A large-scale study led by researchers at Beth Israel Deaconess Medical Center (BIDMC) has found that heavy alcohol consumption - 35 or more drinks per week -- can significantly increase men's risk of developing atrial fibrillation, a dangerous type of arrhythmia and one of the leading risk factors for stroke.
Reported in Circulation, the findings - which showed that risk of this rapid, irregular heartbeat was as much as 45 percent higher among heavy drinkers than abstainers--also support the existence of what has come to be known as "holiday heart syndrome."
"Holiday heart syndrome refers to heart rhythm disturbances which develop while a person is on vacation or away from work, and appears to be linked to heavier-than-normal alcohol consumption," explains the study's lead author Kenneth J. Mukamal, MD, MPH, an internist in BIDMC's Division of General Medicine and Primary Care.
"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 per day, this would seem to confirm what has long been suspected regarding periods of significant alcohol consumption, like during vacations."
Atrial fibrillation develops when muscles in the heart's upper chambers contract too quickly, resulting in an ineffective, irregular heartbeat. As a result, blood is not adequately pumped from the heart, and may pool and form clots. Blood clots that travel to the brain result in a stroke, and, indeed, statistics show that having atrial fibrillation results in a nearly five-fold increase in a person's stroke risk.
Using information obtained from the Copenhagen City Heart Study in Denmark, the researchers studied 16,415 individuals (7,588 men and 8,827 women) with an average age of 50. The study included the administering of routine electrocardiograms (ECGs) on three separate occasions between 1976 and 1994 to measure the hearts' electrical activity for each participant.
After adjusting for numerous factors including smoking, education, income, physical activity, body mass index, and diabetes, the researchers analyzed data concerning the participants' consumption of alcohol (beer, wine or spirits).
The researchers documented 1,071 cases of atrial fibrillation during the study period.
"Our results showed that the risk of developing irregular heart beat was similar among both non-drinkers and individuals who drank fewer than 14 drinks per week," explains Mukamal, who is also an Assistant Professor of Medicine at Harvard Medical School.
"But among men who typically drank 35 or more alcoholic beverages per week, the risk of atrial fibrillation increased significantly, by 45 percent. [Because so few women in the study qualified as "heavy drinkers," the researchers did not see similar results among the female participants.]
"This was certainly the largest study of its type to examine this topic," he adds. "And 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."
Study co-authors include the following researchers from the Center for Alcohol Research, National Institute of Public Health in Copenhagen, Denmark: Janne S. Tolstrup, MD, Jens Friberg, MD; Gorm Jensen, MD, Dr.M.Sci; and Morten Gornbaek, MD, PhD, Dr.M.Sci.