Head-to-head: Zone 2 vs. Zone 3 frozen elephant trunk

Abstract

Total arch replacement via frozen elephant trunk (FET) is a strategy for managing complex thoracic aortic pathologies involving the arch and descending thoracic aorta (DTA). The FET procedure involves the distal anastomosis of the FET hybrid prosthesis at a chosen aortic arch zone. Though distal anastomosis has been traditionally performed at Zone 3 (Z-3-FET) of the aortic arch, recent practice has seen a significant increase in Zone 2 FET (Z-2-FET). The literature concerning independent Zone 2 and 3 studies and head-to-head comparative studies suggest that Z-2-FET is the superior approach, yielding more favourable results overall, except for aortic remodelling. The improved clinical outcomes achieved with Z-2-FET can be attributed to the shorter operative times, including cardiopulmonary bypass duration, due to the ease and increased surgical site exposure at the aortic arch using this technique. The slightly inferior aortic remodelling observed in Z-2-FET can be explained by the decreased coverage of the DTA distally by the FET stent graft. However, this difference in results can also be attributed to the complexity and severity of the underlying pathology and the surgical approach adopted. The prospect of utilising Zone 0 FET (Z-0-FET) is highly promising, with some studies hinting at its superiority over Z-2-FET. Nevertheless, studies are needed to determine the efficacy of Z-0-FET and directly compare it to Z-2-FET to reach a definitive consensus on the most optimal FET technique. The present literature review aims to provide an overview of major intraoperative and postoperative outcomes achieved with Z-2-FET and Z-3-FET and summarise evidence from studies directly comparing them. Another aim of this narrative review is to explore current literature trends on Z-0-FET uptake.