Based on multiple epidemiologic studies, a relationship between alcohol intake and atrial fibrillation (AFib) has been identified, with the lowering of the former potentially being an effective means of preventing the latter. While previous meta-analyses of observational investigations discovered evidence of a linear correlation between these two factors, several of these studies assessed alcohol intake after the AFib event.

A study published July 14 in the Journal of the American College of Cardiology attempted to bring clarity to previous research, and found that even in moderation, consumption of wine and hard liquor may be a risk factor for AFib, but did not identify a similar risk for moderate consumption of beer.

Susanna C. Larsson, PhD, Unit of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden, and her co-authors studied 79,016 adults, ages 45 to 83, who completed an extensive questionnaire about food and alcohol consumption in 1997. The researchers followed the participants for up to 12 years through national registries in Sweden and found 7,245 cases of AFib.

They found that compared with those who consumed less than one drink of alcohol per week, those who ingested between 15-21 and greater than 21 had a 14 percent and 39 percent elevation in their relative risk of developing AFib, respectively. However, consuming less than 15 drinks per week – roughly two drinks per day – was not substantially associated with AFib development. While the results of the study were remarkably similar to the results of the prior meta-analysis involving retrospective data – reiterating that each drink of alcohol consumed per day was associated with an estimated eight percent increase in the relative risk of AFib in both men and women – by focusing on prospective studies only, the response data in the current meta-analysis increases researchers' confidence in the potential causality of the link between alcohol intake and AFib.

In addition to confirming studies performed before it, Larsson and her colleagues had a number of key findings of their own. Among the data was the fact that binge drinking (categorized as more than five drinks on a single occasion) was reported by 18 percent of the population and was associated with an increased risk of new-onset AFib, independent of the number of drinks consumed per week. The study also demonstrated that the type of alcoholic beverage may impact AFib risk, with the highest relative risks observed for liquor followed by wine, and no apparent association for beer consumption.

In a corresponding editorial comment, David Conen, MD, MPH, and Christine M. Albert, MD, MPH, note, "Although the meta-analysis suggests that lower amounts of alcohol also may be associated with elevations in AFib risk, the question of how much is too much is not definitely answered by this study... Because the AFib risk related to consuming low-to-moderate amounts of alcohol (i.e., <2 drinks per day) is small, these data in isolation should not discourage individuals from safely consuming and enjoying such modest amounts of alcohol."