Consumption of alcoholic beverages and Atrial Fibrillation

Commentary and analysis by Prof. Nicolai Worm (WIC chair).

Headlines recently reported “One small drink a day raises risk of irregular heartbeat”.

These reports were based on a study, which found that – even though a moderate amount of alcohol can protect against heart failure – drinking the equivalent of a small glass of wine or beer per day was linked to an increased risk of atrial fibrillation (AF). The researchers assessed the drinking habits and the heart health of almost 108,000 individuals from Sweden, Norway, Finland, Denmark and Italy. Individuals consuming one drink a day were on average 16% more likely to develop the AF, than those who did not drink ^[1].  Such increased risk refers to the relative risk, the absolute risk of an irregular heartbeat (AF) from consuming a small glass of wine per day is small, as indicated by the authors.

What is atrial fibrillation?

Atrial fibrillation (AF) is an irregular heartbeat (arrhythmia) which can lead to blot clots, stroke and other heart-related complications. Normally, the heart contracts and relaxes to a regular beat. In atrial fibrillation, the upper chambers of the heart (the atria) beat irregularly instead of beating effectively to move blood into the ventricles.

AF affects more than 33 million people worldwide and the global prevalence of AF is growing since it parallels the growing global obesity epidemic. Obesity, hypertension, diabetes, sleep apnea, consumption of alcoholic beverages and sedentary lifestyles have been investigated as possible underlying causes.

Various dietary factors have been suggested to play a role in the development or treatment of AF such as caffeine, chocolate, omega-3-polyunsaturated fatty acids as well as a Mediterranean diet. However, so far, little evidence exists to suggest a specific dietary approach.

AF and alcoholic beverages

Concerning the intake of alcoholic beverages and incident AF, unlike its relationship with other aspects of cardiovascular disease, where mild to moderate alcohol intake may have modest benefits, AF (incident AF, recurrent AF or AF progression) seems to increase steadily. With light drinking, results appear to be inconsistent.

The above-mentioned observational study found that drinking the equivalent of a small glass of wine or beer per day was linked to an increased risk of AF. Individuals consuming one drink a day were on average 16% more likely to develop the condition, than those who did not drink ^[1]. This is in accordance with a meta-analysis of seven prospective observational studies including 859,420 patients with over 12 years of follow-up, where a linear association between the intake of alcoholic beverages and incident AF was observed ^[2]. Each extra alcoholic drink per day resulted in an 8% increased AF risk. However, in a more recent meta-analysis of nine prospective observational studies with 249,496 participants, low levels of alcohol intake (up to 1 drink/day) were not associated with the development of AF ^[3]. Gender differences were found in the association between moderate intake of alcoholic beverages and AF, with men showing a greater increased risk, while high alcohol intake was associated with an elevated AF risk in both men and women.

In general, the observed increases in absolute risk per drink are rather small. Moreover, it is important to emphasize that definitions and adjustments for potential confounding factors were not harmonized in the various studies included in these meta-analyses. Thus, in principle, data from these observational studies of limited quality cannot prove causality. This can only be proven by unbiased results with randomized trials of alcohol consumption, even though, it is unlikely that such trials are going to be feasible in the future.

However, one randomized controlled trial (PREDIMEDThe PREDIMED study is one of the few randomized controlled trials about the Mediterranean Diet. More...) aimed to assess the association between the consumption of alcoholic beverages and AF risk when the participants were following a Mediterranean diet ^[4]. For 6527 participants (out of 7447) in the PREDIMEDThe PREDIMED study is one of the few randomized controlled trials about the Mediterranean Diet. More... trial, a validated food frequency questionnaire was used to measure the consumption of alcoholic beverages. Participants were classified as non-drinkers, those with a Mediterranean alcohol drinking pattern (MADP) (10-30 g/d in men and 5-15 g/day in women, preferably red wine consumption with low spirits consumption), low-moderate drinkers (<30 g/day men y and < 15 g/day women), and heavy drinkers. The results showed that the consumption of alcoholic beverages was neither associated with AF incidence among low-moderate drinkers, nor with those adhering to a MADP or heavy drinkers, compared with non-drinkers. Consequently, the authors concluded that a Mediterranean alcohol consumption pattern (low to moderate red wine consumption) was not associated with an increased incidence of AF.

In summary, there is much to be learned about the relationship between alcoholic beverages, incident AF and subsequent outcomes, as there are still many uncertainties, which makes evidence-based counselling with regards to alcohol intake for patients with or at risk of AF difficult.

Notes:

1. Csengeri, D., et al., Alcohol consumption, cardiac biomarkers, and risk of atrial fibrillation and adverse outcomes. Eur Heart J, 2021.
2. Voskoboinik, A., et al., Alcohol and Atrial Fibrillation: A Sobering Review. J Am. Coll. Cardiol, 2016. 68(23): p. 2567-2576.
3. Gallagher, C., et al., Alcohol and incident atrial fibrillation – A systematic review and meta-analysis. Int. J Cardiol, 2017. 246: p. 46-52.
4. Bazal, P., et al., Mediterranean alcohol-drinking pattern, low to moderate alcohol intake and risk of atrial fibrillation in the PREDIMEDThe PREDIMED study is one of the few randomized controlled trials about the Mediterranean Diet. More... study. Nutr Metab Cardiovasc Dis, 2019. 29(7): p. 676-683.