title: Long-term sac behavior after endovascular abdominal aortic aneurysm repair with the Excluder low-permeability endoprosthesis.
abstract: OBJECTIVE
  Sac regression is a surrogate marker for clinical success in endovascular aneurysm repair (EVAR) and has been shown to be device-specific. The low porosity Excluder endograft (Excluder low-permeability endoprosthesis [ELPE]; W. L. Gore & Associates Inc, Flagstaff, Ariz) introduced in 2004 was reported in early follow-up to be associated with sac regression rates similar to other endografts, unlike the original Excluder which suffered from sac growth secondary to fluid accumulation in the sac. The purpose of this study was to determine whether this behavior is durable in mid-term to long-term follow-up.
  
  
  METHODS
  Between July 2004 and December 2007, 301 patients underwent EVAR of an abdominal aortic aneurysm (AAA) with the ELPE at two institutions. Baseline sac size was measured by computed tomography (CT) scan at 1 month after repair. Follow-up beyond 1 year was either with a CT or ultrasound scan. Changes in sac size ≥5 mm from baseline were determined to be significant. Endoleak history was assessed with respect to sac behavior using χ(2) and logistic regression analysis.
  
  
  RESULTS
  Two hundred sixteen patients (mean age 73.6 years and 76% men) had at least 1-year follow-up imaging available for analysis. Mean follow-up was 2.6 years (range, 1-5 years). The average minor-axis diameter was 52 mm at baseline. The proportion of patients with sac regression was similar during the study period: 58%, 66%, 60%, 59%, and 63% at 1 to 5 years, respectively. The proportion of patients with sac growth increased over time to 14.8% at 4-year follow-up. The probability of freedom from sac growth at 4 years was 82.4%. Eighty patients (37.7%) had an endoleak detected at some time during follow-up with 29.6% (16 of 54) residual endoleak rate at 4 years; 13 of the residual 16 endoleaks were type II. All patients with sac growth had endoleaks at some time during the study compared with only 18% of patients with sac regression (P < .0001).
  
  
  CONCLUSIONS
  A sustained sac regression after AAA exclusion with ELPE is noted up to 5-year follow-up. Sac enlargement was observed only in the setting of a current or previous endoleak, with no cases of suspected hygroma formation noted.
authors.affiliation: Northwestern University, Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Melissa E
authors.initials: ME
authors.lastname: Hogg
authors.forename: Mark D
authors.initials: MD
authors.lastname: Morasch
authors.forename: Taeyoung
authors.initials: T
authors.lastname: Park
authors.forename: Walker D
authors.initials: WD
authors.lastname: Flannery
authors.forename: Michel S
authors.initials: MS
authors.lastname: Makaroun
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Cho
mesh_terms: D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000401:mortality / Q000601:surgery*; D001019:Aortic Rupture / Q000209:etiology; D001027:Aortography / Q000379:methods; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D016009:Chi-Square Distribution; D002641:Chicago; D057867:Endoleak / Q000209:etiology; D057510:Endovascular Procedures / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D010414:Pennsylvania; D010539:Permeability; D011474:Prosthesis Design; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D015607:Stents; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D018616:Ultrasonography, Doppler, Duplex