Can Menopause Hormone Therapy (MHT) Protect You From Heart Disease? Here’s the Truth

If you take, or are considering taking, menopause hormone therapy (MHT,) you've probably wondered about its effect on your heart.

Maybe you've heard that estrogen protects women from heart disease. Maybe you've also heard the opposite: that hormone therapy increases the risk of heart attack and stroke.

So which is it?

As is often the case with menopause, the answer is more nuanced than either of those statements.

Can MHT prevent heart disease?

Let's start with the most important point: we do not prescribe MHT to prevent cardiovascular disease.

That doesn't mean MHT is bad for your heart. It means that the evidence does not show that taking MHT specifically to prevent heart attacks or cardiovascular death provides enough benefit to recommend it for that purpose. Major guidelines and reviews agree: MHT should not be used specifically to prevent heart attacks, stroke, or cardiovascular death.

This distinction is important because MHT can be an excellent treatment for menopausal symptoms, including hot flashes and night sweats. It can also be helpful for genitourinary symptoms and can help prevent bone loss.

So why did we ever think estrogen might protect the heart?

Where did the heart-protection theory come from?

The idea made a lot of sense.

Before menopause, women generally have a lower risk of coronary heart disease than men of the same age. Estrogen also has effects on blood vessels and cholesterol, so researchers naturally wondered whether replacing estrogen after menopause might preserve some of that cardiovascular advantage.

Early observational studies appeared to support the idea.

But there was a problem.

The women who chose to take MHT in those studies tended to be healthier in other ways. They were often more physically active, had higher incomes, had better access to healthcare, and had other characteristics associated with lower cardiovascular risk.

That's called healthy-user bias, and it can make a treatment look more beneficial than it actually is.

Animal studies and laboratory research can also help us understand possible mechanisms, but they don't tell us whether a treatment actually prevents heart attacks in women.

For that, we needed randomized clinical trials.

What did the major studies show?

The Women's Health Initiative (WHI) was designed to answer this question.

It was a large randomized clinical trial that studied menopausal hormone therapy and provided some of the most important evidence we have about its long-term risks and benefits.

The results were not what many researchers expected.

The combination of oral conjugated estrogen and medroxyprogesterone acetate did not reduce coronary heart disease. The trial also found increases in some adverse outcomes, including stroke and venous thromboembolism, particularly among women who were older or further from the time of menopause.

In women who had undergone hysterectomy and therefore did not need a progestogen, the estrogen-only arm produced somewhat different results. In later age-stratified analyses, it showed a signal toward reduced coronary heart disease in younger women, but the overall trial result was not statistically significant for coronary heart disease prevention.

But this does not mean we should give estrogen to women to prevent heart disease.

The overall evidence does not establish MHT as a cardiovascular-prevention treatment, and the risks and benefits depend on the type of hormone therapy, route of administration, dose, timing, age, and the individual woman.

This is one reason I am cautious about statements like "estrogen protects your heart." They take a complicated body of evidence and turn it into something much simpler than it really is.

So, is MHT bad for your heart?

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