Even a small amount of calcified coronary plaque in people under the age of 50 is strongly associated with an increased risk of developing coronary heart disease over the following decade, according to a new study led by a Vanderbilt research team. The study, appearing in this month's issue of JAMA Cardiology, shows that individuals with the highest coronary artery calcium scores had a greater than 20 percent chance of having a fatal heart event in the years to follow.

Coronary plaque — also known as coronary artery calcium (CAC) — is common in patients with coronary heart disease (CHD) and is associated with major adverse cardiovascular events. Most research focuses on CAC and CHD in older populations. To date, there had been a paucity of studies on CDC in people in their 30s and 40s, particularly in younger African-Americans and women.

"We always thought you had to have a certain amount of this plaque before you were at risk of having events. What we showed was that, for younger people, any amount of coronary artery calcium or dramatically and statistically significantly increased risk of clinical heart disease," said lead author Jeffrey Carr, M.D., M.Sc., in a press release issued by Vanderbilt. Carr serves as Cornelius Vanderbilt Chair in Radiology and Radiological Sciences at Vanderbilt.

For this prospective community-based study, researchers used data from the National Heart, Lung and Blood Institute (NHLBI) Coronary Artery Risk Development in Young Adults (CARDIA) Study, in which 5,115 individuals participated from March 25, 1985, to June 7, 1986. Participants were black and white, and aged 18 to 30 years. The study followed the participants for 30 years, using computed tomography (CT) scans to measure CAC at 15, 20 and 25 years after recruitment.

Radiologists typically calculate the CAC score based on the intensity of the calcium signal and location of that signal. Higher CAC scores indicate significant narrowing of a coronary artery. Scores of 11 to 100 indicate mild evidence of CHD while scores of 101 to 400 indicate moderate evidence of coronary heart disease.

"Any measurable CAC in early middle age — scores of less than 100, and even less than 20 — has a 10 percent risk of heart attack or acute myocardial infarction, both fatal and nonfatal, over the next decade beyond standard risk factors," Carr said.

The results of the study suggest CAC is a specific imaging biomarker for identifying patients at risk for heart disease earlier in life, and who may benefit from cholesterol and blood pressure management, smoking cessation, weight reduction and other interventions. While these individuals may not be at risk of suffering a myocardial infarction immediately, they are at high risk over the next decade of life. Early intervention can reduce that risk.

Several institutions participated in the study over the years, including Vanderbilt, the American heart Association, the National Heart, Lung and Blood Institute, Northwestern University Feinberg School of Medicine, and University of Minnesota. Over the duration of the study, researchers performed CT scans on 3,330 subjects for the CAC study and found coronary artery calcium of any amount in 30 percent of those tested.

"The presence of any coronary artery calcification, even the lowest score, was associated with between a 2.6 and tenfold increase in clinical events over the next 12.5 years," Carr said. "And when it comes to those with high CAC scores (100 or above), the incidence of death was 22 percent, or approximately 1 in 5.

"Very few times do you get a biomarker — be it genetic or imaging — that predicts death at a level of 22 percent over 12.5 years."