Aortic root dilation with associated progressive aortic insufficiency (AI) may eventually lead to left ventricular (LV) dilation and systolic dysfunction [1]. Aortic valve replacement in patients with AI and LV dilation promotes long-term ventricular remodelling [2]. Valve-sparing root replacement (VSRR) performed in the setting of significant AI has been previously shown to result in improved LV remodelling and function [3]; however, the impact of LV dilation on the valve durability and long-term survival following VSRR have not been previously explored.
In this issue of the European Journal of Cardio-Thoracic Surgery, Dr. Patrick et al. [4] compare long-term outcomes in VSRR patients with and without preoperative LV dilation, defined as an indexed LV internal diameter during systole of ≥2.0 cm/m2. Utilizing a single-institutional aortic surgery database with excellent follow-up (785 person years of echocardiographic follow-up), the cohort included 295 patients, of whom 17.8% (N = 52) had baseline LV dilation. There was no significant increase in hazard of long-term AI or reintervention after VSRR in patients with LV dilation. Although LV dilation patients had progressive improvement in indexed LV internal diameter during systole after surgery, mortality at 7 years was significantly higher compared to VSRR patients without LV dilation (hazard ratio 5.56).
We congratulate the authors for a thoughtful and well-executed analysis of a powerful institutional aortic surgery database, a study that has potential implications on appropriate patient selection criteria for VSRR. First, patients with LV dilation in the context of aortic root aneurysm may be presenting at a different time course in their disease process compared with patients with normal LV dimensions. Although not significantly different in the chi-squared test for multilevel categorical variables, LV dilation patients more frequently presented with 4+ AI (27% vs 7%) and an eccentric AI jet (41% vs 22%). While not completely discernable from the available dataset, one potential hypothesis is that these patients were followed for longer periods of time before having surgery or presented late in their disease process. The clinical outcomes in patients with LV dilation suggest that VSRR can be performed successfully in patients presenting with more severe and eccentric AI with similar operative survival and valve durability to patients with normal LV dimensions.
Second, important points are raised about the appropriate echocardiographic parameters that surgeons use to evaluate patients for being considered for surgical intervention for significant AI. As the authors articulate well, LV ejection fraction is a relatively ‘blunt metric’ when assessing the impact of AI on development of LV dysfunction. While LV dilation does not appear to affect operative and valve-specific outcomes, the reduced long-term survival may reflective of both diastolic and systolic dysfunction [5].
The authors also address the unique interaction between aortic root and LV geometry in the context of root repair and state that ‘LV geometry does not exert a significant effect on the geometry of the neo-ventricular-aortic junction, which is constrained by the graft’. However, it is also known that anatomic relationships between the fibrous and muscular portions of the ventriculo-aortic junction are both complex and asymmetric in height [6]. While further investigation is necessary to fully support the authors’ statement, the presence of an aortic root graft in this study does appear to provide a level of stabilization resistant to the impact of a dilated LV.
Patients with LV dilation have 5 times higher long-term risk of all-cause mortality with 12% dead at 7 years, despite equivalent valve-specific outcomes. With operative times being significantly longer for VSRR compared to root replacement with a conventional composite valve-graft conduit, an important issue centres around whether the early additional cardiopulmonary bypass times are justified in a patient population which may not derive the potential survival benefits of VSRR that are typically observed in the second decade after surgery. While this article fills an important gap in knowledge about the impact of LV dilation on the outcomes of VSRR, the overall message that ‘LV dilation should not deter VSRR when otherwise indicated’ may be overstated.
Funding
This work was supported by the National Institutes of Health (5T32HL069749-17 to Dr. Andrew M. Vekstein).
Contributor Information
Andrew M Vekstein, Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University Medical Center, Durham, NC, USA.
Edward P Chen, Division of Cardiovascular and Thoracic Surgery, Department of Surgery, Duke University Medical Center, Durham, NC, USA.
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