Expansion of the National Amyloidosis Centre staging system to detect early mortality in transthyretin cardiac amyloidosis

Abstract Aims Transthyretin cardiac amyloidosis (ATTR‐CA) is stratified into prognostic categories using the National Amyloidosis Centre (NAC) staging system. The aims of this study were to further expand the existing NAC staging system to incorporate an additional disease stage that would identify patients at high risk of early mortality. Methods and results The traditional NAC staging system (stage 1: N‐terminal pro‐B‐type natriuretic peptide NT‐proBNP ≤3000 ng/L and estimated glomerular filtration rate eGFR ≥45 ml/min; stage 3: NT‐proBNP >3000 ng/L and eGFR 15‐fold higher than that of stage 1 (hazard ratio HR 15.5; 95% confidence interval CI 9.3–26.1) and >3‐fold higher than that of stage 3 (HR 3.4; 95% CI 2.2–5.4). The increased risk of early mortality was consistent across the different genotypes and subclasses of patients based on the severity of heart failure symptoms and echocardiographic parameters. Conclusions The proposed modification of the NAC staging system identifies patients with ATTR‐CA at a high risk of early mortality, who may benefit from a more intensive treatment strategy, and who are most likely to experience an event early in the course of a clinical trial.