Hormone replacement therapy and cardiovascular risk

Cardiovascular risk associated with hormone replacement therapy (HRT) has been analysed by large epidemiological studies. This treatment has different effects depending on the type of vessel (venous or arterial) or site (heart or brain). The several meta-analyses which have been published conclude that there is a significant decrease of about 30 to 50 per cent in ischaemic heart disease associated with HRT. In addition, oestrogen replacement therapy is associated with a 25 per cent decrease in cardiovascular mortality. A recent meta-analysis has analysed the effect of HRT on cerebrovascular risk. A significant 20 per cent increase in ischaemic stroke associated with the use of HRT has been shown. However, a protective association of about 30 per cent has been observed in haemorrhagic stroke with HRT use. Recent epidemiological studies have suggested an increased risk of thromboembolic disease associated with HRT. The results of a randomized blind placebo-controlled secondary prevention trial have recently been published. In this clinical trial, women who receive oestrogen (0.625 mg conjugated equine oestrogen daily) plus progestin (2.5 mg medroxyprogesterone acetate daily) therapy did not experience a reduction in overall risk of non-fatal myocardial infarction and cardiovascular heart disease death. This treatment also significantly increases the rate of thromboembolic events. Other randomized trials of HRT for primary prevention are scheduled to yield results by 2000 or 2005. All these studies have been conducted essentially in Anglo-Saxon countries and have analysed the effects of conjugated equine oestrogens alone or combined with medroxyprogesterone acetate. This treatment is not currently used in France. But no randomized trials are under way with the HRT common in France (transdermic oestrogen combined with natural progesterone). The effects of this treatment on cardiovascular disease remain unknown.