Even among relatively young and healthy men, CT scans that detect calcium deposits in heart arteries can help predict the risk of coronary heart disease, according to a new study in the Sept. 6, 2005, issue of the Journal of the American College of Cardiology.
"Over and above standard risk factors, the presence of coronary calcium portended a roughly 11-fold risk of developing heart disease in the following three years. And these were individuals that didn't have a lot of risk factors and were relatively young: men in their mid-40s, at a time when people are at the prime of their work and family lives," said Allen J. Taylor, M.D., F.A.C.C., at Walter Reed Army Medical Center in Washington, D.C., and the Uniformed Services University of the Health Sciences in Bethesda, Md.
The researchers studied Army personnel, 40 to 50 years old, who were undergoing routine physical examinations. Out of an eligible pool of 2,259 individuals free of known heart disease, 1,627 men and 356 women underwent coronary CT scans and were followed for an average of three years.
During the follow-up period there were only nine heart disease events (heart attack, unstable angina or death due to coronary heart disease) in the study population, but seven of the events were among the 364 men whose CT scans detected coronary calcium. Only two events occurred among the larger group of 1,263 men without detectable calcium deposits. There were no events among the women in the study.
The results indicate that the men with calcium deposits were 11.8 times as likely to suffer an event as men without calcium deposits. In absolute terms, just under 2 percent of the men with calcium deposits suffered a cardiac event within the three year average follow-up, compared to less than two-tenths of a percent of the men without deposits.
Dr. Taylor said that even though these results show that coronary calcium scans can predict risk among men who were younger and healthier than those included in earlier studies, more study is needed before recommending such scans for all healthy, middle-aged people.
"Although it appeared that screening would be relatively cost-effective in the analysis that we did, I think at this time you have to stop short of recommending screening in all asymptomatic individuals, because it is not shown that such a strategy could actually prevent adverse outcomes," Dr. Taylor said.
He emphasized that in order for screening scans to be useful, they would have to be coupled with follow-up treatments and lifestyle changes that could effectively prevent cardiac events. He added that researchers should focus on identifying individuals who might get the most benefit from coronary calcium scans, rather than recommending scans for everyone. Those candidates for screening might include people who are left in a gray area, neither high-risk nor low-risk, based on current risk factor calculations, he said. Dr. Taylor also noted that a family history of heart disease appeared to be associated with both coronary calcium and heart disease events in this study.
"What's nice from a clinician's standpoint is that about one in five men had coronary calcium. So the scan results would let you look at this sub-population of 20 percent of the men and say, okay, you are the group we're going to focus on. As a clinician, that's valuable, because you don't have time to devote the same amount of attention to every single patient, and you want to devote extra time to the people who are more at risk, and not have folks worry when they have low risk." Dr. Taylor said.