Prognostic Value of [^99mTc]Tc-DPD Quantitative SPECT/CT in Patients with Suspected and Confirmed Amyloid Transthyretin–Related Cardiomyopathy and Preserved Left Ventricular Function

Abstract

Quantitative ^99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid ([^99mTc]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 [^99mTc]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 [^99mTc]Tc-DPD SPECT/CT allowing SUV_max and SUV_peak analysis. Patients were divided into 2 groups according to left ventricular ejection fraction (LVEF) at baseline (i.e., ≥50% and &lt;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 &lt; 50%), of whom 99 were diagnosed with ATTR-CM (68.8%; 69 with LVEF ≥ 50% and 30 with LVEF &lt; 50%). A myocardial SUV_max 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 χ² = 6.892, <i>P</i> = 0.02) and an LVEF of at least 50%. SUV_max 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 [^99mTc]Tc-DPD SPECT should be considered to improve early-stage risk stratification.