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Page 4 of 12 Geragotellis et al. Vessel Plus 2023;7:6 https://dx.doi.org/10.20517/2574-1209.2022.41

FET technique can reflect in the results observed.

Overview of clinical outcomes with Z-3-FET
Mortality rates reported in small independent Z-3-FET studies are comparable to Z-2-FET but are
challenged in studies of larger sample sizes. A 32-patient series by Hoffman et al. reporting on FET for acute
[22]
TAAD found 30-day and 6-month mortality rates of 0% and 3.1%, respectively . Similarly, favourable
[23]
results for acute TBAD were seen by Kreibich et al., who reported no deaths . However, more extensive
independent studies have demonstrated early postoperative mortality rates ranging from 6%-15.3% [24-27] .

There appears to be a modest variation in reported Z-3-FET neurological outcomes. The incidence of SCI
was 7.4% in the 2019 single-centre study of 68 patients from the Heidelberg group . On the other hand,
[27]
and surprisingly, some series did not report SCI as a complication [22,23,25] . The same group also reported a
combined incidence of postoperative stroke of 10.3% in their pooled acute and chronic aortic pathology
cohort. The variability in neurological complications is apparent in Goebel et al., which reported a much
lower stroke rate of 2.8%, and in a couple of studies observing no postoperative strokes [22-24] . The literature
has substantial heterogeneity in preoperative patient characteristics and intraoperative factors, including the
exact FET device, deployed and surgical technique used. Furthermore, not all series delineate the precise
surgical technique relevant to our purposes, thus limiting the scope of potentially relevant data. Therefore,
FET studies must incorporate neurological outcomes into their results in addition to unambiguous
identification of the aortic arch zone adopted for FET HP distal anastomosis.

HEAD-TO-HEAD: ZONE 2 VS. ZONE 3 FET
The direct comparison of Z-2-FET and Z-3-FET is challenging as they are ultimately distinct procedures
that vary according to surgical preference and the aortic anatomy of individual patients. There is also a
paucity of evidence in studies that directly compare Z-2-FET and Z-3-FET intraoperative and postoperative
outcomes, including operative times, mortality, neurological complications, RLN injury, respiratory and
renal outcomes, haemostasis, and aortic remodelling. However, contemporary practice has seen an
increased uptake of Z-2-FET due to reduced operative times [Table 1] and a lower risk of postoperative
complications [8,21,28-32] [Table 2].

Intraoperative outcomes
CPB and cerebral perfusion
CPB and cerebral perfusion times are lower with Z-2-FET [8,28,29,31,32] . Leone et al. reported a CPB time of 200
min achieved with Z-2-FET (n = 69) vs. 210 min with Z-3-FET (n = 213) (P = 0.171) . Similarly, but with a
[8]
more pronounced difference in CPB times, Panfilov et al. recorded 188 min in their Z-2-FET group (n = 17)
[31]
vs. 227 min in the Z-3-FET group (n = 27) (P = 0.013) . The overall retrospective analysis of data captured
between 2005-2018 by the Essen group showed 231 min of CPB achieved with ≤ Z-2-FET (n = 204) vs. 250
min in Z-3-FET (n = 103) (P < 0.001) . Cerebral perfusion time was also lower at 56 min with ≤ Z-2-FET
[32]
compared to 65 min in the Z-3-FET cohort (P < 0.001) . Detter et al. additionally demonstrated respective
[32]
cerebral perfusion times of 61 min and 92 min (P < 0.001) . Leone et al. and Panfilov et al. reported
[29]
comparable cerebral perfusion durations between Z-2-FET and Z-3-FET of 91 vs. 88 min and 57 vs. 59.5
min, respectively [8,31] .

Visceral ischaemia time
Since Z-2-FET procedures are technically more straightforward and less time intensive, this has resulted in
[32]
lower visceral ischaemia times and risk of postoperative morbidity. Tsagakis and Jakob recorded an
average of 39 min of visceral ischaemia in their ≤ Z-2-FET cohort (n = 204) compared to 70 min in their Z-