Accelerated aortic stenosis progression is associated with greater CT-derived extracellular volume

Rapid progression of aortic stenosis (AS) is associated with adverse outcomes, yet the myocardial changes accompanying faster progression remain incompletely characterized. We evaluated the association between the rate of AS progression and myocardial fibrosis assessed by computed tomography (CT)-derived extracellular volume fraction (ECV), and the impact on clinical outcomes. We studied 134 patients with classical high-gradient severe AS who underwent pre-transcatheter aortic valve implantation cardiac CT with a delayed dual-energy acquisition for ECV quantification and had at least two echocardiograms ≥ 6 months apart. Progression was defined as the annualized change in peak aortic jet velocity. Rapid progression was defined as an increase > 0.30 m/s/year. Patients were followed for a composite of cardiovascular hospitalization, urgent aortic valve replacement, or death. ECV correlated with progression rate (Spearman ρ = 0.33, p < 0.001). In multivariable linear regression, faster progression remained independently associated with ECV (β = 2.52, p = 0.001). Rapid progressors had higher ECV than slow progressors (31.5% vs. 28.3%, p < 0.001). Over a median follow-up of 16.2 months, 36 patients (26.9%) reached the composite outcome. Patients with both rapid progression and high ECV had an event rate of 69 versus 11 per 100 patient-years in those without (adjusted HR 6.22, 95% CI 3.13-12.32). Faster AS progression is independently associated with greater diffuse myocardial fibrosis, irrespective of stenosis severity, and their combination identified patients at higher risk of adverse events. These findings suggest that AS progression rate and myocardial tissue characterization carry complementary prognostic information in severe AS.