Menopause, Heart Disease, and Benefits of Hormone Therapy

Menopause is a natural and normal part of the aging process, and all women experience it during their midlife. Periods become irregular and eventually stop. Women are no longer able to get pregnant as a result.

During this time, the hormones that control the menstrual cycle undergo large shifts. In turn, many women experience physical symptoms, including ones you may have heard of, like hot flashes. What many people may not know is that these hormonal changes can also affect the body in other, less obvious ways, like increasing the risk of heart disease.

“Midlife women are thought to be at low risk for heart disease, because many of our risk calculators only capture 10-year risk of cardiovascular disease,” says Emily Lau, MD, MPH, a Mass General Brigham cardiologist and researcher. “While it’s true that many of our midlife patients have a low risk of developing heart disease over the next 10 years, I don’t just want my patients to be free of heart disease for the next 10 years. I want them to live their whole lives without heart disease.”

Dr. Lau is the director of the Cardiometabolic Hormones and Health Clinic in the Women’s Heart Health Program at Massachusetts General Hospital, where she cares for patients. For many years, most women thought that hormone replacement therapy (HRT) could put them at greater risk of heart disease. In this article, Dr. Lau describes how hormone replacement therapy can not only help relieve common menopause symptoms, but it’s also safe for many women at risk of heart disease.

“Women are often busy taking care of their families, aging parents, and careers. This is a window of opportunity for us to ensure that we are optimizing cardiovascular risk factors in our midlife women patients, so that we can prevent them from developing heart disease down the line,” she says.

Why does menopause increase risk of heart disease?

Menopause causes metabolic changes that can put women at a greater risk for heart disease. These include:

• High blood pressure or hypertension

• Higher levels of cholesterol

• Slower metabolism

• Changes in weight distribution, including an increase in visceral fat. “That type of fat is known to be more harmful to our cardiovascular system,” says Dr. Lau.

These risk factors can put postmenopausal women at greater risk of heart attacks, coronary artery disease, and stroke.

“After the menopause transition, a woman’s risk of heart disease rises significantly. Before menopause, women have much lower rates of cardiovascular disease than men. And during menopause, we see that risk really start to accelerate,” Dr. Lau says.

For years, it was thought that estrogen was responsible for these changes. “We know that estrogen produced naturally in the body has a lot of good effects on the cardiovascular system. It reduces damage to cells and lowers blood pressure,” explains Dr. Lau. “After menopause, women have much lower levels of estrogen, so this was thought to be the driver of these changes in cardiac risk factors.”

In 1991, the National Heart, Lung and Blood Institute began a large clinical study called the Women’s Health Initiative (WHI). The study focused on how to prevent heart disease, breast and colorectal cancer, and osteoporosis in postmenopausal women. As part of the trial, clinicians gave postmenopausal women high doses of estrogen.

“They found that not only did treatment with estrogen not improve heart health or reduce cardiovascular events, it even, surprisingly, increased these events,” Dr. Lau says.

Prescriptions for hormone replacement therapy, or HRT, plummeted after the Women’s Health Initiative study was published. However, secondary analyses conducted after the trial has shown that HRT can be safe and effective if prescribed carefully and correctly.

Hormone replacement therapy (HRT) to relieve menopause signs and symptoms

The average age of menopause in the United States is 52, according to the National Institute on Aging (NIA). Most women begin transitioning into menopause between the ages of 45 and 55. This transition period, known as perimenopause, can last for several years. Once a woman goes a full year without a period or spotting, she’s officially reached menopause. Some women may go through menopause early due to health conditions like polycystic ovary syndrome (PCOS) or primary ovarian insufficiency, or if the ovaries need to be surgically removed.

“The primary hormonal change that we see with menopause is a drop in estrogen levels,” says Dr. Lau.

During menopause, the ovaries also reduce the production of the hormone progesterone. While both men and women’s bodies produce estrogen and progesterone, in women the hormones play key roles in sexual development, reproductive health, and pregnancy.

These lower hormone levels can result in signs and symptoms like:

• Hot flashes

• Night sweats

• Problems with sleep

• Vaginal dryness and other sexual changes

• Mental health challenges like depression or anxiety

• Fatigue or brain fog

• Changes in body composition or gaining weight

• Bone density loss, known as osteoporosis

“Hot flashes and night sweats are the most common symptoms of menopause. It affects up to 80% of women. Some women can have very, very significant and severe hot flashes to the point that it interferes with their daily lives,” Dr. Lau says.

Benefits of hormone replacement therapy

Hormone replacement therapy, also known as HRT, replaces some of the hormones your body no longer makes after you go through menopause. According to the American College of Obstetricians and Gynecologists (ACOG), there are two main types of hormone therapy:

1. Estrogen therapy

2. Combined hormone therapy, which includes both estrogen and progesterone

Depending on the symptoms being treated, clinicians can prescribe HRT in a variety of different ways, including:

• Oral tablets

• Skin patches

• Gels

• Sprays

• Vaginal rings, tablets or gels

Dr. Lau notes that the Food and Drug Administration (FDA) has approved HRT to prevent or treat the following conditions related to menopause: 

• Hot flashes and night sweats

• Bone loss

• Premature menopause (starting before age 40)

• Severe vulvovaginal atrophy (thinning or drying of the vaginal walls)

“The large majority of women, perimenopausal and postmenopausal, have hot flashes, night sweats, and bone loss. All of these are important indications, and there is a role for hormone therapy in the right population,” Dr. Lau says.

Is hormone replacement therapy safe?

Dr. Lau began the Cardiometabolic Hormones and Health Clinic at Mass General to meet the needs of midlife women. “I consult with patients and their care team, like primary care providers (PCP) or general cardiologists, to determine if it’s safe for the heart to start hormone therapy,” she says.

The more recent findings from the WHI study have shown that for HRT is safest if:

• Prescribed before the patient is 65 years of age

• Started less than 10 years post-menopause

• Given via skin patch (transdermal)

Even though hormone therapy isn’t prescribed solely for the prevention of heart disease, it can be safely prescribed for younger, recently post-menopausal women with heart disease risk factors.

“We do not recommend hormone therapy for women who have a history of heart attack, stroke, or other cardiovascular event,” Dr. Lau explains. For those women, hormone therapy is associated with a higher risk of further heart problems. “But for women who might be at a greater risk of heart disease, with obesity, high blood pressure, or high cholesterol, it’s safe for them to be on hormone therapy if they are less than 65 years of age and less than 10 years post-menopause.”

The latest research on menopause and heart disease

Dr. Lau and her research group are investigating what drives cardiovascular disease in women.

“We have an ongoing, patient-oriented study at Mass General. We are looking at changes in inflammation that take place through the menopause transition as a way of trying to understand what drives the risk of heart disease among menopausal women,” she explains.

The study compares perimenopausal women with pre- and post-menopausal women, as well as a group of age-matched men. Working closely with patients, Dr. Lau and her team take detailed medical histories and blood and tissue samples, and then monitor changes in the group over a 1-year period.

“One of our hypotheses is that there’s an increase in inflammation or activation of the immune system happening during the menopause transition. If this is the case, are there specific molecules we can potentially target in the future to reduce menopause-related cardiac disease?” Dr. Lau says.

Ultimately, there’s more work to needed to prevent cardiovascular disease in postmenopausal women. “Estrogen probably explains some of it, but there are more complex physiological changes that we don’t yet fully understand. That’s an area that I think needs a lot more investigation, and is something I’m very passionate about studying,” says Dr. Lau. “This is a real opportunity for us to improve the health of our women patients.”