Researchers analysed the health records of more than 4,200 women who received a coronary calcium scan, measuring the amount of calcium present in the heart’s arteries, between 1998 and 2012 at the Cedars-Sinai Medical Center in Los Angeles, US.

As many as 41% of the women had reported taking hormone replacement therapy (HRT) at the time of their calcium scan, and just over 6% of the women died during an average follow-up period of eight years.

“Hormone replacement therapy resulted in lower atherosclerosis and improved survival for all age groups and for all levels of coronary calcium,” said Yoav Arnson, lead author of the study.

Therapy group had higher average age by four years

Having accounted for age, coronary calcium score, and other factors posing risk to heart health, including diabetes, hypertension and high cholesterol levels, the researchers found that women using HRT had an overall risk of death that was 30% lower than those not on HRT.

The researchers pointed out that there was a significant age difference in the group who took HRT and the group who did not – the non-therapy group had an average age of 60 years, while the therapy group had an average age of 64 years.

“With proper screening and proper follow-up, from a cardiovascular standpoint I believe it is beneficial to take hormone replacement therapy,” said Arnson.

Women using HRT were also 20% more likely to have a coronary calcium score of zero and 36% less likely to have a coronary calcium score above 399, indicating a low risk of atherosclerosis and heart attack.

Not all HRT is created equal

HRT, which replenishes the low hormone levels in post-menopausal women, was first available in the 1940s but became more widely used in the 1960s. It was prescribed for women to manage the symptoms of menopause, which included hot flushes, sleep disturbances, migraines, psychological and genito-urinary problems – urinary frequency and vaginal dryness – and for the prevention of osteoporosis.

Its popularity dropped over the past two decades as studies emerged, suggesting that the use of HRT increases breast cancer risk and heart risk in women.

In fact, a recent study last year by the Institute of Cancer Research and Breast Cancer Now showed that women who took the combined oestrogen and progestogen pill for around five years were 2.7 times more likely to develop cancer compared to women who took only the oestrogen pill, or did not undergo HRT.

Despite that, the latest research, having examined a greater number of patients over a longer period than most comparable studies, concluded that it was the healthier option overall.

Researchers highlight cardiovascular benefits of oestrogen

Researchers had focused on the use of oestrogen, which has been shown to have beneficial effects on cholesterol levels and circulation, due to increased flexibility of blood vessels and arteries. There have been studies demonstrating that pre-menopausal women, who have high oestrogen levels, have the cardiovascular health of men who are 10 to 20 years their juniors.

“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,” concluded Arnson.

Other healthcare institutions echo this, with NHS stating that the use of HRT for no more than five years provides benefits that outweigh the risks. Cancer Research UK warns that women using HRT face double the risk of breast cancer compared to non-users, but is quick to emphasise that the risk is small compared to that from an unhealthy lifestyle.

Nevertheless, HRT is not suitable for certain groups of women, particularly those who have prior history of heart attacks or heart disease, and those with a history of blood clots. MIMS

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