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

Background. This study sought to evaluate the incidence of and identify risk factors for distal stent graft-induced new entries (dSINEs) after the frozen elephant trunk (FET) procedure. Methods. Patient characteristics and radiographic and follow-up data on 126 patients treated for aortic dissections with the Thoraflex (Vascutek Ltd, Inchinnan, United Kingdom) FET device in 2 centers between November 2013 and December 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. dSINEs were diagnosed in 16 patients (13%). There was no difference in the underlying disease, aortic features, or FET stent graft dimension between patients with and without dSINEs. No predictors for dSINE occurrence in patients treated with the Thoraflex device were identified. The risk for dSINE development was 14% (95% confidence interval [CI], 0% to 22%), 16% (95% CI, 0% to 24%), and 25% (95% CI, 0% to 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, whereas the E-Vita prosthesis showed nearly constant stiffness. In addition, the Thoraflex prosthesis showed an increase in stiffness when confined. Conclusions. dSINEs 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 a potential reason for the occurrence of dSINEs. (C) 2020 by The Society of Thoracic Surgeons