Coronary artery calcium progression: an important clinical measurement? A review of published reports.
Baseline CAC accurately identifies coronary atherosclerosis and improves prediction of future cardiac events. However, whether knowledge of progression of CAC scores over time further improves risk prediction is unclear. We conducted a comprehensive review of published reports on CAC progression and found that CAC progression correlates with worsening atherosclerosis and may facilitate prediction of future cardiac events. These findings support the notion that slowing CAC progression with therapeutic interventions might provide prognostic benefit. However, despite promising early data, such interventions (most notably with statin therapy) have not been shown to slow the progression of CAC in any randomized controlled trial to date, outside of post hoc subgroup analyses. Thus, routine quantification of CAC progression cannot currently be recommended in clinical practice.
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Journal of the American College of Cardiology
- Year: 2010
Cholesterol / Lipids / Statins,
Cardiovascular Risk Assessment
- Read more articles by:
Roger S. Blumenthal, MD,
Michael Blaha, MD, MPH,
Khurram Nasir, MD, MPH,
J. Bill McEvoy, MB BCh, MHS,
Steven Jones, MD
Coronary artery calcium score and cardiovascular event prediction.
In the study by Polonsky et al, the net reclassification index (NRI) for CHD (myocardial infarction, cardiac death, resuscitated arrest, and definite angina) was +25% overall. However, 24 of 209 patients who experienced events (11%) were reclassified to a lower risk group by calcium scoring. As the authors point out, a randomized controlled trial is needed to assess the use of coronary artery calcium score (CACS) reclassification on clinical outcomes. This current study is a compelling argument to provide support for such an endeavor.
Caveat emptor: the coronary calcium warranty.
It would be beneficial for clinicians to have the “warranty period” of a zero coronary calcium score stratified by baseline risk group (<10% and 10% to 20%). It may even be prudent to stratify further, as some have advocated for CAC testing in an expanded intermediate-risk group of 6% to 20% (e.g., <6%, 6% to 10%, and 10% to 20%). The investigators may have been overly prudent to suggest that “caution should be applied to interpreting our results among patients who are not receiving lipid-lowering therapy.” Although they express concern that the 756 patients on statin therapy (72%) may have had retarded CAC progression, randomized trials to date have not shown that statin therapy can achieve this. CAC = 0 has enormous potential for ruling out important coronary artery disease in asymptomatic patients. The duration and application of the “warranty period” remains an important topic for further research.
What is the prognostic value of a zero calcium score? Ask Bayes!
The role of calcium scoring (CS), if any, appears to be in the reclassification of asymptomatic patients at intermediate risk for CAD by traditional risk factor models. This has led to a Class IIb recommendation by the American Heart Association for the use of CS in these patients. Further research is ongoing to study the effect of such reclassification.