Date of Award

January 2020

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

John A. Elefteriades

Abstract

Hypothesis: Thoracic aortic aneurysm (TAA) is a silent but virulent disease. Bicuspid aortic valve (BAV) is the most common congenital heart disease. The association between BAV and ascending TAA (ATAA) is well described. However, the guidelines for surgical management to treat patients with thoracic aortic aneurysms associated with bicuspid aortic valve (ATAA-BAV) remains controversial. We hypothesized that the surgical management of patients with ATAA-BAV should not differ from the management of those who have ATAA with a trileaflet aortic valve (TAV). Additionally, we suspected that BAVs that are free of stenosis and regurgitation can be spared in the setting of ATAA repair. In this study, we aimed to (1) characterize the natural behavior of BAV-ATAA, (2) define surgical guidelines for elective intervention in patients with ATAA-BAV, and (3) characterize the behavior of spared bicuspid aortic valves during ATAA resection.

Methods: A retrospective review of the Yale Aortic Institute database was done to identify patients with ATAA-BAV. We calculated rate of growth, yearly rate of complications, 5-year event-free survival through a Kaplan-Meier curve, as well as a logistic regression that looked into risk of complications as a function of aortic size. Of these patients, the ones whose valve was spared at the time of surgery were further analyzed. Postoperative and preoperative echocardiograms were compared to determine changes in valve function of this smaller cohort.

Results: We identified 514 patients with ATAA-BAV through data collection. The mean growth rate of ATAA-BAV was 0.21 cm/year. The larger the aneurysm, the faster it grew. There was a 13% yearly rate of rupture, dissection, and death in patients with an ATAA diameter ≥ 6cm. These patients have a 13-fold increase risk of suffering an aortic complication compared to patients with an aortic size of 4-4.5 cm (p<0.05). There was a sharp increase in the probability of aortic complications including dissection, rupture, and death at ATAA diameters of 5.0, 5.5, and 6.0 cm. Out of the 514 patients, did not have their valve replaced. There was 100% echocardiogram follow-up for these 23 patients. The average time between preoperative and postoperative echocardiograms was 4.50±4.09 years (0.19-15.63). Aortic stenosis or regurgitation changed from none to mild in 21.7% of patients, with an average echocardiographic interval follow-up of 3.08 years, and from none to severe in 2 (8.7%), with an interval of 11.7 years. One patient required reoperation, including aortic valve replacement, during follow-up.

Conclusion: Prophylactic size-based surgery in BAV-ATAA patients can be considered at 5.0 cm at expert aortic centers as a means to afford protection from natural complication. Non-expert center may wait for 5.5 cm. BAV free of aortic stenosis or insufficiency before surgery and “healthy” appearing at surgery can safely be preserved.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 09/10/2022

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