Atherosclerosis had become one of the leading causes of death in the world.1 It has three main manifestations which involve coronary, cerebrovascular and peripheral arteries. Many studies had shown the association between these artery diseases, including the cerebrovascular disease, peripheral artery disease (PAD) and coronary artery disease (CAD).2 The association between the PAD, high risk cardiovascular events and death also has been proven.3 However, most patients with PAD were underdiagnosed because the asymptomatic clinical presentation and the physician’s awareness of the disease are relatively low.4

The ankle-brachial index (ABI), as a noninvasive and simple modality, has high sensitivity and specificity for PAD diagnosis. ABI is not only useful as a diagnostic tool, but also is a powerful indicator of atherosclerotic disease in other vascular bed and prognostic modality (increased cardiovascular morbidity / mortality with low ABI).5,6Several studies have demonstrated that patients with PAD are at increased risk of adverse cardiovascular events compared to those individuals without PAD. Consequently, there is increasing interest in ABI as a non-invasive tool capable of identifying subclinical atherosclerosis, including coronary artery disease (CAD).7,8 The use of ABI in peripheral arterial disease (PAD) is well established. As the same pathogenesis primarily involves coronary vasculature, ABI (≤0.9or<0.9) can also be used a predictor of cardiovascular events and death.9‒11 Abnormal ABIs, both low (<1.0) and a high (≥1.40) are associated with elevated risk of cardiovascular disease.12

It’s well-known that increased CIMT is a diagnostic tool in patients with stroke. CIMT is also increased in subjects with CAD.13‒15 The cut-off value of CIMT varies depending on the age16,17 and ethnicity. 18 Carotid intima-media thickness (IMT) may be measured by ultrasound, where the distance between a double- line reflex pattern representing the luminal-intimal and the medial-adventitial interfaces corresponds well with IMT measured in histological specimens.19 Thickening of the artery wall is a hallmark of atherosclerosis. It has thus been theorized that IMT measurements could aid in the prediction of cardiovascular disease (CVD) and thereby improve CVD prediction by traditional risk factors alone. However, recommendations regarding the use of carotid IMT for CVD risk prediction are conflicting.20

In this study, we compared and examined the potential efficacy of the combination of carotid US finding and ABI in predicting severity of coronary artery disease.