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Hormone replacement therapy and cardiovascular disease
1Channg Cross Hospital, London. m.seed@ic.ac.uk
Insights
The first randomized controlled trial on hormone replacement therapy (HRT) found unexpected cardiovascular risks, contradicting previous observational studies. Further research is needed to clarify HRT
Area of Science:
- Cardiovascular Medicine
- Endocrinology
- Clinical Trials
Background:
- Observational studies suggested hormone replacement therapy (HRT) benefits cardiovascular health.
- Previous research indicated HRT improves cardiovascular risk factors like endothelial function.
- Concerns exist regarding HRT's impact on clotting variables and thrombosis risk.
Purpose of the Study:
- To report findings from the first randomized controlled trial on HRT and cardiovascular disease, the Heart Estrogen Replacement Study (HERS).
- To investigate the effects of HRT on cardiovascular risk factors and clotting variables.
- To compare HRT's effects with previous observational data and ongoing research.
Main Methods:
- Publication of the Heart Estrogen Replacement Study (HERS), a randomized controlled trial.
- Review of studies on HRT's effects on endothelial function and cardiovascular risk factors.
- Analysis of HRT's impact on prothrombotic factors (fibrinogen, factor VII, PAI, antithrombin III) and route of administration differences.
Main Results:
- The HERS trial yielded findings contrary to previous observational studies on HRT and cardiovascular disease.
- An increased risk of venous thrombosis and cardiac events was observed in the initial 4 months of the HERS trial.
- HRT alters prothrombotic factors, with variations noted based on the route of administration (transdermal HRT showed less change).
Conclusions:
- The HERS trial results challenge the previously perceived cardiovascular benefits of HRT.
- HRT's influence on coagulation markers requires further clarification, especially concerning administration routes.
- Evidence from randomized controlled trials for HRT in primary prevention is still pending, with one trial expected to report in 2005.
Abstract:
This year's work on hormone replacement therapy (HRT) and cardiovascular disease has been remarkable for the publication of the first randomised controlled trial of HRT use, the Heart Estrogen Replacement Study (HERS). The findings go against not only the trend of previous observational epidemiological studies, but also against findings in the very many studies which have previously shown and continue to show this year a beneficial effect of HRT on a large variety of cardiovascular risk factors, including endothelial function, here reviewed. The aspect of the effect of HRT on clotting variables is clearly crucial given the increased risk of venous thrombosis, and also increased number of cardiac events in the first 4 months of the HERS. Prothrombotic factors increase with age in women, and HRT alters these, particularly fibrinogen, factor VII, and PAI (less change with transdermal HRT) and antithrombin III. In normal women therefore the balance should be towards fibrinolysis rather than coagulation. Work has been presented in abstract for clarifying the effects of HRT on coagulation markers and grasping the problem of differences according to its route of administration. The full publications on this work are expected shortly. We are still awaiting evidence from randomized controlled trials of HRT in primary prevention; one is now recruited but will not report until 2005.