1. Introduction
The management of complex pathologies of the thoracic aorta have always presented a challenge to surgeons due to the high associated risk of morbidity and mortality. The introduction of frozen elephant trunk (FET) technique facilitated total arch replacement (TAR) procedures by shortening the aortic occlusion time for proximal anastomosis, providing the opportunity of treating complex aorta pathologies in a single-step procedure, or by offering a more optimal landing zone for secondary endovascular intervention if needed [1]. Due to its hybrid approach, FET has gained great popularity in the field of aortovascular surgery, and since its introduction, it has become the mainstay technique for TAR in a wide spectrum of complex thoracic aortic diseases.
The indications for the FET procedure include chronic aortic aneurysms, acute and chronic type B dissections in cases where endovascular treatment is contraindicated, and furthermore, acute or chronic type A aortic dissections (TAAD) [2]. Despite the highly favorable results associated with FET, particularly aortic remodeling in terms of true lumen (TL) flow maintenance and false lumen (FL) obliteration, the rates of reinterventions following the procedure are minor but present [3-6].
Stent graft-induced new entry (SINE) is one of the major complications of FET defined as a new tear occurring either at the distal or proximal end of the stent-graft portion of the FET device that is caused by the stent-graft itself [7]. This complication was first identified and documented by Ninomiya et al. [8] in 2002, but was named “SINE” later on by Dong et al. [7] in 2010. The incidence of distal SINE (dSINE) post-FET has been associated with the stent-graft size and length, aortic pathology type and location, and the distal landing zone of the FET hybrid prosthesis (HP). Other complications of the FET procedure are, but not limited to, endoleak, spinal cord injury (SCI), renal complications, cerebrovascular events and graft kinking. Yet, it is important to note that the incidence of the above postoperative events is lower with FET compared to conventional arch replacement techniques [9, 10, 11].
Several commercial FET HPs exist on the global market, these include Thoraflex Hybrid (Terumo Aortic, Inchinnan, Scotland, UK), E-Vita (JOTEC GmbH, Hechingen, Germany), J Graft Frozenix (Lifeline Co, Ltd, Tokyo, Japan) and Cronus (MicroPort Medical Co, Ltd, Shanghai, China). However, overall evidence in the literature seem to suggest that the Thoraflex Hybrid (or THP) is the superior FET devices on the arch prosthesis market [9, 10]. Nevertheless, the literature also describes controversial evidence on the association between the aforementioned commercially-available FET devices and clinical outcomes. This meta-analysis aimed to provide a wide and comprehensive perspective on the relationship between FET device type and results, including aortic remodeling and other complications such as dSINE and endoleak.