Contact: Amanda Jekowsky, ajekowsk@acc.org, 202-375-6645

Regularly consuming large amounts of alcohol place people at greater risk of developing atrial fibrillation (AF) than those who are non-heavy drinkers, data from a recently published study in the January 25, 2011, issue of the Journal of the American College of Cardiology suggest. Providing clarity to a research subject that has yielded inconsistent results, the meta-analysis of 14 studies also showed there is a linear dose-response relationship between alcohol consumption and AF, suggesting that the risk of AF increases alongside an increasing amount of consumed alcohol.

Atrial fibrillation is the most common arrhythmia seen in outpatient practices and is accompanied by serious complications, such as embolic stroke. While the association between episodic heavy alcohol use and the onset of AF (“holiday heart syndrome”) has long been recognized, a Japanese team led by a researcher from the University of Tsukuba Institute of Clinical Medicine sought to determine if AF could also be linked to habitual heavy drinking. The researchers also investigated the exact dose-response relationship between drinking and AF to determine the risk associated with moderate alcohol intake.

The team conducted a literature search through two databases, MEDLINE (Jan. 1966 to Dec. 2009) and EMBASE (Jan. 1974 to Dec. 2009). They ultimately included 14 observational studies in their investigation, which comprised 130,820 participants and 7,558 cases. Although the definition of heavy drinking varied among the studies, the team limited their analysis to studies that defined the highest intake category as at least 2 drinks per day for men, at least 1 drink per day for women, or participants described as alcoholics (or alcohol abusers). The lowest intake category, or abstainers, was the referent group.

Using statistical analyses, the researchers compared the risk of AF in both the highest alcohol intake group and the lowest alcohol intake group across the 14 studies. They then conducted regression analysis to determine the shape of the relationship between alcohol consumption and AF risk.

The team found that habitual high alcohol intake was shown to be associated with “a significant elevation in AF risk.” This increased risk existed both in the overall analysis and when the researchers conducted stratified analyses based on key study characteristics, such as age, gender, geographic region, study design, and definition of heavy alcohol consumption. The regression analysis showed that the shape of the relationship between alcohol consumption and AF was linear, indicating that as alcohol consumption increased, so too did the risk of AF.

According to the authors, the results suggest that not only episodic but also habitual heavy drinkers have a higher risk of AF compared to non-heavy drinkers. In addition, the linear relationship between alcohol and AF suggests that “not consuming alcohol at all is the most favorable behavior for avoiding AF,” they write, even though moderate alcohol intake has shown to be beneficial for reducing the risk of cardiovascular disease and all-cause mortality.

While the authors do recognize several study limitations—such as the study’s inability to detect the effect of different types of alcoholic beverages and the possibility of unknown confounders—study authors Satoru Kodama, M.D., Ph.D., and Hirohito Sone, M.D., Ph.D., both of the Department of Internal Medicine at the University of Tsukuba Institute of Clinical Medicine, note that the research “will have a substantially profound implication on the primary prevention of AF, which is especially important given the sparseness of existing epidemiological evidence, the rapid growth of the occurrence of AF, and the seriousness of AF-specific complications.”

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