Hormone Therapy for Hot Flashes May Protect Heart Health

The research found that hormone therapy reduced cardiovascular risk for women if they began taking it in the years leading up to menopause (perimenopause) and in the decade after menopause began, but not later.

The study is the first of its kind to look at the impact of hormone therapy on cardiovascular disease risk during perimenopause, the life stage leading up to menopause, when estrogen levels begin to fluctuate. This transitional stage typically occurs during a woman’s forties and can last for years.

“No one has ever looked at the timing of hormone therapy on cardiovascular disease, and if it will matter,” says Lauren Streicher, MD, a clinical professor of obstetrics and gynecology at Northwestern University Feinberg School of Medicine in Chicago, who did not participate in the study. “These are important findings.”

Hormone Therapy Was Linked to a More Than 20 Percent Lower Heart Disease Risk

All the women reported experiencing hot flashes or night sweats, and they had no history of heart disease or hormone therapy use at the beginning of the study. Researchers followed them for about 20 years.

The analysis found that participants who started hormone therapy had a 22 percent lower risk of cardiac crisis like a heart attack or stroke than those who didn’t use the treatment.

Among the postmenopausal women, those who began hormone therapy within the decade after the onset of menopause had a 27 percent lower risk of heart disease than women who started 10 years after menopause or later. For these late-starters, there seemed to be no heart benefits whatsoever.

The New Study Builds on Earlier Research

This research builds on earlier studies investigating the link between hormone therapy and heart health in postmenopausal women.

Still, “The evidence on menopause hormone therapy and cardiovascular disease risk has been mixed, and important questions remain about the role of timing,” says Samar R. El Khoudary, PhD, MPH , a coauthor of the study and the chair of the department of epidemiology at Virginia Commonwealth University in Richmond.

The Hormonal Changes That Come With Perimenopause and Menopause Can Impact the Heart in a Few Ways

“During the menopause transition, estrogen levels decline, which influences cardiovascular health, says Laxmi Mehta, MD, a cardiologist and the director of preventive cardiology and women's cardiovascular health at the Ohio State University Wexner Medical Center in Columbus.

As estrogen levels fall, women typically experience several changes that impact cardiovascular health, Dr. Mehta says, including:

• Rising LDL (“bad”) cholesterol
• Higher blood pressure
• Higher body fat
• Blood vessel issues, including stiffer blood vessels and failure of the inner lining of the blood vessels to work properly

All these changes “can collectively influence cardiovascular risk,” Dr. El Khoudary says.

But El Khoudary stresses that menopause is a complex biological transition. “We are still learning how the changes in different hormones and other physiological processes interact to influence cardiovascular health,” she says.

How Hormone Therapy Might Protect the Heart

Scientists believe estrogen helps protect the heart by supporting blood vessel elasticity and positively impacting cholesterol, including by lowering LDL and raising HDL (“good”) cholesterol, says Sheryl Ross, MD, an obstetrician-gynecologist at Providence Saint John’s Health Center in Santa Monica, California. Hormone therapy adds estrogen into a woman’s body to promote these benefits, she explains.

“Even though more research is needed to understand how this all comes together, estrogen appears to support heart health,” Dr. Ross says.

This study specifically focused on women with persistent hot flashes, and there may be something about the hot flashes themselves that contributes to the findings, Dr. Streicher says.

“Hot flashes are linked to a chronic increase in inflammation and insulin resistance, which can lead to type 2 diabetes and weight gain,” she says. Regular hot flashes and night sweats can make it hard for women to get a good night’s sleep, Streicher adds — and all these factors can be harmful to the heart.

Mehta agrees. Frequent hot flashes stress the vascular system, “so reduction in symptoms may reduce vascular stress, as well as improve sleep, which has important overall cardiometabolic effects,” she says.

But it’s hard to tell exactly where the benefit is coming from, Streicher says. “Is it the estrogen alone or is it that hormone therapy is getting rid of the hot flashes?” she says.

El Khoudary agrees that the benefit may be from more than estrogen. “These findings suggest that it may not be simply the presence or absence of estrogen that matters, but also how reproductive hormones change over the menopause transition,” she says. “There are other hormones and biological pathways that also change during this period that we have not yet fully studied, so more research is needed to understand the mechanisms linking the menopause transition with cardiovascular health.”

The Study Has Some Limitations

The study was observational, making it difficult to prove that the menopausal hormone therapy caused the drop in cardiovascular disease risk. The findings also focused on women with hot flashes, so it's hard to tell if the findings would apply to those who don’t experience this symptom in menopause.

There’s also a risk of “healthy user bias,” where women who are more likely to focus on their health may also be more likely to take menopausal hormone therapy, Streicher says. That could also explain the lowered risk of cardiovascular disease in this group, she says.

Hot Flashes Should Be Treated, Not Tolerated

Menopause is a time of “cardiovascular transition,” making it important to address changes to support health, Mehta says. Hot flashes are also “not harmless” and may strain the heart and arteries, making them important to address, according to Streicher.

“Vasomotor symptoms such as hot flashes and night sweats shouldn’t be ignored, and women don’t need to ‘survive’ menopause, but need to use this as an important time to discuss their overall cardiovascular risk as well as treatment options with and without menopausal hormone therapy,” Mehta says.

But El Khoudar stresses that the findings don’t suggest hormone therapy should be given solely to prevent heart disease. “The overall balance of benefits and risks depends on the individual woman, including her symptoms, age, time since menopause, medical history, and risk factors,” she says.