Prevalence of Angiographically Defined Obstructive Coronary Artery Disease in Asymptomatic Patients with Type 2 Diabetes According to the Coronary Calcium Score

Objective The aim of this study was to determine whether the absence of coronary artery calcium (CAC) can safely exclude obstructive coronary artery disease (CAD) in asymptomatic patients with type 2 diabetes. Methods We enrolled 478 consecutive asymptomatic patients with type 2 diabetes who visited the diabetes clinic of the Asan Medical Center between October 1, 2009 and December 31, 2010. All patients underwent 64-slice dual-source computed tomography (DSCT) for CAC scoring as well as computed tomography angiography (CTA). Patients with at least one significant coronary stenosis with >50% luminal narrowing were classified as having obstructive CAD. The findings were confirmed using conventional coronary angiography (CAG). Results Among the 478 patients, 157 (33%) had a CAC score of 0 (CAC=0). Of these, 17 (11%) had obstructive CAD confirmed on CAG. The presence of CAC had a negative predictive value for obstructive CAD on CAG of 89% and a sensitivity of 88%, a specificity of 42% and a positive predictive value of 38%. A multivariate logistic regression analysis showed that current smoking habits were significantly associated with the presence of obstructive CAD in patients with CAC=0 after adjusting for traditional cardiovascular risk factors (odds ratio 4.87, 95% confidence interval 1.65-14.42, p=0.004). Conclusion Our findings suggest that CAC=0 on 64-slice DSCT cannot safely exclude obstructive CAD on CAG in asymptomatic patients with type 2 diabetes, particularly in current smokers. CTA should be combined with CAC scoring in screening for CAD in asymptomatic patients with type 2 diabetes.