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Abstract Background Patients with severe aortic stenosis (AS) face a higher risk of mortality, but prognosis is still heterogeneous and tools for prioritizing intervention are needed. Myocardial extracellular volume (ECV), measured non-invasively in pre-TAVR computed tomography (CT), is a marker of fibrosis that may reflect the degree of irreversible damage. The aim of this study was to assess the prognostic value of CT- derived ECV (ECVCT) in patients with severe AS referred for TAVR-planning CT. Methods Consecutive patients with severe symptomatic AS undergoing TAVR-planning CT between April and December 2022 at single centre were prospectively included. CT was performed on a 192-slice dual-source 3rd generation scanner. ECVCT was acquired during TAVR-planning using an additional post-contrast low-radiation-dose prospective acquisition. ECVCT was calculated as the ratio of change in CT attenuation (Hounsfield units HU) of the septal myocardium and the left ventricle (LV) blood pool before and after contrast administration, according to the equation: ECVCT = (1 – hematocrit) x (DHUmyo/DHUblood) – Figure 1A. The primary endpoint was all-cause mortality. The secondary endpoint was a composite endpoint including all-cause mortality and heart failure hospitalization. Results A total of 138 patients were included (mean age 81 ± 7 years; 46% male; mean transaortic gradient 51 ± 15 mmHg; mean aortic valve area 0.75 ± 0.19 cm2; mean LV ejection fraction (EF) by 2D echocardiogram 57 ± 11%). No patient had a clinical diagnosis of cardiac amyloidosis. Mean ECVCT was 33.9 ± 8.0%. During a median follow-up period of 386 days (IQR 332 – 464), there were 18 deaths (13%), 13 before intervention and 5 after intervention; the secondary endpoint occurred in 26 patients (19%), 17 of which before intervention and 9 after. Patients who attained the primary endpoint were significantly older 81 ± 7 vs. 85 ± 7 years, P = 0.011, had lower left ventricular ejection fraction 51 ± 11 vs. 58 ± 11%, P = 0.015, higher NTproBNP levels 4739 (IQR 2003 – 9970) vs. 751 (IQR 314 – 2541), P 0.001 and higher ECV values (39.9 ± 7.4% vs. 33.0 ± 7.7%, P 0.001). After adjustment for age, LVEF and NTproBNP levels, ECVCT remained an independent predictor of all-cause mortality (adjusted HR 1.09 per 1% ECV increase, 95%CI 1.02 – 1.17, p=0.005 – Figure 1B) and also the secondary endpoint (adjusted HR 1.07 per 1% ECV increase, 95%CI 1.01 – 1.13, p=0.002). Conclusion In this prospective observational cohort study, interstitial fibrosis assessed by CT-derived ECV was associated with poor outcomes in patients with severe AS. ECVCT values may be useful to identify a subgroup of patients with higher risk who may benefit from earlier intervention.
Santos et al. (Thu,) studied this question.