Study Points to Ideal Age for CAC Testing in Young Adults

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fairly difficult
Although a robust predictor of atherosclerotic cardiovascular disease, few data are available on coronary artery calcium (CAC) testing in younger adults, for whom the CAC burden is typically lower.
New risk equations can help determine the need for a first coronary artery calcium (CAC) scan in young adults to identify those most at risk for premature atherosclerosis, researchers say.

"To our knowledge this is the first time to derive a clinical risk equation for the initial conversion from CAC 0, which can be used actually to guide the timing of CAC testing in young adults," Omar Dzaye, MD, MPH, PhD, Johns Hopkins University School of Medicine, Baltimore, said in an interview.

CAC is an independent predictor of adverse atherosclerotic cardiovascular disease (ASCVD) but routine screening is not recommended in low-risk groups. US guidelines say CAC testing may be considered (class IIa) for risk stratification in adults 40 to 75 years at intermediate risk (estimated 10-year ASCVD risk 7.5% to 20%) when the decision to start preventive therapies is unclear.

The new sex-specific risk equations were derived from 22,346 adults 30 to 50 years of age who underwent CAC testing between 1991 and 2010 for ASCVD risk prediction at four high-volume centers in the CAC Consortium. The average age was 43.5 years, 25% were women, and 12.3% were non-White.

The participants were free of clinical ASCVD or CV symptoms at the time of scanning, but had underlying traditional ASCVD risk factors (dyslipidemia in 49.6%, hypertension in 20.0%, active smokers 11.0%, and diabetes in 4.0%), an intermediate 10-year ASCVD risk (2.6%), and/or a significant family history of CHD (49.3%).

As reported in the Journal of the American College of Cardiology, 92.7% of participants had a low 10-year ASCVD risk below 5%, but 34.4% had CAC scores above 0 (median, 20 Agatston units).

Assuming a 25% testing yield (number needed to scan equals four to detect one CAC score above 0), the optimal age for a first scan in young men without risk factors was 42.3 years, and for women it was 57.6 years.

Young adults with one or more risk factors, however, would convert to CAC above 0 at least 3.3 years…
Patrice Wendling
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