THURSDAY, May 10, 2007 (HealthDay News) -- Raising a glass too often could put heavy drinkers at risk for atrial fibrillation, a dangerous heart condition that can trip off a stroke or heart failure, British researchers warn.
Luckily, reducing alcohol consumption even a little bit makes a big difference, said the authors of a study slated for presentation Thursday at the annual meeting of the Heart Rhythm Society, in Denver.
"We can't extrapolate from this study that heavy drinking is responsible, but it certainly is an interesting finding," added Dr. Rudolph Nisi, chief of cardiology at Westchester Square Medical Center in New York City. He was not involved in the study.
The finding also underscores the importance of responsible drinking.
"Drinking in moderation . . . is safe and does not significantly increase the chances of developing new atrial fibrillation (AF)," said Dr. Joe Martins, lead author of the study and a cardiologist at the Imperial College, London. "However, drinking in excess of this was strongly associated with an increased probability of developing new AF."
Atrial fibrillation is the most common irregular heart rhythm. A recent study indicates that the problem may be even more common than previously thought. That study, appearing in the journal Circulation, estimated that 5.1 million Americans have atrial fibrillation, not 2.2 million as originally thought.
"AF is becoming an increasing public health burden," Martins said. "It is associated with a fivefold increased risk of stroke, a three-fold risk of heart failure and up to a two-fold increase risk of death."
Drinking has been associated with cardiac disease in the past, including rhythm disturbances, experts said.
There is a higher incidence of arrhythmias around the holidays, thus giving rise to so-called "Holiday Heart Syndrome," noted Dr. John P. Erwin III, assistant professor of internal medicine at Texas A&M Health Science Center College of Medicine and a cardiologist with Scott & White Hospital. "Around the holidays, when people are imbibing more than they're accustomed to, there are more people coming in with new onset atrial fibrillation," Erwin said. "So there's been a somewhat loose correlation with alcohol consumption and atrial fibrillation."
And, according to the study authors, binge drinking has also been associated with atrial fibrillation in the past, even though data on long-term alcohol consumption and risk is less clear.
For this study, all patients arriving at an arrhythmia clinic at Charing Cross Hospital in London with symptoms of a new cardiac arrhythmia were asked about their weekly alcohol consumption.
Participants were grouped according to how much they drank: teetotaler (those who abstained completely), moderate drinkers (1-14 units per week for females and one to 21 units per week for males) and excessive (anything greater than moderate). In the study, two units were about equal to one pint of beer.
Those with confirmed atrial fibrillation were then compared to those without the irregular heart beat.
About half (48 percent) of people in each group were moderate drinkers, suggesting no increase in risk.
Excessive drinking, however, was much higher in patients with atrial fibrillation than in patients without (27 percent versus 17 percent, respectively).
In fact, these heavy drinkers raised their risk of atrial fibrillation by 2 percent for each additional unit they drank compared to non-drinkers.
It's not clear how alcohol and rhythm disturbances might be linked, but the experts offered up some theories.
One is that heavy drinking ramps up the body's "fight-or-flight" response, Erwin said. Another is that drinking can raise the level of fatty acids in the bloodstream.
"Several mechanisms have been suggested from very small studies, including the high adrenaline state of drinking and alcohol withdrawal and impaired vagal heart rate control," Martins said.
Cutting down on drinking could lower the risk, he said.
"We found that nearly one in five of all 984 patients that we evaluated in our study admitted to drinking more than the recommended level," Martins said. "If this behavior could be modified, one might speculate that it could potentially result in a significant reduction in the number of new AF cases."
There's more on atrial fibrillation at the American Heart Association.