Diagnostic value of papillary muscle hypertrophy and mitral valve thickness to discriminate cardiac amyloidosis and Fabry disease.

Background: Cardiac amyloidosis (CA) and Fabry disease (FD) cause myocardial damage but may also affect the valvular and subvalvular apparatus. We aimed to evaluate the diagnostic accuracy of new echocardiographic indices including mitral valve thickness and papillary muscle (PM) hypertrophy to differentiate CA and FD.
Methods: In patients with confirmed CA and FD, a detailed assessment of valvular function, mitral valve leaflet thickness and PM area as well as PM left ventricular area ratio (PM/LV-ratio) was performed in offline analyses. Receiver operating characteristic curve analyses were conducted to determine the diagnostic accuracy of mitral valve thickness, PM hypertrophy, and PM/LV-ratio to distinguish CA from FD.
Results: We retrospectively analyzed a cohort of 129 patients (FD n = 49, CA n = 80). CA patients showed significantly more thickened mitral valve leaflets (4.1 ± 1.3 mm vs. 2.9 ± 1.1 mm, p < 0.001) and a higher PM area [4.0 (3.1-4.6) mm ² vs. 2.8 (2.1-4.6) mm ² , p = 0.009] with a comparable PM/LV-ratio in both groups. Mitral valve thickness showed the highest diagnostic accuracy to discriminate CA [AUC 0.77 (95% CI 0.67-0.87)]. The prevalence of aortic, tricuspid, and pulmonary valve regurgitation was significantly higher in CA (aortic regurgitation ≥ II° 13% vs. 4%, tricuspid regurgitation≥ II° 19% vs. 8%, p < 0.001).
Conclusion: Our results suggest that the assessment of mitral valve thickness may be a new useful echocardiographic parameter to differentiate CA and FD, whereas papillary muscle hypertrophy and PM/LV-ratio showed a limited diagnostic performance to discriminate CA. German clinical trials registry: DRKS00027403.
Competing Interests: Declaration of Competing Interest Isabel Mattig is participant in the BIH Charité Clinician Scientist Program funded by the Charité – Universitätsmedizin Berlin and the Berlin Institute of Health at Charité (BIH). She received research grants from Pfizer Pharmaceuticals and Sanofi, lecture fee and financial reimbursement for advisory board activities from Sanofi outside the submitted work. SSp achieved financial reimbursement for lectures from Pfizer Pharmaceuticals. KH achieved financial reimbursement for consulting, advisory board activities and travel support by Akcea Therapeuticals Inc., Alnylam Pharmaceuticals Inc., Swedish Orphan Biovitrum, and Pfizer Pharmaceuticals, research funding by Alnylam Pharmaceuticals Inc., and Pfizer Pharmaceuticals as well as research funding by the foundation Charité (BIH clinical fellow). AB received lecture fee from Pfizer Pharmaceuticals.
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