[Prevention of atherosclerosis by estrogen substitution?]

Estrogen effects on arteries vary with stage of reproductive life and extent of subclinical atherosclerosis progression

The past several years have been marked by confusion and controversy concerning whether estrogens are cardioprotective. The issue is of utmost public health importance because coronary heart disease (CHD) remains the leading cause of death among postmenopausal women. Fortunately, a unifying hypothesis has emerged that reproductive stage is a major determinant of the effect of estrogens on atherosclerosis progression, complications, and plaque vulnerability.

PREMENOPAUSAL YEARS

Premenopausal atherosclerosis progression seems to be an important determinant of postmenopausal atherosclerosis and thus the risk for CHD. Clearly, plasma lipids/lipoproteins influence this progression; however, estradiol deficiency seems to be the major modulator. Both monkeys and women with premenopausal estrogen deficiency develop premature atherosclerosis, an effect that can be prevented in both species by estrogen-containing oral contraceptives.

PERIMENOPAUSAL/EARLY POSTMENOPAUSAL YEARS

During this stage, there are robust estrogen benefits. Monkeys given estrogens immediately after surgical menopause have a 70% inhibition in coronary atherosclerosis progression. Estrogen treatment prevented progression of atherosclerosis of women in the Estrogen in the Prevention of Atherosclerosis Trial. A meta-analysis of women younger than 60 years given hormone therapy had reduced total mortality (relative risk = 0.61, 95% CI: 0.39-0.95).

LATE POSTMENOPAUSAL YEARS

This stage is one in which there are no or possible deleterious estrogen effects. Monkeys lose CHD benefits of estrogens when treatment is delayed. The increase in CHD events associated with initiating hormone therapy 10 or more years after menopause seems to be related to up-regulation of the plaque inflammatory processes and plaque instability and may be down-regulated by statin pretreatment.

Estrogen effects on arteries vary with stage of reproductive life and extent of subclinical atherosclerosis progression

The past several years have been marked by confusion and controversy concerning whether estrogens are cardioprotective. The issue is of utmost public health importance because coronary heart disease (CHD) remains the leading cause of death among postmenopausal women. Fortunately, a unifying hypothesis has emerged that reproductive stage is a major determinant of the effect of estrogens on atherosclerosis progression, complications, and plaque vulnerability. PREMENOPAUSAL YEARS: Premenopausal atherosclerosis progression seems to be an important determinant of postmenopausal atherosclerosis and thus the risk for CHD. Clearly, plasma lipids/lipoproteins influence this progression; however, estradiol deficiency seems to be the major modulator. Both monkeys and women with premenopausal estrogen deficiency develop premature atherosclerosis, an effect that can be prevented in both species by estrogen-containing oral contraceptives. PERIMENOPAUSAL/EARLY POSTMENOPAUSAL YEARS: During this stage, there are robust estrogen benefits. Monkeys given estrogens immediately after surgical menopause have a 70% inhibition in coronary atherosclerosis progression. Estrogen treatment prevented progression of atherosclerosis of women in the Estrogen in the Prevention of Atherosclerosis Trial. A meta-analysis of women younger than 60 years given hormone therapy had reduced total mortality (relative risk = 0.61, 95% CI: 0.39-0.95). LATE POSTMENOPAUSAL YEARS: This stage is one in which there are no or possible deleterious estrogen effects. Monkeys lose CHD benefits of estrogens when treatment is delayed. The increase in CHD events associated with initiating hormone therapy 10 or more years after menopause seems to be related to up-regulation of the plaque inflammatory processes and plaque instability and may be down-regulated by statin pretreatment.

A critique of the Women's Health Initiative hormone therapy study

OBJECTIVE

This review critiques The Women's Health Initiative (WHI) study, focusing on aspects of the study design contributing to the adverse events resulting in the study's discontinuation.

CONCLUSION(S)

Two aspects of the design contributed to the adverse events: [1] The decision to administer continuous combined conjugated equine estrogen (CEE)/medroxyprogesterone acetate (MPA) or E alone as a standard regimen to a population with little previous hormonal treatment, ranging in age from 50-79 years, who, because of their age, were predisposed to coronary and cerebral atherosclerosis. [2] Selection of an untested regimen of continuous combined CEE plus MPA, which we hypothesize, negated the protective effect of E on the cardiovascular and cerebrovascular systems. Multiple observational studies that preceded the WHI study concluded that the use of E alone and E plus cyclic (not daily) progestin combination treatments initiated in early menopause had beneficial effects. The therapeutic regimens resulted in prevention of atherosclerosis and reductions in coronary artery disease mortality. It is our conclusion that the WHI hormonal replacement study had major design flaws that led to adverse conclusions about the positive effects of hormone therapy. An alternative hormonal regimen is proposed that, on the basis of data supporting its beneficial cardiovascular effects, when initiated appropriately in a population of younger, more recently menopausal women, has promise to yield a more favorable risk/benefit outcome.

A comparative study of two levonorgestrel-containing hormone replacement therapy regimens of efficacy and tolerability variables

OBJECTIVE

To compare the effect of two sequential hormone replacement regimens differing in the dose of levonorgestrel on climacteric symptoms, bleeding pattern and lipid metabolism in postmenopausal women.

STUDY DESIGN

In a multicentre, randomized, double-blind, active-treatment-controlled study, 210 postmenopausal women were assessed at the end of treatment cycles 3 and 6. The high-levonorgestrel group was treated with 2 mg estradiol valerate (days 1-21) sequentially combined with 0.25 mg levonorgestrel (days 12-21). The low-levonorgestrel group received the same estrogen regimen (2 mg estradiol valerate, days 1-21), but levonorgestrel was administered sequentially in a dose of 0.15 mg during the last 12 days of the cycle (days 10-21). Statistical analysis by Student's t-test for dependent variables (measured values versus baseline) and independent variables (differences between groups), and the composite t-test method for comparison of both regimens with respect to efficacy, was performed.

RESULTS

Both groups were statistically comparable. The trial was completed by 137 subjects. Protocol violations occurred in 38 cases. Thirty-five subjects dropped out during the study, 21 of them because of adverse events. Both treatments were equally effective in the treatment of climacteric complaints. There were no clinically significant changes in body weight, blood pressure, haematological tests, and parameters of clinical chemistry. There was a tendency towards a reduction in bleeding intensity in both groups in the second half of the treatment period. The treatment for six cycles with both regimens significantly (P < 0.05) decreased plasma concentrations of triglycerides (significant in the low-levonorgestrel group only), high-density lipoprotein cholesterol, high-density lipoprotein-3-cholesterol, lipoprotein(a) and apolipoprotein A1. In parallel, the serum concentration of total cholesterol increased significantly in both treatment groups, whereas low-density lipoprotein cholesterol increased significantly in the high-levonorgestrel group only. The changes in high-density lipoprotein-2-cholesterol, and apolipoprotein B did not reach statistical significance.

CONCLUSIONS

It can be concluded that both sequential combined oral hormone replacement therapy (HRT) regimens were equivalent with respect to efficacy and tolerability in the treatment of women with climacteric complaints. The preparation with the lower dose of progestin showed a tendency towards a less unfavourable influence on the lipid profile.