Hemoglobin A1c in Nondiabetic Patients: An Independent Predictor of Coronary Artery Disease and Its Severity

Objective: To examine the association between hemoglobin A1c (HbA1c) and the presence, severity, and complexity of angiographically proven coronary artery disease (CAD) in nondiabetic patients. Patients and Methods: We performed a single-center, observational, cross-sectional study of 1141 consecutive nondiabetic patients who underwent coronary angiography from January 1, 2011, through December 31, 2011. The study population was divided into 4 interquartiles according to HbA1c levels (< 5.5%, 5.5%-5.7%, 5.8%-6.1%, and > 6.1%). Results: Patients with higher HbA1c levels tended to be older, overweight, and hypertensive, had higher blood glucose levels, and had lower glomerular filtration rates. Higher HbA1c levels were associated in a graded fashion with the presence of CAD, disease severity (higher number of diseased vessels and presence of left main and/or triple vessel disease), and disease complexity (higher SYNTAX score, higher number of patients in intermediate or high SYNTAX tertiles, coronary calcium, and chronic total occlusions). After adjustment for major conventional cardiovascular risk factors, compared with patients with HbA1c levels less than 5.5%, the odds ratios of occurrence of CAD in the HbA1c quartiles of 5.5% to 5.7%, 5.8% to 6.1%, and greater than 6.1% were 1.8 (95% CI, 1.2-2.7), 3.5 (95% CI, 2.3-5.3), and 4.9 (95% CI, 3.08.1), respectively. Conclusion: The HbA1c level has a linear incremental association with CAD in nondiabetic individuals. The HbA1c level is also independently correlated with disease severity and higher SYNTAX scores. Thus, HbA1c measurement could be used to improve cardiovascular risk assessment in nondiabetic individuals.