The correlation of aortic neck length to late outcomes following EVAR with the Ovation stent graft

Abstract

ObjectiveEndovascular aneurysm repair (EVAR) performed outside manufacturers’ instructions for use due to short aortic neck for the treatment of abdominal aortic aneurysm (AAA) is associated with unfavorable outcomes. Newer endografts now have an indication for shorter neck aneurysms that previous endografts do not, but this cohort has yet to be evaluated individually. The aim of this study is to evaluate 5-year outcomes after EVAR in patients with short aortic necks (<10 mm) using the Ovation stent graft. MethodsThe study comprised 238 patients who underwent EVAR as part of the prospective international multicenter Ovation stent graft trials. The main inclusion criteria were AAA diameter ≥ 5 cm, proximal parallel neck length ≥7 mm, neck angulation ≤60°, and bilateral iliac fixation length ≥10 mm. A clinical events committee adjudicated adverse events through 1 year, an independent imaging core laboratory analyzed imaging through 5 years, and a data safety and monitoring board provided study oversight. Patients were divided into short neck (<10 mm) and standard neck (≥10 mm) groups. End points included long-term survival, freedom from aneurysm-related mortality (ARM), freedom from type Ia endoleak, and freedom from reintervention. ResultsPatients were predominantly male (81%) with a mean age of 73 ± 8 years. Median follow-up time was 58 months (interquartile range, 36-60 months). Of 238 patients, 41 (17.2%) had a proximal neck length <10 mm and would be considered outside the instructions for use with other stent grafts. Baseline characteristics were relatively similar between the two groups. The 5-year overall survival estimates were 77.8% for the standard neck group compared with 59.5% for the short neck group (P = .03). There were no differences in the 5-year freedom from ARM (99.2% vs 100%; P = .7), freedom from type Ia endoleak (96.3% vs 96.3%; P = .8), and freedom from reintervention (77.9% vs 79.7%; P = .7) between the standard and short neck groups, respectively. After adjusting for age and other potential confounders, short proximal neck was associated with a two-fold increase in 5-year all-cause mortality (adjusted hazard ratio, 2; 95% confidence interval, 1.02-3.8; P = .04]. ConclusionsThe Ovation endograft performed well in short AAA neck with no difference in 5-year type Ia endoleak, reintervention, and ARM rates. However, short proximal neck was independently associated with a two-fold increase in the risk of all-cause mortality at 5 years. These findings confirm the prior literature on the association of hostile neck anatomy with late mortality following EVAR.