Extracellular Volume Fraction by Computed Tomography Predicts Long-Term Prognosis Among Patients With Cardiac Amyloidosis.

Background: Light chain (AL) and transthyretin (ATTR) amyloid fibrils are deposited in the extracellular space of the myocardium, resulting in heart failure and premature mortality. Extracellular expansion can be quantified by computed tomography, offering a rapid, cheaper, and more practical alternative to cardiac magnetic resonance, especially among patients with cardiac devices or on renal dialysis.
Objectives: This study sought to investigate the association of extracellular volume fraction by computed tomography (ECV _CT ), myocardial remodeling, and mortality in patients with systemic amyloidosis.
Methods: Patients with confirmed systemic amyloidosis and varying degrees of cardiac involvement underwent electrocardiography-gated cardiac computed tomography. Whole heart and septal ECV _CT was analyzed. All patients also underwent clinical assessment, electrocardiography, echocardiography, serum amyloid protein component, and/or technetium-99m ( ^99m Tc) 3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy. ECV _CT was compared across different extents of cardiac infiltration (ATTR Perugini grade/AL Mayo stage) and evaluated for its association with myocardial remodeling and all-cause mortality.
Results: A total of 72 patients were studied (AL: n = 35, ATTR: n = 37; median age: 67 [IQR: 59-76] years, 70.8% male). Mean septal ECV _CT was 42.7% ± 13.1% and 55.8% ± 10.9% in AL and ATTR amyloidosis, respectively, and correlated with indexed left ventricular mass (r = 0.426; P < 0.001), left ventricular ejection fraction (r = 0.460; P < 0.001), N-terminal pro-B-type natriuretic peptide (r = 0.563; P < 0.001), and high-sensitivity troponin T (r = 0.546; P < 0.001). ECV _CT increased with cardiac amyloid involvement in both AL and ATTR amyloid. Over a mean follow-up of 5.3 ± 2.4 years, 40 deaths occurred (AL: n = 14 [35.0%]; ATTR: n = 26 [65.0%]). Septal ECV _CT was independently associated with all-cause mortality in ATTR (not AL) amyloid after adjustment for age and septal wall thickness (HR: 1.046; 95% CI: 1.003-1.090; P = 0.037).
Conclusions: Cardiac amyloid burden quantified by ECV _CT is associated with adverse cardiac remodeling as well as all-cause mortality among ATTR amyloid patients. ECV _CT may address the need for better identification and risk stratification of amyloid patients, using a widely accessible imaging modality.
Competing Interests: Funding Support and Author Disclosures Drs Moon and Treibel are directly and indirectly supported by the University College London Hospitals National Institute for Health Research Biomedical Research Centre and Biomedical Research Unit at Barts Hospital, respectively. This work was undertaken at University College London Hospital, which received a proportion of funding from the UK Department of Health National Institute for Health Research Biomedical Research Centre’s funding scheme. Dr Patel is funded by the British Heart Foundation Clinical Research Training Fellowship. Dr Gama is supported by a nonrestricted educational grant by Pfizer. Drs Treibel and Fontana are funded by British Heart Foundation intermediate fellowships (FS/19/35/34374 and FS/18/21/33447). Dr Thornton is supported by a British Heart Foundation Clinical Research Training Fellowship (FS/CRTF/21/24128). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
(Copyright © 2022 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)