Prognostic value of 99mTc-DPD quantitative SPECT/CT in patients with suspected and confirmed cardiac ATTR-Amyloidosis and preserved left ventricular function

Abstract Aim Quantitative 99mTc-3,3-diphosphono-1,2 propanodicarboxylicacid (99mTc-DPD) Single Photon Emission Computed Tomography (SPECT) may be used for risk stratifying patients with transthyretin-related amyloidosis-cardiomyopathy (ATTR-CM). We aimed to analyse the predictive value of quantitative 99mTc-DPD SPECT/CT in suspected and confirmed ATTR-CM according to different disease stages. Methods Consecutive patients with suspected ATTR-CM referred to a single tertiary center who underwent quantitative 99mTc-DPD SPECT/CT allowing standardized uptake values (SUVmax, SUVpeak) analysis were enrolled. Patients were divided into two groups according to left ventricular ejection fraction (LVEF) at baseline (i.e. LVEF≥50% and 50%). Correlations between 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) to quantitative uptake values were investigated. Results A total of 144 patients with suspected ATTR-CM were included in the study (98 with LVEF≥50% and 46 with LVEF50%), of whom 99 were diagnosed with ATTR-CM (68,75%; 69 with LVEF≥50% and 30 with LFEV50%). Myocardial SUVmax≥7 was predictive of MACE at 21.9±13.0 months follow-up (HR 2.875, 95%CI 1.23 – 6.71, p=0.015) in suspected ATTR-CM and in patients with confirmed ATTR-CM (global X²= 6.892, p=0.02) and LVEF≥50%. There was no predictive value for patients with LVEF50% in suspected or confirmed ATTR-CM. Conclusions In patients with suspected or confirmed ATTR-CM and preserved LVEF, representing early disease stage, a myocardial SUV≥7 is a predictive marker for MACEs. Quantitative 99mTc-DPD SPECT should be considered for improved early stage risk stratification of patients with ATTR-CM.