Alcohol consumption among cardiovascular disease (CVD) patients, including individuals with stroke, heart disease, diabetes and coronary heart disease, increases the risk of atrial fibrillation (AF), according to results from two large studies.

Prior trials have shown an increased risk of AF among heavy drinkers, and the new study shows the same link between patients who already have CVD.

All of the participants involved in the new study had some type of CVD at one point, and the experts found that even people who drank “moderately” had an increased risk of AF than people who did not consume a lot of alcohol.

However, at follow-up, the researchers determined that the risk of death was lower in moderate drinkers (12.5%) than individuals who said that they did not drink much at all. (12.5%). Apart from binge drinkers, the chance of AF was around 13% higher for the moderate drinkers compared with the “low-alcohol consumers”.

A 2006 report claimed that moderate alcohol intake reduces death risk and benefits our health in many different ways. Although all of the trials were conducted correctly, some were worried about 2 particular aspects of the study. One concern was that the spectrum the authors chose for “moderate” drinkers was rather large. Individuals who report 1 drink every week to 21 drinks per week for men, and 14 per week for women, were all considered moderate drinkers.

Some say that it would have been beneficial to set standards regarding what was considered moderate drinking, such as a 14 drink maximum per week for men and 7 for women, which is the definition of moderate drinking in the U.S., Australia, and other countries. The report states that there is a lack of data involved in the trial which highlights the effects of alcohol consumption boosting the risk of AF.

The second concern is that these results go hand-in-hand with “potential bias in the estimates from what is known as index event bias or collider bias”. According to the report, alcohol consumption before being signed up for the trial could be a reason for participants’ cardiovascular disease development. Judging alcohol effects after a cardiovascular problem has already occurred, and the link to AF is difficult.

In these trials, all participants had already experienced a CVD event. Therefore, the study involved subjects who drank alcohol before they were diagnosed with CVD or diabetes and some who did not.

Because “moderate” alcohol intake has previously been believed to lower the risk of CVD and diabetes, the researchers note that it can be presumed that if individuals developed CVD, even though they drank, they probably had some other type of risk factor which cancelled out any “protection” from the consumption of alcohol.

If the risk factors were not adjusted, this could alter the outcomes of subjects’ CV health, such as the development of AF.

Prior studies have made it well-known that AF can result from heavy consumption of alcohol and binge drinking. AF is a cardiac arrhythmia that is part of the “holiday heart” condition that can present itself after heavy alcohol consumption takes place.

Atrial fibrillation risks from moderate drinking are still not completely clear, due to the concerns addressed in the report. Researchers need to conduct more studies in order to be positive of these effects.

Written by Christine Kearney