Amount and Distribution of CAC in Predicting CV Events
Does information on number of coronary arteries and amount of coronary artery calcium (CAC) add value to the traditional Agatston CAC score in predicting cardiovascular (CV) events?
Data from the MESA (Multi-Ethnic Study of Atherosclerosis) were used for the present analysis. Participants with a baseline CAC score >0 were included. Multivessel CAC was defined as the number of coronary vessels with a CAC score >0 (scored 1-4). The “diffusivity index” was calculated as: 1 - (CAC in most affected vessel/total CAC), and was used to group participants into concentrated and diffuse CAC patterns.
A total of 3,262 adults (mean age 66 years, 42% women) with baseline CAC >0 were included. Median follow-up was 10.0 (9.5-10.7) years, during which time 368 coronary heart disease (CHD) and 493 cardiovascular disease (CVD) events occurred. Addition of number of vessels with CAC significantly improved capacity to predict CHD and CVD events (hazard ratio [HR], 1.9-3.5 for four-vessel vs. one-vessel CAC). The area under the curve analysis (C-statistic improvement, 0.01-0.033) was improved, as was net reclassification improvement (category-less net reclassification improvement, 0.10-0.45). A diffuse CAC pattern was associated with worse outcomes in participants with ≥2 vessels with CAC (HR, 1.33-1.41; p < 0.05); however, adding this variable to the Agatston CAC score and number of vessels with CAC did not further improve global risk prediction.
The investigators concluded that the number of coronary arteries with calcified plaque, indicating increasingly “diffuse” multivessel subclinical atherosclerosis, adds significantly to the traditional Agatston CAC score for the prediction of CHD and CVD events.
These simple calculations may add predictive value in terms of identifying patients at increased risk; however, whether this will change clinical management resulting in lowering of CHD and CVD events remains to be determined.
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