MULTIMODALITY IMAGING ASSESSMENT OF THE ANATOMY OF THE AORTIC VALVE APPARATUS IN TAVI PATIENTS: IMPLICATIONS FOR PROSTHESIS SIZING AND PARAVALVULAR REGURGITATION

Aortic stenosis (AS) has become the most frequent type of valvular heart disease in Europe and North America. As it primarily presents as calcific AS in adults of advanced age (2–7% of the population >65 years), its prevalence is expected to increase further in the future with an aging population. Severe AS is associated with debilitating symptoms (shortness of breath, angina, dizziness, or syncope), and reduced survival if left untreated. According to European Society of Cardiology guidelines, aortic valve replacement (AVR) is the definitive therapy for all patients with symptoms and severe AS, or severe AS with left ventricular systolic dysfunction. However, approximately the 30% of patients referred for AVR are denied surgery because of advanced age, left ventricular dysfunction or comorbidities. Over the last few years, transcatheter aortic valve implantation (TAVI) has been demonstrated to be a feasible and effective therapeutic alternative to traditional AVR for high-risk surgical patients. Clinical trials have shown TAVI to have outcomes similar to surgical AVR up to 2 years after the procedure and excellent outcomes have been confirmed by registry data, with overall survival of 76% at 1 year. TAVI is an invasive technique whose success depends on multidisciplinary team approach, where imaging fulfils a definite part. Pre-procedure imaging is vital to assess the severity of AS, identify eligible candidates, plan the interventional approach, and select the appropriate prosthesis according to the anatomical features. Imaging is pivotal during and after the procedure, guiding prosthesis deployment, providing information regarding valve position, identifying immediate complications, and assessing outcomes. Before TAVI, accurate evaluation of the aortic root dimensions and anatomy is essential for the selection of eligible candidates for the procedure and to ensure the appropriately sized valve prosthesis is chosen. The objective of this thesis is to investigate the incremental value of a multimodality imaging approach to the evaluation of the anatomy of the aortic valve apparatus in TAVI candidates. Chapter 1 illustrates the feasibility and accuracy of 3D transthoracic echocardiography (TTE) compared to 2D TTE and multidetector computed tomography (MDCT) for the measurement of aortic annulus dimensions in the preoperatory evaluation of 100 patients candidates to TAVI. 3D TTE evaluation was feasible in the majority of the patients with low intra and inter observer variability. 3D TTE and MDCT measurements did not differ significantly, with excellent agreement in the selection of cases with too small or too large annulus (recognized exclusion criteria for TAVI) while, as expected due to the oval shape of the aortic annulus, the 2D TTE annulus area, geometrically derived from 2D TTE diameter, was considerably lower in comparison both with 3DTTE and MDCT planimetric surface area. A good agreement in the choice of prosthetic size in cases scheduled for the procedure was found between the 3D TTE and MDCT.…