Association between aspartate aminotransferase to alanine aminotransferase ratio and mortality in critically ill patients with congestive heart failure

Congestive heart failure (CHF) is a complex clinical syndrome that significantly impacts patient outcomes, especially in critically ill patients admitted to intensive care units (ICUs). The aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio (AST/ALT), has also been reported as a risk factor of cardiovascular diseases. However, few studies investigated the correlations between the AST/ALT ratio and ICU mortality in critically ill patients with CHF. This study investigates the association between the baseline AST/ALT ratio measured within the first 24 h of ICU admission and 28-day ICU all-cause mortality in critically ill patients with CHF. This retrospective cohort study included 4869 critically ill patients with CHF from the eICU Collaborative Research Database. Patients were categorized into tertiles based on their AST/ALT ratio: Tertile 1 (0.13-0.97), Tertile 2 (0.97-1.50), and Tertile 3 (1.50-5.89). Univariate and multivariate Cox proportional hazards regression models were used to evaluate the association between the AST/ALT ratio and 28-day ICU all-cause mortality. Nonlinear threshold effects and subgroup analyses were conducted to assess the robustness of the findings. Kaplan-Meier survival curves were generated to compare survival probabilities across tertiles. Participants with higher AST/ALT ratios were older, had higher illness severity, and experienced worse clinical outcomes. In univariate analysis, the AST/ALT ratio was significantly associated with 28-day ICU mortality (HR: 1.24, 95% CI 1.13-1.37, P < 0.0001). This association remained significant in the fully adjusted multivariate model. The highest tertile of AST/ALT ratio was associated with a significantly higher risk of mortality compared to the lowest tertile across all models (HR: 1.48, 95% CI 1.07-2.03, P = 0.0162 in Model 4). A nonlinear relationship was observed, with a threshold identified at an AST/ALT ratio of 2.08. Below this turning point, the association remained strong (HR: 1.47, 95% CI 1.13-1.91, P = 0.0036), while above it, the association was no longer significant. Subgroup analyses revealed no significant interactions, indicating that the association between AST/ALT ratio and mortality was consistent across various patient characteristics. Survival analysis showed that patients in the highest tertile had the poorest survival outcomes (P < 0.0001). An elevated AST/ALT ratio within the first 24 h of ICU admission is independently associated with increased 28-day ICU all-cause mortality in critically ill patients with CHF.