title: Potential impact of therapeutic warfarin treatment on type II endoleaks and sac shrinkage rates on midterm follow-up examination.
abstract: OBJECTIVE
  Successful endovascular aortic aneurysm repair depends on exclusion and spontaneous thrombosis of the aneurysm sac. The need for chronic postoperative anticoagulation therapy could limit the applicability of this technology with delay or prevention of sac thrombosis resulting in endoleak formation and altered remodeling of the aneurysm sac. The purpose of this study was the determination of whether chronic therapeutic anticoagulation therapy with warfarin was associated with an increased incidence rate of early or delayed postoperative endoleaks or altered rates of reduction in aneurysm sac maximum diameter.
  
  
  METHODS
  Two hundred thirty-two consecutive patients underwent abdominal aortic endografting during a 32-month period. The data were recorded prospectively with a current mean follow-up period of 18 months. The patients with endoleaks identified with 30-day postoperative computed tomographic scan angiograms subsequently underwent selective arteriography to characterize the source. The patients who underwent chronic warfarin therapy that resulted in a therapeutic internationalized normalized ratio comprised the study group. The control group was defined as all the patients with healthy coagulation profiles.
  
  
  RESULTS
  Thirty-six patients (15%) were undergoing warfarin therapy after surgery, and their conditions were chronically maintained with a therapeutic international normalized ratio. Forty-three patients (18%) had endoleaks on 30-day computed tomographic scan angiographic results. There were 39 patients with type II endoleaks and four patients with type I endoleaks. None of the type I endoleaks occurred in patients who were undergoing warfarin therapy, and all endoleaks were repaired with either proximal or distal covered extensions. At 30 days, seven patients (19.4%) undergoing chronic warfarin therapy had type II endoleaks as compared with 36 controls (18.4%; P =.798). Four patients had delayed type II endoleaks develop, two in the control group and two in the warfarin group (P =.3). Ten control individuals (31%) had spontaneous resolution of type II endoleaks develop, whereas spontaneous endoleak thrombosis was not observed in the warfarin group (P =.33). Aneurysm sac remodeling assessed with mean percent reduction in maximum sac diameter at 12 months revealed a statistical difference between the control group (17.5%) and the warfarin group (7.6%; P =.04).
  
  
  CONCLUSIONS
  Warfarin treatment is not associated with an increase in the incidence rate of early or delayed postoperative endoleaks. However, the rate of reduction in maximum aneurysm sac diameter after aortic endografting is slower in patients who undergo therapeutic warfarin therapy at 1-year follow-up examination, a statistically significant difference from the control group. In addition, type II endoleaks may be less likely to undergo spontaneous thrombosis in patients who undergo warfarin therapy.
authors.affiliation: Department of Surgery, University of Pennsylvania Medical Center, Philadelphia, 19104, USA. ron.fairman@uphs.upenn.edu
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Fairman
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Carpenter
authors.forename: Richard A
authors.initials: RA
authors.lastname: Baum
authors.forename: Robert A
authors.initials: RA
authors.lastname: Larson
authors.forename: Michael A
authors.initials: MA
authors.lastname: Golden
authors.forename: Clyde F
authors.initials: CF
authors.lastname: Barker
authors.forename: Marc E
authors.initials: ME
authors.lastname: Mitchell
authors.forename: Omaida C
authors.initials: OC
authors.lastname: Velazquez
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use*; D017544:Aortic Aneurysm, Abdominal / Q000188:drug therapy* / Q000601:surgery; D016022:Case-Control Studies; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D011183:Postoperative Complications / Q000188:drug therapy* / Q000453:epidemiology; D012189:Retrospective Studies; D013997:Time Factors; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin