Researchers in Germany have found that getting drunk is associated with abnormal heart rhythms.
Their study was conducted in a place teeming with potential research subjects.
"Basically we were sitting over a beer or two, ironically, and talking about how to design a study about relevance of alcohol consumption on heart rate," remembers Dr. Moritz Sinner, an assistant professor of medicine at University Hospital Munich. "This was summer [2015], and Oktoberfest happens in the fall."
Sinner and his colleagues realized they could do their study at Munich's Oktoberfest, the annual beer festival that attracts huge crowds of people who are enthusiastic about drinking.
So, they got all the necessary approvals and showed up at the festival with breathalyzer tests, electrocardiograms and a question: How did drinking alcohol affect people's heart rhythms?
Doctors have known for a long time that alcohol consumption can cause heart problems, especially drinking a large amount. Past studies have shown that people who drink a lot of alcohol frequently are at risk for dying of cardiac arrest, or suffering a stroke.
Sinner and his team were particularly interested in understanding the underlying causes of a condition known as holiday heart syndrome, in which people who binge drink suffer potentially dangerous atrial fibrillation. Despite decades of scholarly work on the syndrome, scientists are still trying to understand the mechanisms underlying it.
The scientists were surprised to find that a lot of people at Oktoberfest were excited to participate in their study.
"If you go to a festival and you want to have a beer or two or more with friends, you don't want to be bothered by scientists walking around doing funny experiments," says Sinner — or at least that's what he and his colleagues expected to hear from the crowd. "But the overall response was really positive," he says.
"We provided them with the results of the breathalyzer test. That's something they were really interested in," he says. The team excluded people who were severely intoxicated, since such individuals could not reliably give consent to participate in the study.
Over the course of the 16-day festival, the researchers collected data on blood alcohol concentration and heart rate for 3,028 people, using smartphone-based breathalyzer and ECG instruments. The average age was about 35 years old. The average blood alcohol content was 0.85 g/kg, which is approximately equal to a BAC of 0.09 percent using the U.S. blood alcohol measurement system.
To put it in perspective, according to the U.S. Center for Disease Control, a 160-pound man drinking one serving of alcohol an hour would need to imbibe about four or five drinks to reach that BAC level. A BAC of 0.08 percent is the cutoff for drunk driving in the U.S.
They found what they describe in the study as "a profound association of acute alcohol consumption with sinus tachycardia," which Sinner describes as "increased heart rate with no justification." They also found that, while the heart rate generally varies as a person's breathing rate changes, that ability decreased as people drank more.
In fact, the more alcohol people had consumed, the more likely they were to experience both symptoms, the data showed. The study was published in the European Heart Journal.
Sinner says these same symptoms are often experienced by people who have had a heart attack in the past, or who have congestive heart failure, although there is no evidence that the participants in this study had any lasting heart damage from their visits to Oktoberfest.
But, he says, more work needs to be done on the connection between alcohol and the symptoms. And the smartphone ECG only produced 30 seconds of heart data for each participant.
"We don't know what happens to them 2 hours or 12 hours later," Sinner says. In a follow-up study, his team is planning to use ECG monitors that attach to the chest for three days.
The upshot, he says, is that it's never a good idea to drink alcohol to excess. People who consume large amounts of alcohol can also damage their livers and brains.
"Frankly, I do drink alcohol and I like it," he says, "but you need to put a limit on it. The more you drink, the more prominent the findings are. So it's probably not a problem if you go drink a beer or two. But if you exaggerate it, it's certainly not healthy anymore."
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