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.