Background and Purpose-Established "systemic" vascular risk factors do not fully explain the occurrence of atherosclerosis at the carotid bifurcation. Local anatomic and hemodynamic factors may also influence the initiation of the atherosclerotic process. We determined whether the angle of internal carotid artery (ICA) origin is a risk factor for early atherosclerosis. Methods-In 1300 individuals from a normal population aged 40 to 70 years, we measured both carotid intima-media thickness (IMT) at 3 arterial sites (common carotid artery; carotid bifurcation; ICA bulb) and the presence of any atherosclerotic plaque within the ICA bulb bilaterally by means of high-resolution ultrasound. A standardized transverse insonation was used to determine the angle of ICA origin, expressed as the angle of rotation relative to the external carotid artery. Results-This

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