Intima-media thickness: indicator of cardiovascular risk and measure of the extent of atherosclerosis

The measurement of intima-media thickness (IMT) of large superficial arteries, especially the carotid, using high-resolution B-mode ultrasonography has emerged as one of the methods of choice for determining the anatomic extent of atherosclerosis and for assessing cardiovascular risk. IMT measurement obtained by ultrasonography correlates very well with pathohistologic measurements and the reproducibility of this technique is good. Population studies have shown a strong correlation between carotid IMT and several cardiovascular risk factors, and it has also been found to be associated with the extent of atherosclerosis and end-organ damage of high-risk patients. Therefore, increased carotid IMT is a measure of athero-sclerotic burden and a predictor of subsequent events. Because of its quantitative value, carotid IMT measurement is more and more frequently used in clinical trials to test the effects of different preventive measures, including drugs. More recently, there has been interest in the clinical use of this technique for detecting preclinical (asymptomatic) atherosclerosis and for identifying subjects at high risk. Measurement of carotid IMT could influence a clinician to intervene with medication and to use more aggressive treatment of risk factors in primary prevention, and in patients with atherosclerotic disease in whom there is evidence of progression and extension of atherosclerotic disease. For more extensive use of this method in clinical practice a consensus concerning the standardization of methods of measurement and precise definition of threshold between normal and pathologic IMT value is urgently needed.