Coronary Calcium CT Scan May Predict Premature Death Risk

A coronary artery calcification (CAC) CT scan may be useful in identifying patients at risk for early death as long as 15 years from the time of the scan, according to recent research.

Although CAC scores are primarily used to estimate cardiovascular prognosis and all-cause mortality in the short term, authors of a recent study published in the Annals of Internal Medicine determined that CAC scores are highly predictive of long-term mortality in patients without symptoms of coronary artery disease.

“CAC scores markedly improve prediction of all cardiac and cerebrovascular events and all-cause mortality endpoints by as much as 65 percent over other risk factors including age and other biomarkers,” said Leslee Shaw, Ph.D., lead author and a professor of cardiology at Emory University School of Medicine, Atlanta. “These findings give us a better understanding of the importance of coronary calcium scans to predict mortality.”

Researchers conducted a statistical analysis of nearly 10,000 patients who underwent CAC imaging as part of an outreach screening program in the Nashville area. Physicians collected data on 9,715 patients from 1996 to 1999 at an outpatient clinic. All patients received CAC imaging using multi-slice CT or electron beam tomography.

Although these patients did not have symptoms of coronary artery disease, a detailed history of cardiac risk factors was collected at the time of screening. Out of the sample, deaths of 936 patients were confirmed through the National Death Index.

The study’s 15-year outlook is important because it determined that health risks accelerate disproportionately for patients with CAC. The incident mortality curves revealed very low mortality rates through five years, but mortality increased substantively between 5 and 15 years for the same patients.

Previous studies have determined that patients with CAC scores between 300 and 400 have a 4 percent to 9 percent mortality rate after five years. Looking at patients with a similar CAC score, however, Dr. Shaw and colleagues determined a 15-year all-cause mortality rate of more than 20 percent. Figures such as these, according to the study, reflect a “progressive disease and perhaps nonlinear risk that may only be found through lengthier follow-up.”

“Long-term estimates of mortality provide a unique opportunity to examine the value of novel biomarkers, such as CAC, in estimating important patient outcomes,” Dr. Shaw said. “The current findings support effective long-term—that is, approximately 15-years—mortality stratification and risk reclassification based on CAC measurements.”

Dr. Shaw thinks calcium scans ultimately could become part of a person’s regular physical exam, as common as blood cholesterol tests.

“I think it’s headed that way,” she said. “We’re kind of on the edge of this becoming more accepted.”