# Morphology and calcification characterization in patients undergoing TAVI: A 3D statistical shape modelling study

## TL;DR

This study uses 3D modeling to analyze aortic valve shape and calcification in patients undergoing TAVI, finding that female patients with smaller, conic aortic roots face worse outcomes.

## Contribution

The study introduces a 3D statistical shape modeling approach to characterize aortic root morphology and calcification patterns in TAVI patients.

## Key findings

- Female patients with smaller and more conic aortic roots were associated with worse post-TAVI outcomes.
- Higher calcification rates were observed in larger valves and at the junction between left and right coronary leaflets in males.
- Morphological differences were significantly linked to paravalvular leakage assessments.

## Abstract

Aortic stenosis (AS) is a common valvular disease becoming more prevalent globally due to the aging of the population. Transcatheter aortic valve implantation (TAVI) is a minimally invasive intervention indicated for AS patients as alternative to surgical replacement. TAVI is to date an established procedure. However, it has been often associated with complications such as paravalvular leakage (PVL) or conduction abnormalities. Evidence of associations between morphological features of the aortic root, valve calcification measurements and suboptimal procedural outcomes have been suggested but the analyses were limited by availability and reproducibility of clinical measurements. In this work, we aim to enrich the characterization of AS patients referred for TAVI by analyzing the clinical findings in conjunction with advanced morphological analysis of the implantation site including aortic root, left ventricular outflow tract and 3D calcification patterns. A population of consecutive patients with AS (n = 130) who underwent TAVI at our clinical centre were retrospectively selected for this study. Demographic and clinical measurements were collected before and after TAVI. Pre-operative CT images were used to reconstruct 3D models of patient-specific anatomies. Statistical shape modelling was carried out and outcomes were analyzed in conjunction with clinical outcomes. The 3D modelling of the valve calcification rate matched previous clinical descriptions; including the crescent shapes visible on each leaflet and the higher calcification rate of the non-coronary cusp. Higher calcification rate was found in larger valves together with a positive association between each coronary height and the calcification of their respective leaflet. Sexual dimorphism, on both shape and calcification, was recorded beyond the size differences with straighter aortas and higher calcification rate at the junction between the left and right coronary leaflets for males compared to females. Morphological differences were significantly associated (p = 0.005) with PVL assessments based on post-operative echocardiograms. Larger aortas and shorter left coronary sinus were associated with less leakage. The outcome distribution appeared to be directly affected by sexual differences and device design. Female phenotypes, smaller and more conic aortic root, were associated with worse outcome. Different patterns in calcification distribution on the leaflets were identified but the association with outcomes is not conclusive. In the future, the presented morphological characterization of patients with AS could contribute to predict post-TAVI PVL and design and test improved TAVI devices.

With age, the aortic valve can stiffen and calcify. The valve opening narrows leading to a partial obstruction of the left ventricular outflow tract. Estimates suggest that around 9 million patients are affected with aortic valve stenotic disease globally. The valve then need to be surgically repaired or replaced depending on the disease severity and the patient’s comorbidities. In this work, we present a description of a population of aortic stenosis patients who underwent transcatheter aortic valve implantation (TAVI) at our clinical centre. Our approach enriches the clinical description and the manual measurements with a complete 3D morphological model of the aortic root and its calcification. We highlighted new morphological correlations with post-operative risk assessments, and in particular, we observed that female phenotypes, smaller and more conic aortic root, were associated with worse outcome in average. The observed average calcification reflected the clinical descriptions including the crescent shapes visible on each leaflet, and the higher calcification rate on the non-coronary cusp, but calcification association with outcomes remains unclear. We believe that the novel 3D description of the valve area and of the calcification pattern presented in this work may help clinicians better characterise the disease presentation and inform futures clinical and simulation studies in order to improve device design and treatment processes to reduce the risk of post-operative complications.