Abstract
Background : Acute type A aortic dissection (ATAAD) is a
life-threatening medical condition requiring urgent surgical attention.
It is estimated that 50% of ATAAD die within 24 hours of onset, with
the mortality rate is increasing by 1-2% every additional hour without
prompt intervention. A variety of ATAAD surgical repair techniques exist
which has sparked controversy within the literature, with the main two
strategies being proximal aortic replacement (PAR) and total arch
replacement (TAR). Nevertheless, the question of which of these two
strategies if the more optimal is still debatable.
Aims : This commentary aims to discuss the recent study by Sa and
colleagues which presents a pooled analysis of Kaplan-Meier-derived
individual patient data from studies with follow-up comparing aggressive
(TAR) and conservative (PAR) approaches to manage ATAAD patients.
Methods : A comprehensive literature search was performed using
multiple electronic databases including PubMed, Ovid, Google Scholar,
EMBASE and Scopus in order to collate the relevant research evidence.
Results : The more aggressive TAR approach for treating ATAAD
seems to yield more favourable results including more optimal long-term
survival as well as a lower need for reoperation. The frozen elephant
trunk (FET) technique can be considered the mainstay TAR technique.
Conclusion : It is valid to conclude that TAR with FET is the
superior strategy for managing ATAAD patients.
Acute type A aortic dissection (ATAAD) is a life-threatening medical
condition requiring urgent surgical attention. It is estimated that 50%
of ATAAD patients die within 24 hours of onset, with the mortality rate
is increasing by 1-2% every additional hour without prompt intervention
[1]. Although surgical intervention is well-established as being the
gold standard approach for treating ATAAD, a variety of surgical
techniques exist which has sparked controversy within the literature.
The main two strategies for ATAAD surgical repair are proximal aortic
replacement (PAR), either limited to the ascending aorta or extending to
include the lesser curvature of the aortic arch (i.e. hemi-arch), and
total arch replacement (TAR) using the elephant trunk technique
(conventional or frozen) [2]. Nevertheless, the question of which of
these two strategies if the more optimal is still debatable, which was
addressed in a recent meta-analysis by Sa et al. [2].
We read with great interest the above study which comparatively
investigated the effects of both strategies on the all-cause mortality
risk and need of reoperation over time. The authors performed a pooled
analysis of Kaplan-Meier-derived individual patient data (IPD) from
studies with follow-up comparing aggressive (TAR) and conservative (PAR)
approaches to manage ATAAD patients. The study benefits from a highly
robust methodology including a thorough literature search strategy,
effective inclusion/exclusion criteria, assessment of risk of bias and
advanced comprehensive statistical analyses, all of which have led to a
well-written and very impactful research piece. A total of 18 studies
were included in the meta-analysis comprising 5243 patients with
follow-up (conservative: 3676 patients; aggressive: 1567 patients). It
is worth noting that this study can be considered the first of its kind
using reconstructed time-to-event data and Kaplan-Meier-derived IPD to
directly compare PAR and TAR. The authors concluded that TAR seems to be
the more favourable approach for treating ATAAD due to improved
long-term survival and lower risk of need of reoperation [2].
Several cohort studies have compared PAR and TAR for ATAAD, with the
majority of results aligning with those of Sa et al. [2] suggesting
TAR’s superiority over PAR (with or without hemiarch). In the 14-year
study of 213 ATAAD patients by Vendramin et al. [3], Group 1
consisted of 138 patients who underwent PAR while Group 2 included 75
TAR patients. Overall hospital mortality was 12% and 5% in Group 1 and
2, respectively, whilst survival at 5 and 10 years was 72 ± 4% and 49 ±
5% in Group 1 and 77 ± 6% and 66 ± 9% in Group 2 (P = 0.073).
Furthermore, freedom from reoperation at 5 and 10 years was 92 ± 2% and
89 ± 3% in Group 1 and 98 ± 1% at both follow-up points in Group 2 (P
= 0.068) [3]. In their 21-year experience, Ok et al. [4]
operated on a total of 365 ATAAD patients using hemiarch replacement
technique in 248 and TAR in 117. Both early and late mortality rates
were lower in the TAR group than the hemiarch group (early: 6.8% vs
9.3%, P = 0.56; late: 22.2% vs 27.4%, P = 0.35). On the other hand, a
higher proportion of TAR patients required late reintervention (17.9%
vs 12.5%, P = 0.22) [4]. Additionally, out of the 253 ATAAD
patients in Uchida et al. [5], 169 underwent PAR and 84 TAR. Similar
to the above results, the TAR group experienced lower mortality (6% vs
7.1%). Similarly, freedom from all-cause mortality at 9-years of
follow-up was 84.5% with TAR compared to 80.5% with PAR. Moreover,
only 6% of TAR patients required reparative surgery whilst this was
needed in 13.6% of PAR patients [5]. All the aforementioned
evidence, in addition to the results of Sa et al. meta-analysis, prove
that TAR is the more effective treatment for ATAAD.
The frozen elephant technique (FET) has become the mainstay approach for
TAR in a range of thoracic aortic pathologies not limited to ATAAD,
predominantly phasing out conventional elephant trunk techniques. This
is due to the superior clinical outcomes it can achieve as evident
across the literature [6-8]. FET has been demonstrated to yield
excellent survival, both on the short- and long-term, as well as a low
incidence of postoperative complications and, in turn, minimal need for
reintervention. A recent meta-analysis of 85 studies totalling 10960
patients revealed a pooled in-hospital mortality rate of 7% (95% CI
0.05-0.09; I2=76%), 12% for renal failure (95% CI 0.09-0.15;
I2=88%), 3% (95% CI 0.02-0.04; I2=0%) for paraplegia and 6% (95%
CI 0.05-0.08; I2=73%) for cerebrovascular accidents [9].
Furthermore, a study of 931 patients who underwent TAR with FET using
the Terumo Aortic Thoraflex Hybrid prosthesis lends further evidence to
support TAR’s high efficacy. To note, ATAAD accounted for 17.5% of the
total cases. The authors reported a 0.6% 30-day mortality rate and a
7-year survival rate of 99%. Additionally, freedom from adverse events
at 84 months was 95% [10]. Lastly, a recent review by Geragotellis
et al. [11] showcased the favourable reintervention rates associated
with TAR using FET.
In conclusion, TAR with FET should be considered the gold-standard
management strategy for ATAAD as it has shown to yield more optimal
long-term survival as well as a reduced need for reoperation.