Critique 033: Moderate-to-heavy alcohol intake may increase risk of atrial fibrillation – 12 February 2011

Kodama S, Saito K, Tanaka S, Horikawa C, Saito A, Heianza Y, Anasako Y, Nishigaki Y, Yachi Y, Iida KT, Ohashi Y, Yamada N, Sone H.  Alcohol consumption and risk of atrial fibrillation.  A meta-analysis.  J Am Coll Cardiol 2011;57:427–436.

Authors’ Abstract 

Objectives The purpose of this meta-analysis is to summarize the estimated risk of atrial fibrillation (AF) related to alcohol consumption.

Background Results from observational studies examining the relationship between alcohol consumption and AF are inconsistent.

Methods A systematic electronic search of Medline (January 1966 to December 2009) and Embase (January 1974 to December 2009) databases was conducted for studies using key words related to alcohol and AF. Studies were included if data on effect measures for AF associated with habitual alcohol intake were reported or could be calculated. The effect measures for AF 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 AF risk.

Results Fourteen eligible studies were included in this meta-analysis. The pooled estimate of AF 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 10 g 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 AF risk increased with increasing levels of alcohol consumption.

Conclusions Results of this meta-analysis suggest that not consuming alcohol is most favorable in terms of AF risk

Forum Comments

Background:  There is no doubt that heavy alcohol intake can lead to cardiac arrhythmias, with the “Holiday Heart Syndrome” being known for more than three decades.1  This syndrome often includes atrial fibrillation; the syndrome is usually not associated with long-standing heart disease and the arrhythmia tends to resolve when alcohol consumption is ceased.2,3  Nissen and Lemberg4 stated that even moderate drinking can lead to this syndrome, but others5,6 have found no effect on the risk of atrial fibrillation for moderate alcohol intake, only for heavy drinking. 

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 with a mean follow up of 5.8 years.7  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 with a consumption of >2 drinks/day and no association between alcohol consumption and risk of atrial fibrillation in women.7

There is much evidence that heavy alcohol consumption is associated with an increased incidence of atrial fibrillation, among other health risks.  Differentiating heavy from moderate consumption not only redefines risk, but also redefines disordered abusive behavior from a generally healthy dietary habit.  The pattern of consumption, not often addressed, as well as other confounders, likely also play a role in the occurrence of AF, as well as incidence of other adverse events.  Binge drinking is associated with a greater incidence of arrhythmias, especially atrial fibrillation.8

In a review by Gronroos and Alonso,9 the following was reported: “A review of published observational studies and randomized trials identified 4 dietary exposures that had been investigated regarding AF risk: alcohol, fish-derived n-3 polyunsaturated fatty acids, caffeine, and ascorbic acid.  Though studies were highly heterogeneous in their design and results, they showed a consistently increased risk of AF in heavy alcohol drinkers, but no risk associated with moderate alcohol intake.”9 

A recent publication from the Framingham Study showed no increase in risk of AF during a 4-year follow up among subjects reporting any level of alcohol consumption.10  A recent book on  atrial fibrillation by Thelle and Lochen from Norway estimated that approximately 2.5 – 5% of the total incidence of AF in Norway may be due to alcohol consumption.11  They stated that <3 units/day for men and <1.5 units/day for women were not associated with increased risk for AF in otherwise healthy hearts.11  An extensive review of experimental, clinical, and epidemiologic data on atrial fibrillation did not find evidence that alcohol is a factor, certainly not a major factor, in the development of atrial fibrillation.12

References from Forum Review

1.  Ettinger PO, Wu CF, De La Cruz C, Jr, et al: Arrhythmias and the “holiday heart”: alcohol-associated cardiac rhythm disorders, Am Heart J 1978;95:555-562.

2.  Menz V, Grimm W, Hoffmann J, Maisch B: Alcohol and rhythm disturbance: the holiday heart syndrome, Herz 1996;21:227-231.

