Medscape.com
More Bad Booze News: Even Moderate Drinking Linked With AF
Michael O’Riordan
July 14, 2014

STOCKHOLM, SWEDEN — Drinking alcohol, even light to moderate consumption, appears to be associated with an increased risk of developing atrial fibrillation, according to a new analysis^[1].

Among individuals who drank between 15 and 21 drinks per week and those who drank more than 21 drinks in a week, the risk of atrial fibrillation was increased 14% and 39%, respectively, when compared with nondrinkers. Binge drinking, defined as having five or more drinks on any one occasion, was associated with a 13% higher risk of developing atrial fibrillation regardless of how many drinks were consumed in the week.

The risk of atrial fibrillation was also increased among those who consumed just one to two drinks per day, or seven to 14 drinks per week. Among those who drank lightly and who had no coronary heart disease or heart failure at baseline, the risk of atrial fibrillation was increased 12% compared with nondrinkers. However, in the entire cohort, which included those with baseline heart disease, the risk of atrial fibrillation was not elevated among the light drinkers.

“We know that heavy alcohol consumption increases the risk of atrial fibrillation,” lead investigator Dr Susanna Larsson(Karolinska Institutet, Stockholm, Sweden) told heartwire . “There are also studies showing that moderate consumption increases the risk, but what’s new here is that this is quite a small amount of alcohol [consumed], and the risk is also increased.”

Prospective Study plus Meta-Analysis

The study, published online July 14, 2014 in the Journal of the American College of Cardiology, included 79 019 men and women who completed a questionnaire about alcohol consumption as part of the Cohort of Swedish Men (COSM) and Swedish Mammography Cohort (SWM) studies. After 12 years of follow-up, there were 7245 incident cases of atrial fibrillation.

Alcohol Drinking Status and Risk of Atrial Fibrillation

In addition to light and moderate alcohol consumption, the risk of atrial fibrillation was also observed among those who drank heavily. The relationship between alcohol consumption and atrial fibrillation remained even after excluding patients who were identified as binge drinkers. When stratified by the type of alcohol consumed, the relationship with atrial fibrillation was strongest for those who drank liquor, weaker for those who drank wine, and weakest for those who drank beer.

In addition to the COSM and SWM analysis, the researchers also conducted a meta-analysis. Combining COSM and SWM with five additional studies, the researchers “observed a linear dose-response relationship between alcohol consumption and atrial-fibrillation risk, with no evidence of departure from linearity.”

In an editorial^[2], Dr David Conen (University Hospital, Basel, Switzerland) and Dr Christine Albert (Brigham and Women’s Hospital, Boston, MA) say the meta-analysis, which is in line with the prospective data, enhances their “confidence in the potential causality of the link between alcohol intake and atrial fibrillation.”

The editorialists point out that hypertension and obesity are two important risk factors that explain about 40% of the population-attributable risk for atrial fibrillation, but there is no explanation for the remaining 50% or 60%.

“In comparison, modifiable risk factors explain 80% to 90% of the attributable risk for sudden cardiac death and MI, respectively,” they write. “The present study supports the widely held contention that significantly elevated alcohol consumption, particularly binge drinking, is related to atrial fibrillation and should be avoided. The study also agrees with other prospective data suggesting that chronic levels of alcohol intake above two drinks per day may modestly elevate atrial fibrillation in men and women.”

Although there is a weak association with even less amounts of alcohol, this study does definitively answer how much alcohol is too much, write Conen and Albert.

Neither the paper’s authors nor the editorialists have any conflicts of interest.

References

1. Larsson SC, Drca N, Wolk A. Alcohol consumption and risk of atrial fibrillation: prospective study and dose-dependent meta-analysis.J Am Coll Cardiol 2014; DOI:10.16.j.jacc.2014.04.048. Available at:http://content.onlinejacc.org/journal.aspx.
2. Conen D, Albert CM. Alcohol consumption and risk of atrial fibrillation: how much is too much? J Am Coll Cardiol2014; DOI:10.16.j.jacc.2014.04.038. Available at: http://content.onlinejacc.org/journal.aspx