Prognostic Value of [<sup>99m</sup>Tc]Tc-DPD Quantitative SPECT/CT in Patients with Suspected and Confirmed Amyloid Transthyretin–Related Cardiomyopathy and Preserved Left Ventricular Function
Federico Caobelli, Nasir Gözlügöl, Adam Bakula, Axel Rominger, Robin Schepers, Stefan Stortecky, Lukas Hunziker Munsch, Stephan Dobner, Christoph Gräni
Abstract
Quantitative <sup>99m</sup>Tc-3,3-diphosphono-1,2-propanodicarboxylic acid ([<sup>99m</sup>Tc]Tc-DPD) SPECT may be used for risk-stratifying patients with amyloid transthyretin–related cardiomyopathy (ATTR-CM). We aimed to analyze the predictive value of quantitative [<sup>99m</sup>Tc]Tc-DPD SPECT/CT in suspected and confirmed ATTR-CM according to different disease stages. <b>Methods:</b> The study enrolled consecutive patients with suspected ATTR-CM who were referred to a single tertiary center and underwent quantitative [<sup>99m</sup>Tc]Tc-DPD SPECT/CT allowing SUV<sub>max</sub> and SUV<sub>peak</sub> analysis. Patients were divided into 2 groups according to left ventricular ejection fraction (LVEF) at baseline (i.e., ≥50% and <50%). Clinical, laboratory, and echocardiographic parameters and major adverse cardiac events (i.e., all-cause death, sustained ventricular tachyarrhythmia, hospitalization for heart failure, implantation of a cardioverter defibrillator) were investigated for any correlation with quantitative uptake values. <b>Results:</b> In total, 144 patients with suspected ATTR-CM were included in the study (98 with LVEF ≥ 50% and 46 with LVEF < 50%), of whom 99 were diagnosed with ATTR-CM (68.8%; 69 with LVEF ≥ 50% and 30 with LVEF < 50%). A myocardial SUV<sub>max</sub> of at least 7 was predictive of major adverse cardiac events at 21.9 ± 13.0 mo of follow-up (hazard ratio, 2.875; 95% CI, 1.23–6.71; <i>P</i> = 0.015) in patients with suspected or confirmed ATTR-CM (global χ<sup>2</sup> = 6.892, <i>P</i> = 0.02) and an LVEF of at least 50%. SUV<sub>max</sub> was not predictive in patients with an LVEF of less than 50% and suspected or confirmed ATTR-CM. <b>Conclusion:</b> In patients with suspected or confirmed ATTR-CM and preserved LVEF, representing an early disease stage, quantitative [<sup>99m</sup>Tc]Tc-DPD SPECT should be considered to improve early-stage risk stratification.