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Clinical cardiovascular studies of hormone replacement therapy
1Department of Cardiac Medicine, National Heart and Lung Institute, Imperial College School of Medicine, London, United Kingdom. perer.collins@ic.ac.uk
Insights
Hormone replacement therapy (HRT) has potential benefits for coronary artery disease (CAD) risk factors, but studies like HERS show no overall cardiovascular benefit. Further research is needed to determine optimal HRT regimens for women.
Area of Science:
- Cardiovascular Medicine
- Endocrinology
- Women's Health
Background:
- Coronary artery disease (CAD) is a leading cause of death, with incidence increasing with age.
- Women typically develop symptomatic CAD approximately 10 years later than men.
- Hormone replacement therapy (HRT) was hypothesized to reduce CAD due to potential favorable effects on vasoreactivity, atherosclerosis, lipids, hemostasis, and glucose tolerance.
Purpose of the Study:
- To evaluate the potential benefits of hormone replacement therapy (HRT) in reducing coronary artery disease (CAD) incidence.
- To address the uncertainty regarding the optimal type and duration of HRT regimens.
- To assess the effect of a specific HRT regimen on lipid and hemostatic risk markers in the WHISP pilot study.
Main Methods:
- Review of prospective cohort studies suggesting HRT benefits for cardiovascular disease.
- Analysis of the Heart and Estrogen/progestin Replacement Study (HERS) results.
- The Women's Hormone Intervention Secondary Prevention (WHISP) pilot study using a distinct HRT regimen.
Main Results:
- Prospective cohort studies suggested a beneficial effect of HRT on cardiovascular disease.
- The Heart and Estrogen/progestin Replacement Study (HERS) found no beneficial effect of HRT on cardiovascular morbidity and mortality.
- Different estrogen and progestin combinations have yielded varied results, indicating uncertainty in HRT efficacy.
Conclusions:
- While HRT was believed to reduce CAD, evidence is conflicting, with HERS showing no benefit.
- Uncertainty remains regarding the optimal HRT regimen for cardiovascular health.
- Ongoing trials, including the WHISP pilot study, aim to clarify HRT's role in cardiovascular disease prevention and risk marker modification.
Abstract:
Coronary artery disease (CAD) is the number 1 cause of death and disability in the Western world. The incidence of CAD increases with age, although, on average, women present with symptomatic CAD about 10 years later than men. The belief that hormone replacement therapy (HRT) may reduce the incidence of CAD is based on its favorable effects on (1) vasoreactivity, (2) progression of atherosclerosis, (3) lipids and lipoproteins, (4) hemostasis, and (5) impaired glucose tolerance. However, unopposed estrogen may be related to an increased risk of endometrial cancer. The belief that HRT has an overall beneficial effect on cardiovascular disease comes from the results of prospective cohort studies. The Heart and Estrogen/progestin Replacement Study (HERS), however, showed no beneficial effect of HRT on cardiovascular morbidity and mortality. Uncertainty exists about the duration and optimal type of HRT regimen to use, because different estrogens and progestins have yielded different results. Results of ongoing trials addressing similar questions will be published in future years. The Women's Hormone Intervention Secondary Prevention (WHISP) pilot study, using a different HRT regimen from that used in HERS, will assess the effect of HRT on lipid and hemostatic risk markers of heart disease, and it may provide the rationale for a large trial evaluating the effect of HRT on morbidity and mortality.