Proximal Bare Stent May Reduce Bird-Beak Configuration, Which is Associated with Distal Migration of Stent Graft in the Aortic Arch

Background: Prior studies have shown that a bird-beak configuration causes serious complications after thoracic endovascular aortic repair (TEVAR). However, factors that cause bird-beak configurations are poorly understood. The purpose of this study was to assess the influences of anatomical and device-related factors on bird-beak configuration.

Methods: Sixty-eight consecutive patients (47 men, mean age, 72.8 ± 9.8 years) who underwent TEVAR with proximal fixation in zones 1 to 3 from March 2009 to February 2017 were included. Preoperative and postoperative computed tomography (CT) scans were retrospectively reviewed. Relationships between the incidence of a bird-beak configuration, preoperative aortic arch morphology, and type of stent graft were estimated. The influence of a bird-beak configuration on endograft migration over time was also estimated for 47 patients who underwent CT 12 months after TEVAR.

Results: The patients' aortic arch pathologies included 52 aneurysms, 11 aortic dissections, 4 pseudoaneurysms, and 1 patent ductus arteriosus. Stent grafts with (the proximal bare stent group [PBS group]) and without (the nonbare stent group [NBS group]) a proximal bare stent were implanted in 24 and 44 patients, respectively. A bird-beak configuration was detected in 30 patients (mean length ± standard deviation [SD], 6.2 ± 3.4 mm; mean angle ± SD, 31.7 ± 14.7°) and was significantly more frequent in the NBS group (n = 29) than in the PBS group (n = 1) (P < 0.001). Proximal landing zone, aortic lengths, and aortic arch morphology, including the radius, tortuosity, and angulation of aortic arch curvature, were not associated with the bird-beak configuration. The migration distance after 1 year was significantly longer in patients with a bird-beak configuration (3.5 ± 6.1 mm) than in patients without a bird-beak configuration (0.5 ± 1.0 mm) (P = 0.015).

Conclusion: This study demonstrated that in aortic arch TEVAR, the use of stent graft with a proximal bare stent may reduce bird-beak configuration, which is associated with distal migration of the stent graft during follow-up.