Computed tomography calcium scoring in aortic stenosis: bicuspid versus tricuspid morphology

Objective CT aortic valve calcium score (AVC_score) and density (AVC_density) thresholds have been recommended for aortic stenosis (AS) severity assessment in tricuspid aortic valve (TAV). We aimed to compare AVC_score and AVC_density in bicuspid aortic valve (BAV) versus TAV. Methods Retrospective single-centre study of patients with echocardiographic AS-severity and CT-AVC assessments within 6 months, and left ventricular ejection fraction ≥50%, all referred for clinical AS evaluation. Severe AS was defined as aortic valve area (AVA) ≤1 cm² or indexed AVA ≤0.6cm²/m² plus mean gradient ≥40 mm Hg or peak velocity ≥4 m/s. AVC was assessed by Agatston method. Results Of the 1957 patients, 328 had BAV and 1629 had TAV, age 65±11 vs 80±9 years (p<0.001), men 65% vs 56% (p=0.006), respectively. BAV morphology was associated with higher AVC_score and AVC_density independent of age, comorbidities and AS severity (p<0.001) in men only (sex and BAV interaction p<0.001). In patients with severe AS, mean AVC_score and AVC_density were higher in BAV-men than that in TAV-men (both p<0.001), but similar in BAV-women and TAV-women (both p≥0.4). Such patterns remained the same after adjustment for clinical covariates and AS severity. Best thresholds for severe AS diagnosis in BAV-men were 2916 AU by AVC_score and 600 AU/cm² by AVC_density which were higher than the guideline-recommended thresholds, while thresholds in BAV-women (1036 AU and 282 AU/cm²) were similar to guideline-recommended ones. Conclusion Valve calcification in AS differs according to valve morphology and sex. BAV-men with severe AS exhibit greater AVC_score and AVC_density than TAV-men. This presents a diagnostic challenge to the current guidelines, which needs confirmation in larger studies.