Role of Cardiac Scintigraphy With 99mTc-DPD in the Differentiation of Cardiac Amyloidosis Subtype

Abstract

Introduction and objectivesWe investigated the diagnostic accuracy of technetium-99m-3,3-diphosphono-1,2 propanodicarboxylic acid (99mTc-DPD) scintigraphy in differentiating between monoclonal immunoglobulin light chain and transthyretin-related cardiac amyloidosis. MethodsNineteen patients with documented cardiac amyloidosis were included: 8 with transthyretin-related amyloidosis (group A) and 11 with light chain amyloidosis (group B). All the patients underwent scintigraphy with 99mTc-DPD and technetium-99m-methylene diphosphonate (99mTc-MDP). ResultsOn visual scoring, cardiac 99mTc-DPD uptake could be characterized as moderate to severe (scores of 2-3), with ventricular or biventricular distribution, in all group A patients (transthyretin-related cardiac amyloidosis), and was absent or mild (scores of 0-1) and diffusely distributed in all group B patients (monoclonal immunoglobulin light chain cardiac amyloidosis). 99mTc-DPD uptake was also absent (score of 0) among unaffected controls and in 2 unaffected relatives of patients with hereditary transthyretin-related amyloidosis who harbor a mutation in the transthyretin gene. With 99mTc-MDP, all the patients had a myocardial uptake score of 0-1. In our series, selective myocardial uptake of 99mTc-DPD provided 100% accuracy (95% CI, 97.37%-100%) for the differentiation between transthyretin-related and light chain cardiac amyloidosis. ConclusionsWe conclude that 99mTc-DPD scintigraphy is a useful test for the differential diagnosis of transthyretin versus light chain etiology in patients with cardiac amyloidosis.