The effect of continuous combined hormone replacement therapy on arterial reactivity in postmenopausal women with established angina pectoris

Most epidemiological studies have suggested that the administration of estrogen reduces cardiovascular risk in healthy postmenopausal women. More recently, however, in the large Heart Estrogen/progestin Replacement Study (HERS), it was unexpectedly found that in women with established cardiovascular disease, there was overall no difference in cardiovascular events between those treated with combined oestrogen/progestin hormone replacement therapy and those on placebo. The aim of this study was to examine the effect of combined hormone replacement therapy on arterial reactivity in women with existing angina pectoris. Seventy-four postmenopausal women with angina pectoris were recruited into a 16 week double-blind, placebo-con trolled study of treatment with 2 mg of estradiol combined with 1 mg of norethisterone acetate daily. The median endothelium-dependent change in arterial relaxation increased from 5.00 to 7.69% in the treatment group and decreased from 5.57 to 3.64% in the controls. The median endothelium-independent change in arterial relaxation increased from 6.49 to 7.27% in the treatment group and decreased from 4.39 to 2.07% in the controls. The changes in arterial relaxation between the treatment and control groups were not statistically significant. The administration of estrogen/progestin did not significantly improve either endothelium-dependent or -independent arterial relaxation in postmenopausal women with established cardiovascular disease. We have previously shown that estrogen/progestin treatment improves endothelium dependent relaxation in healthy women. The results of our study provide one possible explanation for the clinical findings of the HERS study. In women with established cardiovascular disease, arterial relaxation does not increase significantly in response to treatment with combined hormone replacement therapy. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.