Abdominal aortic bifurcation anatomy and endograft limbs size affect the use of adjunctive iliac stenting after bifurcated ebdograft deployment for abdominal aortic aneurysms

BACKGROUND: The aims of the study are: 1) to define the incidence of intraoperative endograft limb stenosis >50% (ELS) after bifurcated EVAR, 2) to find risk factors for ELS considering morphology of aortic bifurcation and structural characteristics of endograft iliac limbs, and 3) to evaluate early and follow-up outcomes of intraoperative adjunctive endograft iliac stenting. METHODS: Patients treated with bifurcated EVAR for abdominal aortic aneurysm were prospectively collected from 2005 to 2011. Patient demographics, clinical risk factors, preoperative aortic bifurcation morphology (minimum and maximum diameter [ABD], calcification [ABC]), endograft iliac limb parameters (diameters [ELDs], stent material, type of endograft), ratio between ELDs and ABD), perioperative ELS and results during follow-up were analyzed. Primary outcomes were incidence of perioperative ELS and risk factors for its occurrence. Considering adjunctive stenting procedure, secondary outcomes were technical success, 30-day and mid-Term iliac endograft leg patency and clinical success. RESULTS: Two hundred and forty-seven patients (men 233; mean age 74±7 years) were included. Mean maximum ABD was 28.9±12.9 mm. ABC was ≥50% in 56 (22.7%) cases. Median sum of ELDs was 31 mm (IQR 13-46). Endograft limb with stainless steel and nitinol stents was deployed in 69 (27.9%) and 178 (72.1%) patients. Median ELDs/ABD ratio was 1.2 (IQR: 0.9-1.5). ELS in aortic bifurcation occurred in 42 (8.5%) endograft limbs in 36 (14.6%) patients. ABD≤20 mm, ABC≥50%, ELDs≥30 mm, nitinol endograft stents and ELDs/ABD>1.4 were identified as possible positive predictive factors. At univariate and multivariate analysis, ELDs/ABD>1.4 resulted a positive prognostic factor for ELS (0.008 and 0.022, respectively). Forty-Two adjunctive stents were deployed in 36 (14.6%) patients as intraoperative adjunctive procedure. Technical success, 30-day iliac endograft leg patency was 100%. Mean follow-up was 33 months (range 6-55 months) and mid-Term clinical success and iliac endograft limb patency were 100%. CONCLUSIONS: ELS is a common event after EVAR with bifurcated endograft and ELDs/ABD>1.4 results positive predictive factor. Adjunctive stenting is a safe and effective procedure and ensures optimal mid-Term endograft limb patency.