Carotid Artery Disease
- Atherosclerosis (plaque build-up) is a systemic disease that is responsible for most cardiovascular disease (CVD) events such as heart attack, stroke, and sudden cardiac death. Two out of three sudden deaths occur in people who have not been diagnosed with heart disease.1
- Narrowing of the carotid arteries from plaque buildup is a strong predictor of stroke similar to the mechanism occurring in the coronary arteries.
- Epidemiologic studies and intervention trials based on the incidence of acute CVD end points require years of follow-up, the participation of large populations, or both. As a consequence, such studies consume considerable time and financial resources. The use of surrogate markers, therefore, is of paramount relevance because it allows researchers to have reliable data in less time and from smaller number of subjects.2 Carotid Intima-media thickness (CIMT) measured by B-mode ultrasound is a well studied surrogate marker and has been validated by several expert bodies.2
- Large observational studies and atherosclerosis regression trials of lipid-modifying pharmacotherapy have established that intima-media thickness of the carotid and femoral arteries, as measured noninvasively by B-mode ultrasound, is a valid surrogate marker for the progression of atherosclerotic disease. To exploit fully the potential of ultrasound imaging in atherosclerosis research, standardized and strictly implemented imaging protocols are used in research studies.
- CIMT studies have clearly documented the dramatic differences in atherosclerosis progression from childhood into old age in subjects with familial hypercholesterolemia (genetically elevated cholesterol levels) compared with healthy controls.3
- CIMT increase is associated with a raised risk of heart attack and stroke.4 However, regression or slowed progression of CIMT, induced by cardiovascular drug therapies, do not reflect reduction in cardiovascular events.5 Accordingly, CIMT changes do not reflect the benefit of therapies with proven beneficial effects on CVD risk profile.
- Despite all the theoretical advantages, CIMT is not ready for prime time in clinical practice and remains in the research arena.
Sources
1. Enas EA, Thomas I. Immigrant Indian Males – Sitting Ducks for Heart Attacks; A Cause for Alarm – And Call for Action. J Am Assoc Phys India 1990;2:5-8.
2. Coll B, Feinstein SB. Carotid intima-media thickness measurements: techniques and clinical relevance. Curr Atheroscler Rep. Oct 2008;10(5):444-450.
3. de Groot E, Hovingh GK, Wiegman A, et al. Measurement of arterial wall thickness as a surrogate marker for atherosclerosis. Circulation. Jun 15 2004;109(23 Suppl 1):III33-38.
4. Lorenz MW, Markus HS, Bots ML, Rosvall M, Sitzer M. Prediction of clinical cardiovascular events with carotid intima-media thickness: a systematic review and meta-analysis. Circulation. Jan 30 2007;115(4):459-467.
5. Costanzo P, Perrone-Filardi P, Vassallo E, et al. Does carotid intima-media thickness regression predict reduction of cardiovascular events? A meta-analysis of 41 randomized trials. J Am Coll Cardiol. Dec 7 2010;56(24):2006-2020.