Dear Dr. K: I’m in my third year of menopause, and my doctor won’t prescribe hormone therapy. He says it increases the risk of heart disease. I think I recall that you told another reader that this is not true. Is my doctor right, or are you?
Dear Reader: You won’t be surprised to learn that I think I’m right. But in the previous column you refer to, I didn’t say exactly what you remember. I said that the effect of hormone therapy (HT) on heart disease depends on a woman’s age and how recently she entered menopause. In younger women, in their first six to 10 years after menopause, HT protects against heart disease. In contrast, in older women, HT increases the risk of heart disease. It’s called the “age effect.”
Hormone therapy usually involves a combination of both estrogens (the main female hormones) and progestins (other important female hormones). Estrogen helps reduce the symptoms of menopause, such as hot flashes. Progestin reduces the risk of cancer of the uterus.
When we talk about the effect of HT on heart disease, we’re focusing on the most common type of heart disease: atherosclerosis. Atherosclerosis causes cholesterol-filled “plaques” in the walls of the arteries that supply blood to the heart. As these plaques grow, they can block the flow of blood through the arteries. When blood flow to a part of the heart muscle stops, the muscle dies. That’s what happens in a heart attack.
A plaque has a cap made of fibers that hold in the plaque’s pool of cholesterol. In some plaques, called “vulnerable plaques,” inflammation inside the plaque eats away at the fibrous cap. Suddenly, the fibers rupture, cholesterol spills into the artery, a blood clot forms — and blood flow to a part of the heart stops.
Estrogen slows the development of plaques. By the time a woman reaches menopause, her own natural estrogen has helped protect her against developing plaques. By 10 years after menopause, however, the average woman has vulnerable plaques that threaten to rupture. Estrogen increases inflammation inside the plaques and causes blood to clot more easily. So estrogen now increases the risk of heart attacks.
A study published in March 2016 in The New England Journal of Medicine supports what I’m saying. Over 600 women were divided into two groups: those less than six years past menopause (called the “early postmenopause” group) and those 10 years or more past menopause (the “late postmenopause” group). Each group was treated for up to seven years with either HT or a placebo.
In the early postmenopause group, HT slowed the development of atherosclerosis. In the late postmenopause group, it did not. Several other studies of a similar type have come to the same conclusion. Also, studies in animals — including monkeys, which are biologically similar to humans — conclude that there is an “age effect.”
You are just three years into menopause. Unless you already have heart disease, or have risk factors for heart disease, HT is more likely to protect you from heart disease than to put you at risk.