The Women's Health Initiative (WHI) has had a major impact on the use of hormone replacement therapy (HCT) for post-menopausal women. The latest and final analysis of the effect of conjugated equine estrogen (CEE) alone on cardiovascular events in women who had a hysterectomy is found in a recent issue of the Archives of Internal Medicine (subscription required for full text).
Overall, no increase in CV risk and in one age subgroup, the suggestion of an apparent benefit was found.
The study began in 1993 and 10,739 women were randomized to placebo or 0.625 conjugated equine estrogen daily.The follow up was 6.8 years. In the group who were 50-59 years of age at entry into the study the hazard ratio for coronary artery disease events was 0.63 ( C.I.-0.36 to 1.08) while the hazard ratio for revascularization was statistically significantly reduced with a hazard ratio of 0.55 ( C.I.- 0.35 to 0,86).
These results differ from the WHI estrogen plus progestin arm in which an increase in cardiovascular events was demonstrated (7 more events per 10,000 patients per year as well as 8 more strokes).
Why the difference? The simple or perhaps simplistic answer is maybe the progestin is the culprit.The study's authors tended to favor that explanation as their statistical analyses seemed to make baseline risk factor differences and differential statin use not likely to account for the difference between CEE alone and CEE plus a progestin.
I doubt we will see large scale recommendations for estrogen to prevent heart disease, but at least women who are post-menopausal and who are taking estrogen may be somewhat less concerned about their HRT increasing their heart attack risk.