Uric Acid-to-Magnesium Ratio as a Novel Biomarker of Angiographic Coronary Artery Disease Burden: A Retrospective Cross-Sectional Comparative Analysis with the Uric Acid-to-HDL Ratio and Frontal QRS-T Angle in Patients Undergoing Elective Coronary Angiography

Background: Non-invasive biomarkers may facilitate early risk stratification in patients with coronary artery disease (CAD). Although the uric acid-to-HDL cholesterol ratio (UHR) has been identified as a novel marker associated with coronary atherosclerosis, the relationship between the uric acid-to-magnesium ratio (UA/Mg ratio) and the angiographic burden of coronary artery disease has not been sufficiently investigated. This study evaluated the association between the UA/Mg ratio and angiographic coronary artery disease burden in patients undergoing elective coronary angiography and compared its discriminative performance with that of the UHR and the frontal QRS-T angle. Methods: In this retrospective cross-sectional study, patients who underwent elective coronary angiography between 2022 and 2025 were evaluated. Patients with atrial fibrillation, left ventricular ejection fraction <50%, eGFR < 50 mL/min/1.73 m2, severe valvular disease, uric acid-lowering therapy, or acute coronary syndrome were excluded. A total of 351 patients were included in the study and divided into three groups—low (n = 117), intermediate (n = 117), and high (n = 117)—based on their Gensini scores. Independent associations were evaluated using multivariable ordinal logistic regression analysis. Receiver operating characteristic (ROC) analysis was performed to evaluate discrimination of the high Gensini tertile. Results: The UA/Mg ratio was strongly correlated with the Gensini score (ρ = 0.699, p < 0.001), showing a correlation comparable to that of the UHR (ρ = 0.717, p < 0.001) and stronger than that of the frontal QRS-T angle (ρ = 0.546, p < 0.001). In the multivariable ordinal logistic regression analysis, the UA/Mg ratio remained independently associated with higher Gensini tertiles (OR = 2.34, 95% CI: 1.23–4.45; p = 0.009). In the ROC analysis, the UA/Mg ratio demonstrated excellent discriminative performance for identifying the high Gensini tertile (AUC = 0.907, 95% CI: 0.877–0.938). The AUC of the UA/Mg ratio was comparable to that of the UHR (DeLong p = 0.978), whereas it was significantly higher than that of the frontal QRS-T angle (DeLong p < 0.001). Conclusions: The uric acid-to-magnesium ratio was strongly and independently associated with the burden of angiographic coronary artery disease in patients undergoing elective coronary angiography. The UA/Mg ratio demonstrated discriminative performance comparable to that of the UHR and superior to the frontal QRS-T angle. These findings suggest that the UA/Mg ratio may serve as a complementary biomarker for assessing angiographic coronary artery disease burden. Further prospective studies are warranted to validate its clinical utility.