Oestrogen replacement therapy and cardiovascular disease in post-menopausal women. A review

The possible role played by oestrogens in modifying the occurrence of ischaemic heart disease (IHD) in particular and cardiovascular disease (CVD) in general in post-menopausal women has long been controversial. Analysis of the literature reveals a difference between the findings of epidemiological studies published before 1980 and those published more recently. In the former, it was reported that the risk in women using oestrogen replacement therapy (ERT) either remained unchanged or increased in relation to that in non-users. In the latter, the trend changed and ERT was shown to have a definite protective effect. These contradictory results might be explained by a change in prescribing habits, involving the use of lower oestrogen doses and the selection of women with no CVD risk factors as recipients of long-term ERT. The protective effects of ERT have been attributed to metabolic changes induced by oestrogens, namely the increase in high density lipoprotein (HDL) cholesterol observed after oral therapy. Recently, long-term studies using non-oral oestrogens delivered either by implant, or the percutaneous or transdermal routes have indicated the same favourable changes in lipid profiles as seen with oral ERT, provided follow-up is maintained for at least 6 mth. Factors other than lipids that are involved in CVD should also be evaluated in order to clarify the mechanism via which ERT affords cardiovascular protection in post-menopausal women.