Transcatheter aortic valve replacement for bicuspid aortic valve disease: does conventional surgery have a future?

Abstract

Bicuspid aortic valve (BAV) disease is the most common form of congenital heart valve defect. It is associated with aortic stenosis (AS), aortic insufficiency, and aortopathy. Treatment of severe AS requires valve replacement which historically has been performed with surgical aortic valve replacement (SAVR). Recently, transcatheter aortic valve replacement (TAVR) has emerged as a promising alternative. However, increased rates of adverse outcomes following TAVR have been shown in BAV patients with high amounts of calcification. Comparison between TAVR and SAVR in low surgical risk BAV patients in a randomized trial has not been performed and TAVR for BAV long-term performance is unknown due to lack of clinical data. Due to the complexity of BAV anatomies and the significant knowledge gap from the lack of clinical data, SAVR still has many benefits over TAVR in low surgical risk BAV patients. It also remains common for BAV patients to have an aortopathy, which currently can be treated with surgical techniques. This review aims to outline BAV associated diseases and their treatment strategies, the main TAVR adverse outcomes associated with anatomically complex BAV patients, TAVR strategies for mitigating these risks and the current state of cutting-edge 3D printing and computer modeling screening methods that can provide otherwise unobtainable preoperative information during the BAV patient selection process for TAVR.

Keywords: Transcatheter aortic valve replacement (TAVR); bicuspid aortic valve disease; surgical aortic valve replacement (SAVR).

Figure 1

BAV classification scheme factoring valve shape consisting of tricommissural, bicommissural raphe-type, and bicommissural non-raphe-type groups with coronary cusp fusion and mixed cusp fusion subgroups (6). Reprinted by permission from Elsevier (6). BAV, bicuspid aortic valve.

Figure 2

Study performed by Yoon et al. comparing TAVR outcomes with leaflet calcification volume and distribution across BAV types with tricuspid control. Mild leaflet calcification on the top row and excess leaflet calcification on the bottom row with the tricuspid control, non-raphe BAV, noncalcified raphe BAV, and calcified raphe BAV from left to right. Excess leaflet and raphe calcification BAV had highest rates of PVR and aortic root rupture following TAVR. Reprinted by permission from Elsevier (13). TAVR, transcatheter aortic valve replacement; BAV, bicuspid aortic valve; PVR, paravalvular regurgitation.

Figure 3

PVR and aortic root rupture risk factors in BAV patients. Isolated PVR risks including valve undersizing/underexpansion, absence of post balloon dilation, native elliptical opening, isolated aortic root rupture risk factors including oversizing/overexpansion, post balloon dilation, and low tissue compliance, and factors increasing both risks including excess leaflet calcification and presence of a calcific raphe. PVR, paravalvular regurgitation; BAV, bicuspid aortic valve.

Figure 4

Hemodynamics of asymmetrical stent deployments commonly seen post TAVR in BAV patients. Eccentric deployment showing a localized area of high Reynolds shear stress and a region of elevated turbulence intensity compared to the circular case (left), tilted deployment with respect to the native sinus showing increased fluid residence in the sinus that the TAV is tilted away from (right), and underexpanded deployment showing increased leaflet folding and increased neo-sinus blood residence time (bottom) (35-37). The images included in this figure are reprinted with the source acknowledged as following: Left: reprinted by permission from Springer Nature (35); right: reprinted by permission from Springer Nature (37); bottom: reprinted by permission from Oxford University Press and European Association for Cardio-Thoracic Surgery (EACTS) (36). TAVR, transcatheter aortic valve replacement; BAV, bicuspid aortic valve; TAV, transcatheter aortic valve.

Figure 5

Current and future state of computer modeling for TAVR outcome prediction. Anatomical reconstruction, stent deployment and risk assessment for coronary obstruction and PVR (top) and future fluid-structure interaction approach modeling hemodynamics assessing blood flow and bioprosthetic leaflet strain after deployment (bottom). Reprinted by permission from Elsevier (57). TAVR, transcatheter aortic valve replacement; PVR, paravalvular regurgitation; MIPE, maximum in-plane strain.

Video

Transcatheter aortic valve replacement (TAVR) for bicuspid aortic valve disease: does conventional surgery have a future?