Consuming any alcohol can exacerbate the risk of atrial fibrillation (A-fib), a common type of cardiac arrhythmia, among people with a history of the condition, according to a new study in the Annals of Internal Medicine­—and the findings may have implications for those with no history of the disorder.

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Background

According to the New York Times' Anahad O'Connor, A-fib is the most common heart rhythm abnormality, affecting roughly 3 million adults in the United States alone. It occurs when the heart's upper chambers, called the atria, beat irregularly. This in turn disrupts blood flow to the heart's lower chambers and can, over time, lead to heart failure or stroke. The condition can be persistent or occur only occasionally, which is called paroxysmal A-fib.

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Physicians have long suspected alcohol could worsen A-fib, but did not have concrete evidence until the recent study was published. Prior research has been largely observational, relying on people to self-report their alcohol consumption, which tends to be underreported. In addition, people asked to remember an A-fib episode can incorrectly identify several other behaviors as potential triggers.

Study details

For the study, researchers recruited 100 people—of whom 79% were men and 85% were white—with a history of paroxysmal A-fib and closely monitored them for four weeks, tracking their alcohol intake and cardiac rhythms in real time.

Specifically, the participants wore electrocardiogram monitors that provided 24/7 tracking of their cardiac rhythms and also had a button participants had to press whenever they consumed alcohol. In addition, the researchers equipped every participant with an ankle monitor that could detect their blood alcohol levels, and they conducted routine finger-stick blood tests to assess participants' levels of phosphatidylethanol, a biomarker that provides some indication of an individual's recent alcohol consumption.

Key findings

The researchers found that over the four weeks of monitoring, 56 of the participants experienced at least one A-fib episode—and the study data suggested alcohol consumption was frequently a trigger for these arrhythmias.

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Specifically, the researchers found that consuming one alcoholic beverage doubled an individual's risk of having an A-fib episode within the following four hours, while consuming two or more alcohol beverages tripled the risk of such an event. Overall, the higher a participant's level of blood alcohol, the more likely they were to have an arrhythmia.

Implications for those with A-fib—and without

Gregory Marcus, an author of the study and a professor of medicine in the division of cardiology at the University of California, San Francisco, said the findings could be potentially helpful for people with A-fib, as it provides them a potentially effective way to reduce their odds of having an episode. "This shows that these atrial fibrillation events are not simply due to random chance, and that there are modifiable factors that can be harnessed to reduce the chances that an event will occur," he said.

Moreover, Marcus and the other study authors also hypothesized that the findings could have implications for people without the disorder as well, since it suggests that any alcohol consumption can disrupt heart function.

"This demonstrates that whenever we consume alcohol, it is presumably having a nearly immediate effect on the electrical workings of our hearts," Marcus said. He added, "Despite the conventional wisdom that alcohol is healthy for the heart, these data add to others that too much alcohol is almost certainly harmful to the heart."

Separately, Mariann Piano, a professor and associate dean for research at the Vanderbilt University School of Nursing, who was not involved with the study, said the findings shed light on how alcohol can affect heart function. She encouraged health care providers to talk with patients, especially those with A-fib, about their alcohol consumption and whether it would be wise to cut back.

"Atrial fibrillation is an arrhythmia that can have life-changing effects, like having a stroke, and so understanding what might be an acute trigger is really important to communicate to our patients," she said. "Drinking is something that we can both monitor and modify on an individual basis. It's something that we can easily be mindful of." (O'Connor, New York Times, 8/30)