A new study has found that drinking alcohol, even just a can of beer or a glass of wine, can quickly increase the risk of a common type of heart arrhythmia, atrial fibrillation, in people who already have a history of this problem.
Doctors had suspected for some time that there was a link between alcohol and atrial fibrillation, but until now had no definitive evidence that drinking can cause arrhythmias.
The new study is one of the most rigorous to date: The researchers recruited 100 people with a history of atrial fibrillation and followed them intensively for four weeks, monitoring their alcohol intake and heart rates in real time.
Scientists have found that drinking alcohol makes people more likely to have an episode of atrial fibrillation, or cardiac arrhythmia, within hours. And the more a person drank, the greater the likelihood.
The study was published in August 2021 in the Annals of Internal Medicine. Added to data from previous studies, the findings suggest that people with a history of atrial fibrillation may reduce their chances of experiencing arrhythmias if they reduce their alcohol intake or avoid it altogether.
The authors speculated that the findings may have broader implications for healthy adults as well. While moderate alcohol consumption is widely seen to be beneficial for heart health, new research shows that in some people, at least, alcohol has the potential to disrupt heart function.
“This demonstrates that whenever we drink alcohol, it presumably has an almost immediate effect on the electrical functioning of the heart,” said Dr. Gregory Marcus, one of the authors of the study and professor of medicine in the division of cardiology at the University of California at San Francisco (USA).
Atrial fibrillation is the most common heart rhythm abnormality. They estimate that it affects 3 million adults in the United States. It occurs when the upper chambers of the heart, the atria, begin to beat irregularly, which can disrupt the flow of blood to the lower chambers, the ventricles.
Over time, this can lead to complications such as heart failure and stroke. Atrial fibrillation can be persistent or it can occur sporadically with symptoms such as palpitations, shortness of breath, and fatigue lasting a few minutes or a few hours. When episodes occur occasionally, the condition is known as paroxysmal atrial fibrillation.
People are more likely to develop atrial fibrillation as they age, and the condition also occurs more often in people who have risk factors such as high blood pressure, heart disease, obesity, European ancestry, or a family history of arrhythmias.
About four decades ago, doctors began documenting cases of people experiencing arrhythmias after heavy drinking sessions on weekends or holidays, a phenomenon that became known as post-holiday heart syndrome.
Since then, several large observational studies have found that people who consume alcohol regularly, even just one drink a day, are more likely to develop atrial fibrillation compared to people who abstain.
Many of these earlier studies had important shortcomings. In most cases, they relied on participants to self-report their alcohol intake, which is not always reliable. Studies have found, for example, that people tend to underestimate how much they drink.
Another limitation is that when people are asked to recall an episode of atrial fibrillation, they may mistakenly identify several different behaviors as triggers. But the new study is designed to get around those limitations. Marcus and his colleagues recruited 100 people, mostly men, with a history of paroxysmal atrial fibrillation, and had them wear electrocardiogram monitors that monitored their heart rate 24 hours a day.
The devices have a button that participants were instructed to press whenever they had an alcoholic beverage. The researchers also used other objective means to monitor alcohol intake. They equipped the participants with anklets that could detect their blood alcohol level. They also had routine blood tests to measure levels of phosphatidylethanol, a biomarker that gives some indication of a person’s recent alcohol consumption.
During four weeks of monitoring, the researchers found that at least 56 participants experienced an episode of atrial fibrillation. The data indicated that in many cases alcohol had been the trigger of the arrhythmias.
One drink of alcohol doubled a person’s chances of having an episode of atrial fibrillation in the next four hours, and two drinks or more tripled them. The higher the concentration of alcohol in the blood, the more likely a person is to experience an arrhythmia.
Mariann R. Piano, a researcher who has published many studies on alcohol and cardiovascular health and who was not involved in the new study, said the findings represent an important advance in our understanding of how alcohol affects the heart. She said doctors need to talk to their patients, especially those with atrial fibrillation, about how much alcohol they consume and whether it would be prudent to reduce its consumption or cut it out altogether.
“Atrial fibrillation is an arrhythmia whose effects can affect people’s lives profoundly, such as causing a stroke. So it’s very important to be able to convey to our patients what factors can be really acute triggers,” said Piano, who is a professor and associate director of research at the Vanderbilt University School of Nursing.
“Drinking is something we can monitor and we can modify individually. It’s something that’s easy to pay attention to.”
But she called the study rigorous and said the findings are timely because the incidence of atrial fibrillation has been rising rapidly.
According to the CDC (Centers for Disease Control and Prevention), by 2030 it is estimated that 12.1 million people in the US will have atrial fibrillation. Piano said doctors should explain to their patients who drink alcohol how to practice “low-risk alcohol intake,” a definition made by the National Institute on Alcohol Abuse and Alcoholism.
For women, that means no more than three drinks of alcohol on any given day and a maximum of seven drinks a week. For men, low-risk intake means a maximum of 14 drinks per week and no more than four drinks in a day.
The US government defines a standard serving as 340 ml of regular beer, 150 ml of wine or 45 ml of distilled beverage (40% alcohol).
Gregory Marcus of UCSF said the study’s findings are potentially empowering for people with atrial fibrillation because they suggest there is a way to control a major trigger of arrhythmias. “This shows that these atrial fibrillation events are not due to chance and that there are factors that can be modified to reduce the chances of an episode occurring,” he explained.
This does not mean, of course, that everyone who drinks will end up with heart problems. But, Gregory said, for people who already have a history of arrhythmia, the findings indicate that they should avoid excessive alcohol intake, as it appears to interfere with the heart’s electrical properties.
Translation by Clara Allain
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