CT-derived extracellular volume mapping revealed a median basal/appical ECV ratio of 1.13, indicating higher fibrosis in basal segments in severe aortic stenosis patients.
Does CT-derived extracellular volume mapping demonstrate a basal-to-apical gradient of myocardial fibrosis in patients with severe aortic stenosis?
CT-derived ECV mapping reveals a basal-to-apical gradient of myocardial fibrosis in severe aortic stenosis, providing a structural basis for the functional apical sparing often observed in these patients.
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Abstract Background Myocardial fibrosis is a key driver of left ventricular remodeling in pressure-overload conditions such as aortic stenosis. While global fibrotic burden has been increasingly studied, its regional distribution within the myocardium remains poorly defined. Evidence from myocardial strain imaging — in both cardiac amyloidosis and aortic stenosis — has shown relative preservation of apical function compared to basal segments, a phenomenon referred to as apical sparing. This has raised the hypothesis that myocardial injury and fibrotic remodeling may follow a similar basal-to-apical gradient at the tissue level. Purpose To characterize the segmental distribution of myocardial extracellular volume (ECV) using computed tomography (CT) in patients with severe aortic stenosis, and to determine whether a basal-to-apical gradient consistent with apical sparing is present. Methods A total of 207 patients with severe aortic stenosis undergoing CT as part of transcatheter aortic valve implantation (TAVI) planning were retrospectively analyzed. All patients underwent opportunistic delayed-phase dual-energy acquisition, enabling ECV quantification. ECV values were measured in basal, mid, and apical short-axis slices to assess regional variation and calculate basal/apical ratios. Results A subtle but consistent basal-to-apical gradient was observed. Median ECV was highest in basal segments (31.2%, IQR 28.4–34.0), followed by mid-ventricular segments (29.3%, IQR 26.4–32.3), and lowest in apical regions (27.0%, IQR 24.2–30.6). The median basal/apical ECV ratio was 1.13 (IQR 1.01–1.29), indicating systematic regional variation in myocardial fibrosis. This pattern parallels functional apical sparing described in strain imaging. Conclusion CT-derived ECV mapping demonstrates a regionally heterogeneous distribution of myocardial fibrosis in severe aortic stenosis, with a relative predominance in basal segments. Although differences are modest, the observed compositional gradient supports the presence of structural apical sparing. These findings provide novel insight into myocardial remodeling in aortic stenosis. Given the potential influence of unrecognized cardiac amyloidosis on segmental ECV values, further validation in stratified populations and external cohorts is warranted. To our knowledge, this is the first study to describe this regional ECV pattern using CT.
Lobo et al. (Thu,) reported a other. CT-derived extracellular volume mapping revealed a median basal/appical ECV ratio of 1.13, indicating higher fibrosis in basal segments in severe aortic stenosis patients.