Atrial fibrillation, also known as A-fib, is the most commonly occurring heart rhythm abnormality, affecting an estimated three million adults in the United States. It occurs when the upper chambers of the heart, the atria, start beating irregularly, which can disrupt blood flow to the lower chambers of the heart, called the ventricles. Over time, it can lead to complications like heart failure and strokes. A-fib can be persistent, or it can occur sporadically, with symptoms such as palpitations, shortness of breath and fatigue that last for a few minutes or hours at a time. When the episodes occur occasionally, the condition is known as paroxysmal atrial fibrillation.
People have a greater chance of developing atrial fibrillation as they get older. It’s also more likely to occur 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 bouts of heavy drinking on weekends and holidays, a phenomenon that came to be known as holiday heart syndrome. Since then, a number of large observational studies have found that people who regularly consume alcohol, even as little as one drink a day, have an increased likelihood of going on to develop atrial fibrillation compared with people who abstain.
Many of these previous studies had important weaknesses. In most cases, they relied on people self-reporting 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 people who are asked to recall an episode of atrial fibrillation can mistakenly identify a variety of behaviors as triggers. The new study, however, was designed to get around those limitations. Dr. Marcus and his colleagues recruited 100 people with a history of paroxysmal atrial fibrillation, most of them men, and had them wear electrocardiogram monitors that tracked their cardiac rhythms around the clock.
The devices contained a button that the participants were told to press any time they had an alcoholic beverage. The researchers used other, objective measures to track alcohol intake as well. They fitted the participants with special ankle monitors that could detect their blood alcohol levels. And they did routine finger-stick blood tests to measure participants’ levels of phosphatidylethanol, or PEth, a biomarker that gives some indication of a person’s recent alcohol consumption.
During four weeks of tracking, the researchers found that at least 56 participants had experienced an episode of atrial fibrillation. The data indicated that alcohol was often a trigger for arrhythmias. Having one drink doubled a person’s odds of having an episode of atrial fibrillation over the next four hours, while having two or more drinks tripled the odds of an event. The higher a person’s blood alcohol concentration, the greater their likelihood of having an arrhythmia.