Women who take hormone replacement therapy (HRT) have reduced levels of atherosclerosis and a lower risk of death compared with women who don’t, according to new research.
Presenting their findings at the American College of Cardiology’s 66th Annual Scientific Session, the researchers say their results could help more women to benefit from HRT, as many have been deterred from using the drugs over their association with cancer risk
“With proper screening and proper follow-up, from a cardiovascular standpoint I believe it is beneficial to take hormone replacement therapy,” says lead author Yoav Arnson, a postdoctoral scientist at Cedars-Sinai Medical Center in Los Angeles, California.
“Our results confirm and enhance previous work in terms of showing lower atherosclerosis. In addition, we’ve shown very clear survival benefits of using hormone replacement therapy.”
The researchers retrospectively studied 4,286 post-menopausal women who underwent coronary artery calcium (CAC) scanning over a 14-year period. The scan, performed via computed tomography, indicates the level of calcification in the coronary arteries, which is a marker of atherosclerotic plaque development.
Forty-one percent of women were taking HRT at the time of their scan. The CAC results showed that these women had a lower build-up of plaques in the arteries, with a mean score of 72.1 compared with 119.2 in women not taking HRT. This held true for every age group when they stratified women in five-yearly intervals.
A CAC score can range from zero – indicating no risk of imminent coronary event – to over a 1,000, which indicates a very severe risk of an event (a score of 11–100 indicates mild risk and 101–400 moderate risk).
The researchers found that, after adjusting for confounders, HRT was associated with a 37% lower risk of having a high CAC score (>399). Women on HRT were also significantly more likely to have a CAC score of 0, indicating a complete absence of identifiable coronary plaque.
Women who were taking HRT at baseline were also 30% less likely to die during a mean follow-up of 8.4 years, with a mortality rate of 5.8% versus 6.8% in those not taking HRT.
It has been suggested that oestrogen has a protective effect on cardiovascular health because it helps increase the flexibility of blood vessels and has beneficial effects on cholesterol levels. However, evidence to support a cardiovascular benefit of oestrogen supplementation through HRT has been mixed, and some studies have suggested that the timing of beginning HRT may be crucial to determining any cardiovascular benefit.
In the current study, however, the researchers note that they observed a benefit of HRT at all ages.
“HRT resulted in lower atherosclerosis and improved survival for all age groups and for all levels of coronary calcium,” says Arnson. “From this we do think it is beneficial, but we would need prospective or randomised studies to determine which groups might not benefit or even be harmed by this therapy.”
Emily Reeve, senior cardiac nurse at charity organisation the British Heart Foundation, comments: “This study builds on previous research that suggests oestrogen helps protect heart health, by showing HRT could help combat the furring of the arteries that causes a heart attack.
“However, to draw any firm conclusions, we need data from larger trials, as previous research has also shown some forms of HRT could increase the risk of a heart attack or stroke.”
She adds that the appropriateness of HRT should be considered on an individual basis, but “for most menopausal women – especially those under the age of 60 – the benefits of taking HRT outweigh any potential risks”.
 Arnson Y, Rozanski A & Gransar H et al. Hormone replacement therapy is associated with less coronary atherosclerosis and lower mortality. To be presented at: American College of Cardiology 66th Annual Scientific Session; Washington, DC; 17-19 March 2017.