In a recently published article in JAMA Cardiology, Dr John Carr from Vanderbilt University Medical Center and coauthors evaluated data from the Coronary Artery Risk Development in Young Adults study also known as CARDIA1.
The study examined whether the presence of coronary artery calcium (CAC) in younger individuals, as evaluated by a non-contrast computed tomography scan (CT), was associated with an increased risk for developing clinically significant coronary heart disease.
For the study, 5115 participants — ages 18 through 30 — were recruited between March 1985 and June 1986, and baseline demographics and cardiovascular risk factors were collected. Their CAC scores were measured using standard non-contrast CT scan at years 15 and 20 of the study, when the participants were age 32 to 46.2
The researchers found that those who had any measurable CAC — any score above zero — had a 5 times greater risk for having a fatal or nonfatal coronary event than those with no coronary calcium. Further, after breaking CAC scores into groups, they found that risk of a coronary event for participants with a CAC score between 1 and 19 was 2.6 times higher than for those with CAC scores of zero. Participants with CAC scores of 100 or more had a 3.7-fold increase in all-cause mortality.2
These results are very different from prior studies, which have found that elevated risk for adverse cardiovascular events is associated only with CAC scores greater than 100. Individuals with scores less than 100 have traditionally been considered to be at low cardiovascular risk.
However, Carr, et al. argue that exponential increases in CAC burden occurs at a younger age than previously thought — as early as age 32 and 56 — and that those individuals with high CAC are at higher risk for poor outcomes, despite the fact that their CAC scores are reasonably low and irrespective of their Framingham risk.2
What does this mean for future practice?
For starters, we already know that we need to do a better job of identifying younger patients who are at high risk for developing coronary artery disease. Unfortunately, for patients younger than age 40, few tools are available. Framingham risk and other more modern risk scores are based on traditional risk factors that are not as good at predicting future morbidity or mortality in younger patient populations. CAC may be a better way of assessing that risk for these younger patients.