BACKGROUND In patients with severe degenerative aortic stenosis (DAS) the operative mortality risk is 3% for isolated aortic valve replacement (AVR), but it significantly increases in patients with concomitant coronary artery disease (CAD) and internal carotid artery stenosis (ICAS). OBJECTIVE To assess the frequency of ICAS > or = 50% and factors determining its occurrence in patients with severe calcified DAS referred for AVR. METHODS The study included 104 patients (67 men), aged 63.4+/-8.4 years, with symptomatic moderate-to-severe DAS (aortic valve area <1.5 cm2) undergoing coronary angiography prior to valve surgery. In all patients Doppler ultrasound of carotid arteries was performed with the assessment of lumen stenosis. RESULTS Significant CAD, defined as at least one lumen reduction > or = 50% in a main coronary artery, was found in 44 (42.3%) patients and ICAS > or = 50% in 13 (12.5%) patients. Among patients with DAS, 12 (27.3%) out of 44 patients with significant CAD and 1 (1.7%) out of 60 patients without CAD had ICAS > or = 50% (p <0.001). The frequency of ICAS > or = 50% increased with advancing CAD, occurring in 4 (25%) out of 16 patients with 1-vessel CAD, 3 (25%) out of 12 with 2-vessel CAD and (31.3%) out of 16 patients with 3-vessel CAD (p <0.001). The independent ICAS predictors by multivariate regression analysis were identified as: concomitant CAD (p <0.001), diabetes (p=0.054), cigarette smoking (p=0.08) and decreased left ventricular ejection fraction (p=0.039). ICAS > or = 50% was found to be an independent predictor of CAD (p=0.002). CONCLUSIONS ICAS > or = 50% occurs in 13% of patients with isolated DAS and in 27% of those with DAS and CAD. Independent ICAS risk factors were identified as CAD, diabetes and cigarette smoking. Duplex ultrasound of carotid arteries should be considered in patients with DAS and concomitant CAD prior to AVR.