Coronary Artery Calcification Quantified by Electron Beam Tomography as a Screening for Coronary Artery Disease in Asymptomatic Non-Insulin-Dependent-Diabetes Mellitus

Yun, Yong Seok; Rhee, Yu Mie; Sim, Dae Keun; Sin, Sung Kwan; Park, Byung Ku; Rhu, Dong Reul; Han, Seol Hae; Park, Seok Won; Song, Young Duk; Lim, Sung Kil; Kim, Kyung Rae; Lee, Hyun Chul; Rim, Se Joong; Cho, Seung Yun; Huh, Kap Bum; Choi, Kye Ok; Lee, Jong Ho

Abstract

Patients with NIDDM are at increased risk for the development of coronary atherosclerosis and experience more silent myocardial infarction than non-diabetic subjects. The screening tools for early detection of coronary artery disease without significant narrowing has been requested in diabetic patients. Coronary artery calcification (CAC) score, quantified by electron beam computed tomography (EBT), have been reported to correlate with the amount of atherosclerotic plaque and vascular luminal narrowing. We investigated the distribution of CAC score and associated risk factors in asymptomatic NIDDM patients and patients with ischemic heart disease to estimate the usefulness of CAC as a screenig tool for ischemic heart disease in asymptomatic diabetes. METHOD: 136 NIDDM patients without any symptom of coronary artery disease and 37 patients with significant coronary artery stenosis were included. CAC were measured by electron bean tomography (ultrafast CT). Forty contiguous 3-mm thickness transverse two-dimensional sections were obtained through root of aorta and heart. Coronary calcification were defined as the presense of at least two adjacent pixel within the border of visualized coronary artery with CT number of at least 130 HU. Body mass index, waist-hip ratio were measured and body fat components were counted by impedence method. Visceral fat versus subcutaneous fat ratio were calculated by abdominal computed tomography. Plasma lipid profile, fasting insulin, C-peptide level, HbA1c concentration were measured. Correlations between natural log of CAC score and clinical parameters were evaluated and multiple regression analysis with natural log of CAC score as a independent variable was performed. Coronary angiography were performed in 17 asymptomatic NIDDM patients.. RESULT: CAC score was significantly higher in male than female subjects and increased significantly with aging (p<0.01). In patients with hypertension, previous history of cerebrovascular or peripheral vascular disease (p<0.05), CAC score was significantly increased. The CAC score showed significant positive correlations with smoking amount, duration of diabetes and a negative correlation with HDL-cholesterol (p<0.05). There were no association between CAC score and total cholesterol, LDL-cholesterol, waist to hip circumference ratio, or fasting insulin levels. After adjustment of compounding variables (age, sex), duration of diabetes, amount of smoking and previous history of atherosclerotic vascular disease were shown to be associated with CAC score. In multiple logistic regression analysis with natural log of CAC score as dependent variable, age, HDL-cholesterol, duration of diabetes, male gender were found to be significant independent variables. Seventeen diabetic patients with high CAC score, were taken coronary angiography and significant luminal narrowings (more than 50%) of coronary artery were documented in 16 patients. But, In 7 out of 17 patients with coronary one-vessel disease, coronary calcification were not detected by EBT.
CONCLUSION
coronary artery calcium score quantified by electron beam computed tomography may be useful for screening of preclinical or asymptomatic coronary artery disease in asymptomatic NIDDM patients.