If you like to have a glass or two of wine each night, your heart won't skip a beat over the latest research. A new study of more than 16,000 people has found that drinking alcohol in light and moderate amounts may not be linked to atrial fibrillation, a form of irregular heartbeat.
Atrial fibrillation (AF) is a known cause of strokes and is also associated with congestive heart failure and other heart disease, according to the study's lead author, Dr. Kenneth Mukamal of Beth Israel Deaconess Medical Center in Boston, who is at the forefront of research on alcohol and heart health. (His previous studies have found, among other things, that drinking wine after a heart attack may help prevent another, that how often you drink may be more important in reducing heart disease than what you drink or how much.) His latest work, the largest to date on the relationship between drinking habits and AF, was published in the September issue of Circulation.
While the findings are supported by an earlier study from Boston University on AF and light to moderate drinking, Mukamal said that the scientific research to date has not been conclusive. "There has been a general consensus that episodes of heavy drinking can lead to AF," he said, "but no such consensus about usual alcohol intake."
Mukamal and his team, which also included noted Danish wine-and-health researcher Morten Grønbæk, pulled data from the larger Copenhagen City Heart Study, which took place between 1976 and 1994. The 19,698 volunteers, ages 20 to 49, were randomly selected from the Copenhagen Population Register. They provided extensive data on their dietary and drinking habits, income and education levels and other lifestyle factors. Over the course of the study, each volunteer also received three exams, at which they were tested with electrocardiograms for AF.
The researchers evaluated information from 16,415 participants, after excluding those with incomplete or inconsistent data on their drinking patterns or prior incidences of stroke or heart disease.
The participants were categorized according to how much they drank in a typical week. Nondrinkers and those who consumed less than one drink per week were used as the control group. The other categories were one to six drinks per week, seven to 13, 14 to 20, 21 to 27, 28 to 34 and 35 or more. (Participants were told that a drink equals a 4- or 5-ounce glass of wine, a bottle of beer or a 1- to 1.5-ounce shot of liquor.) During the study, 1,071 cases of AF were documented.
By comparing the rates of AF to the patients' alcohol consumption, the researchers found that men and women who drank lightly to moderately did not show a greater risk of AF than abstainers or those who rarely drank. This pattern held steady across the consumption levels until the heaviest category, 35 drinks or more per week. The drinkers in this category were found to have a 45 percent higher risk of AF. (Few women drank that much, the study noted, so men are better represented by this result.)
The researchers also broke down the data according to the type of alcohol the subjects preferred and came up with similar results. "We really didn't find statistically meaningful differences across beverage types," Mukamal said. "If there is a beverage-specific effect, it will require much larger studies."
While no increased risk of AF was seen for consumption of three or four drinks per day (a quantity defined as moderate by the Dutch, though considered heavy drinking in the United States), the authors of the study cautioned that they cannot definitively "exclude a modest increase in risk" at this level. They instead concluded that the study shows, more importantly, the "cardiotoxic effects of heavy drinking."
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