Association of elevated albumin-corrected anion gap with all-cause mortality risk in atrial fibrillation: a retrospective study

Abstract

Background Compared to the conventional anion gap, albumin-corrected anion gap (ACAG) offers a more precise measure of acid-base imbalance in patients than, providing superior prognostic insight. However, the prognostic relevance of ACAG in individuals of atrial fibrillation (AF) remains insufficiently explored. This research seeks to evaluate the correlation between ACAG levels and mortality risk in individuals with AF. Methods We identified individuals diagnosed with AF from the Medical Information Mart for Intensive Care (MIMIC)-IV database. Participants were categorized into quartiles in accordance with their ACAG levels. The outcomes included 30 days and 365 days all-cause mortality. Cumulative survival across the quartiles was assessed using Kaplan–Meier survival curves. We applied Cox regression and restricted cubic spline regression analyses to evaluate the correlation between ACAG levels and prognosis. Subgroup analyses and interaction assessments were applied to confirm the robustness of the findings. Results A total of 2920 AF patients (54.93% male) were incorporated into the analysis. The 30 and 365-day mortality were 22.91% and 39.21%, respectively. Kaplan–Meier survival curves demonstrated that elevated ACAG levels were significantly linked to increased mortality (log-rank P < 0.001). In multivariate Cox proportional hazards analyses, increased ACAG independently predicted mortality at 30 days (adjusted hazard ratio [aHR], 1.04; 95% CI, 1.02–1.05; P < 0.01) and 365 days (aHR, 1.03; 95% CI, 1.02–1.05; P < 0.01) after adjusting for potential confounders. A positive relationship between rising ACAG levels and mortality risk, as showed by restricted cubic spline analysis. Subgroup analyses revealed no significant interactions (all interaction P-values > 0.05). Conclusions In individuals with AF, higher ACAG levels are related to a greater mortality risk at 30 and 365 days. These results show the potential value of ACAG as a prognostic indicator for patient stratification. Incorporating ACAG into clinical decision-making could support improved therapeutic strategies and enhance patient outcomes.