The conflict of early outcomes
The Bentall procedure is considered a “gold standard” technique for
aortic root replacement.16 Over the decades the
procedure itself has greatly evolved with many modifications to the
original technique.11 For the repair of ATAAD the
Bentall procedure can be performed for a radical root replacement, or a
conservative approach can be considered using a supra-commissural graft
repair. By repairing the primary tear without pursuing the extensive
approach, it allows the preservation of the native valvular structures.
Across the literature, in-hospital and 30-day mortality are the main
early outcome recorded across various studies, with a broad range of
results for the comparison between the conservative repairs of the root,
versus a more aggressive root replacement approach.4,
7, 17
In a retrospective study, 226 patients underwent repair for ATAAD at a
single center between 1990 and 2010 (mean follow up of 9.1 years),
undergoing either the Bentall method or a supra-commissural graft
repair.7 The authors reported in-hospital mortality of
34% for the graft repair group, which was significantly higher (p=0.03)
than the 20% in-hospital mortality using the Bentall and VSRR David
procedures. Hysi I and colleagues concluded using their results that a
more extensive approach allowed more favorable early
outcomes.7
When critically analyzing this study by Hysi I and
colleagues7 it is vital to recognise, as the authors
reported, that patients undergoing the more radical root replacement
were much younger (p=0.00001). Older age was reported as a significant
independent factor for early mortality. Furthermore, the authors stated
that the majority of the root replacements were performed more recently
in the study period. When considering how strategies of surgery have
evolved over the years alongside the significant effects on
pre-operative characteristics, there is the strong risk of arising bias
in the conclusion that are drawn. 7
A fellow retrospective study published by Geirsson A and colleagues, who
similarly compared the early outcomes of ATAAD repair in 221 patients
also at a single center.17 During the study period of
1993 to 2004 (mean follow up of 3.31 years; 99.1% complete), the center
had developed an algorithmic approach for treatment. Patients always
underwent aortic valve (AV) resuspension whenever feasible, only
undergoing a composite root replacement when the indications were met
making the initially desired valve resuspension no longer feasible. The
authors reported contrasting results to those reported by Hysi I and
colleagues.7 The in-hospital mortality of 8.1% for AV
resuspension was far lower (p=0.004) than the 23.1% recorded for
composite root replacement. The reasons for this however, although not
completely clear, may possibly be attributed towards the primary
indicators for root replacement which included fewer co-morbidities and
a more severe primary dissection.17
Both above discussed studies have similar indications and frequencies of
presented pre-operative characteristics for pursuing the extensive root
replacement procedure: the presence of a connective tissue disorder such
as Marfan syndrome, aortic insufficiency > 2, as well as a
more proximal extension of the intimal tear towards the
sinus.7, 17 Geirsson and colleagues further reported
that annuloaortic ectasia, bicuspid aortic valve, and aortic stenosis,
were also significant pre-operative indicators sought for a root
replacement. These and other aspects of the algorithm in the study by
Geirsson A and colleagues allows us to infer that the higher early
mortality for root replacement, maybe due to the more severe
pre-operative patient characteristics and indicators which had resulted
in the initially preferred AV suspension procedure to no longer be
feasible.
Whilst comparing both of these single-center retrospective
studies,7, 17 it is important to consider the
indications and methodologies put in place for the decision making
process regarding the surgical approach targeting the aortic root.
Geirsson A and colleagues had a standardized and structured algorithmic
approach towards the surgical management of ATAAD, always performing AV
resuspension wherever feasible. The surgical strategy in the study by
Hysi I and colleagues, although without such an algorithmic approach,
was only well guided by “perioperative findings and surgeon’s
habitude” 7 The resultant homogenous cohort allowed
by the standardised strategies reported by Geirsson A and
colleagues17, allows it to be well recognized as a
strength for their study. The authors had reported that their management
strategies discussed in the paper were able to contribute to their
improved overall entire cohort in-hospital mortality rate of
12.7%.17
The results for operative mortality reported by Peterss S and colleagues
(2016)18, comparing the operative mortality between
the two groups showed statistically insignificant results, however the
study did show that the in-hospital stay was significantly longer by 5.1
days (p=0.048) in the root replacement group compared to that of root
sparing technique in the repair of ATAAD.
In other articles that were reviewed (refer to Table A), there were no
further statistically significant differences when comparing early
outcomes between whether or not a root replacement is performed in the
treatment of ATAAD.