The ascending aorta and arch in the sights of transcatheter
therapy. A time for reappraisal.
Walter J. Gomes, MD, PhD1.
1 Cardiovascular Surgery Discipline. Escola Paulista
de Medicina and São Paulo Hospital, Federal University of São Paulo, São
Paulo, SP, Brazil
Conflict of interest: None.
Funding: None.
Text word count: 1287
Address for Correspondence
Walter J. Gomes, Cardiovascular Surgery Discipline, Escola Paulista de
Medicina and São Paulo Hospital - Federal University of São Paulo - Rua
Botucatu 740 - São Paulo, SP 04023-900 Brazil. Telephone 55-11-55726309.
E-mail wjgomes1012@gmail.com
Keywords - Ascending aorta, Aortic arch, Stent-graft, Thoracic
endovascular aortic repair, Type A aortic dissection
Article type - Commentary
The ascending aorta and arch have
until recently been one of the last bastions of cardiovascular surgery,
where life-threatening diseases impose the need for prompt correction
and reversal of the impending adverse prognosis [1].
However, the article from Ahmed and colleagues in this issue reveals the
incipient but steadily venturing of transcatheter therapies in this so
far untouchable domain of cardiovascular surgery [2].
Though a disease where dogmatic
recommendations prevail, with upfront surgical intervention in the mind
of every physician, type A acute aortic dissection (AAD) is a subject
still blurred by many uncertainties [1]. No randomized trial has
ever been performed; many shreds of evidence used for recommendation are
decades old. From the latest International Registry of Acute Aortic
Dissection (IRAD) report, the in-hospital mortality rate of patients
presenting with type A AAD dropped over time, significantly from 31% to
22% in top reference centers located in the USA and Europe [1].
These mortality numbers are obviously higher in low-volume centers and
with less well-trained surgeons, which comprises the vast majority
worldwide. Major predictors of death, such as tamponade and shock,
forced the surgeon to operate sooner on the most critical patients, and
type A AAD complicated by hypotension and its consequences increased
mortality to 55% [3]. The mortality of patients with pericardial
tamponade remains significantly high, even after adjustment for baseline
clinical characteristics (44% versus 20%, P<0.001) [4].
From the IRAD data, type A AAD in-hospital mortality was highly
dependent on patient risk profiles before surgery, patients classified
as unstable had much higher in-hospital mortality, 31% versus 17% in
those without unstable features. Independent preoperative predictors of
mortality were age >70 years, previous cardiac
surgery, hypotension, or shock at presentation, migrating pain, cardiac
tamponade, any pulse deficit, and myocardial ischemia or infarction.
[IRAD] Not surprisingly, in up to 20% of patients with type A AAD
surgery is withheld [5,6] and that makes the need for an alternative
treatment in this cohort even more relevant.
Clearly, there are subgroups were urgent surgery is not beneficial and
indeed harmful, and recent evidence brings paradoxical findings, where
in acute type A AAD the watch-and-wait strategy was employed in a
selected cohort of patients with intramural hematoma (IMH) and acute
aortic dissection with thrombosed false lumen of the ascending aorta,
and showed outcomes even superior to emergency surgery [7]. Kitamura
et al. reported that the watch-and-wait strategy was selected in 46
patients, 10 of them underwent emergency pericardial drainage for
cardiac tamponade at the time of presentation. In-hospital mortality
occurred in 4% of patients, during follow-up the survival at 1 and 2
years was 95% and 92%, respectively [7]. These results have been
reproduced by other centers and Kitai et al reported long-term clinical
outcomes of 66 patients with type A IMH who were treated with emergent
procedure or medical therapy and timely operation. The 30-day mortality
rate was 6% with emergent surgery and 4% with supportive medical
therapy. The actuarial survival rates of patients were 96+/-3%,
94+/-3%, and 89+/-5% at 1, 5, and 10 years, respectively [8,9].
Initial medical treatment in selected cases is now classified as
recommendation class IIa in the Japanese Circulation Society guidelines
[10].
These figures frontally challenge the ingrained and long-lasting notion
of the near-fatal outcome related to the type A AAD if left untouched.
