Atrial fibrillation explained:
To pump blood around the body, our human heart beats about 60 to 100 times a minute. During this process, the heart repeatedly contracts (i.e. contraction). These contractions are driven by what is called an excitation lead, which are special heart cells. The cells transmit electrical signals to the human ventricles in a specific sequence, thus causing a regular interval. It is precisely this sequence of excitation conduction that is disturbed in atrial fibrillation, as the electrical signals cannot be properly transmitted, but merely linger in the atria. Due to this incomplete contraction, the heart chambers cannot pump the blood on effectively. As a result, the amount of blood transported to the individual blood vessels per heartbeat decreases by an average of 15%.
This cardiac arrhythmia is not directly life-threatening, but if left untreated it can lead to serious consequences such as strokes or heart failure. Possible causes could include high blood pressure, age, coronary heart disease, diabetes or hyperthyroidism. In some cases, atrial fibrillation can even occur for no immediately apparent reason in patients with healthy hearts. Excessive consumption of alcohol could also potentially correlate to the cause of the arrhythmia. This correlation has now been investigated by the study published in January 2021.
Study Design and Methods:
The study, published in the European Heart Journal, included five cohorts of 107,845 people from Denmark, Finland, Italy, Norway, and Sweden. At baseline, participants were medically screened when they entered between 1982 and 2010, providing information on their medical history, lifestyle (including alcohol and tobacco use), employment, and education level. Approximately 93% of the participants had no cardiac arrhythmia at baseline and the mean age was 48 years, of which 48.3% were male.
Evaluation of risk factors using the MORGAM project:
Risk factor information was available from the baseline visits, at baseline. Among other things, data on body mass index (BMI), hypertension, diabetes, antihypertensive drugs and history of myocardial infarction were measured locally. The results were centralized and analyzed by the so-called MORGAM Project. This project is a multinational collaborative study funded by the EU Commission that investigates the relationship between development of cardiovascular diseases, their classical and genetic risk factors and biomarkers (i.e. measurable parameters of biological processes).
Average alcohol consumption was assessed in grams per day and classified according to WHO alcohol consumption categories. To calculate the amount of alcohol, it was assumed that 120ml of wine, 330ml of beer or 40ml of spirits contained approximately 12g of ethanol.
Increased results with alcohol consumption:
Of all study participants, 5854 developed atrial fibrillation during the 14-year observation period. For all types of alcoholic beverages and for both men and women, the associations between alcohol consumption and risk of atrial fibrillation were similar. The risk of the arrhythmia was increased by 16% for people who consumed only one alcoholic drink per day compared with those who were abstinent from alcohol. The researchers therefore concluded that an increased risk could be associated with increasing alcohol consumption. Up to two drinks per day resulted in a 28% increase in risk, whereas more than four glasses of alcohol meant an increase of up to 47%. An association was shown from an average alcohol consumption of 3g per day. However, for the risk of chronic heart failure it was evaluated that here a daily consumption of 20g per day, or 1.6 drinks, showed the lowest values. However, people who drank less or more alcohol were more likely to develop chronic heart failure.
No statistically significant association was found among former drinkers, occasional drinkers, or people who drank up to one drink per day. Drinking patterns also did not show significance.
Limitation of this study:
Limitations of the study include the fact that study participants reported the type and amount of alcohol they drank and this may lead to biased reporting.
In addition, the available information did not allow researchers to examine the effects of binge drinking. Because atrial fibrillation can also occur asymptomatically, it is possible that some episodes were not reported.
Note: Because the study was observational, it can only show an association between alcohol consumption and atrial fibrillation and not that alcohol causes atrial fibrillation.
However, the results of this study were consistent with previous studies, as two drinks a day was associated with a significantly increased risk of atrial fibrillation in a women's health study published in 2008. A meta-study published in 2014 in the Journal oft he American College of Cardiology also found an 8% increase in risk per daily drink.
Unlike other cardiovascular diseases, even a low alcohol intake of 1.2 drinks per day was associated with an increased risk of atrial fibrillation. Given the findings of recent studies that even low alcohol consumption carries a risk, the study suggests that there may be an association in this regard.