Institutional differences in endovascular aneurysm repair and aneurysm morphology.

Background: Variability exists between institutions in the application of endovascular aneurysm repair (EVAR). This study compares patient-specific variables from a high-volume North American institution with one from the UK.
Methods: One hundred consecutive patients from each institution were studied. All were treated for an intact, infrarenal aortic aneurysm. Patient characteristics and aneurysm-related variables, measured from computed tomography according to Society for Vascular Surgery (USA) reporting standards, were examined.
Results: The median (range) age of the American patients was 74 (55-97) years and that of the British patients, 73 (49-89) years. There were 78 men in the American group and 79 men in the British group. All American patients were treated by EVAR compared to 11 % of the British group. Mean (SD) aneurysm diameter for the former was 55 (9) mm and for the latter 64 (11) mm (P < 0.001). While there was no difference in mean diameter of the infrarenal aortic neck (P = 0.918), the aneurysms of British patients (22 %) were more likely to be angulated >60° than those of the American patients (11 %) (P = 0.039). Furthermore, the mean (SD) length of infrarenal aortic neck was shorter in the British patients [21 (11) mm] compared to the American group [25 (12) mm] (P = 0.003). The mean diameter of the common iliac arteries was larger in the British patients than in the American group (P < 0.001). Mean external iliac artery diameter was no different between the groups (P = 0.507).
Conclusions: This group of British patients have a more advanced pattern of aneurysm morphology than American patients of similar age. This difference may, in part, explain variability in the application of EVAR.