Expert Opinion on Hostile Neck Definition in Endovascular Treatment Abdominal Aortic Aneurysms (a Delphi consensus)

Background: Endovascular aneurysm repair (EVAR) is currently accepted as an alternative to open repair for the treatment of abdominal aortic aneurysm (AAA). Approximately 40-60% of AAA patients are not considered eligible for EVAR due to unfavorable anatomy. There is currently no consensus on the definition of "hostile'' aortic neck for EVAR procedure. Methods: An Expert Panel (EP), made up of 9 Italian vascular surgeons from high-volume centers (>50 EVAR procedures/year), was assembled to share their opinion about the definition of hostile aortic neck anatomy for EVAR procedure. The process included a review of the current literature by the EP, a face-to-face meeting, and an on-line survey completed by the EP prior to and following the face-to-face meeting, using the Delphi method. Results: Of the 66 reviewed studies, only 38 (58%) reported at least 1 aortic neck hostility criterion. Five anatomic parameters were identified, namely, aortic neck length, aortic neck angulation, aortic neck diameter, conical neck, and presence of circumferential calcification. Based on the results of the first survey round, these criteria and related definitions were discussed in depth during the face-to-face meeting. For 3 parameters (aortic neck diameter, aortic neck angulation, conical neck), the agreement among the EP members was already high during the first survey round while for the remaining 2 (aortic neck length, circumferential calcification) it remarkably increased from the first to the second survey round. For each of these criteria, as well as combinations of at least 2 of these criteria, specific threshold values were identified above or below which a standard EVAR approach was not considered ideal by the EP due to high/moderate risk of complications. Conclusions: EP agreed on the definition of 5 aortic neck hostility criteria, according to which they gave their opinion on the feasibility and risks of a standard EVAR approach. Further agreement will be needed and examined on the best nonstandard EVAR technique which may be offered in the presence of different combinations of hostility criteria.