Hormone replacement therapy and cardiovascular disease.

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.