The likelihood of a major cardiovascular event was 33 per cent lower in women taking HRT after a natural menopause than those who took no HRT.
In 2000, the value of HRT was brought into question by the WHI study, which was terminated early after women were found to have an increased risk of heart disease, stroke and breast cancer after taking HRT.
Since the findings were published, the consensus has been to prescribe HRT only for a short time. But now data presented at the American Heart Association scientific sessions in Orlando, Florida, suggest that, rather than creating cardiovascular risk, HRT may prevent it.
Findings come from the Women's Ischaemia Syndrome Evaluation (WISE) study, that began in the mid-1990s before the concerns over HRT safety.
A cohort of 654 postmenopausal women, aged an average of 62, taking part in the WISE study were assessed for the latest research.
Overall, 42 per cent had obstructive coronary artery disease (CAD), defined as 50 per cent or more stenosis of at least one coronary vessel.
Among them, 23 per cent had had a major cardiovascular event. But HRT was also associated with a 33 per cent lower likelihood of major cardiovascular event, researchers say.
Analysis also showed that among the 520 women who underwent a natural menopause, over 40 per cent of those taking no HRT had CAD.
In comparison, around 10 per cent of those who had started taking HRT before the age of 45 developed CAD.
CAD was also less prevalent among those who started HRT after 45, but 20-25 per cent still had this diagnosis. The researchers did not identify if any one HRT was involved with this association. But they did find that duration of HRT use had no influence over the effect.
No such patterns were seen among the surgical menopause group. Researchers said the results were 'not an advocation for HRT'.
AHA scientific sessions 4-7 November 2007, Orlando, Florida
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