Risk factors for endoleak and the evidence for stent-graft oversizing in patients undergoing endovascular aneurysm repair

Objectives: the aim of this study was to assess the relationship between pa tient factors, the anatomy of the proximal aneurysm neck; the type of endov ascular graft; and the consequences of graft/neck size mismatch and the occ urrence of proximal endoleak. Design: multicentre clinical study. Materials: of a total of 2194 patients, 2146 underwent successful endovascu lar repair of infra-renal abdominal aortic aneurysms (AAA). Methods: endoleaks were identified by radiological imaging immediately afte r completion of the procedure as per study protocols. Clinical and anatomic al features of AAA in patients with endoleak were compared to patients with out endoleak and data were analyzed using the Chi-square test. A multivaria te logistic regression model was constructed by selecting variables found t o be significantly associated with complications in a univariate analysis. Results: intra-operative endoleak was observed in 16.7% overall, and 3.3% w ere noted to have proximal endoleak. Aneurysm size larger than 60 mm (p = 0 .004), ex-smokers (p = 0.005) and age over 75 years (p = 0.01) were indepen dently associated with endoleak of all types. Univariate and multivariate a nalysis revealed correlation between proximal endoleak aortic neck length ( p = 0.0001); (iii) aortic device diameter (p = 0.0024). No correlation was identified for angulation and form of the aortic neck. A model of the freq uency of proximal endoleak, in relation to the ratio of the aortic device d iameter to the distal aortic neck diameter, revealed that endoleak decrease d when the aortic device diameter became oversized by more than 10% and con fidence intervals remained tight for up to and over 20% oversize.