[Value of coronary artery calcium measurements in primary prevention]

Frequently, myocardial infarction or sudden coronary death are the index manifestations of coronary artery disease. In view of the high out-of-hospital mortality of acute myocardial infarction, medical care is unable to provide a benefit for many patients. Against this background, it is an important aim of measuring coronary calcium to identify asymptomatic subjects with an increased coronary risk who are likely to derive a benefit from risk-modifying therapy. Coronary calcium is a largely specific expression of coronary atherosclerosis and is correlated with overall coronary plaque volume. Due to the complex biology of the vessel wall and its ability to undergo compensatory remodelling, coronary calcium does not necessarily indicate significant stenosis. Coronary calcium is found in 70-80% of plaque ruptures but only in a minority of plaque erosions. It neither indicates a "vulnerable" nor a "stable" plaque. Six independent studies including healthy self-referred and physician-referred volunteers consistently describe the predictive value of coronary calcium with regard to coronary and cardiovascular clinical events. After adjusting for coronary risk factors, increased amounts of coronary calcium are associated with a 5- to 10-times elevated relative risk. Only recently have the first results from strictly unselected, population-based cohorts been reported which confirm the predictive ability of coronary calcium measurements. Concordant with actual guidelines issued by US-American and European expert panels, coronary calcium measurements can be used especially in patients with an indeterminate risk on the basis of clinical assessment and risk factor analysis. Substantially elevated coronary calcium scores provide a rationale for intensified risk-modifying therapy. This is also true for elderly patients in whom the established risk factors lose some of their predictive power. The use of coronary calcium measurements in self-referred patients or as a primary means for risk stratification is not encouraged.