Wild-Type Transthyretin Amyloid Cardiomyopathy With Positive 18F-FDG/13N-Ammonia Cardiac Positron Emission Tomography
- 1Department of Internal Medicine, Mayo Clinic, Jacksonville, Florida, USA
- 2Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
- 3Department of Cardiovascular Diseases, Mayo Clinic, Jacksonville, Florida, USA
Abstract
Background: Wild-type transthyretin amyloid cardiomyopathy (wtATTR-CM) is increasingly recognized with advances in noninvasive imaging and disease-modifying therapies. However, atypical imaging findings may mimic other cardiomyopathies and delay diagnosis.
Case Summary: An 85-year-old man was treated for presumed isolated cardiac sarcoidosis after 18F-fluorodeoxyglucose (FDG)/13N-ammonia positron emission tomography/computed tomography (PET/CT) showed matching perfusion defects with focal FDG uptake. Despite methotrexate therapy, he developed progressive heart failure. Serial echocardiography demonstrated increasing left ventricular wall thickness and worsening global longitudinal strain with apical sparing, raising suspicion for amyloidosis. Repeat PET/CT showed persistent perfusion defects but resolution of FDG uptake. Cardiac amyloid scintigraphy revealed grade 3 myocardial tracer uptake (heart-to-contralateral ratio 1.74). Negative monoclonal studies and transthyretin genetic testing confirmed wtATTR-CM. Methotrexate was discontinued, tafamidis was initiated, and symptoms improved.
Discussion: In wtATTR-CM, 18F-FDG/13N-ammonia PET/CT may demonstrate myocardial FDG uptake, mimicking inflammatory cardiomyopathy such as cardiac sarcoidosis. Proposed mechanisms include localized inflammation from amyloid deposition, altered myocardial glucose metabolism, or coexistence of inflammatory processes. Serial multimodality imaging was essential for diagnostic clarification and timely targeted therapy.
Take-Home Messages: wtATTR-CM may present with myocardial FDG uptake, mimicking inflammatory cardiomyopathy. Multimodality imaging is critical to avoid diagnostic delay and guide appropriate treatment.
Related
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- Stage-Specific Cost-Effectiveness of Early vs. Delayed Tafamidis for Transthyretin Amyloid Cardiomyopathy in Japan
- Stage-dependent timing of relative and absolute treatment benefit in transthyretin amyloid cardiomyopathy
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BibTeX
@article{elalfy2026wildtype,
title = {{Wild-Type Transthyretin Amyloid Cardiomyopathy With Positive 18F-FDG/13N-Ammonia Cardiac Positron Emission Tomography}},
author = {Aya Elalfy and Zeyad Kholeif and Rana Rashwan and Carlos Vergara Sanchez and Awais Malik},
journal = {JACC Case Reports},
year = {2026},
month = jul,
doi = {10.1016/j.jaccas.2026.109541},
url = {https://doi.org/10.1016/j.jaccas.2026.109541},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Wild-Type Transthyretin Amyloid Cardiomyopathy With Positive 18F-FDG/13N-Ammonia Cardiac Positron Emission Tomography
AU - Aya Elalfy
AU - Zeyad Kholeif
AU - Rana Rashwan
AU - Carlos Vergara Sanchez
AU - Awais Malik
PY - 2026
DA - 2026/07/31
JO - JACC Case Reports
DO - 10.1016/j.jaccas.2026.109541
UR - https://doi.org/10.1016/j.jaccas.2026.109541
AB - Background: Wild-type transthyretin amyloid cardiomyopathy (wtATTR-CM) is increasingly recognized with advances in noninvasive imaging and disease-modifying therapies. However, atypical imaging findings may mimic other cardiomyopathies and delay diagnosis. Case Summary: An 85-year-old man was treated for presumed isolated cardiac sarcoidosis after 18F-fluorodeoxyglucose (FDG)/13N-ammonia positron emission tomography/computed tomography (PET/CT) showed matching perfusion defects with focal FDG uptake. Despite methotrexate therapy, he developed progressive heart failure. Serial echocardiography demonstrated increasing left ventricular wall thickness and worsening global longitudinal strain with apical sparing, raising suspicion for amyloidosis. Repeat PET/CT showed persistent perfusion defects but resolution of FDG uptake. Cardiac amyloid scintigraphy revealed grade 3 myocardial tracer uptake (heart-to-contralateral ratio 1.74). Negative monoclonal studies and transthyretin genetic testing confirmed wtATTR-CM. Methotrexate was discontinued, tafamidis was initiated, and symptoms improved. Discussion: In wtATTR-CM, 18F-FDG/13N-ammonia PET/CT may demonstrate myocardial FDG uptake, mimicking inflammatory cardiomyopathy such as cardiac sarcoidosis. Proposed mechanisms include localized inflammation from amyloid deposition, altered myocardial glucose metabolism, or coexistence of inflammatory processes. Serial multimodality imaging was essential for diagnostic clarification and timely targeted therapy. Take-Home Messages: wtATTR-CM may present with myocardial FDG uptake, mimicking inflammatory cardiomyopathy. Multimodality imaging is critical to avoid diagnostic delay and guide appropriate treatment.
SN - 2666-0849
ER -