The association of hemoglobin A1c and high risk plaque and plaque extent assessed by coronary computed tomography angiography

The objective of this study was to investigate the relationship of Hemoglobin A1c (HbA1c) and plaque characteristics including high risk plaque and plaque extent. We retrospectively examined 1079 consecutive coronary computed tomography (CT) angiography scans and the HbA1c results. We divided the patients into four groups by the HbA1c status: non-diabetic, ≤6.0; borderline, 6.1–6.4; diabetic low, 6.5–7.1; diabetic high, >7.1. We determined segment involvement score >4 as extensive disease. High risk plaque was defined as two feature positive (FP) plaque which consists of positive remodeling (remodeling index >1.1) and low attenuation (<30 HU). Univariate and multivariate analysis including conventional cardiovascular risk factors, symptoms and medication was performed. Univariate analysis showed that diabetic patients as well as borderline patients were significantly related with 2FP plaque and extensive disease. Although the relationship of borderline patients and 2FP plaque was marginal in multivariate analysis [odds ratio (OR) 1.53, 95 % confidence interval (CI) 0.95–2.40, p = 0.07], the elevation of HbA1c was strongly associated with 2FP plaque (diabetic low, OR 2.19, 95 % CI 1.37–3.45, p < 0.005; diabetic high, OR 4.14, 95 % CI 2.57–6.67, p < 0.0005). The association of HbA1c elevation and extensive disease was quite similar between borderline and diabetic patients (borderline, OR 1.96, 95 % CI 1.29–2.95, p < 0.005; diabetic low, OR 1.94, 95 % CI 1.25–3.01, p < 0.005; diabetic high, OR 2.19, 95 % CI 1.39–3.43, p < 0.005). Patients with elevated HbA1c of >6.0 are potentially at risk for future cardiovascular events due to increased high risk plaque and extensive disease, even below the diabetic level of 6.5. Coronary CT could be used for risk stratification of these patients.