Purpose: To analyze the overall performance of flexible nitinol stents used to line chimney grafts (CGs) during chimney endovascular aneurysm repair (chEVAR) of pararenal pathologies.
Materials and methods: A retrospective review was conducted of all 116 elective patients (mean age 74.3±7.2 years; 103 men) who underwent chEVAR with balloon-expandable Advanta V12/iCAST CGs in combination with the Endurant stent-graft between January 2009 and December 2017 at a single center. CG lining with a nitinol stent was electively performed in 43 target vessels of 32 patients. The Kaplan-Meier method was used to estimate the primary outcomes of CG patency and freedom from reintervention (FFR) at the patient level and according to the use of a stent to line the CG. Estimates are reported with the 95% confidence interval (CI). Adjusted odds ratios (ORs) were calculated to identify any confounding effect between the presence/absence of a stent lining or according to the number of CGs.
Results: The mean radiological follow-up was 27.3 months (range 22.1-32.6). During this time, 8 CGs (4.7%) became occluded, 6 of them were lined with stents. Restoration of patency was possible in 3 of the 4 occluded stents that were associated with symptoms. First-year primary patency estimates were 96.9% (95% CI 92.5% to 100%) for the unlined group vs 77.1% (95% CI 58% to 95.3%; p=0.001) for the lined group, while FFR was 87.6% (95% CI 79.9% to 95.2%) vs 83.4% (95% CI 68.1% to 98.6%; p=0.82), respectively. Lining represented an independent risk factor for CG occlusion (OR 9.9, p=0.006).
Conclusion: CG lining performed mainly in angulated renal arteries during chEVAR was significantly associated with CG occlusion. These findings highlight the importance of not having the distal part of the CG impinge on the angulated segment of the target vessel.
Keywords: balloon-expandable stent-graft; chimney grafts; covered stent; endovascular aneurysm repair; occlusion; parallel grafts; pararenal aneurysm; patency; reintervention.