Lactate-to-albumin ratio as a short‑term prognostic biomarker in atrial fibrillation

While the lactate-to-albumin ratio (LAR) has shown prognostic relevance in general critical care populations, its utility in patients with atrial fibrillation (AF) remains underexplored. This study aimed to evaluate the association between LAR and 28-day all-cause mortality in patients with AF using the updated MIMIC-IV v3.1 database.

This retrospective cohort study included 3,962 patients with AF from the MIMIC-IV v3.1 database. Clinical data, including LAR, demographic characteristics, vital signs, laboratory parameters, and comorbidities, were analyzed for their associations with 28-day all-cause mortality. Univariate and multivariate Cox regression models were used to identify risk factors, whereas receiver operating characteristic (ROC) curves were used to evaluate the discriminative ability of the LAR. Subgroup analyses were performed to examine the robustness of the LAR across different clinical settings.

The LAR was independently associated with 28-day all-cause mortality in multivariate Cox regression analysis (HR: 1.12, 95% CI: 1.05-1.19, p < 0.001). The optimal LAR cutoff was 0.675, with a sensitivity of 56.2% and specificity of 63.8%. Kaplan‒Meier survival analysis confirmed that patients with higher LARs had significantly worse outcomes. Subgroup analyses revealed that the LAR maintained its prognostic value across most clinical subgroups, with some variability observed in patients receiving beta-blocker therapy.

The LAR may be useful as an auxiliary biomarker for risk stratification in critically ill patients with AF, particularly in those without confounding end-stage organ diseases. The identification of a risk inflection point (0.58) and an optimal cutoff (0.675) further suggests that LAR may be helpful for early risk stratification in this population.