Biomarkers and Prediction of Prognosis in Transthyretin-Related Cardiac Amyloidosis: Direct Comparison of Two Staging Systems

Background: The severity of heart disease varies widely among patients with transthyretin-related cardiac amyloidosis (ATTR-CA) at presentation, and availability of tools able to predict prognosis is essential for clinical and research purposes. Currently, two biomarker-based staging systems are available. The aim of this study was to compare their predictive performance. Methods: A total of 175 patients diagnosed with ATTR-CA (133 wild-type and 42 hereditary) were stratified into different stages based on 2 systems: the first system included N-terminal pro–B-type natriuretic peptide (NT-proBNP) and estimated glomerular filtration rate (eGFR), and the second one included NT-proBNP and troponin I (TnI). Survival estimates and age-adjusted survival for all-cause mortality were analysed over a median follow-up of 27 months (interquartile range 16-43 months). Results: Predictive performance was more accurate when NT-proBNP and eGFR were used, resulting in effective survival stratification: 64.4 months for stage 1, 44.6 months for stage 2, and 20.5 months for stage 3 (P < 0.01 for stages 1 vs 2; P < 0.0001 for stages 1 vs 3; P < 0.0001 stages 2 vs 3). The combination of NT-proBNP and TnI was unable to effectively differentiate survival: 64.5 months for stage 1, 50.9 months for stage 2, and 27.3 months for stage 3 (P = 0.223 for stages 1 vs 2; P < 0.0001 for stages 1 vs 3; P < 0.0001 for stages 2 vs 3). The same results were seen after age adjustment. Conclusions: A staging system using NT-proBNP and eGFR had better prognostic accuracy for ATTR-CA patients compared with one using NTproBNP and TnI.