Do we need clinical trials to test the ability of transdermal HRT to prevent coronary heart disease?

Postmenopausal hormone replacement therapy (HRT) with oral oestrogen was predicted to reduce coronary heart disease (CHD) risk by 50%. Randomized controlled trials show no such benefit, however, pointing instead to an initial increase in CHD events. Although the cardiovascular effects of transdermal HRT are largely unknown, improvements in arterial function are maintained when oestrogen is administered transdermally.