Usefulness of quantitative (99m)Tc-pyrophosphate SPECT/CT for predicting the prognosis of patients with wild-type transthyretin cardiac amyloidosis

PURPOSE: Wild-type transthyretin-related amyloidosis cardiomyopathy (ATTRwt-CM) is an increasingly recognized cause of heart failure especially in elderly patients. The purpose of the present study was to determine retrospectively whether the quantitative indices of (99m)Tc-pyrophosphate (PYP) SPECT/CT help to predict the prognosis of ATTRwt-CM patients when compared with other clinical parameters. MATERIALS AND METHODS: Sixty-eight patients with biopsy-proven ATTRwt-CM who underwent PYP SPECT/CT were enrolled. Baseline clinical characteristics, echocardiographic parameters, and qualitative and/or quantitative indices of planar and SPECT/CT imaging in PYP scintigraphy for each patient were included. For quantitative analysis of SPECT/CT, the accumulation ratio of PYP in the septum, posterior, anterior, lateral, and apex walls to the cavity pool was calculated as the septal wall-to-cavity ratio (Se/C), lateral wall-to-cavity ratio (La/C), anterior wall-to-cavity ratio (An/C), inferior wall-to-cavity ratio (In/C), and apical wall-to-cavity ratio (Ap/C), respectively. Endpoints for prognostic accuracy evaluation were cardiac death or hospitalization due to heart failure. Event-free survival rate was evaluated through Cox proportional hazards regression analysis, providing estimated hazard ratios (HRs) with 95% confidence intervals (CIs) and Kaplan–Meier curves. RESULTS: High-sensitivity cardiac troponin T (hs-cTnT), La/C, age, interventricular septal thickness in diastole, and E/e′ ratio in the septal wall were significantly associated with event-free survival (P < 0.05). For a multivariable Cox proportional hazards analysis, hs-cTnT (HR 1.153; 95% CI 1.034–1.286; P < 0.01), La/C (HR 2.091; 95% CI 1.012–4.322; P = 0.046), and age (HR 1.116; 95% CI 1.007–1.238; P = 0.037) were significant independent prognostic factors. CONCLUSION: This study indicated that the quantitative indices of PYP SPECT/CT can help to predict the prognosis of ATTRwt-CM patients.