Thrombosis / Q000150:complications / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D055815:Young Adult
chemical_list: D000925:Anticoagulants