Atlanta, GA - The use of coronary artery calcium (CAC) screening is an effective risk-stratification tool in elderly patients, according to the results of a new study [1]. Investigators showed that CAC scoring discriminates mortality risk in these older patients, despite their advanced age and reduced life expectancy, allowing a reclassification of patient risk based on the calcium score.

"The use of coronary artery calcium scoring is an effective risk-stratification tool in the elderly as well as young patients, rendering CAC of potential utility even in high-risk patients such as those with diabetes, those with renal failure, smokers, and now the elderly," Dr Paolo Raggi (Emory University School of Medicine, Atlanta, GA) told heartwire. "This study closes the loop around the high-risk patients."

The findings are published in the June 24, 2008 issue of the Journal of the American College of Cardiology.

Current risk-estimation tools are heavily influenced by age as a surrogate marker of atherosclerosis burden, said Raggi, but despite atherosclerosis progressing with advancing age, substantial heterogeneity exists among adults of the same age. "It's a long-held belief that calcium accumulation in the arteries is an age-related phenomenon," he said. "This is true, but it's a gross oversimplification. It's like saying all diabetic patients are the same. We know that's not the case."

If plaque burden assessed by CAC were shown to be an accurate estimate of risk in older subjects, coronary calcium screening could be substituted for age in risk calculations. To estimate the clinical utility of CAC in older patients, Raggi and colleagues included 35 388 asymptomatic patients referred by primary-care physicians for CAC screening with electron-beam tomography. Of these patients, 3570 were older than 70 years of age at the time of screening. Patients were followed for 5.8 years after CAC screening, with the occurrence of all-cause mortality the primary measurement in the six age categories.

Investigators report that cumulative survival for CAC subsets varied with age. In men, a CAC score from 0 to 10 was associated with risk-adjusted survival rates of 99.8% to 96.8% for those younger than 40 years old and those older than 80 years old, respectively, at 5.8-year follow-up. In contrast, survival rates among those younger than 40 and older than 80 years were 88.0% and 19.0%, respectively, for those with CAC scores >400. Similar trends among the CAC subsets were observed for women.

Raggi told heartwire that having a lot of calcium is bad for everybody regardless of age and that having little, no matter how old the patient, is beneficial. He pointed out there were a sizable number of elderly patients who had little to no calcium accumulation and that these could be reclassified as lower-risk subjects.

Investigators also reclassified the risk of patients based on a CAC score >400, with 14.1% of women younger than 40 years of age and 43.1% of those 80 years of age and older reclassified. Among men younger than 40 years, 9.0% were reclassified, whereas 30.8% of subjects 80 years of age and older were reclassified. Approximately one-third of the oldest women and men—those 80 years of age and older—were reclassified as lower risk and slightly more than two-thirds were reclassified to a higher-risk group. Among men and women 60 to 69 years of age, approximately 25% were reclassified based on their CAC score.

"Coronary calcium screening basically allows us to rebalance or recalibrate our risk-assessment tools," said Raggi. The use of CAC screening in the elderly, he said, could possibly allow the implementation of new risk-scoring methods, where the burden of atherosclerosis is substituted for age.