When thinking about alcohol consumption over the holiday period, the results of a new study published this week may give a little reassurance on the effects of the odd festive tipple.
The large cohort study found no association of total alcohol consumption with ventricular arrhythmia, and a U-shaped association for sudden cardiac death.
While it has been well established that alcohol use is linked to atrial fibrillation, a phenomenon known as “Holiday Heart Syndrome,” the current results suggest this does not appear to extend to ventricular fibrillation.
“Based on our results, there is no clear association of alcohol use and increased risk of ventricular arrhythmia,” senior author Christopher Wong, MBBS, PhD, University of Adelaide, Australia, told theheart.org | Medscape Cardiology.
“While there is good evidence that any amount of alcohol increases the risk of atrial fibrillation, there is very little data on the relationship of alcohol with ventricular arrhythmia. We believe this is the first large study to look at the relationship between alcohol and ventricular arrhythmia,” he added.
Wong said there wasn’t a good mechanistic explanation of why there would be a difference in the effect of alcohol on atrial and ventricular arrhythmias. “It may be a balance of two completely different mechanisms, and our results should prompt further investigation into this.”
The results on alcohol and sudden cardiac death confirm previous observational studies suggesting a J- or U-shaped curve. “This leads us to believe that light drinking may lower the risk of a sudden cardiac death, but heavy drinking increases the risk,” Wong said.
“We did not see the same relationship between alcohol and ventricular arrhythmia and the relationship between alcohol and sudden cardiac death. This may be because the term ‘sudden cardiac death’ is often not an accurate assessment of the cause of death, and many of these sudden deaths may not actually have a cardiac cause. So, we may be picking up two different things here,” he explained.
The study was published online in Heart Rhythm on December 20.
For the study, the researchers used data from the UK Biobank to characterize associations of total and beverage-specific alcohol consumption reported by by more than 408,000 participants with incident ventricular arrhythmia and sudden cardiac death over a median follow-up of 11.5 years.
Alcohol consumption reported at baseline was calculated as UK standard drinks (8 g of alcohol) per week. Outcomes were assessed through hospitalization and death records. A total of 1733 incident ventricular arrhythmia events and 2044 sudden cardiac deaths occurred in the follow-up period.
Results showed that after adjustment for multiple baseline characteristics, no clear association was seen for total alcohol consumption and incident ventricular arrhythmia.
Although consumption of greater amounts of spirits was associated with increased ventricular arrhythmia risk, no other significant beverage-specific associations were observed.
For sudden cardiac death, a U-shaped association was seen for total alcohol consumption, such that consumption of less than 26 drinks per week was associated with lowest risk.
Consumption of greater amounts of beer, cider, and spirits was potentially associated with increasing risk of sudden cardiac death, whereas increasing red and white wine intake was associated with reduced risk.
Wong noted that the definition of a standard drink varies from country to country. “In this study we used the UK standard drink which contains less alcohol (8g) than the US standard drink (14g),” he reported.
“Alcohol is such a commonly used substance. It would be of great public health relevance if positive or negative effects on various disease conditions could be definitely established,” Wong commented. “Data so far suggest different effects of alcohol on different conditions. We think light drinking may reduce the risk of MI, and several other cardiovascular conditions, but we know that it increases the risk of AF.”
But he notes that the evidence is far from clear. “There is not enough good evidence to recommend that non-drinkers start drinking small amounts of alcohol for cardiovascular benefits, and it is quite clear that large amounts of alcohol are harmful.”
On what is believed to be an optimum amount to drink, Wong said: “We can’t be sure what is safe, but it is thought that one standard drink per day may be acceptable. The confidence around that estimate is not precise. Where light drinking becomes moderate drinking is not at all clear.”
An “Important Contribution”
In an accompanying editorial, Stacey J. Howell, MD, and Gregory M. Marcus, MD, from the University of California San Francisco, say, “The current study does not appear to provide compelling evidence that the Holiday Heart Syndrome extends to the ventricles.”
“I think this is an important contribution,” Marcus commented to theheart.org | Medscape Cardiology. “A large amount of research has been focused on the effect of alcohol on the upper chambers of the heart, but this is a foray into its effect on the lower chambers.”
On the apparently different results regarding ventricular arrhythmias and sudden cardiac death, Marcus agreed with Wong that this is probably explained by other conditions being included in the term sudden cardiac death.
“It is important to distinguish between a diagnosis of ventricular arrhythmia specifically versus the phenomenon of sudden cardiac death. There is likely to be an overlap between two conditions, but they don’t fully overlap,” Marcus noted. “So sudden cardiac death may not be the best way to describe these deaths. The term ‘sudden death’ may be more appropriate.”
He says the observations in this paper fit with what has already been seen on the relationship between alcohol and overall mortality, and MI ― that abstaining completely seems to give a higher risk than light to moderate drinking, but that heavy drinking increases risk.
“Taking everything together this adds more evidence to a consistent picture across the literature. While excess alcohol consumption is harmful to the heart, light to moderate alcohol consumption on a regular basis appears not to be harmful, apart from the effect on AF,” he commented.
Randomized Trial on the Horizon?
But Marcus points out that because all the data so far come from observational studies, this conclusion must still be considered hypothesis generating.
“Alcohol is the most consumed drug in the world, and we still don’t really know what the physical effects are. This paper is reassuring on light to moderate drinking, but we need more reliable evidence,” he said. “A randomized trial is needed to know for sure.”
Marcus is hoping to conduct such a trial and is currently working on a grant submission for a study that would randomize people to abstain from drinking or to regular light drinking.
“There is good evidence that people will adhere to instructions to abstain or to drink in moderation as long as the right individuals are enrolled. Some people won’t be able to abstain completely and others won’t like the idea of drinking lightly on a regular basis, but in a survey, 20 – 30% of people polled said they would be willing to be randomized to one of these strategies,” he noted.
“Effects of even one drink a day can be very far reaching. It can affect almost every organ in the body, but it may have different effects in different conditions,” Marcus says.
He points out that there is “compelling evidence” that alcohol increases AF risk. “There are two randomized studies that have shown this, and the results fit with epidemiological studies done previously.”
But other studies suggest light drinking may be beneficial on MI risk, and overall mortality. In addition, data so far suggest that light to moderate drinking increases the risk of breast cancer but reduces the risk of lymphomas and leukemia. And it increases blood pressure but may reduce diabetes, he notes.
“My suspicion is that the health effects of alcohol are complex and divergent. Our hope is that we can characterize those effects in a randomized trial so people can select their own health priorities and make individual decisions based on rigorous evidence,” Marcus adds.
This research has been conducted using the UK Biobank Resource. Wong reports that the University of Adelaide has received on his behalf lecture, travel, and/or research funding from Abbott Medical, Bayer, Boehringer Ingelheim, Medtronic, Novartis, Servier, St. Jude Medical, and Vifor Pharma. Marcus receives research funding from the National Institutes of Health, PCORI, Baylis Medical, is a consultant for Johnson and Johnson and InCarda, and holds equity in InCarda.