Prognostic value of the Glucose-to-Potassium Ratio in patients with Atrial Fibrillation: A U-shaped Association

Background Atrial fibrillation (AF) is an increasing global health challenge. The glucose-to-potassium ratio (GPR) has shown prognostic value in various critical illnesses, but its role as a biomarker for predicting outcomes in AF patients remains unclear. This study aimed to evaluate the prognostic significance of GPR for both short- and long-term outcomes in AF. Methods Data were extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV, v2.2) database and the Second Affiliated Hospital of Wenzhou Medical University. Patients were stratified into three groups based on GPR levels. The primary endpoint was 365-day all-cause mortality, while secondary endpoints were 30-day and 90-day all-cause mortality. Kaplan–Meier survival analysis, Cox regression models, and restricted cubic spline (RCS) curves were employed to assess associations between GPR and outcomes. Subgroup analyses and interaction effects were conducted, and mediation analysis was used to evaluate the role of heart rate. Results A total of 3,368 patients from the MIMIC-IV database and 309 patients from the Wenzhou cohort were included. Patients with high GPR had significantly higher mortality. GPR demonstrated a U-shaped relationship with mortality: each 1-unit increase in GPR above 1.22 was associated with a 24%, 23%, and 24% higher risk of death at 30, 90, and 365 days, respectively (all P < 0.001). Subgroup analysis revealed a significant interaction with chronic kidney disease (CKD) status (interaction P < 0.001). GPR was strongly predictive of mortality in non-CKD patients (HR = 1.29, 95% CI: 1.20–1.38), but not in those with CKD (HR = 1.03, 95% CI: 0.92–1.15). Conclusion GPR is an independent predictor of both short- and long-term mortality in AF patients. Its U-shaped association with mortality highlights its potential value for risk stratification in this population.