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Research Summary

Is “Moderate” Alcohol Consumption Associated with an Increased Risk of Atrial Fibrillation in Patients with Cardiovascular Disease?

Previous research in the general population has suggested an increased risk of atrial fibrillation (AF) in people who drink heavily. Results on the association with lower drinking amounts have not been consistent. This study analyzed the association between alcohol consumption and AF in subjects diagnosed with coronary heart disease, stroke, diabetes, or other manifestations of cardiovascular disease (CVD) based on patient data from 2 large antihypertensive-drug treatment trials (N=30,433). Median follow-up was 56 months.

  • Subjects who drank “moderate” amounts* had a higher risk of AF than those who drank light amounts,** although the risk of death during follow-up was lower for those who drank moderately (9.9%) compared with those who drank lightly (12.5%).
  • Excluding subjects with heavy episodic drinking (>5 drinks per single occasion or per day on average), the risk of AF was 13% higher in subjects who drank moderately compared with those who drank lightly.

*Defined in this study as 1–21 drinks per week for men and 1–14 drinks per week for women (1 drink = 12–15 g alcohol).
**Less than 1 drink per week (reference category).

Comments:

Although the multiple analyses in this paper were done appropriately, the wide range chosen for moderate drinking, which exceeds US guidelines, likely leads to an overestimate of AF risk associated with moderate drinking. Another concern is the possibility of “collider bias” in the estimates; i.e., given that moderate alcohol consumption is associated with a lower risk of both CVD and diabetes, it can be assumed that subjects in this study who developed CVD despite consuming alcohol had other risk factors that overcame any potential protection afforded by drinking. Unless adjusted for, these other risk factors could affect the subsequent course of subjects following the onset of CVD, including the development of AF. Thus, the association between “moderate” alcohol consumption and atrial fibrillation after someone has developed CVD remains unclear. R. Curtis Ellison, MD

Reference:

Liang Y, Mente A, Yusuf S, et al. Alcohol consumption and the risk of incident atrial fibrillation among people with cardiovascular disease. CMAJ. 2012;184(16):E857–E866.

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