Harvard Women's Health Watch

In the journals: Alcohol can increase the risk of heart rhythm problems in middle-aged women

In the journals

Alcohol can increase the risk of heart rhythm problems in middle-aged women

Atrial fibrillation is a common heart rhythm disturbance that occurs when the upper chambers of the heart — the atria — contract abnormally. Symptoms range from a fluttering sensation in the chest to shortness of breath and fainting. Atrial fibrillation isn't immediately life-threatening, but it increases the likelihood of having a stroke. Age is the main risk factor, but drinking too much can also play a role. But how much alcohol is too much?

According to a study, middle-aged women may slightly increase their chances of developing atrial fibrillation by taking as few as two drinks per day, compared with women who drink less than that or not at all. Results were published in The Journal of the American Medical Association (Dec. 3, 2008).

Researchers at Harvard Medical School and in Switzerland noted episodes of atrial fibrillation over a 12-year period in 34,715 healthy women, ages 45 and over, who were part of the Women's Health Study. At the beginning of the study, again four years later, and annually thereafter, participants answered questions about their daily intake of beer, wine, or spirits in the previous year. Episodes of atrial fibrillation were tracked and confirmed through medical records.

There were 653 cases of atrial fibrillation during the 12-year follow-up. Compared with the women who didn't drink or who had fewer than two drinks per day, those who reported having two or more drinks per day experienced a 60% increased risk of developing atrial fibrillation. Because the total number of cases of atrial fibrillation was small, this difference amounted to less than one extra atrial fibrillation event per 1,000 women per year. The study focused on healthy middle-aged women (most of whom were white). Results might vary in other populations of women.

In this study, women could take up to two drinks per day without increasing their risk of atrial fibrillation. But that doesn't mean women should drink at that level. It's important to keep in mind that, for women, moderate drinking is generally defined as no more than one drink per day — an intake level that takes into account what's known so far about the benefits (such as for the heart) and the risks (including an increased risk of breast cancer starting at less than one drink per day) of alcohol in women. So for now, it's best to limit your alcohol intake to no more than one drink daily. (To find out how many ounces constitute one drink of different kinds of alcoholic beverages, see "What's a drink?")

What's a drink?

Illustration of various alcoholic beverages