Hormone Replacement Therapy and Heart Health

February is Heart Health Month, and while we usually focus on pelvic floor health at Gaia Women's PT, today we're talking about something that affects every woman as she ages: heart health. And here's something that might surprise you: hormone replacement therapy (HRT) plays a much bigger role in this conversation than most people realize. Let's dive into this topic that's been misunderstood for over two decades, but is finally getting the attention it deserves.

The Reality Check: Heart Disease and Women

First, let's get one thing straight: cardiovascular disease is the leading killer of women, causing 1 in 3 deaths each year. You heard me right, 1 in 3. Cardiovascular disease kills more women than all forms of cancer combined.

And here's the kicker: only 44% of women recognize heart disease as their number one killer. Somewhere along the way, many of us internalized the myth that heart disease is a "man's disease." It's not. It never was. And it's time to take it seriously.

What does this have to do with hormone replacement therapy and your pelvic floor physical therapist writing about it? Everything, actually. Because the hormones we talk about for pelvic health, estrogen in particular, don't just affect your pelvic floor. They're intimately connected to your cardiovascular health, too.

The Women's Health Initiative: What It Actually Found

If you've heard anything about HRT and heart health, it probably relates back to a study from 2002 called the Women's Health Initiative (WHI). This landmark study fundamentally changed how we think about hormone therapy.

The WHI studied over 27,000 postmenopausal women (average age 63). In 2002, it was stopped early because the study found increased risks of breast cancer, stroke, blood clots, and heart disease in women taking combined hormone therapy. Hormone therapy use dropped by 70-80% almost overnight.

These were legitimate findings that changed medical practice. However, in the years that followed, researchers discovered something important when they took a closer look at the data.

The Plot Twist: Age and Timing Matter More Than Anyone Realized

In the years following 2002, researchers took a closer look at the WHI data. What they found changed everything: the cardiovascular risks weren't the same for all women. They varied dramatically based on when women started hormone therapy.

Here's what made all the difference: how old you are and how recently you went through menopause when you start HRT.

When researchers separated the women in the study into age groups, a pattern emerged. Women who were younger (in their 50s) or had gone through menopause recently (within the last 10 years) had very different outcomes than women who were older or many years past menopause.

In fact, in one part of the study (looking at women who'd had hysterectomies and were taking estrogen alone), younger women in their 50s actually had a 30% lower risk of dying from any cause compared to women taking placebo. Not just "no increased risk"—but potential benefit.

This pattern led researchers to develop what's now called the "timing hypothesis" or "window of opportunity", which is the idea that when you start matters just as much as whether you start at all.

Why Timing Makes Such a Difference

So why does starting HRT at age 52 have such different effects than starting it at age 67?

Think of it this way: estrogen protects your heart and blood vessels throughout your adult life. It keeps arteries flexible, reduces inflammation, and helps prevent plaque buildup. When menopause hits and estrogen drops, your blood vessels start to change. Vessels become less flexible, plaque starts to form, inflammation increases.

Here's the crucial part: it matters whether you start HRT when your arteries are still in good shape or after they've already been damaged.

If you start soon after menopause (when blood vessels are still relatively healthy), estrogen can help maintain that health and slow the damage. But if you wait 15-20 years, significant changes have already happened. Starting estrogen at that point doesn't reverse those changes and might even be risky.

A study called the ELITE trial tested this directly: HRT started within 6 years of menopause slowed artery thickening (an early sign of heart disease), while HRT started 10+ years after menopause had no effect. It's the difference between maintaining a house versus trying to renovate one that's been neglected for decades.

The "Window of Opportunity"

Since that initial 2002 study, dozens more studies have looked at this timing question. Here's what they've consistently found:

When women start HRT before age 60 or within 10 years of menopause, the picture looks very different than it did in the original WHI study. Multiple studies have shown that starting HRT in this window may actually reduce the risk of death and heart disease compared to taking nothing at all.

One large analysis that combined results from many studies found that women starting HRT in this window had a 30% lower risk of dying from any cause and a 48% lower risk of coronary heart disease.

It's important to note that HRT isn't currently recommended just to prevent heart disease. But if you're having bothersome menopausal symptoms (hot flashes, night sweats, sleep problems, vaginal dryness) and you're in this "window"—roughly the first 10 years after menopause or before age 60—HRT may help your symptoms AND potentially benefit your heart at the same time.

All four major medical societies that focus on menopause and women's health now support the use of HRT for managing symptoms in appropriately selected women within this window.

Not All HRT Is Created Equal

Here's another piece of the puzzle: the type of hormone therapy matters, and so does how you take it.

The original WHI study used pills containing a specific combination of hormones. But there are other types of HRT available, and newer research suggests they may have different effects on your heart.

One big difference is between pills and patches/gels (called transdermal therapy). When you take estrogen as a pill, it goes through your digestive system and liver first, which can affect things like blood clotting factors. Patches and gels deliver hormones directly through your skin into your bloodstream, bypassing that first trip through the liver.

A large 2024 study from Sweden found that women using transdermal HRT (patches or gels) didn't have increased cardiovascular risk, while some women using oral combined therapy did show increased risk.

This doesn't mean one is always better than the other. It's just another factor your healthcare provider can consider when helping you find the right approach for your individual situation.

Who Should Consider HRT?

Let's be clear: HRT is not currently recommended solely for preventing heart disease. Current evidence suggests it can be safely used to treat menopausal symptoms in appropriately selected women close to menopause, but it's not indicated as a primary prevention strategy for cardiovascular disease.

However, for women experiencing bothersome menopausal symptoms who are within that crucial window, HRT may offer cardiovascular benefits alongside symptom relief.

According to the American College of Cardiology's 2023 guidance, women fall into risk categories:

Low-risk candidates: Women with recent menopause, normal weight and blood pressure, who are physically active, have low cardiovascular disease risk (less than 5% over 10 years), and low breast cancer risk.
Intermediate-risk candidates: Women who have one or more risk factors including diabetes, smoking, hypertension, obesity, sedentary lifestyle, autoimmune disease, hyperlipidemia, metabolic syndrome, or those with 10-year cardiovascular disease risk from 5% to 10%.
High-risk candidates: Women with existing cardiovascular disease, history of blood clots, stroke, heart attack, breast cancer, or 10-year cardiovascular disease risk of 10% or greater should generally not use systemic HRT.

The Bottom Line: It's Complicated, But We Know More Now

What we've learned since 2002: when you start HRT matters just as much as whether you start it. For appropriately selected women starting close to menopause, the cardiovascular risks look very different than they did in the original WHI study of older women.

If you're approaching menopause or in its early stages and experiencing symptoms, here's what we want you to know:

Have the conversation. Talk with your healthcare provider about your personal risk factors, family history, and symptoms. Discuss whether you're in that window of opportunity.
The science has evolved. What your doctor learned 20 years ago might not reflect current understanding. Many healthcare providers are now more comfortable discussing HRT within the context of the timing hypothesis.
Think holistically about your health. Your pelvic floor, your cardiovascular system, your bones, your brain: they're all connected, and estrogen plays a role in all of them.
Don't let outdated fear drive your decision. Yes, HRT has risks, and it's not right for everyone. But the blanket fear that emerged from the 2002 WHI findings doesn't tell the whole story, especially for younger, recently menopausal women with symptoms.
Individualize your choice. There is no one-size-fits-all answer. Your personal health history, risk factors, symptoms, and values all matter in this decision.
This Heart Health Month, we encourage you to take your cardiovascular health seriously and to consider the whole picture of your menopausal health: not just your symptoms, but your long-term wellbeing. Your heart and your pelvic floor will thank you.