Coronary Calcium and Risk Among Young Adults
Does coronary artery calcium (CAC) improve cardiovascular risk classification among younger adults?
Data from the Dallas Heart Study were used for the present analysis. The Dallas Heart Study is a multi-ethnic probability-based population sample (with oversampling of African-Americans), of patients ages 30-65 years at time of enrollment (between 2000 and 2002). Participants with uninterpretable CAC scans, cardiovascular disease, and/or diabetes at baseline were excluded from the present analysis. The primary outcome of interest was incident coronary heart disease (CHD) including CHD death, myocardial infarction, and coronary revascularization over a median follow-up of 9.2 years (through 2010). Participants were grouped by 10-year risk categories (<6%, 6 to <20%, and ≥30%). In addition, a meta-analysis of studies, published through December 2014, was conducted; identifying results that assessed the addition of CAC to models which comprised traditional CHD risk factors and reported net reclassification improvement.
A total of 2,084 participants (mean age 44.4 ± 9.0 years, 56.2% women, and 45.9% African American) were included in the analysis. Most participants had CAC scores of <10 with increasing age associated with higher CAC scores and more traditional risk factors. CAC was significantly associated with incident CHD during follow-up (hazard ratio per standard deviation of 1.90 [95% confidence interval, 1.51-2.38]). The addition of CAC to a model with traditional risk factors significantly improved the C-statistic for the prediction model (delta = 0.03, p = 0.003). Among participants with CHD events during follow-up, the addition of CAC to models upwardly reclassified 21% of participants. Among those participants without CHD during follow-up, CAC corrected downward 0.5%. Results remained significant when the outcomes were restricted to CHD death and myocardial infarctions. The net reclassification improvement observed in the Dallas Heart Study was similar to that observed in the pooled estimated of prior studies.
The authors concluded that CAC scoring improves CHD risk classification in younger adults.
These data suggest that CAC can identify adults ages <65 years who may be at higher risk for CHD events. It is likely that more aggressive risk factor management, such as initiation of statin therapy among such adults, would translate into lower CHD risk. Further study is warranted to address this question.
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