Comparison of aortic neck dilatation after open and endovascular repair of abdominal aortic aneurysm

Objective: This study evaluated the changes of the aortic diameter at the suprarenal and infrarenal segment after open repair (OR) and endovascular repair (EVAR) of abdominal aortic aneurysms (AAAs). Methods: This was a retrospective analysis of all patients undergoing AAA repair between 1997 and 2008. Inclusion criteria were at least 3 months of follow-up at our institution, elective aneurysm repair, and absence of false, mycotic, or inflammatory aneurysms. For EVAR, standard computed tomography (CT) scans from follow-up were used; in the OR group, CT scans performed for unrelated nonvascular indications were used. Diameters of the aorta were measured at the first slice below the lowest renal artery and at the first slice above the highest renal artery. A 2-mm change was defined as measurable aortic neck dilatation. Results: Inclusion criteria were met by 46 patients in the OR group and 103 in the EVAR group. After a follow-up of 34.1 months (range, 5.5-131.7 months) in the OR group and 39.4 months (range, 3-108.9 months) in the EVAR group, the mean changes were 1.75 +/- 3.50 mm (OR) and 0.9 +/- 2.3 mm (EVAR; P = .305) in the suprarenal diameters and 0.8 +/- 2.9 mm (OR) and 1.2 +/- 2.5 mm (EVAR; P = .311) in the infrarenal diameters. The absolute suprarenal vs infrarenal sizes were 29.7 +/- 7.1 and 28.7 +/- 6.8 mm in the OR group and 28.7 +/- 3.2 and 28.5 +/- 3.6 mm, respectively, in the EVAR group (suprarenal, P = .749; infrarenal, P = .273). Increase of the aortic diameter >2 mm, defined as aortic neck dilatation, was found in 23 of 103 EVAR patients (22.3% +/- 0.862%), and in nine of 46 OR patients (19.57% +/- 0.484%; P = .870). Increase in the suprarenal change >2 mm occurred in 21 of 103 EVAR patients (20.39% +/- 1.04%) and in 14 of 46 OR patients (30.4% +/- 0.446%; P = .260). Reintervention rate of patients with an increase >2 mm was 31% (seven of 23) in EVAR and 11.1% (one of nine) in the OR group (P = .386). Conclusions: The AAA groups treated with EVAR or OR demonstrated similar increases of aneurysmal neck diameters. This suggests that aortic neck dilatation may be caused by a natural progression of the disease rather than by deviating therapeutic strategies. (J Vasc Surg 2012;55:929-34.)