DPD quantification correlates with ECV and disease severity in patients with ATTR-CM

Abstract Background The pathophysiological hallmark of transthyretin amyloid cardiomyopathy (ATTR-CM) is the deposition of amyloid within the myocardium. However, the association between myocardial amyloid load and quantitative cardiac 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) uptake is barely investigated. Purpose We aimed to investigate the relationship between quantitative cardiac 99mTc-DPD uptake and myocardial amyloid load, assessed by extracellular volume (ECV) on cardiac magnetic resonance (CMR) imaging, along with cardiac function in patients with ATTR-CM. Methods Forty ATTR-CM patients underwent 99mTc-DPD single-photon emission computed tomography/computed tomography (SPECT/CT) and CMR imaging. Results We observed significant correlations (r, Spearman's correlation coefficient) between the standardized uptake value (SUV) retention index and myocardial amyloid load (ECV: r=0.677, p<0.001; native T1 time: r=0.430, p=0.006), longitudinal cardiac function [right ventricular longitudinal strain (RV-LS): r=0.472, p=0.002], cardiac biomarkers (NT-proBNP: r=0.543, p<0.001; troponin T: r=0.401, p=0.011), exercise capacity [6-min walking distance (6MWD): r=-0.410, p=0.010] and disease stage [National Amyloidosis Centre (NAC) ATTR stage: r=0.479, p=0.002]. ATTR-CM patients were divided into two cohorts based on the median of the SUV retention index (low cardiac uptake: <5.19 mg/dL, n=20; high cardiac uptake: ≥5.19 mg/dL, n=20). We observed significant between-cohort differences in terms of ECV (p<0.001), native T1 time (p=0.011), RV-LS (p=0.007), NT-proBNP (p<0.001), troponin T (p=0.030), 6MWD (p=0.002) and NAC ATTR stage (I: p<0.001, II: p=0.030, III: p=0.021). Conclusions In ATTR-CM, quantitative cardiac 99mTc-DPD uptake correlates with myocardial amyloid load, longitudinal cardiac function, cardiac biomarkers, exercise capacity, and disease stage. DPD quantification may provide a valuable tool for quantifying and monitoring cardiac disease burden in affected individuals.Table.Baseline Characteristics.Figure.Correlations.