Abstract Body (Do not enter title and authors here): Background: Transthyretin cardiac amyloidosis (ATTR-CA) is a progressive cardiomyopathy that commonly presents with concomitant chronic kidney disease. Impaired renal function is associated with worse outcomes, but the prognostic value of changes in renal function over time are yet to be defined.
Objectives: This study aimed to assess the prognostic importance of a decline in estimated glomerular filtration rate (eGFR) as a marker of renal progression in a large cohort of patients with ATTR-CA.
Methods: A retrospective analysis of 2001 patients diagnosed with ATTR-CA at the National Amyloidosis Centre (NAC) who underwent a baseline and follow-up eGFR assessment at 1-year between 2000-2024.
Results: Between baseline and 1-year visits, 208(10.4%) patients experienced renal progression (defined as a decrease in eGFR of >30%). Renal progression was associated with a 2.4-fold higher risk of mortality (HR=2.37,95%CI[1.91-2.94],P<0.001) and the risk was similar across the 3 genotypes (interaction P=0.972) and the 3 NAC disease stages (interaction P=0.172). Deterioration of the cardiorenal axis is tracked through a biomarker progression score composed of NT-proBNP progression (defined as an increase of >700ng/L and >30%) and renal progression. When compared with patients with a stable NT-proBNP and eGFR, a higher risk of mortality was observed in patients experiencing either NT-proBNP or renal progression (HR=2.02,95%CI[1.70-2.40],P<0.001) and those experiencing both NT-proBNP and renal progression (HR=3.77,95%CI[2.84-5.00],P<0.001).
Conclusions: Renal progression is frequent and consistently associated with an increased risk of mortality. Combining renal and NT-proBNP progression produces a biomarker progression score that reflects worsening of the cardiorenal axis and identifies patients at the highest risk.