Association of the ApoB/ApoA1 Ratio with Angiographically Documented Coronary Artery Disease: Comparison with Conventional Lipid Markers

Background/Objectives: The apolipoprotein B/apolipoprotein A1 (ApoB/ApoA1) ratio has been proposed as an integrated marker of atherogenic and anti-atherogenic lipoprotein balance. This study assessed its association with the presence and angiographic severity of coronary artery disease (CAD) and compared its discriminatory performance with conventional lipid markers. Methods: This retrospective, observational, cross-sectional study included 63 adults undergoing coronary angiography for suspected or established CAD. Pre-procedural ApoB, ApoA1, and conventional lipid parameters were measured. Significant CAD was defined as ≥50% stenosis in at least one major epicardial coronary artery. Associations with angiographic severity were assessed using Gensini and SYNTAX scores. Statistical analyses included between-group comparisons, Spearman correlations, ROC analysis with DeLong comparisons, and logistic regression. Results: Significant CAD was present in 46 patients (73.02%). ApoB and ApoB/ApoA1 were higher in patients with significant CAD (p = 0.011 and p = 0.013), whereas ApoA1 was not (p = 0.101). ApoB/ApoA1 correlated weakly with Gensini score (ρ = 0.30, p = 0.046), but not with SYNTAX Scores I or II. In the complete-case subset (n = 55), ApoB/ApoA1 had an AUC of 0.68, with no significant differences versus LDL-C, HDL-C, total cholesterol, or triglycerides. Each 0.1-unit increase in ApoB/ApoA1 was associated with higher odds of significant CAD after adjustment for age, diabetes mellitus, and smoking (adjusted OR 1.63, 95% CI 1.08–2.48; p = 0.021). Conclusions: ApoB/ApoA1 was associated with significant CAD after adjustment for selected clinical variables, but this association was attenuated after additional adjustment for LDL-C. Its discriminatory performance was modest and not significantly different from conventional lipid markers, requiring further evaluation as a potential pre-angiographic risk marker.