Harvard Women's Health Watch

In the journals: Studies find a link between hot flashes and cardiovascular risk

In the journals

Studies find a link between hot flashes and cardiovascular risk

It's little wonder that hot flashes have come to symbolize the downside of menopause. The sudden increases in body temperature that trigger flushing and night sweats can be disruptive and, in some cases, debilitating. In fact, recent evidence indicates that severe hot flashes may be more than a nuisance: they may be linked to increased risk for cardiovascular disease.

Since 2007, three large-scale investigations have associated hot flashes with risk factors for heart disease and stroke. The studies and their findings are these:

  • The Women's Health Initiative (WHI). In the Journal of the American Medical Association (April 4, 2007), WHI researchers reported the results of an analysis designed to determine whether the age at which women begin hormone therapy (HT) affects their heart disease risk. Researchers studied more than 27,000 postmenopausal women, ages 50 to 70, who were randomly assigned to take either HT or a placebo. They subdivided these women into three groups: those with no history of hot flashes, those with mild hot flashes, and those who had moderate to severe hot flashes. The investigators found that the increased risk of cardiovascular disease seen in women who were more than a decade out from menopause was largely limited to women who continued having moderate to severe hot flashes.

  • The Eindhoven Perimenopausal Osteoporosis Study. This large prospective investigation was initiated in the city of Eindhoven, the Netherlands, in the mid-1990s to identify factors associated with low bone density during the menopausal transition. Data collected from Eindhoven residents born between 1938 and 1948 have since been used to study other health conditions that affect women in midlife. In Hypertension (June 2008), researchers analyzed information from 5,523 Eindhoven study participants who answered questions about the frequency and intensity of hot flashes and night sweats. About half of the women had no symptoms, while the other half reported flushing, night sweats, or both. The researchers found that as these symptoms increased in severity, so did blood cholesterol, high blood pressure, and body mass index.

  • The Study of Women's Health Across the Nation (SWAN). SWAN Heart — one component of this nationwide study of the physical changes that occur during perimenopause (the handful of years preceding menopause) — examined the relationship between hot flashes and early, undetected heart disease. In Circulation (October 2008), SWAN Heart investigators reported the results of a study involving 492 perimenopausal women who weren't taking hormone therapy. The women completed questionnaires assessing their menopausal symptoms and underwent ultrasound tests of arterial function and CT scans of their hearts. The investigators found that, as a group, women with hot flashes had significantly greater calcification of their aortic valves — and their blood vessels were less able to dilate as blood flow increased. Both changes are early signs of cardiovascular disease.

These studies raise important questions: Are hot flashes a risk factor for heart disease or vice versa? What mechanisms might connect the two? Will quelling hot flashes improve cardiovascular risk or perhaps even reverse early heart disease? Until the answers are in, the best advice for women with severe or persistent hot flashes is to consider reviewing their cardiovascular risk factors with their clinicians — and to pay special attention to lifestyle practices that reduce the risk of heart disease and stroke, including exercise, weight control, and not smoking.

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