Progression of Coronary Artery Calcium and CVD Risk
Does progression of coronary artery calcium (CAC) on repeat computed tomography (CT) studies identify patients at risk of cardiovascular events?
This prospective observational study examined 5,933 patients with subsequent CT scans for CAC scores, and evaluated the relationship between progression and adverse cardiac events (cardiac death, myocardial infarction, stroke, or revascularization).
CAC was observed at baseline in 48% of individuals. Mean time between scans was 3.5 ± 2.0 years. After the second CT, 161 individuals experienced an adverse event during a mean follow-up of 7.3 years. CAC progression was associated with adverse events (hazard ratio [HR], 1.14 per interquartile range; 95% confidence interval [CI], 1.01-1.30; p = 0.042) in the model including baseline CAC. However, CAC progression was not associated with adverse events in the model using follow-up CAC instead of baseline CAC (HR, 1.05; 95% CI, 0.92-1.21; p = 0.475).
Progression of CAC is modestly associated with increased adverse events, but does not add to CAC noted on the follow-up study.
Based on these results, the best approach for risk stratification is to use the most recent CAC score in patients with available repeat testing, rather than examining progression of CAC. While follow-up CAC results perform marginally better than baseline results, the magnitude of the difference is small, and probably not clinically meaningful. Although the mean interval between the two CAC scans was relatively short, these results do not suggest a meaningful benefit from repeat testing.
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