CT-derived Extracellular Volume Fraction in Aortic Stenosis, Cardiac Amyloidosis and Dual Pathology

Aims: To investigate CT-derived extracellular volume fraction (CT-ECV) in patients with lone aortic stenosis (AS), dual pathology of AS and transthyretin cardiac amyloidosis (AS-ATTR), and lone ATTR, and to examine the diagnostic performance and optimal cutoff values of CT-ECV for differentiating between patients with lone AS and AS-ATTR, and between patients with lone AS and lone ATTR.

Methods and results: This retrospective study included consecutive patients with severe AS (including lone AS and AS-ATTR) and lone ATTR who underwent CT-ECV analysis and technetium 99m pyrophosphate (99mTc-PYP) scintigraphy. The diagnostic performance of CT-ECV for detecting cardiac amyloidosis was evaluated using the area under the receiver operating characteristic curve (AUC). Of 138 patients (mean age, 80 ± 8; 96 men), 55 had lone AS, 19 had AS-ATTR and 64 had lone ATTR. CT-ECV of patients with lone AS was 31 ± 5%. CT-ECV was significantly lower in patients with AS-ATTR than lone ATTR (45 ± 12% vs 53 ± 13%, P =.04). The AUC for differentiating patients with AS-ATTR from lone AS was lower than for lone ATTR from lone AS (0.90 [95% CI: 0.81, 0.96] vs 0.95 [95% CI: 0.90, 0.98]). The cutoff values of CT-ECV for differentiation between patients with lone AS and AS-ATTR were lower than those between patients with lone AS and lone ATTR (36.6% vs 38.5% [Youden index]). There was no significant difference in the proportion of 99mTc-PYP scintigraphy grade between patients with AS-ATTR and lone-ATTR (P = .20).

Conclusion: Despite no significant difference in degree of ATTR between patients with AS-ATTR and lone ATTR, CT-ECV of patients with dual AS-ATTR pathology was significantly lower than that of patients with lone ATTR. The diagnostic performance and optimal cutoff values of CT-ECV for differentiating between patients with lone AS and AS-ATTR were lower than those between patients with lone AS and lone ATTR.