Even Low Coronary Calcium Scores in Young Adults Predict CHD Risk: CARDIA

Larry Hand

February 15, 2017

NASHVILLE, TN — The presence of any coronary artery calcium (CAC), even at low levels, in individuals 32 to 45 years old predicts coronary heart disease (CHD) events and all-cause mortality later in life, suggests new research[1].

"Even if you have very small amounts of coronary calcium, or what I would call premature coronary atherosclerosis, individuals are at a very high risk of clinical events and cardiovascular death over the next 10 to 15 years," first author Dr John Jeffrey Carr (Vanderbilt University) told heartwire from Medscape.

In an editorial accompanying the report from Carr and associates[2], Dr Ron Blankstein (Brigham and Women's Hospital, Boston, MA) and Dr Philip Greenland (Northwestern University Feinberg School of Medicine, Chicago, IL) write, "The results . . . raise the question of whether there may be a role for screening individuals younger than 45 years with computed tomographic scanning for CAC."

Carr and colleagues analyzed data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, in which researchers enrolled 5115 black and white men and women 18 to 30 years old between March 1985 and June 1986 in four US cities. During the study, researchers conducted examinations of surviving participants at years 15 (2000–2001), 20 (2005–2006), and 25 (2010–2011).

Researchers measured CAC using noncontrast computed tomography (CT) in a cohort of 3980 participants who underwent imaging, comparing them with 1135 who did not undergo imaging. They followed up for a median of 12.5 years, from the year 15 scan until the end of August 2014, according to their article, published online February 8, 2017 in JAMA Cardiology.

They developed a CAC score model "based on participant age, race/ethnicity, sex, educational level, field center, smoking status, LDL cholesterol, body-mass index, systolic BP, presence of diabetes, and use of medication(s) for BP and lipid control," the researchers write.

Carr and colleagues modeled participants' risk factors in their 30s and were able to predict with reasonable accuracy who would develop CHD over over the next 10 to 15 years, he said.

Researchers measured CAC scores in 3043 participants at year 15, 3141 at year 20, and 3189 at year 25. Mean patient ages were 40.3, 45.3, and 50.1, respectively.

The researchers found, overall, the 10-year incidence of CAC between years 15 and 25 to be 488 of 2209 (22.1%) participants. They found the prevalence of CAC to be 10.2% (309 of 3043) at year 15, 20.1% (631 of 3141) at year 20, and 28.4% (907 of 3189) at year 25.

The researchers found the adjusted hazard ratio (HR) to be 5.0 (95% CI 2.8–8.7, P<0.001) for CHD, compared with participants with no CAC. They found that the incidence density was:

  • 4.8 events per 100 persons with a CAC score of 1 to 19 (HR 2.6, 95% CI 1.0–5.7; P=0.03).

  • 10.6 events per 100 persons with a CAC score of 20 to 99 (HR 5.8, 95% CI 2.6–12.1; P<0.001).

  • 26.1 events per 100 persons with a CAC score of 100 or higher (HR 9.8, 95% CI 4.5–20.5; P<0.001).

They also found that presence of any CAC carried an incidence density of 8.1 all-cause deaths per 100 people during follow-up (HR 1.6, 95% CI 1.0–2.6; P=0.05), but the incidence density increased to 22.4 deaths in individuals with CAC scores of 100 or higher (HR 3.7, 95% CI, 1.5–10.0; P<0.001).

"What this paper adds is that in those people who may be at elevated risk, coronary calcium is a very specific biomarker of identifying people who are anywhere from a 10% to 25% 10- to 15-year risk of having a clinical event," Carr told heartwire.

Carr said he and his colleagues are not recommending that all young adults go out and get a CT scan.

"Many people get CT scans for other causes," he said, and those scans could be checked for CAC levels.

"If, say, a young 25-year-old woman has coronary artery calcification, that should be identified as a biomarker risk, and we should advise her and her providers of this elevated risk and then they can do a risk-factor assessment and decide what steps may be taken to lower her risk," he said.

"Currently we will use traditional risk factors to calculate one of several scores, such as the Framingham risk score or the pooled cohort risk equation, where we predict an individual's 10-year risk of heart disease," he said. "Current strategy, based on the amount of elevated risk, is to increase the intensity of our prevention activities. We should match what prevention we do based on the individual's personalized risks," he said.

"Unfortunately," he added, "for these risk models, just like coronary calcium, we have no randomized controlled trial showing that measuring someone's risk and tying that to a treatment reduces events."

Current guidelines include screening for CAC as an option for people in whom risk is uncertain, with threshold CAC scores of 100, 300, and 400.

"However," the researchers write, "in light of our findings, these recommendations might be reconsidered in favor of lower thresholds in middle-aged and younger adults."

The National Heart, Lung, and Blood Institute supported this research. The authors reported no relevant financial relationships.

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