The diagnostic accuracy of aortic valve calcium score in patients with low gradient and high gradient aortic stenosis
Authors: Juhasz D , Jermendy A , Szilveszter B , Apor A , Bartykowszki A , Molnar L , Suhai F I , Panajotu A , Papp R , Szigethi T , Manouras A , Maurovich-Horvat P , Merkely B , Vecsey-Nagy M , Nagy A I 
Published: June 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Introduction
The gold standard imaging modality for diagnosing aortic stenosis (AS) is echocardiography (echo); the definition of severe AS is based on the transvalvular mean gradient (AMG) (&gt;40 mmHg) and aortic valve area (AVA) (&lt;1 cm2). However, in around one quarter of the cases echo provides discordant findings (AVA&lt;1 cm2, despite of an AMG &lt;40 mmHg), complicating clinical decision making. Computed tomography aortic valve calcium scoring (CT-AVC) offers an alternative diagnostic method. In cases with discordant echo measurements current guidelines recommend CT-AVC to decide on severity.

Purpose
Our aim was to validate the sensitivity of the recommended calcium score (CAS) thresholds within our patient population, as well as to identify any factors associated with below cut-off CAS values despite confirmed severe AS (CAS false negativity).

Methods
Our retrospective study included 332 consecutive patients with severe AS (AVA ≤1 cm2), who underwent CT angiography (CTA) for transcatheter aortic valve implantation (TAVI) planning. Based on the AMG the patients were classified into high gradient (HG: AMG ≥ 40 mmHg) and low gradient (LG: AMG &lt;40 mmHg) groups. In the LG group AS severity was assessed by a multiparametric algorithm. To specify the predictors of CAS false negativity among patients with HG-AS, logistic regression analysis was used. The patients were followed for 50 months. Cox proportional hazard model was used to assess the risk of death from any cause.

Results
The HG-AS group consisted of 244 and the LG-AS cohort of 88 patients. In the HG-AS population the sensitivity of CAS to diagnose severe AS was 89%.
Within the HG severe AS group, logistic regression analysis revealed an association between CAS false negativity and the AMG (OR 0.89, CI 0.83 – 0.95, p &lt;0,001), whereas none of the other tested factors (age, sex, hypertension, diabetes, left ventricle function, renal function) showed a predictive value. In the LG-AS group, contrary to the HG-AS patients, the sensitivity of CAS to define severe LG AS was limited (53% in males and 67% in females).
Over a median follow-up of 50 months, the prognosis of HG AS patients with low CAS (false negative group) was more favourable than that of the high CAS patient population (HR 0.41; CI 017 – 097; p = 0.04).

Conclusions
Our results confirmed that among patients with HG AS, the recommended CAS thresholds provide a good diagnostic sensitivity for severe AS. Nonetheless, the number of severe AS patients with low CAS is not negligible, especially within the LG-AS population, where the diagnosis is the most challenging. Our findings underline that in patients with discordant echocardiographic findings, a personalized, multiparametric diagnostic approach is needed, instead basing the final diagnosis exclusively on CAS.