Optimising Transcatheter Aortic Valve Implantation (TAVI) with pre procedural Computed Tomography (CT)

Abstract

Introduction
Transcatheter aortic valve implantation (TAVI) has revolutionised the treatment of severe aortic stenosis but despite new valve iterations, procedure-related complications such as new conduction abnormalities (CA), remain stubbornly common with deleterious effects on mortality and morbidity. Furthermore, as TAVI is deployed in younger patients with a longer life expectancy, minimising the interaction between the valve and the coronary arteries is increasingly important for future percutaneous coronary intervention (PCI) and valve-in-valve procedures. We sought to address the hypothesis that Computed Tomography (CT) imaging could be used to optimise TAVI to reduce these risks.

Methods and results
First, the incidence of new CA after TAVI in a high-risk cohort with right bundle branch block (RBBB) was determined and the effect of prophylactic permanent pacemaker implantation (PPI) on mortality and length of hospital stay (LOS) were assessed. New CA occurred in over half of patients and prophylactic PPI reduced LOS but did not affect mortality. Next, the membranous septum (MS), a surrogate for the penetrating atrioventricular bundle was resolved in 2-dimensions using CT to estimate its area. In a multivariable model developed to predict new CA after TAVI MS area was significantly associated with new CA and outperformed known predictive variables.

The focus then switched to reducing the interaction between TAVI commissures and coronary arteries. CT was used to define the relationship between the coronaries and native valve commissures which was used to simulate valve deployment with commissural and coronary alignment. The former aims to align the valve commissures with the native commissures and the latter aims to maximise the coronary-to-commissural angular distance. The results indicate that both strategies are successful in minimising the coronary-to-commissural angle, although a coronary alignment strategy led to more centred coronary arteries and was more resistant to potential rotational error introduced during deployment.

Using pre-procedural CT to determine a patient-specific implant view to achieve coronary alignment, this strategy was subsequently tested in-vivo using two supra-annular devices with CT imaging after TAVI demonstrating ≤mild misalignment in over 90% of cases. Additionally, the relationship between coronary-to-commissural angle and coronary access was explored with no clear relationship identified.

Conclusions
In conclusion, CT can be used to characterise a key component of the conduction system to identify patients at highest risk of new CA and optimise valve alignment to facilitate future coronary intervention or re-do TAVI.

Date of Award	Oct 2024
Original language	English
Awarding Institution	University of Brighton
Supervisor	Prof David Hildick-Smith (Supervisor), Dr James Cockburn (Supervisor) & Dr Michael Michail (Supervisor)