Does moderate alcohol consumption increase the risk of atrial fibrillation?

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Results of a meta-analysis conducted by Japanese researchers suggest that even moderate alcohol consumption can lead to the development of atrial fibrillation. The paper has been published in the Journal of the American College of Cardiology.

“Results from observational studies examining the relationship between alcohol consumption and atrial fibrillation are inconsistent.The purpose of this meta-analysis is to summarise the estimated risk of atrial fibrillation related to alcohol consumption,” the authors, led by Hirohito Sone, Department of Internal Medicine, University of Tsukuba, Institute of Clinical Medicine, Mito, Japan, wrote.

The investigators performed a systematic electronic search of Medline (January 1966 to December 2009) and Embase (January 1974 to December 2009) databases. Studies were included if data on effect measures for atrial fibrillation associated with habitual alcohol intake were reported or could be calculated. The effect measures for atrial fibrillation for the highest versus lowest alcohol intake in individual studies were pooled with a variance-based method. Linear and spline regression analyses were conducted to quantify the relationship between alcohol intake and atrial fibrillation risk.

Fourteen eligible studies were included in the meta-analysis.The pooled estimate of atrial fibrillation for the highest versus the lowest alcohol intake was 1.51 (95% confidence interval: 1.31 to 1.74). A linear regression model showed that the pooled estimate for an increment of 10g per day alcohol intake was 1.08 (95% confidence interval: 1.05 to 1.10; R2=0.43, p<0.001). A spline regression model also indicated that the atrial fibrillation risk went up with increasing levels of alcohol consumption.

“Results of this meta-analysis suggest that not consuming alcohol is most favourable in terms of atrial fibrillation risk reduction,” the authors concluded.

Members of the International Scientific Forum on Alcohol Research commented on the paper, saying that other studies found no effect for moderate alcohol intake, only for heavy drinking. They stated that one of the best studies on alcohol consumption and risk of atrial fibrillation is a Danish cohort study (the Danish Diet, Cancer and Health Study) examining the issue among 22,528 men and 25,421 women followed over six years. The study included a large number of cases with atrial fibrillation, detailed information on potential confounding factors, and complete follow-up through nationwide population-based registries. The results included a modest increase in risk of atrial fibrillation in men drinking more than two drinks/day and no association between alcohol consumption and risk of atrial fibrillation in women.

“There is much evidence that heavy alcohol consumption is associated with an increased incidence of atrial fibrillation, among other health risks. The pattern of consumption (speed, time frame and without food), not often addressed, affects risk too – we know that binge drinking is associated with a greater incidence of arrhythmias, especially atrial fibrillation,” said R Curtis Ellison, Boston University Medical Center, member of the scientific forum.

“A weakness of this paper, and of essentially all meta-analyses, is that there were varying definitions for categories of alcohol consumption, and the highest category of alcohol intake included alcoholics and six or more drinks/day for some studies, while the highest category of alcohol intake was 1–2 drinks/day in other studies.

“The consistent message is that there is a difference between heavy and moderate use of alcohol, between binge drinking and a healthy pattern of drinking, and inherent health risk. The most important question would be: Does light to moderate drinking increase the risk of atrial fibrillation? The conclusion of the authors of this paper seems to be yes, while many other studies find little effect of such drinking. Previous basic scientific data of mechanisms of atrial fibrillation have suggested that alcohol has little effect on this arrhythmia.”

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