Relationship between hemoglobin A1C and characteristics of plaque vulnerability in stable coronary disease: an optical coherence tomography study

Patients with diabetes mellitus are at increased risk of cardiovascular events. We aimed to analyze the impact of serum HbA1c levels on coronary plaque characteristics in stable coronary disease. Two hundred sixty-one patients who underwent optical coherence tomography (OCT) examination before elective percutaneous coronary intervention for a de novo obstructive lesions were included in this single-center retrospective analysis. Patients were divided into tertiles according to HbA1c level (tertile 1: HbA1c < 6.3%, tertile 2: 6.3 ≤ HbA1c < 7.8%, tertile 3: HbA1c ≥ 7.8%) and OCT findings were compared. Fibrous cap thickness (FCT) was significantly thinner in tertile 3 compared to tertile 1 and tertile 2 (103.9 ± 48.2 µm [tertile 1] vs. 107.5 ± 60.6 µm [tertile 2] vs. 86.2 ± 35.8 µm [tertile 3], p = 0.03). Higher prevalence of thin-cap fibroatheroma (TCFA) was observed in tertile 3 vs tertile 1 and tertile 2 (19.5% [tertile 1] vs. 19.5% [tertile 2] vs. 33.3% [tertile 3], p = 0.04). HbA1c inversely correlated with FCT (beta coefficient - 4.89, 95% confidence interval - 8.40 to - 1.39, p < 0.01). The logistic regression model revealed that the probability of having TCFA was positively associated with HbA1c with a small change in the range of low and medium HbA1c and a big change in the range of high HbA1c. Furthermore, minimal lumen area and reference lumen area were smaller in tertile 3. In patients with stable coronary disease, high serum HbA1c levels are associated with higher plaque burden and thinner FCT on OCT, while low and medium HbA1c levels result in similar plaque vulnerability.