Moderate alcohol consumption raised risk for AF

Alcohol consumption, even in moderation, raised risk for atrial fibrillation in a study of men and women in Sweden.

In the cohort study, researchers observed that consumption of more than 14 drinks per week of liquor or wine was associated with increased risk for AF. However, there was no association between beer consumption and AF risk. In a meta-analysis, the researchers reported a dose-response relationship between alcohol consumption and AF risk.

The prospective cohort study included 79,019 men and women who were free from AF at baseline. All participants had completed a questionnaire about alcohol consumption and other risk factors for chronic diseases. Diagnoses of AF were confirmed using the Swedish Inpatient Register.

The researchers identified 7,245 cases of incident AF during 859,420 person-years of follow-up from 1998 to 2009. The association between alcohol consumption and AF did not differ by sex (P=.74).

Compared with consumption of less than one drink per week, the multivariable RRs for AF were as follows:

1 to 6 drinks per week, RR=1.01; 95% CI, 0.94-1.09.
7 to 14 drinks per week, RR=1.07; 95% CI, 0.98-1.17.
15 to 21 drinks per week, RR=1.14; 95% CI, 1.01-1.28.
22 or more drinks per week, RR=1.39; 95% CI, 1.22-1.58.

The results did not change after excluding binge drinkers, the researchers found.

Wine, liquor differ from beer

The association between consumption of liquor and AF risk became statistically significant at 7 to 14 drinks per week (RR=1.13; 95% CI, 1.01-1.28), and the association between consumption of wine and AF risk became statistically significant at 14 or more drinks per week (RR=1.3; 95% CI, 1.06-1.61). The association between beer consumption and AF risk was not significant even at 14 or more drinks per week (RR=1.06; 95% CI, 0.93-1.23), according to the researchers.

“We have no explanation for the lack of association with beer consumption,” Susanna C. Larsson, PhD, associate professor in the unit of nutritional epidemiology at the Institute of Environmental Medicine at the Karolinska Institute, Stockholm, Sweden, said in a press release. “It is more likely that beer is consumed regularly during the week, whereas wine and liquor is more often consumed during weekends only. Adverse effects of alcohol on [AF] risk may be less pronounced if alcohol consumption is spread out over the week compared with consumption of larger amounts of alcohol during a few days per week.”

The researchers also conducted a meta-analysis of 7 prospective studies, including their own. The meta-analysis did not differentiate between types of alcohol.

The association between alcohol consumption and AF risk was present even in those drinking one drink per day, and the risk became greater for each extra drink per day consumed. The RRs compared with nondrinkers were as follows:

1 drink per day, RR=1.08; 95% CI, 1.06-1.1.
2 drinks per day, RR=1.17; 95% CI, 1.13-1.21.
3 drinks per day, RR=1.26; 95% CI, 1.19-1.33.
4 drinks per day, RR=1.36; 95% CI, 1.27-1.46.
5 drinks per day, RR=1.47; 95% CI, 1.34-1.61.

Results did not differ by sex or by continent, and excluding the researchers’ own study did not change them.

Question of alcohol intake

Lowering alcohol intake could now join lowering BP and lowering BMI as AF prevention strategies, David Conen, MD, MPH, and Christine M. Albert, MD, MPH, both from the Center for Arrhythmia Prevention at Brigham and Women’s Hospital, wrote in a related editorial.

“The present study supports the widely held contention that significantly elevated alcohol consumption, particularly binge drinking, is related to AF and should be avoided,” they wrote. However, they added, “the question of how much is too much is not definitively answered by this study. Because the AF risk related to consuming low-to-moderate amounts of alcohol (ie, <2 drinks per day) is small, these data in isolation should not discourage individuals from safely consuming and enjoying such modest amounts of alcohol.”

For more information:

Conen D. J Am Coll Cardiol. 2014;64:290-292.

Larsson SC. J Am Coll Cardiol. 2014;64:281-289.

Disclosure: The researchers, Conen and Albert report no relevant financial disclosures.