Outcomes after concomitant aortic root and aortic arch replacement: what came first—the root or the arch?

In the report by Hage et al. [1], the authors compile data from the cardiac surgery centres in the Canadian Thoracic Aortic Collaborative (CTAC) to examine the effects of adding an aortic root procedure to aortic arch repair. Using multivariate analysis, they demonstrate that concomitant aortic root and aortic arch procedures were associated with increased in-hospital mortality and reoperation for bleeding, without increased incidence of stroke or renal failure. There were no differences in the secondary outcomes (delirium, transient neurologic deficit, prolonged ventilator support, sepsis, intensive care unit and hospital length of stay), except for an increased incidence of blood product transfusion with the addition of an aortic root procedure. Besides the addition of aortic root replacement, age, prior sternotomy, preoperative renal failure, non-elective status and total arch replacement were identified as additional risk factors for mortality, while the use of cerebral perfusion was found to be protective. In subgroup analysis, there was no difference in the risk of mortality, stroke or dialysis-dependent renal failure for elective procedures, while the risk of reoperation for bleeding was higher with the addition of an aortic root procedure. In the non-elective cases subgroup, there was an increased risk of mortality with the addition of aortic root procedure, but the risk of stroke, dialysis-dependent renal failure and reoperation for bleeding was similar between the 2 groups.

The underlying question here is how best to manage the borderline aortic root when addressing the aortic arch? While the data in the manuscript by Hage et al. suggest the safety of concomitant aortic arch and root surgery for elective procedures and potential harm when performed for emergencies, one must note that their study comprises patients with heterogeneous indications for operation. It is quite likely that many patients in the elective subgroup were operated on for a primary aortic root problem and the arch (especially when a hemiarch replacement was performed) was added to the root procedure and not vice versa. This question of ‘root vs no root’ is irrelevant to these patients, as the root must be replaced regardless. Similarly, in the dissection subgroup, if the aortic root is involved with the dissection (extension of the intimal tear into the sinus segment, or coronary involvement), aortic root replacement must be performed, despite the higher risk. For both these groups of patient, the risk of complications associated with aortic root replacement, whether additive or not, must be incurred.

The dilemma (or choice) regarding replacing the root exists only when the primary pathology is in the ascending aorta or the aortic arch, with a concomitant borderline aortic root dilation. With the data available to the CTAC investigators, it is not possible to delineate how many patients in their study were operated on for primary aortic root pathology versus primary ascending/arch pathology. For most surgeons, performing a ‘hemiarch + aortic root’ is a fairly straightforward operation, but adding an aortic root replacement to an already planned total arch replacement adds time and complexity, and certainly worth careful consideration. While the authors demonstrate that the addition of an aortic root procedure to hemiarch replacement did not increase mortality, a similar analysis for patients who underwent total arch replacement is not presented. Interestingly, in the report from IAASSG [2], patients who underwent concomitant aortic root and total arch replacement had a higher mortality in both the unmatched (root vs.non-root root, 12% vs 7.8% respectively) and propensity-matched cohorts (root vs. non-root, 11.3% vs 7.3% respectively)—while these differences were not statistically significant, an increase in mortality risk ∼50% is certainly clinically relevant.

Nonetheless, the authors have demonstrated that aortic root and arch replacement can be safely performed concomitantly at experienced centres, at least in the elective setting. A review of the univariate comparison of patient characteristics in the current manuscript underscores the good judgement demonstrated by the CTAC surgeons in patient selection: an aortic root procedure was more frequently combined with a hemiarch replacement, where the risk is lower than with total arch replacement, and performed more often for younger patients, and those with aortic regurgitation or connective tissue disorders—subgroups at an increased risk of requiring an aortic root intervention in the future, if it were not addressed at the current operation.

Without information regarding the relevant aortic diameters and the knowledge of the prospective decision-making process, it is difficult to recommend the best approach towards a borderline dilated aortic root during arch surgery based on these data. The addition of an aortic root procedure to an aortic arch procedure is not entirely benign (as highlighted in the central figure of the manuscript), and as we make the decision to ‘add the root’, the likelihood of requiring an aortic root intervention in the future must be weighed against the immediate increased complexity of concomitant aortic root replacement.

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