Utility of Prognostic Staging Systems in Transthyretin Amyloidosis Cardiomyopathy in the Era of Available Disease-Modifying Treatment.

BACKGROUND: Prognostic staging systems in transthyretin amyloid (ATTR) cardiomyopathy were developed before the introduction of disease-modifying treatment. We therefore evaluated contemporary risk stratification according to different staging systems in patients with ATTR cardiomyopathy. METHODS: All patients with newly diagnosed ATTR cardiomyopathy and baseline biomarker measurements from 2019 to 2023 were included from Mayo Clinic, Rochester, MN. Prognostic outcomes were calculated with Kaplan-Meier analysis for 3e staging systems in the main analysis: the National Amyloidosis Centre (NAC) staging system; a modified Mayo staging system using hsTNT (high-sensitivity troponin T) cutoff >65 ng/L; the extended NAC model with a fourth stage (NT-proBNP [N-terminal pro-B-type natriuretic peptide] >10 000 ng/L). RESULTS: The study population consisted of 441 patients with a median age of 76 years, 93% were men, 85% were initiated on tafamidis, and 94% had wild-type ATTR. Median follow-up was 3.4 years, and 109 deaths occurred during follow-up. The 3-year survival for the Mayo stages were 92.3% (88.7-95.9) for stage I, 71.6% (63.0-81.3) for stage II, and 43.5% (32.4-58.5) for stage III. For the NAC system, 3-year survival were 92.0% (89.0-95.7), 67.5% (59.0-77.3), and 47.0% (34.7-63.5) for stages I, II, and III, respectively. The 3-year survival by the extended NAC system was 92.0 (69.0-79.2), 69.0% (60.1-79.2), 53.2% (39.9-70.8) and 34.4% (17.4-68.0) for stages I, II, III, and IV, respectively. CONCLUSIONS: In a contemporary cohort of patients with ATTR cardiomyopathy, the NAC and modified Mayo staging systems remained equally effective in delineating clinically meaningful prognostic groups, whereas the extended NAC system identified a stage IV subgroup with high mortality.