On this site we have followed with interest the controversy in the medical community surrounding calcium scores, as measured by cardiac CT scanning. (See hereand here). Now, an American Heart Association (AHA) writing group has published a new statement on coronary CT scanning that is substantially different from past statements.
Electron Beam CT, or EBCT scans (formerly called ultrafast CT scans) are useful in detecting the presence of calcium deposits in the lining of the coronary arteries. The presence of calcium deposits is a strong indicator that coronary artery disease is also present. Further, a more advanced type of CT scanning (MDCT, or multislice CT scans) can also detect discrete blockages in coronary arteries with at least a modest degree of accuracy. Until now, professional organizations and the federal government have been reluctant to recommend CT scans for the purposes of screening for coronary artery disease, because data have been lacking to prove their worth (and, more cynically, because widespread screening with CT scanning would be extremely expensive.)
But this month, the AHA writing group recommends, for the first time, CT scans in some individuals for the purpose of detecting calcium deposits in coronary arteries (specifically, to measure Agatston calcium scores). The AHA now recommends calcium scores for people whose risk for clinical coronary artery disease, based on traditional risk factors, is judged to be "intermediate." (You can easily categorize your own risk for coronary artery disease - click here.) A high calcium score in these individuals would tip the scale strongly in favor of aggressive risk factor management, aspirin therapy, and probably high-dose statin therapy.
On the other hand, measuring the calcium score in patients whose risk for coronary artery disease is "low" or "high" would likely not change the need for therapy. If your risk based on traditional risk factors is "low," the odds that you will have a high calcium score is also very low - so there's not much need to spend the money doing the CT test. Those whose risk is already known to be "high" already have a strong indication for aggressive therapy, and measuring the calcium score would not change that indication.
The AHA writing group pointedly did not recommend using CT scanning to look for actual blockages (noninvasive angiography) in the coronary arteries, but only to measure the calcium score. You can read about the pros and cons of non-invasive angiography with multislice CT scans here.
While the recommendations made by the AHA writing group are viewed by many as being overly conservative, they nonetheless represent a major change for the AHA, whose last set of guidelines, issued in 2000, recommended against using this test in virtually anybody. Earlier this year, a more aggressive (or as many would say, progressive) task force recommended a much more liberal application of CT testing for coronary artery disease. As technology improves, and as ongoing clinical trials are completed, it is very likely that the AHA will also continue to liberalize its recommendations for this diagnostic test.
Budoff MJ, Achenbach S, Blumenthal RS, et al. Assessment of coronary artery disease by cardiac computed tomography, a scientific statement from the American Heart Association Committee on Cardiovascular Imaging and Intervention, Council on Cardiovascular Radiology and Intervention, and Committee on Cardiac Imaging, Council on Clinical Cardiology. Circulation 2006; DOI: 10.1161/CIRCULATIONAHA.106.178458. Available at: http://www.circulationaha.org.