And suggests that in carefully selected patients and properly medically
managed, the results would be less deadly than previously believed by
older and outdated evidence.
Surgeons too are in search of less invasive procedures in high-risk
patients with type A AAD. An approach consisting of wrapping the
dissected ascending aorta has been performed as an alternative in
high-risk or aged patients requiring emergent surgical treatment, with
in-hospital mortality of 6.6% and the follow-up mortality rate being
13.3% with a median follow-up of 15 months [11]. This experience
has been replicated by other surgeons and Lopez et al described a series
of six patients with a poor functional status, and no severe neurologic
complications or deaths occurred during the postoperative period
[12]. Suematsu et al reported the utilization of this technique in
82 patients since January 2015 and describe the new surgical approach
which entails “stepwise external wrapping” using a zero-porosity
artificial graft and applied in extremely high-risk patients. Patient
outcomes after external wrapping were excellent with zero in-hospital
mortality, successful aorta remodeling, and no aorta-related death
during three years of follow up, thus very encouraging results of a
feasible alternative to conventional graft replacement surgery
[13,14].
While medical management is emerging as a reasonable approach in
selected patients who are not surgical candidates,
endovascular intervention for the
treatment of type A AAD are rapidly progressing. Utilization of
transcatheter therapies in the ascending aorta for treating type A AAD
has demonstrated technical success in small studies, low early mortality
rates, and relatively acceptable aorta-related mortality rates in the
long-term [15].
The systematic review from Ahmed et al. shows that the procedure is
feasible, however shortcomings were frequent, and to this date evidence
of long-term effectivity is elusive. Collecting a total of 31 articles,
of which 19 were case reports and 12 case series, resulting in 92
patients, the median follow-up was 6 months for case reports and the
average follow-up was 14 months for case series. Overall technical
success was 95.6% and 30-day mortality of 9%. Stroke and early
endoleak rates were 6% and 18%, respectively. Two patients (2%)
required intraoperative conversion to open surgery and reintervention
was required in 14 patients (15%), of which four patients underwent
endovascular repair and five patients underwent open repair [2].
These findings strengthen the
preponderant role of the endovascular heart surgeon on the management of
these procedures, where a combination of wire skill training and
surgical proficiency encompassing all technical options available makes
it distinctive and resourceful, able to provide complete resolution to
each multicomponent of this disease in one setting, besides the
promptness to repair the inherent complications that are to accompany
these interventions [16].
Conventional surgery and its technical variants are to remain the
treatment of choice for a large proportion of patients with type A AAD,
however ongoing progress points that interventional transcatheter
procedures will continue to evolve, a share of cardiovascular diseases
may become amenable to this treatment approach. This underscores the
importance of surgeons to become familiar and be involved with these
percutaneous procedures. The further trend towards referring patients
with aorta diseases to centers of excellence, a policy aimed at
achieving better outcomes and cost reduction, will add elements favoring
the insertion and role of the surgeon in this multidisciplinary program.
A pending issue is to determine which patient could most benefit from
the emerging assorted array of therapeutic options, from surgical delay
or permanent deferral of surgery to interventional transcatheter
procedures with transfer to specialized centers [16,17]. Given the
complexity of designing a randomized controlled trial in a disease with
a multivariate presentation like the type A AAD, a scoring system
derived from a large dedicated database would be effective to predict
the 30-day mortality rate for patients undergoing surgery for type A AAD
and provide recommendation for procedure selection [18].
Transcatheter procedures and open
surgery are to coexist side by side and to be regarded as complementary
rather than competing. In this way, the role of the Cardiovascular
Surgery Societies worldwide, partnering with medical device companies,
and establishing ongoing educational and training programs, with
certification for heart surgeons who complete training, should support
the prospect of acquiring these ground-breaking and complementary new
skills [16,17].
Substantial more refinement and
technological innovation will be necessary before endovascular repair of
type A AAD comes to widespread use, the ideal timespan for
cardiovascular surgeons to be involved, and prepared to take on the
challenges of leading this new enterprise.
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