Alcohol Intake and Atrial Fibrillation: Even Moderation Is Risky

As the incidence of atrial fibrillation (AF) increases worldwide, awareness of risk factors for this arrhythmia is also on the rise. For some risk factors, such as aging, obstructive sleep apnea, and hypertension, the association with increased risk for AF is clear. The danger associated with other possible risk factors is less certain and results from previous studies have been variable. Moderate alcohol intake has long fallen into this latter category. An expansive new study, however, sheds new light on this association.

The recent study and meta-analysis published in the Journal of the American College of Cardiology prospectively followed 79,019 Swedish subjects and studied the association of self-reported baseline alcohol intake with incident AF over 859,420 person-years of follow-up. Of the 7245 incident cases of AF studied, there was no increased risk for those who consumed 1 to 6 alcoholic drinks per week or 7 to 14 drinks per week compared with those who consumed less than 1 drink per week. However, there was a 14% higher risk for incident AF among those who had 15 to 21 drinks per week (95% CI, 1.01 to 1.28) and a 39% higher risk for those who had more than 21 drinks per week (95% CI, 1.22 to 1.58). Results were similar in a sensitivity analysis that excluded binge drinkers, and there was no difference in these results based on sex. Interestingly, there was some heterogeneity with respect to type of alcohol consumed: wine and liquor were associated with increased risk for AF, whereas beer, regardless of amount consumed, was not.

In the meta-analysis portion of the study, 7 prospective studies were pooled with a total of 12,554 cases of AF, and results were slightly different. Even 1 drink per day was associated with an 8% higher incidence of AF (95% CI, 1.06 to 1.10), with a dose-response relationship for AF risk: 17% for 2 drinks; 26% for 3 drinks; 36% for 4 drinks and 47% for 5 drinks (approximately 8% increase in AF risk per daily drink consumed).

With its large number of cases of incident AF, this meta-analysis provides definitive evidence that intake of even moderate amounts of wine or liquor significantly increases the risk for incident AF. The pathophysiologic mechanisms of this association are poorly understood, but it may be mediated by alcohol-induced atrial myocyte toxicity or by comorbidities, such as hypertension. Additional studies are needed to determine biological mechanisms.

On the basis of these results, which clearly establish this association, physicians ought to educate their patients on the approximately 8% increased risk for incident AF per daily drink consumed.

References:

Larsson SC, Drca N, Wolk A.  Alcohol consumption and risk of atrial fibrillation: a prospective study and dose-response meta-analysis. J Am Coll Cardiol. 2014;64:281-289. doi:10.1016/j.jacc.2014.03.048.