Significance of Coronary Artery Calcium Measurements

Calcium deposits in the coronary arteries are a highly sensitive marker of underlying coronary atherosclerotic disease. The amount of coronary artery calcium is claimed to reflect the patient's individual coronary artery plaque burden and is considered to be associated with the likelihood of future cardiac events [1-3]. Thus, measurements of coronary artery calcium are generally used for clinical

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Alexander Lembcke, MD

Institut für Radiologie, Charité - Universitätsmedizin Berlin Campus Charité Mitte, Charitéplatz 1 DE-10117 Berlin (Germany)

Tel. +49 30 450 527 082, Fax +49 30 450 527 911, E-Mail [email protected]

risk stratification and individual lifestyle modification [1]. However, a probably more important role of coronary artery calcium measurements may be the evaluation of the response of atherosclerotic plaque burden to medical treatment, for example in patients receiving lipid-lower-ing drugs or in hemodialysis patients receiving phosphate binders.

Especially patients with chronic renal failure suffer from a significantly increased cardiovascular morbidity and mortality due to accelerated atherosclerotic disease [4]. Renal failure patients have more advanced stages of atherosclerosis when compared to patient with normal renal function. Remarkably, type VII lesions according to the Stary classification, i.e. calcified coronary artery plaques, are found significantly more frequently in renal failure patients. However, it has to be noted that the relationship between coronary artery calcification and coronary artery stenosis is complex and that calcification and luminal obstruction are two different features of coronary atherosclerotic disease [5]. Whereas the absence of calcifications in the coronary arteries makes significant stenosis very unlikely [6-9], even advanced atherosclerotic lesions with heavy calcifications do not necessarily cause significant luminal obstruction. Calcium deposits are frequent elements of ruptured plaques causing significant stenosis, but calcium deposits can also be found in stable, non-obstructing plaques [3]. Although the likelihood of an occlusive coronary artery increases with the amount of calcium, there is no one-to-one relationship. Therefore a calcification does not unavoidably predict lu-minal obstruction and the sites of coronary artery calcifications do not correlate with the sites of significant coronary artery stenoses [5, 6, 9], Thus, it remains controversial whether coronary artery calcium scoring is useful for the individual prediction of an adverse coronary event in each individual, for example in a patient with chronic renal failure, an increased calcified coronary artery plaque burden but absence of any other evidence for isch-emic heart disease.

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