Serum Albumin and Albumin-Based Nutritional-Inflammatory Indices Across the 2026 ESC Heart Failure Phenotypes: Associations with Recorded All-Cause Mortality

Background: Serum albumin reflects nutritional status, inflammation, congestion, and organ dysfunction in heart failure (HF). We examined its association with recorded all-cause mortality and compared it with the prognostic nutritional index (PNI) and hemoglobin–albumin–lymphocyte–platelet (HALP) index. Methods: This retrospective single-center study included 492 patients hospitalized with decompensated HF with available serum albumin, left ventricular ejection fraction (LVEF), and N-terminal pro-B-type natriuretic peptide (NT-proBNP), classified as heart failure with reduced ejection fraction (HFrEF; LVEF < 50%) or heart failure with preserved ejection fraction (HFpEF; LVEF ≥ 50%) using the 2026 European Society of Cardiology (ESC) framework. Exact death dates were unavailable, and potential observation time varied between patients. Logistic regression evaluated each marker separately after adjustment for clinical characteristics, NT-proBNP, and renal function. Results: There were 177 recorded deaths. Lower albumin (odds ratio [OR] 1.60 per 5 g/L decrease, 95% confidence interval [CI] 1.30–1.96), PNI (OR 1.43 per 5-unit decrease, 95% CI 1.21–1.67), and HALP (OR 1.15 per 10-unit decrease, 95% CI 1.04–1.27) were associated with mortality. Adding albumin to the clinical + NT-proBNP model improved model fit (likelihood-ratio p < 0.001) and increased apparent area under the receiver operating characteristic curve (AUC) from 0.689 to 0.731; PNI and HALP yielded AUCs of 0.730 and 0.710. For the primary albumin model, bootstrap optimism correction reduced the AUC from 0.735 to 0.702, with a corrected calibration slope of 0.822. Associations were similar in the sensitivity analysis restricted to at least 12 months of potential observation. Interaction tests provided no evidence that the associations differed by HF phenotype, but did not establish equivalence. Conclusions: Lower serum albumin was associated with recorded mortality and added information beyond clinical variables and NT-proBNP. Comparisons with PNI and HALP remain exploratory. Clinical use requires external validation and follow-up with known event dates.