Association between Glycated Hemoglobin and Angiographic Coronary Artery Disease Complexity in Nondiabetic Patients with Acute Coronary Syndrome

Abstract

Objectives: To determine the association between glycated hemoglobin (HbA1c) levels and angiographic coronary artery disease (CAD) complexity, assessed using the SYNTAX score, among nondiabetic patients presenting with acute coronary syndrome (ACS) and angiographically significant obstructive CAD. Methodology: This analytical cross-sectional study with prospective data collection was conducted at the Choudhary Pervaiz Elahi Institute of Cardiology, Multan, Pakistan, from 1 June to 30 November 2025. A total of 183 patients with ACS and angiographically significant obstructive CAD were included through consecutive sampling. Patients with established diabetes or HbA1c ≥6.5% were excluded. HbA1c was analyzed continuously and categorized as normal (<5.7%) or prediabetes (5.7–6.4%). Angiographic CAD complexity was assessed using the original anatomical SYNTAX score. Spearman's rank correlation was used for the primary unadjusted association, while multivariable linear regression assessed the association between HbA1c and SYNTAX score after adjustment for age, sex, obesity, hypertension, smoking, dyslipidemia, family history of premature CAD, and ACS subtype. Results: Of the 183 participants, 125 (68.3%) were male. The mean HbA1c was 5.56 ± 0.51%, and the median SYNTAX score was 20 (IQR 7). HbA1c demonstrated a strong positive correlation with SYNTAX score (Spearman's ρ = 0.742, 95% CI 0.669–0.801; P <0.001). Patients with prediabetes had significantly higher median SYNTAX scores than those with normal HbA1c [22 (IQR 20–25) vs. 17 (IQR 15–19); P <0.001]. In multivariable analysis, HbA1c remained positively associated with SYNTAX score (B = 7.577, 95% CI 6.469–8.685; P <0.001), with an adjusted R² of 0.512. Conclusion: Higher HbA1c levels were significantly associated with greater angiographic CAD complexity among nondiabetic patients presenting with ACS and established obstructive CAD. This association persisted after adjustment for measured clinical covariates. However, the cross-sectional design does not establish temporality, causality, or clinical predictive utility. Larger multicenter prospective studies are required to determine whether HbA1c provides incremental prognostic value beyond established cardiovascular risk factors.