Thoracic Stent-Graft Migration: The Role of the Geometric Modifications of the Stent-Graft at 3 years

Background: To date, clinical and experimental studies on stent graft (SG) migration have focused on aortic morphology and blood flow. However, thoracic endovascular aortic repair (TEVAR) is not an instant fixation of the SG in the aortic lumen but rather a continuous process of deformation and three-dimensional change in the configuration and the geometry of the SG. The aim of this study was to analyze the geometric evolution of the aortic SG in the proximal attachment zone at midterm follow-up and its impact on the SG migration. Methods: Sixty-two patients underwent TEVAR for thoracic aortic aneurysm from 2007 till 2013. Thirty patients were treated and had a complete clinical and morphological follow-up at 1 month and 3 years. We calculated the SG radius of curvature (RC) change at the proximal attachment zone P'' on the postoperative computed tomography scan at 1 month and 3 years. Results: There were 19 atheromatous aneurysms, 8 postdissection aneurysms, and 3 posttraumatic aneurysms. Two patients were treated at zone 1, seven at zone 2, and twenty-one at zone 3. The median decrease of the RC at P'' was 11 mm (interquartile range, 6.5 mm; range, 1-29 mm. A greater decrease in RC was identified in patients with hostile proximal neck having a large diameter (P = 0.006), short neck length (P = 0.04), and neck thrombus grade II and III (P = 0.02). In the migration group, the RC of P'' decreased significantly at 3 years (27.5 mm vs 18.25 mm; P = 0.03). Three patients had type I endoleak and showed a decrease of the RC at P'' (42 vs 13 mm; 28 vs 15 mm; 24 vs 9 mm). Conclusions: The SG seems to have geometric changes in the proximal attachment zone over time. The increase of SG curvature might be a predictor for SG migration and may prompt prophylactic reintervention.