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Background: The pathophysiological hallmark of wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) is the deposition of amyloid within the myocardium., Objectives: This study aimed to investigate associations between quantitative cardiac 99m Tc-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) uptake and myocardial amyloid burden, cardiac function, cardiac biomarkers, and clinical status in ATTRwt-CM., Methods: Forty ATTRwt-CM patients underwent quantitative DPD single photon emission computed tomography/computed tomography to determine the standardized uptake value (SUV) retention index, cardiac magnetic resonance imaging to determine extracellular volume (ECV) and cardiac function (RV-LS), and assessment of cardiac biomarkers (N-terminal prohormone of brain natriuretic peptide [NT-proBNP], troponin T) and clinical status (6-minute walk distance [6MWD], National Amyloidosis Centre [NAC] stage). ATTRwt-CM patients were divided into 2 cohorts based on median SUV retention index (low uptake: <5.19 mg/dL, n = 20; high uptake: ≥5.19 mg/dL, n = 20). Linear regression models were used to assess associations of the SUV retention index with variables of interest and the Mann-Whitney U or chi-squared test to compare variables between groups., Results: ATTRwt-CM patients (n = 40) were elderly (78.0 years) and predominantly male (75.0%). Univariable linear regression analyses revealed associations of the SUV retention index with ECV (r = 0.669, β = 0.139, P  < 0.001), native T1 time (r = 0.432, β = 0.020, P  = 0.005), RV-LS (r = 0.445, β = 0.204, P  = 0.004), NT-proBNP (log 10 ) (r = 0.458, β = 2.842, P  = 0.003), troponin T (r = 0.422, β = 0.048, P  = 0.007), 6MWD (r = 0.385, β = -0.007, P  = 0.017), and NAC stage (r = 0.490, β = 1.785, P  = 0.001). Cohort comparison demonstrated differences in ECV ( P  = 0.001), native T1 time ( P  = 0.013), RV-LS ( P  = 0.003), NT-proBNP ( P  < 0.001), troponin T ( P  = 0.046), 6MWD ( P  = 0.002), and NAC stage (I: P  < 0.001, II: P  = 0.030, III: P  = 0.021)., Conclusions: In ATTRwt-CM, quantitative cardiac DPD uptake correlates with myocardial amyloid load, longitudinal cardiac function, cardiac biomarkers, exercise capacity, and disease stage, providing a valuable tool to quantify and monitor cardiac disease burden., Competing Interests: Dr Rettl has received speaker fees and congress support from Akcea Therapeutics, Alnylam Pharmaceuticals, and Pfizer Inc, as well as research grants from 10.13039/100004319Pfizer Inc. Dr Duca has received speaker fees and congress support from 10.13039/501100015086AOP Orphan Pharmaceuticals GmbH, 10.13039/100006400Alnylam Pharmaceuticals, 10.13039/100004326Bayer AG, 10.13039/100004336Novartis AG, 10.13039/100004319Pfizer Inc and, as well as research grants from the 10.13039/501100015797Austrian Society of Cardiology and 10.13039/100004319Pfizer Inc. Dr Beitzke has received speaker fees from GE Healthcare and Siemens. Dr Nitsche receives speaker fees and research grants from 10.13039/100004319Pfizer Inc. Dr Badr Eslam has received speaker fees from Merck Sharp & Dohme Ges.m.b.H., AOP Orphan Pharmaceuticals GmbH, and OrphaCare GmbH, as well as research grants from OrphaCare GmbH and Astra Zeneca GmbH. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (© 2024 The Authors.)