Alcohol consumption and risk of atrial fibrillation: Observational and genetic estimates of association

Abstract

Background

The aim of this study was to test the hypothesis that alcohol consumption, both observational (self-reported) and estimated by genetic instruments, is associated with a risk of atrial fibrillation and to determine whether people with high cardiovascular risk are more sensitive towards alcohol than people with low risk.

Methods

We used data for a total of 88,782 men and women from the Copenhagen City Heart Study 1991–1994 and 2001–2003 and the Copenhagen General Population Study 2003–2010. Information on incident cases of atrial fibrillation was obtained from a validated nationwide register. As a measure of alcohol exposure, both self-reported consumption and genetic variations in alcohol metabolizing genes (ADH1B/ADH1C) were used as instrumental variables. The endpoint was admission to hospital for atrial fibrillation as recorded in a validated hospital register.

Results

A total of 3493 cases of atrial fibrillation occurred during follow-up. High alcohol consumption was associated with a risk of atrial fibrillation among men, but not among women. Among the men who drank 28–35 and 35+ drinks/week, the hazards ratios were 1.40 (95% confidence interval 1.09–1.80) and 1.62 (95% confidence interval 1.27–2.05) compared with men who drank < 1 drink/week. Using genotypes as instrumental variables did not reveal a higher risk. Associations in those with high cardiovascular risk were similar to those at lower risk.

Conclusions

Observational alcohol consumption was associated with a higher risk of atrial fibrillation in men. In women, only a high alcohol intake (28+ drinks/week) was associated with a higher risk. Participants with a high cardiovascular risk were no more sensitive towards alcohol than those at low risk. Genetic analysis did not support a causal relationship of linear association between alcohol intake and atrial fibrillation.