Disease progression in cardiac transthyretin amyloidosis is indicated by serial calculation of National Amyloidosis Centre transthyretin amyloidosis stage

AIMS: Cardiac transthyretin amyloidosis (ATTR‐CM) is a progressive and fatal condition. Prognosis can be determined at diagnosis according to the National Amyloidosis Centre (NAC) transthyretin amyloidosis (ATTR) stage. We sought to examine how NAC ATTR stage changes during follow‐up and whether it maintains its prognostic value throughout the disease course. METHODS AND RESULTS: We performed a retrospective study of 945 patients with wild‐type ATTR‐CM (wtATTR‐CM) or hereditary ATTR‐CM associated with the V122I variant (V122I‐hATTR‐CM) who were diagnosed and serially evaluated at the UK NAC. Patients who commenced any disease‐modifying therapy for amyloidosis were censored at the time of doing so. Landmark Kaplan–Meier survival analyses were performed at diagnosis (n = 945) and at 6 ± 1 (n = 432), 12 ± 3 (n = 562), and 24 ± 3 (n = 316) months and stratified by recalculated NAC ATTR stage at the relevant time point. Cox regression analyses were performed to assess the prognostic significance during follow‐up of an increase in NAC ATTR stage from Stage I at diagnosis. Mortality in ATTR‐CM was predicted by NAC ATTR stage at each time point [Stage II vs. I, hazard ratios (HRs) 1.95–2.67; P < 0.001; Stage III vs. II, HRs 1.64–2.25; P < 0.001–0.013]. An increase from NAC ATTR Stage I, which occurred in 21%, 32%, and 44% of evaluable patients at 6, 12, and 24 months of follow‐up respectively, was highly predictive of ongoing mortality at each time point (HRs 2.58–3.22; P < 0.001) and in each genotypic subgroup (HRs 1.86–4.38; P < 0.05). Increase in NAC ATTR stage occurred earlier in V122I‐hATTR‐CM than in wtATTR‐CM (43% vs. 27% at 12 months of follow‐up; P = 0.003). CONCLUSIONS: National Amyloidosis Centre ATTR stage predicts ongoing survival throughout the disease natural history in ATTR‐CM, and an increase from NAC ATTR Stage I at diagnosis to a higher NAC ATTR stage predicts mortality throughout follow‐up. Serial calculation of NAC ATTR stage suggests a more aggressive phenotype in V122I‐hATTR‐CM than in wtATTR‐CM.