Value of Electrocardiographic and Ankle–Brachial Index Abnormalities for Prediction of Coronary Atherosclerosis in Asymptomatic Subjects With Type 2 Diabetes Mellitus

Abstract

Type 2 diabetes mellitus (DM) is associated with increased cardiovascular risk, in part due to accelerated subclinical atherosclerosis. Electrocardiographic (ECG) and ankle-brachial index (ABI) abnormalities are used to screen for cardiovascular risk in the clinic. However, their capacity to identify patients with type 2 DM with nonobstructive subclinical atherosclerosis is unknown. Associations of ECG and ABI abnormalities with coronary artery calcium (CAC), a measure of coronary atherosclerosis, were examined using multivariable ordinal regression modeling in 589 asymptomatic patients with type 2 DM. Sensitivity, specificity, and positive and negative predictive values were determined. CAC was prevalent (44% CAC>00; 32% CAC>5th percentile score) despite normal electrocardiograms (64%) and ABIs (97%) in most subjects. Neither ECG nor ABI changes predicted CAC after adjusting for age, gender, and race. ECG abnormalities were neither sensitive nor specific for detection of CAC>100, >400, or>75th percentile (sensitivities 0.43, 0.45, and 0.34; specificities 0.69, 0.66, and 0.63, respectively). ABI abnormalities were not sensitive (0.03, 0.04, and 0.03) but had high specificity (0.98, 0.98, and 0.98). In subjects with normal electrocardiograms and ABIs, extensive CAC was remarkably prevalent (CAC>00 in 24%). In conclusion, ECG and ABI abnormalities failed to detect patients with subclinical coronary atherosclerosis and therefore may be of limited value in identifying many asymptomatic patients with type 2 DM at increased risk of cardiovascular disease.