Heavy drinking tied to heart rhythm problem in men

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."

Atrial fibrillation/flutter is a heart rhythm disorder (arrhythmia). It usually involves a rapid heart rate, in which the upper heart chambers (atria) are stimulated to contract in a very disorganized and abnormal manner.
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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.

Arrhythmias are caused by a disruption of the normal functioning of the electrical conduction system of the heart. Normally, the atria and ventricles contract in a coordinated manner.

In atrial fibrillation and flutter, the atria are stimulated to contract very quickly and differently from the normal activity originating from the sinoatrial node. This results in ineffective and uncoordinated contraction of the atria in atrial fibrillation, and in a peculiarly organized contraction pattern in atrial flutter.

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.