Hormone replacement therapy and cardiovascular disease.

Oestrogen alone probably confers a degree of protection against ischaemic heart disease and stroke and is appropriate for women requiring hormone replacement therapy (HRT) who have undergone hysterectomy. However, the cardiovascular effects of the progestogens used with oestrogen in the much larger number of women who have not undergone hysterectomy are unknown. Some widely used progestogens have adverse effects on lipoprotein levels and may raise blood pressure. The antithrombin III level may be involved in determining the response to oestrogen in different settings. The indications for HRT and the effects of different formulations on cardiovascular disease constitute one of the most pressing but complex issues in present-day medical practice. These questions can only be satisfactorily answered by the randomised controlled trials that should have been initiated several years ago and the feasibility of which is only now being investigated.