The large scale study of over 16,000 Danes found that 35 or more drinks a week can increase the risk of atrial fibrillation, a condition 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. Statistics show that having atrial fibrillation results in a nearly five-fold increase in a person's stroke risk.
Risk of this rapid, irregular heartbeat was as much as 45 per cent higher among heavy drinkers than abstainers, report researchers at the Beth Israel Deaconess Medical Center (BIDMC).
This, they say, also supports 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.
The risk of developing atrial fibrillation begins to increase at about four drinks per day, and clearly goes up at five drinks per day, they add.
The researchers used information from the Copenhagen City Heart Study in Denmark that tracked 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 analysed data concerning the participants' consumption of alcohol (beer, wine or spirits).
The researchers documented 1,071 cases of atrial fibrillation during the study period.
The risk of developing irregular heart beat was similar among both non-drinkers and individuals who drank fewer than 14 drinks per week, they further conclude.
With regards to women, the researchers said that because so few women in the study qualified as "heavy drinkers," they did not see similar results among the female participants.
Full findings are published in the 13 September 2005 issue of Circulation.