title: Chronological Change of the Sac after Endovascular Aneurysm Repair.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the potential risk factors of type II endoleak and sac growth after endovascular aneurysm repair (EVAR) and the outcomes of secondary interventions.
  
  
  METHODS
  Ninety seven patients underwent elective EVAR for infrarenal abdominal aortic aneurysms in two tertiary centers between April 2005 and July 2013. Clinical and imaging parameters were compared among sac growth (>5 mm) and non-growth groups. Risk factors associated with sac growth and persistent type II endoleak were analyzed. The outcomes of reinterventions for persistent type II endoleak were determined.
  
  
  RESULTS
  Sac growth was observed in 20 cases (20.6%) and endoleak was found in 90% of them compared to 28.6% (22/77) in the non-growth group (P<0.001). The majority of endoleaks were type II (36/40) and 80.5% were persistent. Sac diameter, neck diameter and number of patent accessory arteries were also statistically significant for sac growth. On multivariate analysis, grade of calcification at the neck, grade of mural thrombus at the inferior mesenteric artery and number of patent accessory arteries were risk factors of persistent type II endoleak. Twenty six reinterventions were done for 16 patients with persistent type II endoleak, with a technical success rate of 88.5%, yet 55.5% showed sac growth regardless of technical success. There were no ruptures during the follow-up period.
  
  
  CONCLUSIONS
  Sac growth after EVAR was mostly associated with persistent type II endoleak. Secondary interventions using transarterial embolization is partially effective in achieving clinical success.
authors.affiliation: Department of Surgery, Seoul National University Bundang Hospital, Seongnam.
authors.forename: Min Hyun
authors.initials: MH
authors.lastname: Kim
authors.affiliation: Department of Surgery, Seoul National University Bundang Hospital, Seongnam.
authors.forename: Hyung Sub
authors.initials: HS
authors.lastname: Park
authors.affiliation: Department of Surgery, Seoul National University Hospital, Seoul, Korea.
authors.forename: Sanghyun
authors.initials: S
authors.lastname: Ahn
authors.affiliation: Department of Surgery, Seoul National University Hospital, Seoul, Korea.
authors.forename: Sang-Il
authors.initials: SI
authors.lastname: Min
authors.affiliation: Department of Surgery, Seoul National University Hospital, Seoul, Korea.
authors.forename: Seung-Kee
authors.initials: SK
authors.lastname: Min
authors.affiliation: Department of Surgery, Seoul National University Hospital, Seoul, Korea.
authors.forename: Jongwon
authors.initials: J
authors.lastname: Ha
authors.affiliation: Department of Surgery, Seoul National University Bundang Hospital, Seongnam.
authors.forename: Taeseung
authors.initials: T
authors.lastname: Lee
keywords: Abdominal aortic aneurysm; Endoleak; Sac enlargement