ABSTRACT
HRT. Despite beneficial effects on lipids and
lipoproteins there was no reduction in
coronary artery disease.
There are little published data on the effects of
tibolone on blood flow, and further work is
needed. It has been demonstrated that
tibolone increases cardiac output without
increasing the heart rate, leading to an
increase in blood flow through capillaries as
well as the larger arteries of the upper
extremities.53,54 In a pilot study, tibolone was
reported to reduce exercise-induced
myocardial ischemia in postmenopausal
women with angina pectoris, comparable to
the changes seen with oestrogens.55 From
studies in the cholesterol fat rabbit model for
atherosclerosis prevention it appears that
tibolone could also preserve the ability of the
The evidence for a beneficial effect on CHD
risk when oestrogens are used alone as HRT is
considerable, but the effects of oestrogens and
progestogens are less clear. The recent HERS
study puts into doubt the use of continuous
combined HRT for the secondary prevention
of CHD. It appears that oestrogens reduce
vascular resistance to flow, which is likely to
be a mechanism for reducing atheroma
formation and acute vasospasm. The effect of
added progestogen on this mechanism is still
uncertain. The androgenicity of a progestogen
to a certain extent predicts its effects on serum
lipids and lipoproteins. It is not known
whether the androgenicity of a progestogen
predicts the magnitude of its effects on
vascular tone in a similar manner.
