Association between CT-derived extracellular volume and echocardiographic parameters in severe aortic stenosis

Introduction

Diffuse myocardial fibrosis is a key determinant of adverse prognosis in severe aortic stenosis (AS). CT-derived extracellular volume (ECV) is a non-invasive surrogate of diffuse fibrosis that can be obtained opportunistically during routine pre-transcatheter aortic valve implantation (TAVI) assessment. Its relationship with echocardiographic markers of myocardial dysfunction remains incompletely defined. We evaluated the association between CT-derived ECV and echocardiographic parameters in patients with severe AS.

Methods

Patients with severe AS undergoing pre-TAVI dual-energy CT between April 2024 and April 2025 were retrospectively included. Global ECV was quantified from delayed acquisitions as the mean of basal and mid-ventricular short-axis values. Transthoracic echocardiography was performed according to guidelines. Associations between ECV and echocardiographic parameters were assessed.

Results

A total of 253 patients were included (median age 81 years; 48.6% male). Higher ECV was associated with adverse myocardial remodeling and dysfunction. ECV correlated positively with left atrial size (ρ = 0.187, p = 0.005) and worsening global longitudinal strain (ρ = 0.217, p = 0.008), and inversely with left ventricular ejection fraction (ρ = −0.298, p < 0.001), stroke volume (ρ = −0.237, p = 0.005), and TAPSE (ρ = −0.245, p < 0.001). Significant inverse correlations were also observed with aortic valve area (ρ = −0.188, p = 0.003) and mean transvalvular gradient (ρ = −0.139, p = 0.027), while no association was found with peak aortic jet velocity. Higher ECV was associated with a greater prevalence of low-flow, low-gradient AS (p < 0.001).

When analyzing only patients with classical high-gradient AS, ECV remained significantly associated with left atrial size (ρ = 0.212, p = 0.007) and worsening GLS (ρ = 0.197, p = 0.042), and inversely with left ventricular ejection fraction (ρ = −0.166, p = 0.027), TAPSE (ρ = −0.175, p = 0.027), and aortic valve area (ρ = −0.218, p = 0.003). No associations were observed with peak velocity or mean gradient.

Conclusion

CT-derived ECV is consistently associated with echocardiographic markers of myocardial dysfunction and reduced stroke volume in severe aortic stenosis, including in classical high-gradient disease. These findings support ECV as a complementary marker of myocardial disease burden beyond valve obstruction severity.