Information on 107,845 people from European countries of Sweden, Norway, Finland, Denmark, and Italy was analyzed. The participants joined the study between 1982 and 2010, and their average age was 48 years (ranging from 24 to 97 years) at the time of enrollment. They underwent medical examinations when they joined and provided information on their medical histories, lifestyles (alcohol and tobacco consumption), employment and education levels.
In totality, 100,092 participants did not have atrial fibrillation during enrollment. During the follow-up period, 5,854 people developed atrial fibrillation. The associations between the risk of atrial fibrillation and alcohol consumption were similar for all alcoholic drinks and men and women.
Findings showed that drinking even just one alcoholic drink a day was linked to a 16% increased risk of atrial fibrillation, compared to drinking no alcohol at all. The follow-up time of the study was at an average of nearly 14 years for all. More than 75% of participants consumed up to one drink a day. One alcoholic drink is characterized as containing 12 g of ethanol, equivalent to a small glass of wine (120 ml), a small beer (330 ml), or 40 ml of spirits.
In addition to the 16% increased risk of atrial fibrillation, researchers also found that the risk increased with increasing alcohol intake - with up to two drinks a day, the risk increased to 28%, and for more than four drinks, it was up to 47%.
Heart failure can increase atrial fibrillation, and people who consume large amounts of alcohol regularly are at increased risk of developing heart failure. Studies have also shown a slightly higher risk of heart problems for people who never consume alcohol and a reduced risk for people consuming a modest amount. This risk increases the more alcohol is consumed, creating a 'J' shaped graph.
Professor Renate Schnabel led this study and found that a similar reduction in risk was not seen for atrial fibrillation, suggesting that the increased risk of atrial fibrillation among those who drink small amounts of alcohol was not related to heart failure.
Prof. Schnabel said "To our knowledge, this is the largest study on alcohol consumption and the long-term incidence of atrial fibrillation in the community. Previous studies have not had enough power to examine this question. However, they have shown a relationship between alcohol intake and other heart and blood vessel problems, such as heart attack and heart failure. In our study, we can now demonstrate that even very low regular alcohol consumption may increase the risk of atrial fibrillation."
"These findings are important as the regular consumption of alcohol, the 'one glass of wine a day' to protect the heart, as is often recommended, for instance in the lay press, should probably no longer be suggested without balancing risks and possible benefits for all heart and blood vessel diseases, including atrial fibrillation." he adds.
It is still unknown exactly how modest amounts of alcohol can trigger atrial fibrillation. Heavy drinking over a short period of time can trigger 'holiday heart syndrome' in some people, and small amounts of alcohol can trigger arrhythmia episodes in some patients with atrial fibrillation.