Women who use hormone replacement therapy to relieve the symptoms of menopause significantly improve their chances at a longer life due to a decreased risk of heart attack or stroke, according to new research.

A study conducted at the Cedars-Sinai Medical Center in Los Angeles looked at the health records of more than 4,200 women who received coronary calcium scans between 1998 and 2012. The scans measure the amount of calcium in the heart’s arteries. Higher calcium levels indicate plaque build-up, which increases the risk of having a heart attack or stroke.

Heart disease and stroke are the second and third most common causes of death in Canada, behind cancer, according to Statistics Canada.

“Women using hormone replacement therapy were found to be 30 per cent less likely to die than those not on hormone therapy,” said the report led by postdoctoral scientist Dr. Yoav Arnson.

Hormone replacement therapy users were also found to be 20 per cent more likely to have a coronary calcium score of zero, the lowest possible score. And 36 per cent were less likely to score above 399, indicating a high risk for heart attack and severe atherosclerosis -- a hardening and narrowing of the arteries.

Estrogen is believed to have a beneficial effect on heart health and cholesterol levels because it increases the flexibility of blood vessels and arteries, allowing for better blood flow. 

Studies have shown pre-menopausal women, who produce more estrogen, have the heart health of a man 10 to 20 years younger, but the rate of heart disease skyrockets after menopause.

The number of women replacing natural estrogen lost during menopausehas dramatically decreased over the last 15 yearsdue to fears of potential cancer development and other risks, the study said.

Forty-one per cent of the women studied reported taking hormone replacements at the time of their calcium scan. The practice was found to be most prevalent between 1998 and 2002, and gradually decreased during the course of the study from more than 60 per cent in 1998 to 23 per cent in 2012.

Arnson notes that risk factors need to be weighed carefully on an individual basis, but said the findings bolster evidence that hormone therapy has an undeniably positive impact on heart health. 

“Hormone replacement therapy resulted in lower atherosclerosis and improved survival for all age groups and for all levels of coronary calcium,” he said.

The women included in the research were 60 years old on average, while the average hormone replacement therapy user among that group was 64. To account for the age difference, researches adjusted for external factors like age and cardiovascular risks like diabetes, high blood pressure, and high cholesterol.

Arnson notes his findings are based on a larger number of patients and longer follow-up times than most other recent studies on the subject. However, he feels more research is needed to determine who is most likely to benefit when all of the risks are factored in.

“We would need prospective or randomized studies to determine which groups might not benefit, or even be harmed by this therapy,” he said.