The role of nutritional status, measured by serum albumin, as a prognostic factor in wild-type transthyretin amyloidosis

Abstract Background Nutritional status is a well-established prognostic factor in various diseases, with serum albumin levels serving as a key indicator of clinical outcomes. However, its utility in patients with wild-type transthyretin cardiac amyloidosis (ATTRwt) remains largely unexplored. Purpose To evaluate the prognostic impact of serum albumin at diagnosis in patients with ATTRwt. Methods Retrospective cohort study including ATTRwt patients from our Institutional Amyloidosis Registry from 2008 to 2023. Serum albumin was measured for all patients at the time of diagnosis. Patients with incomplete data for serum albumin were excluded. The primary outcome was all-cause mortality, with administrative censoring at 2 years of follow-up. A receiver operating characteristic (ROC) curve was used to determine the optimal serum albumin cutoff for predicting the primary outcome, with the optimal cutoff defined as the point maximizing sensitivity and specificity. Patients were then stratified into two groups based on this cutoff point. A Kaplan-Meier curve was created to estimate the incidence of the primary endpoint in each group. Finally, a multivariable Cox regression model was performed, adjusting for clinically relevant variables. Results A total of 129 patients were included. The mean age was 81 years (±7), 86% male. The median serum albumin level was 3.97 3.70 - 4.20 g/dL and the optimal cutoff was 3.88 g/dL (AUC: 0.74, sensitivity: 73.5%, specificity: 75.7%; FIGURE 1A). Patients with serum albumin levels 3.88 g/dL (36%, n=47) were older (83 vs. 80 years; p=0.02), more likely to have heart failure and atrial fibrillation at diagnosis (81% vs. 60%; p=0.01 and 72% vs. 48%; p=0.006), and had higher serum creatinine (1.35 mg/dL vs. 1.19 mg/dL; p=0.03) and NT-ProBNP levels (4111 pg/mL vs. 2509 pg/mL; p=0.006) compared to those with serum albumin levels 3.88 g/dL (TABLE). The incidence of all-cause mortality was significantly higher in patients with lower albumin levels (51% vs. 12%; log-rank test p 0.001; FIGURE 1B). In a multivariate Cox regression analysis, adjusted for age, NT-proBNP, and heart failure at diagnosis, serum albumin levels 3.88 g/dL were independently associated with the primary outcome (HR: 3.61; 95% CI: 1.69–7.74; p =0.001). Conclusion Serum albumin levels 3.88 g/dL were associated with a higher incidence of all-cause mortality in patients with ATTRwt. This simple measure may serve as an independent prognostic factor, highlighting the relevance of nutritional status in the ATTRwt population.table FIGURE