Diagnostic performance of aortic valve calcium and CT-derived aortic valve area in low-gradient aortic stenosis

Practice guidelines recommend the use of computed tomography (CT) aortic valve calcium (AVC) scores for patients with low-gradient aortic stenosis (LG-AS). AVC has not been studied in comparison to invasive aortic valve study (IAVS).

To determine the diagnostic performance of AVC and CT-derived aortic valve area (CT-AVA) compared to IAVS as a reference standard.

We included consecutive patients with LG-AS with echocardiography, CT and IAVS performed within 1 year at a single tertiary center. Severe AS was defined by aortic valve area (AVA) ≤1.0 cm² measured by IAVS. CT-AVA was retrospectively measured by a blinded reader. CT-AVA and sex-based AVC were compared to AS defined by IAVS. Diagnostic performance was compared using receiver operating characteristic (ROC) curves. AVC and CT-AVA were compared to cardiac events consisting of death, aortic valve replacement and cardiovascular hospitalization.

Out of 294 patients in the overall cohort, 206 patients with definite AS severity by IAVS were included as the primary diagnostic cohort. Severe AS according to invasive AVA (≤1.0 cm²) was present in 72 patients (35.0%). Sex-based AVC scores had relatively poor diagnostic performance compared to the reference IAVS with AUCs of 0.59 (95% confidence interval [CI] 0.48-0.70) and 0.58 (95% CI 0.45-0.71) for men and women, respectively. CT-AVA had better diagnostic performance with an AUC of 0.82 (95% CI 0.77-0.87).

In our study population, CT-AVA had significantly better diagnostic performance than AVC compared to the reference standard, IAVS.