Distal Stent-Graft-Induced New Entries following the Frozen Elephant Trunk Procedure.

Abstract Background To evaluate the incidence and to identify risk factors for the occurrence of distal stent-graft induced new entries (dSINE) following the frozen elephant trunk (FET) procedure. Methods Patient characteristics, radiographic, and follow-up data of 126 patients treated for aortic dissections with the Thoraflex (Vascutek Ltd, Inchinnan, UK) FET device in two centers between 11/2013 and 12/2018 were evaluated. Stress-strain behavior and load-displacement curves of the Thoraflex and the E-Vita Open (Jotec Inc., Hechingen, Germany) FET prosthesis were evaluated by applying axial load to the most distal ring of the prostheses. Results dSINE were diagnosed in 16 patients (13%). There was no difference in the underlying pathology, aortic, or FET stent-graft dimension between patients with and without dSINE. No predictors for dSINE occurrence in patients treated with the Thoraflex device were identified. The risk for dSINE development was 14% [95%-CI: 0-22%], 16% [95%-CI: 0-24%], and 25% [95%-CI: 0-45%] after 12, 24, and 36 months respectively. When prostheses were loaded axially to 2 mm maximal displacement, the Thoraflex prosthesis exhibited strongly nonlinear behavior with maximal stiffness for minimal displacements, while the E-Vita prosthesis showed nearly constant stiffness. Also, the Thoraflex prosthesis showed an increase in stiffness when confined. Conclusions dSINE may develop at any time after the FET procedure and the risk for dSINE development is high. No clinical or patient specific risk factors were identified in this study. The design of the Thoraflex graft with a stiff distal ring may be one potential reason for the occurrence of dSINE.