"Why Oktoberfest could be damaging your heart" is the somewhat strange headline in The Times.
Researchers who attended the annual Bavarian beer and folk festival found binge drinkers were more likely to have abnormal heart rhythm patterns.
This could be of potential concern - in extreme cases, abnormal heart rhythms (arrhythmias) can trigger serious complications, such as stroke. No complications of this type were found in the study.
Researchers included more than 3,000 people who attended Oktoberfest in Germany and used a smartphone app to take recordings of the heart, while a breathalyser was used to measure alcohol levels.
The findings were compared with those of another study involving more than 4,000 people believed to represent the general public.
A novel feature of this approach is it provided "real-time" measurements of alcohol consumption, rather than relying on people recalling how much alcohol they'd drunk, which is often unreliable.
The researchers found binge drinking was linked with an increased risk of having an irregular heartbeat, but this was mainly a type called sinus tachycardia. This is not life threatening, but involves the heart beating at an abnormally fast rate of over 100 beats a minute, which can be very unpleasant.
While these findings do not prove there's a significant link between alcohol and dangerous heart problems, less serious irregularities were found. It's unclear whether this would cause problems further down the line.
To reduce health risks associated with drinking alcohol, government guidelines advise having no more than 14 units a week and spreading your drinking over three or more days if you regularly drink as much as 14 units a week.
Where did the story come from?
The study was carried out by researchers from University Hospital Munich and the German Cardiovascular Research Centre.
Funding was provided by University Hospital Munich and the European Commission's Horizon 2020 research and innovation programme.
The researchers also used data from the KORA study, which was funded by the Helmholtz Zentrum München, the German Research Centre for Environmental Health, the German Federal Ministry of Education and Research, and the State of Bavaria.
The study was published in the peer-reviewed European Heart Journal.
Generally, the UK media's reporting of the study was accurate. BBC News helpfully explained: "These odds are very low, which meant there was no significant link between alcohol and dangerous heart arrhythmias in the study. But there was a significant link between alcohol consumption and more benign arrhythmias."
What kind of research was this?
This cross-sectional study aimed to investigate the link between alcohol and having an irregular heart rhythm.
Volunteers at Oktoberfest (who were expected to binge drink to some extent) had their heart rate and rhythm recorded using a smartphone-based electrocardiogram (ECG). The amount of alcohol in their system was measured using a breathalyser.
The researchers contrasted these findings with findings from another study involving people from the general population taking part in a community-based study about long-term diseases.
They also had an ECG, but their alcohol levels were assessed using a questionnaire asking how much they had drunk over the past week.
Acute excessive alcohol consumption, or binge drinking, has been associated with so-called "holiday heart syndrome", which causes irregularities in the heart rhythm in people without any history of cardiac issues.
The researchers thought an increase in breath alcohol concentration would be associated with a higher level of irregular heart rhythms (arrhythmias), and wanted to compare this with day-to-day alcohol intake.
As this was a cross-sectional study where the measurements were only taken at one point in time, this type of study isn't able to prove that alcohol intake causes abnormal heart rhythms.
What did the research involve?
Adults visiting Oktoberfest in Munich between September and October 2015 volunteered to take part in the study as part of the acute alcohol group (people likely to drink a lot in a short space of time).
Participants of the community-based KORA study, Co-operative Health Research in the Region of Augsburg, were also recruited to represent the chronic alcohol group (people likely to drink at an "everyday" level).
Electrocardiogram (ECG) recordings lasting 30 seconds were taken from the acute alcohol group using a smartphone-based AliveCor device.
The device wirelessly communicates with a software application, and was held in both hands by the participant. The KORA group had a 10-second digital ECG.
Two cardiologists, who were unaware which group the participants were in, analysed the ECG recordings to identify and classify the arrhythmias.
To assess alcohol consumption, a handheld device called Alcotest 7510 was used in the acute alcohol group - this accounts for any remaining alcohol in the mouth. The KORA group was assessed using a validated seven-day recall method.
