Analysis of Calcium Score of Severe Aortic Stenosis in Patients With and Without Cardiac Amyloidosis (CAUSATIVE Study)

Overview

The concomitant presence of cardiac amyloidosis (CA) in patients with aortic stenosis (AS) may challenge the estimation of stenosis degree. In patients with dual pathology (AS + CA) the most frequent AS hemodynamic profile is paradoxical low-flow, low-gradient AS. In this setting, estimating stenosis degree with cardiac ultrasound may be challenging and aortic valve calcium score estimation by cardiac CT is a valuable exam. Preliminary findings from small case series showed that patients with severe AS and CA presented less valvular calcium deposition compared to patients with severe AS alone. On this basis, confirmation of these findings would have a huge clinical impact on diagnosis, choice of treatment strategy and understanding of the pathophysiology of these patients. The aim of the study is to study the correlation between valvular calcium score (assessed by EKG-gated CT) and effective orifice area (assessed through echocardiogram) according to cardiac amyloidosis presence (in the overall population and among hemodynamic phenotypes of cardiac amyloidosis). As secondary endpoints the study will sought to assess TAVI/SAVR efficacy, procedural complications, in-hospital mortality, all-cause death and heart failure hospitalization at 1 year, according to absence or presence of CA.

Aortic stenosis (AS) is the most common valvular pathology in the elderly population, and there is an anticipated increase in prevalence and associated costs for treating this condition in the future. In a non-negligible percentage of cases (approximately 15%), another pathology is associated, namely cardiac amyloidosis, especially in the wild-type ATTR form. Patients with both pathologies (AS+ATTR) have a worse prognosis compared to those with AS alone. Based on the available data up to now, ATTR-associated amyloidotic cardiomyopathy does not appear to significantly influence the immediate outcome of TAVI or short-term outcomes. However, among patients with amyloidosis, there is an increased frequency of heart failure in subsequent follow-ups. The mechanism behind this dual pathology remains unclear. Epidemiological similarities (advanced age) alone do not explain the association. It is possible that there is a direct causal link between amyloidosis and aortic stenosis (amyloidosis as a co-cause or contributing factor to valvular stenosis), or that the elevated intramyocardial strain due to degenerative valvular stenosis promotes amyloidogenesis and myocardial infiltration. Understanding the extent of valvular calcifications in individual cases would provide better insights into the pathogenesis of this dual pathology. There are also diagnostic implications. Amyloidosis could potentially complicate the accurate classification of the severity of aortic pathology. For example, patients with AS+ATTR often exhibit a "low-flow low-gradient" paradoxical hemodynamic profile. In these cases, estimating the valve area with an echocardiogram is challenging, and evaluating the valvular calcium score through CT assumes an important diagnostic role. Preliminary studies suggest that, for the same degree of stenosis severity, there may be a lower quantity of calcium in the valves of patients with AS+ATTR compared to those with AS alone. Preliminary studies suggest that, for the same degree of stenosis severity, there may be a lower quantity of calcium in the valves of patients with AS+ATTR compared to those with AS alone. In a 1:1 propensity matching of over 300 patients (mostly without aortic stenosis), those with amyloidosis had lower aortic valvular calcium scores (p\<0.01). In a small series of 13 cases with AS+ATTR, 12 had aortic valvular calcium scores below the severity cut-offs recommended by the guidelines. If confirmed, traditionally used calcium score cut-offs may be inadequate, with significant implications for treatment selection and therefore prognosis.