A coronary artery calcification (CAC) test to measure the amount and density of calcium in a patient's heart arteries can accurately predict mortality over a 15-year period in patients who were at risk for coronary artery disease but did not have any symptoms at baseline. .
Lead researcher Leslee J. Shaw, PhD, of Emory University in Atlanta, and colleagues published their findings online in Annals of Internal Medicine on July 6.
Insurance companies do not cover CAC examinations, so patients must pay out-of-pocket for the test. The CAC test is a non-invasive procedure that lasts less than five minutes and typically costs around $100, according to James K. Min, MD, co-author of the study from Weill Cornell Medical College in New York City.
“Without any exaggeration, it is the strongest predictor of who’s going to have a heart attack or die in the future that we have in cardiovascular diagnostic testing,” Min told Cardiovascular Business. “For the asymptomatic patient, there is no better predictor than this test. It’s a shame that insurance providers aren’t covering this test…I sort of think of it as a cardiac mammogram. We need to find the people who are at risk. We know that if you are not at risk, you have a good warranty period for 15 years, and if you are at risk, we know exactly what that risk is because it’s very predictable and linear. “
The researchers evaluated 9,715 patients who participated in a cardiology outreach screening program from 1996 to 1999 in Nashville, Tenn. Of the patients, 86 percent were white, and the median annual income was $33,000.
Patients paid $69 out-of-pocket for the CAC test. None of the patients had symptoms of coronary artery disease.
Before the test, patients underwent screening to assess cardiac risk factors such as age, hypertension, prescription for antihypertensive medications and blood pressure of 140/90 mm Hg or higher.
All patients underwent CAC imaging using electron beam tomography or multislice CT. Researchers calculated the Agatston CAC score and grouped patients by their scores.
After a mean follow-up of 14.6 years, the mortality rates ranged from 3 percent to 28 percent for people with CAC scores of 0 to 1,000 or greater. The relative hazard for all-cause mortality was 1.68 for a CAC score of 1 to 10, and ranged up to 6.26 for a score of 1000 or greater.
“The relationships between the amount of calcium that you have in your heart arteries and your risk of death in the future is very linear,” Min said. “It’s very predictable based upon somebody’s calcium score – not only what they’ll do tomorrow or next year, but what they’ll do 10, 15 years later, as well. It gives us a very good metric on which to be able to judge somebody’s risk and then how aggressively we need to treat those patients in order to reduce that risk.”