Available online 14 September 2022
AbstractBackgroundBone scintigraphy is extremely valuable when assessing patients with suspected cardiac amyloidosis (CA), but the clinical significance and associated phenotype of different degrees of cardiac uptake across different types is yet to be defined.
ObjectivesThis study sought to define the phenotypes of patients with varying degrees of cardiac uptake on bone scintigraphy, across multiple types of systemic amyloidosis, using extensive characterization comprising biomarkers as well as echocardiographic and cardiac magnetic resonance (CMR) imaging.
MethodsA total of 296 patients (117 with immunoglobulin light-chain amyloidosis [AL], 165 with transthyretin (TTR) amyloidosis [ATTR], 7 with apolipoprotein AI amyloidosis [AApoAI], and 7 with apolipoprotein AIV amyloidosis [AApoAIV]) underwent deep characterization of their cardiac phenotype.
ResultsAL patients with grade 0 myocardial radiotracer uptake spanned the spectrum of CMR findings from no CA to characteristic CA, whereas AL patients with grades 1 to 3 always produced characteristic CMR features. In ATTR, the CA burden strongly correlated with myocardial tracer uptake, except in Ser77Tyr. AApoAI presented with grade 0 or 1 and disproportionate right-sided involvement. AApoAIV always presented with grade 0 and characteristic CA. AL grade 1 patients (n = 48; 100%) had characteristic CA, whereas only ATTR grade 1 patients with Ser77Tyr had characteristic CA on CMR (n = 5; 11.4%). After exclusion of Ser77Tyr, AApoAI, and AApoAIV, CMR showing characteristic CA or an extracellular volume of >0.40 in patients with grade 0 to 1 cardiac uptake had a sensitivity and specificity of 100% for AL.
ConclusionsThere is a wide variation in cardiac phenotype between different amyloidosis types across different degrees of cardiac uptake. The combination of CMR and bone scintigraphy can help to define the diagnostic differentials and the clinical phenotype in each individual patient.
Key Wordsbone scintigraphy
cardiac amyloidosis
cardiac magnetic resonance
Abbreviations and AcronymsAApoAIapolipoprotein AI amyloidosis
AApoAIVapolipoprotein AIV amyloidosis
ALimmunoglobulin light-chain amyloidosis
ATTRtransthyretin amyloidosis
CMRcardiac magnetic resonance
LGElate gadolinium enhancement
LVEFleft ventricular ejection fraction
MWTmaximal wall thickness
SAPserum amyloid P component
SPECTsingle-photon emission computed tomography
99mTc-DPD99mtechnetium-labeled 3,3-diphosphono-1,2-propanodicarboxylic acid
© 2022 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.
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