Alcohol’s Harms Last Beyond Active Binge Drinking: MunichBREW II

Binge drinking seems to increase heart rates and arrhythmias, not only while alcohol is consumed but also during the days that follow, according to data from the MunichBREW II study.

Researchers say these results are a reminder that the so-called Holiday Heart Syndrome, where seasonal festivities inspire people to drink more than usual at the risk of facing potential cardiovascular consequences, is a real phenomenon. While debates continue over whether moderate alcohol consumption can promote cardiovascular health—with most reports leaning towards no benefit—binge drinking is consistently linked to harm, not health.

The new study, published in the December 7, 2024, issue of the European Heart Journal, follows the original MunichBREW, which drew attention to the acute impact of alcohol on the heart among Oktoberfest revelers. This time around, said senior author Moritz F. Sinner, MD (LMU University Hospital, Munich, Germany), investigators looked at what happened over a longer time span after a night of drinking, and did so in more-controlled conditions.

“This is valuable information that gives us much more insight into how the time-varying effects of alcohol come into play,” Sinner told TCTMD, noting that there was no clear cutoff for how much alcohol led to harm. “The more you drink, the larger the effect becomes.”

Notably, there also was lower heart rate variability with binge drinking. However, “what really surprised us was the large number of patients”—one in 20 participants—“who actually developed arrhythmias” considered clinically relevant despite their young age and lack of history with the condition, he said.

Jamal Rana, MD, PhD (The Permanente Medical Group, Oakland, CA), commenting on the new paper for TCTMD, praised how comprehensively MunichBREW II investigators gathered breath alcohol concentration (BAC) levels and ECG readings, for up to 8 hours and through 48 hours, respectively.

“It was a very well-done study,” said Rana, who pointed out that many of these arrhythmias happened after—not during—the heavy drinking. “During this season, we should be counseling our patients to be careful about this. It may not happen while you’re having all these drinks. But in fact you have to be vigilant in the 6 to 19 hours [after].”

Warning signs that merit quick medical attention include palpitations that persist during rest and a feeling of being lightheaded, Rana advised.

Based on this and other studies, awareness of alcohol’s cardiovascular risks is growing, he said. “This notion that alcohol is somehow good for the heart is going away.”

Risky Recovery Period

For MunichBREW II, lead author Stefan Brunner, MD (LMU University Hospital), and colleagues enrolled 202 volunteers who were planning to consume enough alcohol that their peak BAC would reach ≥ 1.2 g/kg. Alcohol levels were quantified by BAC in the time when participants were drinking. Electrocardiogram monitoring was done for 48 hours from baseline (hour 0) through a drinking period (hours 1-5), recovery period (hours 6-19), as well as during two control periods corresponding to 24 hours after drinking and recovery.

The final analysis included 193 people (mean age 30 years; 36% women) with sufficient ECG data. None had a history of cardiac arrhythmias. On average, they reported consuming 6.8 standard drinks per week, with a median amount of alcohol per day of 22.9 g. Within the past 6 months, their median number of binge-drinking sessions was five.

During the acute drinking period, participants consumed various combinations of beer, wine, liquor, and long drinks. BAC showed a continuous, near-linear increase that reached an average maximum of 1.4 ± 0.4 g/kg, with no difference between men and women.

As participants consumed higher amounts of alcohol, they developed faster heart rates. The average beats per minute rose from 89.5 ± 12.6 bpm at baseline to a maximum of 97.0 ± 16.2 bpm after 4 hours of drinking. “During the subsequent night of recovery, heart rate is lower, but relatively elevated compared to the second night after alcohol consumption,” the paper notes.

The excess of atrial tachycardia beats also was highest while participants were drinking, then followed a similar trajectory to heart rate over the 2 nights of recovery. Heart rate variability was depressed during both drinking and recovery periods.

In all, 10 participants (5.2%) had clinically relevant arrhythmia; these included atrial fibrillation and ventricular tachycardias, and they primarily happened during the recovery period.

There were no differences based on sex or height. Patients accustomed to regularly consuming high amounts of alcohol tended to have higher heart rates and more atrial tachycardia, as well as less heart rate variability, compared with those who tended to drink less.

Their study, while it can’t prove causation, offers “supporting evidence that alcohol causes arrhythmias, and that is something we should follow up on” in future research to better understand mechanism and risk factors, said Sinner.

The MunichBREW II population was relatively young, stressed Rana. “The impact could be much higher for older patients and especially patients with known heart disease. It could be amplified.”