Commentary
The treatment of aortic arch pathologies remains a great challenge due
to the associated high rates of mortality and morbidity. Open surgical
repair (OSR) is considered as the first-line treatment strategy in
patients with dissections or aneurysms involving the aortic arch. The
high invasiveness and the radical approach in replacing the aortic arch
via the frozen elephant trunk (FET) procedure predisposes the patient to
disabling complications including stroke, organ malperfusion, and
coagulopathy [1, 2]. The interest in the use of thoracic
endovascular aortic repair (TEVAR) as an alternative to OSR in the
treatment of arch pathologies has been continuously rising since its
introduction. Still, it presents a challenge in the control and
deployment of the endograft around the arch and poses the omnipresent
risks of supra-aortic vessels malperfusion [3]. However, specialized
TEVAR endografts complementing the anatomy of the arch have been
developed. One major example is the RELAY™ Branched (Terumo Aortic,
Scotland) which comes in single-, double-, or triple-branched
configurations to preserve patency of the supra-aortic vessels. The
endovascular approach to treating arch pathologies is reserved for
high-risk patients who meet certain criteria to optimise the proximal
deployment and sealing of the endograft. These require the presence of
primary entry tears more than 20 mm distal to the sinotubular junction
and a proximal landing zone diameter of more than 38 mm [3, 4].
We read with great interest the recent original study by Tan and
Colleagues [5] which discussed the neurological outcomes after
endovascular aortic arch repair using the RELAY™ Branched device. The
authors presented original perioperative data on the clinical use of
RELAY™ device in patients with arch pathologies. This study’s great
scientific value comes from the highly robust methodology which includes
comprehensive statistical analyses performed and very well-presented
clinical data. Also, the authors delineated where the evidence in the
literature stand in terms of neurological outcomes after endovascular
arch repair. A total of 148 patients underwent endovascular aortic arch
repair using the RELAY™ Branched device, out of whom 107 suffered of
proximal aortic aneurysm and 41 patients had aortic dissection.
Sixty-eight patients, representing 46% of the cohort, underwent the
procedure in the acute setting whilst the remaining 54% (n = 80) were
treated electively. Additionally, the majority of patients (73%; n =
108) received the double-branched configuration of the RELAY™ device.
The single-branched and tripe-branched devices were only employed in
11.5% (n = 17) and 15.5% (n = 23) of patients, respectively. The
authors also reported comprehensive follow-up data for all patients
after 30 days, 6 months, 12 months, and 24 months post-operatively.
The primary reported outcome in Tan et al. [5] is the presence of
neurological deficit as patients were screened for the presence of
disabling or non-disabling stroke. The authors used the VARC-2 criteria
which define a disabling stroke with a modified Rankin scale (mRS) score
> 3 and a non-disabling stroke with a modified Rankin scale
score < 2. After 24 months of follow-up, a total of six
patients (4%) suffered from disabling stroke, out of which 2 occurred
within the first 30 days post-TEVAR. On the other hand, a non-disabling
stroke was documented in 8 patients (5.4%) over 24 months of follow-up,
yet, 5 cases were identified during the first 30 days postoperatively.
Whilst more than half of stroke incidences were recorded in the
perioperative period, which is usually attributed to operative
manipulation of the arch and the supra-aortic vessels, the authors
highlighted that stroke, in a smaller percentage, can still occur even
over an extended period postoperatively. Tan et al. [5] also
highlighted further advantages of the RELAY™ Branched endograft
including high technical success (99.4%) as well as a relatively short
endovascular time during the procedure (100-150 minutes in 64% of
patients). However, the authors noted that more extensive disease might
lead to longer procedural duration and more extensive manipulation,
hence this should be assessed pre-operatively to optimise results in
suitable candidates.
The neurological results yielded by the RELAY™ Branched device can be
considered superior to its market competitors. For example, Tazaki et
al. [6] observed a combined stroke rate of 33% in patients who
received the Inoue™ double-branched endograft, which is substantially
higher than the combined rate of 9.5% reported by Tan et al. [5]
(9.5%) in patients who received the double-branched configuration of
the RELAY™ device. In addition, Tan et al. [5] reported a 0% rate
of stroke in patients who received the triple-branched RELAY™ Branched
device. In contrast, Tazaki et al. reported a 40% combined stroke rate
in patients who received a triple-branched configuration of the Inoue™
device. Nonetheless, it seems there is no significant relationship
between the incidence of stroke and the branching configuration of the
graft.
The underlying mechanism of perioperative stroke in patients who receive
TEVAR is yet not fully understood. Malperfusion and embolization are the
main hypothesized mechanisms that drive the development of stroke. It is
worth noting that the coverage of arch vessels during TEVAR may lead to
cerebral malperfusion Control of each of these two factors could lead to
superior neurological outcomes in this group of patients [7]. The
left subclavian artery (LSA) is the most commonly covered supra-aortic
vessel in TEVAR for descending aortic pathologies. This risk is even
higher whilst stenting the arch without complete debranching of the
supra-aortic vessels. Hence, the Society for Vascular Surgery guidelines
recommend routine LSA revascularisation in elective TEVAR of the arch
cases [8]. Moreover, atheromatous disease of the aortic arch has
been linked to perioperative stroke in patients receiving TEVAR. This
has been demonstrated by Katz et al. [9] who observed the strong
association between >5 mm of atheromatous diseases in the
aortic arch and the incidence of stroke following TEVAR (OR = 14.8, CI =
1.7 – 675.6, P = 0.0016). Therefore, following screening and
evaluation, candidates with atheromatous disease in the aortic arch
should be weighed for the risk of postoperative neurological insult.
Unfortunately, Tan et al. [5] did not fully provide the baseline
characteristics of their patients. This information could present the
foundation to understanding the pathophysiology of perioperative stroke
and should be addressed in future studies.
The RELAY™ Branched is a well-described devices for endovascular aortic
arch repair, achieving highly favourable neurological outcomes. Multiple
factors in the perioperative assessment can predict the risk of
neurological outcomes in patients undergoing TEVAR. These include the
presence of atheromatous aortic disease, the extent of the pathology and
the technique of supra-aortic vessels revascularization.