Men who consume 35 or more alcoholic drinks per week are 45 percent more likely to experience Atrial fibrillation, a heart rhythm problem, than their peers who consume less than one drink per week, according to new research.

The same probably holds true in women, but no firm conclusions could be reached because there weren’t enough women in the study who were classified as heavy drinkers.

Atrial fibrillation is a common problem in which the upper chambers of the heart beat erratically. Because blood does not empty from the chambers as it should, clots can form, which, if dislodged and passed to the brain, can cause a stroke. For this reason, patients with atrial fibrillation are often treated with blood thinners as well as with medications to slow down the rapid heart rate.

Previous evidence on drinking and atrial fibrillation “has been all over the map,” said lead author Dr. Kenneth J. Mukamal, from Beth Israel Deaconess Medical Center in Boston. “I think the clinical assumption has always been that if there is a higher risk of atrial fibrillation among alcohol drinkers, it is among people who drink a lot. Our results confirm this belief.”

The findings, which appear in American Heart Association’s journal Circulation, are based on analysis of data from 16,415 men and women who participated in the Copenhagen City Heart Study, a population-based study that began in 1976. During follow-up, a total of 1071 new cases of atrial fibrillation occurred.

As noted, heavy alcohol consumption was associated with a significantly increased risk of Atrial fibrillation in men. Moreover, the researchers estimate that about 5 percent of atrial fibrillation cases in men were due to heavy alcohol use.

There was no evidence that one type of alcoholic beverage was any more culpable than another in raising atrial fibrillation risk, Mukamal noted. However, he added that it was difficult to sort out the effects of each beverage since most heavy drinkers did not stick to just one type.

Asked if the present study provides the “final word” on the link between alcohol use and atrial fibrillation, Mukamal said, “It is certainly the largest study to look at this topic and I think this is probably as good as can be done.”

The take-home message from this study and others seems to be “don’t expect any benefit or risk from moderate drinking, but expect an elevated risk of atrial fibrillation with heavy drinking,” he concluded.

SOURCE: Circulation, online September 13, 2005.