Details of other possible confounding factors were collected:
Acute group (self-reported)
- country of origin
- history of heart disease
- use of cardiovascular and anti-arrhythmic drugs
- active smoking status
KORA (standardised interview)
- history of heart disease
- smoking status
- use of cardiovascular and anti-arrhythmic drugs
What were the basic results?
There were 3,028 volunteers in the acute alcohol cohort, with an average age of 34.4 (29% female).
The findings for this group were as follows:
- average breath alcohol level was 0.85g per kg, considered to be a moderate intake - 3g per kg is considered "disabled due to intoxication" under German law
- heart arrhythmias occurred in 30.5% of the group - sinus tachycardia, where the heart beats at over 100 beats per minute, occurred in 25.9%; other arrhythmias were present in 5.4% of the group
- breath alcohol concentration was significantly associated with heart arrhythmias overall, with a 75% increase in the chance of having a heart arrhythmia for each additional 1g per kg of breath alcohol (odds ratio [OR] per unit change 1.75, 95% confidence interval [CI] 1.50 to 2.05)
- each increase in breath alcohol of 1g per kg doubled the risk of sinus tachycardia (OR 1.96, 95%CI 1.66 to 2.31)
There were 4,131 people in the KORA group, with an average age of 49.1 (51% female). The findings were:
- average alcohol consumption was 15.8g per day, equivalent to about 2 units
- each additional 1g per kg consumed was associated with increased risk of sinus tachycardia - but this increase was quite small (OR 1.03, 95%CI 1.01 to 1.05)
How did the researchers interpret the results?
The researchers concluded that acute alcohol consumption is associated with heart arrhythmias and sinus tachycardia in particular.
They say this may lead to more serious heart rhythms problems, such as atrial fibrillation, though this was only present in less than 1% of each group.
The researchers also didn't follow the people over time to see who developed more serious arrhythmias that could lead to further complications.
This cross-sectional study found binge drinking is associated with an increased risk of having an irregular heartbeat.
However, the type of irregular heartbeat found was mainly sinus tachycardia, which isn't life threatening but involves the heart beating at an abnormally fast rate of over 100 heartbeats a minute.
This research also has some notable limitations:
- The ECG recordings from the acute alcohol group were taken using a smartphone application operated outside the manufacturer's recommended environment. The lively atmosphere within the beer tent may have caused inaccurate recordings.
- The population recruited from Oktoberfest was varied in ethnic origin and only 69% were from Germany - it may not be appropriate to compare them with the KORA community population, where more than 99.5% were of German descent.
- The volunteers in the acute alcohol group were self-selected and might not be representative of the average binge drinker in terms of potential confounding factors like health background. They also provided details of their age, sex, heart disease history and use of heart medications, which may not be accurate because of recall bias and alcohol consumption.
- But the main limitation is the study design - cross-sectional studies cannot prove cause and effect.
These findings do not prove there is a significant link between alcohol and dangerous heart arrhythmias, but the researchers did find less serious heart irregularities.
To reduce the risk of any health risks associated with drinking alcohol:
- drink no more than 14 units a week on a regular basis
- spread drinking over at least three days a week if you regularly drink 14 units a week
Better still, cut down and aim to have several alcohol-free days a week.
"Why Oktoberfest could be damaging your heart" is the somewhat strange headline in The Times. Researchers who attended the annual Bavarian beer and folk festival found binge drinkers were more likely to have abnormal heart rhythm patterns.
Links to Headlines
Why Oktoberfest could be damaging your heart. The Times, April 26 2017 (subscription required)
Alcohol binge can upset heart's rhythm, say researchers. BBC News, April 26 2017
Links to Science
Brunner S, Herbel R, Drobesch C, et al. Alcohol consumption, sinus tachycardia, and cardiac arrhythmias at the Munich Octoberfest: results from the Munich Beer Related Electrocardiogram Workup Study (MunichBREW). European Heart Journal. Published online April 25 2017