Women who initiated hormone therapy during their 50s showed a lower prevalence of coronary plaque and less extensive calcification 8 years later than did those who took placebo, reported Dr. JoAnn E. Manson and her associates in the WHI-CACS trial.
The findings support the hypothesis that estrogen therapy is cardioprotective in younger but not older postmenopausal women. They “provide some reassurance that estrogen is unlikely to have an adverse effect on the risk of coronary events among women who have recently undergone menopause and are considering hormone therapy for the treatment of menopausal symptoms,” the researchers said.
A total of 1,064 women, who had been age 50–59 years at randomization for Women's Health Initiative and were recruited to participate in The WHI-Coronary Artery Calcium Study, underwent CT assessment of coronary plaque at a mean age of 65 years, approximately 8 years after they had been randomized to receive either estrogen or placebo. The intention-to-treat analysis showed that women who had taken estrogen therapy were 42% less likely to have high levels of coronary calcification than were women who had taken placebo.
In the subgroup of subjects who had been most adherent to the study medication for at least 5 years, those who had taken estrogen were 61% less likely to have high levels of coronary calcification than were those who had taken placebo, the investigators said (N. Engl. J. Med. 2007;356:2591–602).
Subjects who took active medication also showed less extensive coronary calcification than did the placebo group.
“It is possible that estrogen could reduce coronary artery calcium scores but still increase the risk of clinical CHD events, owing to adverse effects on thrombosis and plaque rupture, which are more likely in older women with advanced stages of atherosclerosis. Such a duality of effects would not necessarily apply to younger women with lower burdens of atherosclerosis,” Dr. Manson and her associates said.
The investigators stressed that these new findings should not alter current hormone therapy recommendations.