Women with a “low-risk” Framingham heart score who are found to have coronary artery calcification on chest CT have a sixfold greater risk of a coronary event and a fivefold greater risk of a cardiovascular event developing within 4 years than those with no calcification.
In the Multi-Ethnic Study of Atherosclerosis (MESA), 90% of women aged older than 45 years were classified as low risk based on the Framingham score, yet about one-third of them had coronary artery calcification on chest CT. Cardiovascular risks in these women were significantly higher than in women without such calcification.
The study is a prospective epidemiologic assessment of subclinical atherosclerosis measures in more than 6,800 men and women aged 45–84 years. They had no known cardiovascular disease at baseline in 2000, said Dr. Susan G. Lakoski of Wake Forest University, Winston-Salem, N.C., and her associates.
They followed 2,684 of the female subjects whose Framingham scores classified them as low risk, meaning that their estimated risk of coronary heart disease (CHD) or cardiovascular disease (CVD) events was less than 10% over the next 10 years. Chest CT showed 870 (32%) of these women had occult coronary artery calcification, including 105 (4%) with advanced calcification. During 4 years of follow-up, 24 of these “low-risk” subjects had CHD events, and 34 had CVD events.
The absolute risk of a CHD event was 0.9%, and of a CVD event, 1.3%. But “there was a sixfold greater risk for a CHD event in women with prevalent [calcification] compared with women [who had] no detectable coronary calcium,” which remained significant after adjusting for factors such as age, and body mass index. Similarly, “there was a fivefold greater risk of a CVD event in women with prevalent [calcification].” This risk was also maintained in adjusted models (Arch. Intern. Med. 2007;167:2437–42).