Excessive alcohol intake is responsible for injuries, cancer, premature death and loss of productivity.^1,2 The World Health Organization (WHO) estimates that alcohol accounts for 3.3 million deaths per year, more than tuberculosis and AIDS, and roughly 6% of global deaths.² Similar to many pharmaceutical compounds, the effects of alcohol relate to dose and a complex interaction with the host. Unlike pharmaceuticals, alcohol is mainly used for recreational purposes under different cultural, climate and religious norms across the globe. Significant geographic variations exist in patterns of alcohol consumption.² For example, in Russia and the former Soviet states, the average person consumes more than 12.5 liters of alcohol in a year (>26 grs of pure alcohol per day). In contrast, in the African region alcohol per capita consumption is 6 liters and 90% of the population are lifetime abstainers.²

The study by Leong et al. on behalf of the INTEHEART investigators is an important step in trying to understand the effects of alcohol consumption on cardiovascular health at a global scale.³ Previous case-control studies have focused primarily in men living in middle or high-income countries. In such studies, moderate alcohol consumption (three to four days a week) has been associated with an inverse risk of myocardial infarction (MI).^4,5 

INTERHEART was designed as an observational case-control study of risk factors for acute MI in 52 countries representing all regions of the world.⁶ For this report, patterns of alcohol consumption among 12,195 cases of first occurrence of MI were compared with a control group of subjects, matched by age and gender, recruited from the hospital (58%) or community (36%) without evidence of heart disease. Alcohol use was defined as the consumption of ³1 alcoholic beverage within the previous year. Heavy episodic drinking was defined as consumption of ³6 alcoholic drinks within 24 hours prior to MI. The main results of this manuscript are as follows:

Alcohol consumption within the previous year was associated with lower risk of MI: pooled odds ratio of 0.84 (95% CI 0.71-0.99, P = 0.04).

There were significant differences in the association of alcohol intake and MI risk based on gender, geographic region and age. The protective effect of alcohol was greatest among women and individuals aged ³45 years. South Asians had a paradoxical increase in MI risk (OR: 1.4, 95% CI: 1.1-1.8, P = 0.007) that was not seen among South Asians living abroad (OR: 0.80, 95% CI: 0.53-1.2, P = 0.3), which suggests complex gene-environment interactions.

Heavy episodic drinking was associated with a 40% increase in the risk of MI (OR: 1.4, 95% CI: 1.1-1.9, P = 0.01), particularly in older individuals.

The findings of the INTERHEART study are in concordance with prior studies^4,5 and the known pharmacological properties of alcohol. In vitro platelet testing has shown that alcohol in moderate amounts decreases platelet aggregation in response to thrombin, ADP, epinephrine and collagen,^7,8 all of which could reduce MI rates. In addition, alcohol raises high-density lipoprotein cholesterol (HDL-C) and its major apo lipoprotein A-I (apo A-I, both involved in reverse cholesterol transport.^8,9 Alcohol also lowers LDL-C, but the magnitude of this reduction is small and partially offset by increases in blood pressure.⁹ In contrast, binge drinking is associated with adverse changes in serum lipoproteins and increased platelet aggregation in response to thrombin.^10-12

This analysis of INTERHEART extends previous observations on the beneficial effects of moderate alcohol consumption to multiple ethnic groups in different parts of the world; therefore increasing the generalizability of this association. Translating this knowledge into practice may be difficult as alcohol is used around the globe for recreational purposes; too often with no regard on the adverse consequences of excessive consumption. The American Heart Association recommendation “if you choose to drink alcohol, do so in moderation” is supported by the findings of INTERHEART. The problem for many, as Saint Augustine put it, is that “complete abstinence is easier than perfect moderation.”

References:

1. White A, Hingson R. The burden of alcohol use: Excessive alcohol consumption and related consequences among college students. Alcohol Res 2013;35:201-18.
2. World Heart Organization. Global status report on alcohol and health – 2014 edition. (WHO website). 2014. Available at:
   http://apps.who.int/iris/bitstream/10665/112736/1/9789240692763_eng.pdf. Accessed 07/11/14.
3. Leong DP, Smyth A, Teo KK, et al. Patterns of alcohol consumption and myocardial infarction risk: observations from 52 countries in the interheart case-control study. Circulation 2014;130:390-8.
4. Mukamal KJ, Conigrave KM, Mittleman MA, Camargo CA, Jr., Stampfer MJ, Willett WC, Rimm EB. Roles of drinking pattern and type of alcohol consumed in coronary heart disease in men. N Engl J Med 2003;348:109-18.
5. Ronksley PE, Brien SE, Turner BJ, Mukamal KJ, Ghali WA. Association of alcohol consumption with selected cardiovascular disease outcomes: A systematic review and meta-analysis. BMJ 2011;342:d671.
6. Lim SS, Vos T, Flaxman AD, et al. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: a systematic analysis for the global burden of disease study 2010. Lancet 2012;380:2224-60.
7. Renaud SC, Ruf JC. Effects of alcohol on platelet functions. Clin Chim Acta 1996;246:77-89.
8. Rimm EB, Williams P, Fosher K, Criqui M, Stampfer MJ. Moderate alcohol intake and lower risk of coronary heart disease: meta-analysis of effects on lipids and haemostatic factors. BMJ 1999;319:1523-8.
9. Langer RD, Criqui MH, Reed DM. Lipoproteins and blood pressure as biological pathways for effect of moderate alcohol consumption on coronary heart disease. Circulation 1992;85:910-5.
10. Gall N. Is wine good for your heart? A critical review. Postgrad Med J 2001;77:172-6.
11. Mukamal KJ, Maclure M, Muller JE, Mittleman MA. Binge drinking and mortality after acute myocardial infarction. Circulation 2005;112:3839-45.
12. Ruf JC. Alcohol, wine and platelet function. Biol Res 2004;37:209-21.

Keywords: Adenosine Diphosphate, Alcohol Drinking, Alcoholic Beverages, Apolipoprotein A-I, American Heart Association, Binge Drinking, Blood Pressure, Cholesterol, Collagen, Epinephrine, Ethnic Groups, Gene-Environment Interaction, Mortality, Premature, Myocardial Infarction, Neoplasms, Platelet Aggregation, Risk Factors, Thrombin

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