Cardiovascular disease risk and hormone replacement therapy (HRT): A review based on randomised, controlled studies in postmenopausal women

Epidemiological data suggest that the use of oestrogen replacement therapy (ERT) and combined oestrogen/progestagen replacement therapy (HRT) in healt hy postmenopausal women is associated with a decreased risk of cardiovascul ar events. In sharp contrast, the HERS study, a secondary prevention trial in postmenopausal women with established coronary heart disease, did not sh ow a favourable effect, with a trend towards an increased risk of cardiovas cular disease in the first year of treatment. This paper provides an overvi ew of randomised, controlled trials (RCTs) in postmenopausal women publishe d in the literature and discusses possible explanations for the contrast be tween data from the epidemiological studies and the results of the HERS stu dy. ERT and HRT are associated with: 1) an improved lipid profile; and 2) a dec rease in homocysteine and endothelin levels. Data on factor VII and fibrino gen were not consistent. There were insufficient data on the effects on blo od pressure, glucose metabolism, vasomotor regulation, arterial stiffness, thrombomodulin, adhesion molecules, and clotting and fibrinolysis, as well as on the effects of route of administration and the role of progestagens. Finally, endothelium-dependent vasodilatation appears to increase with ERT, but the effects of HRT are less clear. This paucity of controlled data indicates that, although ERT and HRT improv e surrogate measures of risk of atherothrombosis, adverse effects of ERT an d HRT on biological mechanisms related to risk of atherothrombosis can by n o means be excluded.