Coronary artery disease progression assessed by electron-beam computed tomography

The ability to observe changes in atherosclerotic plaque burden over time s hould provide an accurate measure of efficacy for different cardiovascular therapies. Electron-beam computed tomography (EBCT), by quantification of c oronary artery calcification, is a noninvasive measure of atherosclerosis b urden. This article summarizes data from abstracts and publications related to coronary artery calcium measurement and its use in progression studies. The issues related to interscan variability and reproducibility of this me asure are detailed. The limitations of multidetector spiral computed tomogr aphy (high radiation dose and poor reproducibility) are also addressed. Sev eral studies of progression using 2 scans, administered greater than or equ al to1 year apart, demonstrate significant annual progression (22% to 52% p er year). All studies demonstrate that therapy with cholesterol-lowering ag ents slows the atherosclerotic process, and that it may lead to regression of coronary calcium over time. There are 2 small prognostic studies that de monstrate that coronary events predominantly occur in those patients who ex hibit significant progression of coronary artery calcium. Large multicenter trials are underway to evaluate the prognostic significance of coronary ar tery calcium progression. The progression of coronary artery atherosclerosi s can be observed noninvasively by monitoring the progression of coronary c alcification with EBCT. With annual progression rates of 22% to 52% and a m edian interscan variability of only 5% to 8%, this technology provides an o pportunity to noninvasively monitor patients to assess the clinical efficac y of medical therapies in studies as short as 1 year. (C) 2001 by Excerpts Medico, Inc.