Coronary Calcium and Regular CT Scans Predict Mortality
Are coronary artery calcium (CAC) scores on 3 mm electrocardiography (ECG)-gated computed tomography (CT) scans and standard 6 mm chest CT scans correlated and similarly associated with risk of death?
This was a nested case-control study design with 1:3 matching in age and sex. Community-dwelling participants were recruited through one imaging clinic in San Diego, CA, and received “whole-body” CT scans between 2000 and 2003. CT scans were completed as 3 mm ECG-gated CTs or standard 6 mm chest CTs. The Agatston method quantified CAC on both scan types. The primary outcome of interest was mortality, which was collected through 2009.
A total of 4,544 adults were included in this analysis. Participants were a mean age of 68 years and 63% were male. A total of 157 deaths (cases) were matched with 494 controls. Cases and controls had similar body mass index, total cholesterol, high-density lipoprotein cholesterol, and use of lipid-lowering medications. However, a greater proportion of cases had diabetes and hypertension, were former or current smokers, and had a family history of cardiovascular disease (CVD) compared to controls. The Spearman correlation of CAC scores between the two scan types was 0.93 (p < 0.001); median CAC scores were lower on 6 mm CTs compared to 3 mm CTs (22 vs.104 Agatston units, p < 0.001). After adjusting for traditional CVD risk factors, each standard deviation higher CAC score on 6 mm CTs was associated with 50% higher odds of death (odds ratio, 1.5; 95% confidence interval, 1.2-1.9), similar to 50% higher odds on the 3 mm ECG-gated CTs (odds ratio, 1.5; 95% confidence interval, 1.1-1.9).
The investigators concluded that CAC scores on standard 6 mm chest CTs are strongly correlated with 3 mm ECG-gated CTs and similarly predict mortality in community-living individuals. Chest CTs performed for other clinical indications may provide an untapped resource to garner CVD risk information without additional radiation exposure or expense.
It makes sense that information already collected should be provided to the patient. CAC data from any type of CT scan can provide information that may change CVD prevention management. Further study including cost analysis is warranted.
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