3.  Klatsky AL: Alcohol and cardiovascular diseases: a historical overview, Ann N Y Acad Sci 2002;957:7-15.  

4.  Nissen MB, Lemberg L: The “holiday heart” syndrome, Heart Lung 1984;13:89-82.

5.  Djousse L, Levy D, Benjamin EJ, et al: Long-term alcohol consumption and the risk of atrial fibrillation in the Framingham Study, Am J Cardiol 2004;93:710-713.

6.  Mukamal KJ, Tolstrup JS, Friberg J, et al: Alcohol consumption and risk of atrial fibrillation in men and women: the Copenhagen City Heart Study, Circulation 2005;112:1736-1742.

7.  Frost L, Vestergaard P.  Alcohol and risk of atrial fibrillation and flutter.  Arch Intern Med 2004;164:1993-1998.

8.  Puddey IB, Rakic V, Dimmitt SB, Beilin LJ.  Influence of pattern of drinking on cardiovascular disease and cardiovascular risk factors-a review.  Addiction 1999;94:649-663. 

9.  Gronroos NN; Alonso A.  Diet and risk of atrial fibrillation — epidemiologic and clinical evidence.  Circ J 2010:74:2029-2038.

10.  Shen J, Johnson VM, Sullivan LM, Jacques PF, Magnani JW, Lubitz SA, Pandey S, Levy D, Vasan RS, Quatromoni PA, Junyent M, Ordovas JM, Benjamin EJ.  Dietary factors and incident atrial fibrillation: the Framingham Heart Study. Am J Clin Nutr 2011;93:261-266. Epub 2010 Nov 24.

11.  Thelle DS, Løchen, M-J: “Kaotiske hjerter” (Chaotic hearts), Gyldendal 2010. (ISBN 978-82-05-40453-1)

12.  Balbao CE, de Paola AA, Fenelon G: Effects of alcohol on atrial fibrillation: myths and truths, Ther Adv Cardiovasc Dis 2009;3:53-63.

Comments on present study:  The present paper is based on both case-control and cohort studies with varying degrees of control for potential confounders.  Stronger associations between alcohol and AF were seen in the case-control studies.  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 6 or more drinks/day for some studies, while the highest category of alcohol intake was ≥ 1-2 drinks/day in some 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 heath risk.  The most important question would be: Does light to moderate drinking increase the risk of AF? The conclusion of the authors of this paper seems to be yes, while many other studies find little effect of such drinking. 

Forum Summary:  A number of well-done studies have shown an increase in the risk of atrial fibrillation to be associated with heavy alcohol intake or with alcoholism.  Most previous studies suggest little if any increase in risk from light-to-moderate drinking.  The present study was a meta-analysis based on 14 studies from Europe or North America.  It showed an increase in risk with alcohol, but there were limited dose-response data to determine if there was a threshold above which the risk was increased. 

Overall, the scientific evidence from many studies suggests that at least heavy drinking may increase the risk of atrial fibrillation, although whether light-to-moderate intake increases the risk seems unlikely.  Previous basic scientific data of mechanisms of atrial fibrillation have suggested that alcohol has little effect on this arrhythmia.

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Contributions to this critique by the International Scientific Forum on Alcohol Research were made by the following members:

Arne Svilaas, MD, PhD, general practice and lipidology, Oslo University Hospital, Oslo, Norway

Erik Skovenborg, MD, Scandinavian Medical Alcohol Board, Practitioner, Aarhus, Denmark

R. Curtis Ellison, MD, Section of Preventive Medicine & Epidemiology, Boston University School of Medicine, Boston, MA, USA

Harvey Finkel, MD, Hematology/Oncology, Boston University Medical Center, Boston, MA, USA

Tedd Goldfinger, DO, FACC, Desert Cardiology of Tucson Heart Center, Dept. of Cardiology, University of Arizona School of Medicine, Tucson, Arizona, USA