Clinical Phenotyping of Transthyretin Cardiac Amyloidosis with Bone-Seeking Radiotracers in Heart Failure with Preserved Ejection Fraction
Purpose of Review
The two most common types of cardiac amyloidosis are caused by fibril deposits of immunoglobulin light chains (AL) and transthyretin (TTR), each with distinct prognosis and clinical management. Cardiac amyloidosis is under-recognized among heart failure patients with preserved ejection fraction (HFpEF). Bone-seeking tracers like 99mTc-PYP and 99mTc-DPD have long been used to identify cardiac amyloidosis, and more recently, to differentiate TTR from AL cardiac amyloidosis in symptomatic patients. However, results are mainly derived from single-center retrospective studies, with comparable but not standardized imaging protocols and interpretation criteria.
The clinical scope of cardiac amyloidosis among HFpEF patients and current literature supporting the use of bone-seeking tracers for TTR cardiac amyloidosis are presented. The differences of imaging techniques for cardiac amyloid and bone disease evaluation, bone tracer pharmacodynamics, and imaging interpretation criteria for cardiac amyloidosis diagnosis are discussed. Finally, a diagnostic algorithm to use bone scintigraphy in cardiac amyloidosis diagnosis among HFpEF patients is proposed.
Bone scintigraphy with 99mTc-PYP or 99mTc-DPD can be a useful tool with high sensitivity and specificity for detecting TTR-related cardiac amyloidosis in patients with HFpEF. It is needed to standardize the imaging protocol and interpretation criteria and to perform prospective clinical studies.
KeywordsHeart failure with preserved ejection fraction Amyloidosis Transthyretin Light chain 99mTc-pyrophosphate (99mTc-PYP) 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) Bone scintigraphy
Compliance with Ethical Standards
Conflict of Interest
Wengen Chen, Van-Khue Ton, and Vasken Dilsizian declare that they have no conflict of interest.
Human and Animal Rights and Informed Consent
This article does not contain any studies with human or animal subjects performed by any of the authors.
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