As an internist, individuals frequently ask me to help weigh their risk of cardiovascular disease. I use traditional risk factors for cardiovascular disease such as elevated LDL, tobacco use and hypertension, which have been well described, and recommendations to lower risk, which have been summarized in the recent ATP-III guidelines. However, there is wide individual variation of the burden of atherosclerotic disease present in individuals with each risk factor. Undoubtedly, there are many other atherogenic and protective factors, which may someday be discovered and incorporated into the Framingham risk model. Emerging risk factors such as C-reactive protein, homocysteine, microalbuminuria, and protective factors such as ApoA1 Milano and physical exercise would ideally be incorporated to allow a more accurate risk prediction. Therefore, there is a theoretical appeal for a non-invasive, inexpensive test that could reflect the final common balance of both atherogenic and protective factors well, prior to the development of symptomatic disease. Carotid intima-medial thickness (CIMT) has the potential to do just this.
Therefore, there is a theoretical appeal for a non-invasive, inexpensive test that could reflect the final common balance of both atherogenic and protective factors well prior to the development of symptomatic disease. Carotid intima-medial thickness has the potential to do just this.
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| Extensive scientific research conducted in the United States, Europe and Asia over the last twenty years has demonstrated the importance of carotid artery wall thickness in the evaluation of cardiovascular disease risk and prevention strategies. |
The carotid arteries are easily visualized with high resolution using B-mode ultrasonography (see figure). With age, the inner layers of the carotid artery, the intima and the media, thicken as a precursor to atherosclerotic plaque formation. Some heritable factors, such as familial hypercholesterolemia, accelerate the thickening. Persons with familial hypercholesterolemia reach an IMT of 0.8mm by age 40, whereas healthy controls do not reach this level of thickness until age 80. This parallels the dramatically earlier age of first myocardial infarction in familial hypercholesterolemia.Other traditional, well described risk factors such as smoking, abdominal obesity, hypertension, and diabetes cause premature thickening.
