False lumen thrombosis and aortic remodelling
The extent of FL thrombosis and positive aortic remodelling following FET implantation can be considered an indicator of therapeutic efficacy of the FET stent. Coverage and rectification of intimal tears in AAD serve to improve distal TL integrity and limit FL patency, thereby promoting thrombosis and obliteration, particularly in the locality of the FET stent.25 In cases of chronic aortic dissection, proximal FL thrombosis around the stented aorta is associated with improved distal positive remodelling, while negative aortic remodelling is associated with reintervention in the distal aorta.25 Jakob and colleagues, in their review of the E-vita Open hybrid graft for Z-2-FET and Z-3-FET, report complete exclusion of aortic disease and positive remodelling around the graft region in 94% (n=167) and 92% (n=163) of AAD patients treated with Z-2-FET, but that 82% (n=145) of such patients were also found to have residual disease distal to the FET stent.11Interestingly, similarly mixed results were reported by both Yamamotoet al. and Jakob et al. in their respective reviews on Z-0-FET.16, 17 Jakob and colleague’s 3-zone Z-0-FET prosthesis procedure showed thrombosis of the FL around the aortic arch and DTA in only 40% (n=2) and 60% (n=3) of cases respectively, while 3 of 6 patients reviewed demonstrated residual arch FL patency while remaining clinically stable.17 Yamamoto et al.highlighted that thrombosis of FLs of the aortic arch, DTA, and abdominal aorta was achieved in 74.1% (n=80), 29.6% (n=32), and 5.5% (n=6) of cases respectively.16 Interestingly, 3% (n=3) patients demonstrated re-opening of the FL around the coeliac arteries following Z-0-FET repair.16 Undoubtedly, the clinical factors surrounding the effect of FET on FL thrombosis and aortic remodelling is complex and multifactorial – yet Yamamoto and colleague’s results are promising, particularly for cases of DeBakey Types I and II AAD.