Study: Heavy drinking tied to risk of having irregular heart rhythm

People with atrial fibrillation have an increased risk of suffering a stroke.
SCRIPPS HOWARD
Heavy drinking -- even if it's not steady -- may be linked to an increased risk of developing an irregular heart rhythm, according to the authors of a new study.
The study, reported today in the journal Circulation, showed that the risk of developing a rapid, irregular heartbeat, called atrial fibrillation, was up to 45 percent higher among heavy drinkers (those who drank 35 or more servings of alcoholic beverages a week) compared with nondrinkers.
But the findings also suggest one possible cause for what cardiologists term "holiday heart syndrome" -- heart-rhythm disturbances that develop when a person is on vacation or away from work, and often drinking more than usual.
"Since our research found that the risk of developing atrial fibrillation begins to increase at about four drinks per day, and clearly goes up at five drinks a day, this would seem to confirm what has long been suspected regarding periods of significant alcohol consumption, like during vacations," said Dr. Kenneth Mukamal, lead author of the study and an internist at Beth Israel Deaconess Medical Center in Boston.
Used Danish study
The Boston researchers tapped data from the Copenhagen City Heart Study in Denmark, which included 16,415 people with an average age of 50. The study included administering an electrocardiogram on three separate occasions between 1976 and 1994 to measure the electrical activity of the heart in each patient.
Researchers documented 1,071 cases of atrial fibrillation during the study period.
Atrial fibrillation develops when the muscles in the heart's upper chambers contract too quickly, causing an ineffective quiver rather than a regular heartbeat. About 2.2 million Americans have this condition, which becomes more likely in old age.
As a result of the irregular heartbeat, blood is not adequately pumped from the heart and is more likely to pool and form clots. Blood clots that travel to the brain cause strokes. People with atrial fibrillation face nearly five times the risk of having a stroke as people who don't have the condition.
Atrial fibrillation is generally treated with drugs and less frequently by surgery or the insertion of a pacemaker.
Risk increased with drinking
After taking into account such factors as smoking, education, income, physical activity, body mass index and diabetes, the researchers analyzed information gathered on the participants' consumption of beer, wine or spirits.
The results showed that while risk increased with alcohol consumption, the odds of developing an irregular heartbeat was similar among both nondrinkers and individuals who drank fewer than 14 drinks a week, said Mukamal, who is also an assistant professor of medicine at Harvard Medical School.
A single serving of alcohol is considered the equivalent of a 12-ounce beer, 4 ounces of wine or 1.5 ounces of liquor. With a cutoff of 35 drinks a week and more for "heavy drinkers," very few of the 8,827 women in the study qualified and the researchers did not see similar results among the female participants.
"While it is reassuring that moderate drinkers did not seem to have an increased risk of this hazardous heart rhythm, our findings provide yet more evidence of the risks of heavy drinking to the heart," Mukamal said.