PET/CT exams indicate that a coronary artery calcium (CAC) score of 0 is an accurate indicator of low coronary heart event risk -- even as a person ages, investigators have reported.
The findings are good news for people entering their "golden years," wrote a team led by Jeffrey Anderson, MD, of Intermountain Health in Salt Lake City. The research was presented March 29 at the American College of Cardiology (ACC) annual meeting being held in Chicago.
"Our findings show that having little or no coronary plaque predicts that people will live longer, healthier lives, including into their golden years," Anderson said in a statement released by Intermountain Health.
A CAC score of 0 has long been accepted as a marker of very low risk of a cardiac event within the next five years, according to the group. But risk of these events increases as a person matures because as cholesterol-laden plaques in the heart's coronary arteries age, they attract calcium, it explained. (A CAC score of 0 indicates no advanced coronary plaque; a score of one to 99 indicates mild levels of plaque; a score of 100 to 299 indicates moderate levels of plaque; and a score of 300 or more indicates high levels of plaque.)
Since it's been unclear whether age-related risk factors diminish the low risk predicted by a 0 CAC score, Anderson and colleagues conducted a study that included 40,820 symptomatic patients from Intermountain Health in Salt Lake City who were at primary coronary risk and who underwent a PET/CT scan.
Of the total patient cohort, 8,170 had a CAC score of 0; of these, 5,185 were under age 65, and 2,782 patients were 65 or older.
The group assessed patients' coronary prognosis over an average follow-up of more than two years, finding that a 0 coronary artery calcium score predicted very low risk of coronary death or non-fatal heart attack. They also reported the following:
- Coronary events occurred in only 0.12% of patients younger than 65 and 0.25% of those older than 65 (these individuals had CAC scores of 0).
- Comparing overall death or heart attack rates between those with CAC to those without it showed two- to three-fold lower event rates in both older and younger people with 0 coronary artery calcium scores.
Anderson noted that if individuals have disease in their coronary arteries, they may also have vascular complications in other organs, stating that "given these results, a 0 coronary artery calcium score may also be a predictor of not only very low coronary death but also of a lower risk of other causes of death." He and his team also wrote that "a 0 burden of calcified coronary plaque predicts an excellent coronary prognosis that extends to older patients in whom age otherwise would indicate an increased coronary risk … and usually an indication for statin therapy."
