As we approach the eve of the New Year, the skeptical cardiologist recognizes that many of you will be consuming vast quantities of alcohol tomorrow night.
Whether this is done in celebration or in hopes of transiently forgetting pandemical stressors please be aware that as the fermented beverage of your choice begins to cloud your consciousness it may also be triggering irregularities of your heart rhythm.
We have known for some time that higher levels of chronic alcohol consumption are associated with a higher chronic risk of atrial fibrillation (AF) based on evidence from both clinical anecdotes (wherein patients clearly note AF beginning after drinking) and from large observational studies.
In addition, the Alcohol-AF study published in 2020 showed that abstinence reduced AF recurrence in patients after cardioversion.
The Alcohol-AF trial gave me precise numbers to present to my AF patients to show them how important eliminating alcohol consumption is if they want to have fewer AF episodes. The study further emphasized how lifestyle changes (including weight loss, exercise, and stress reduction) can dramatically reduce the incidence of atrial fibrillation.
In 2021 I felt several studies substantially improved our understanding of the link between AF and alcohol.
The J-shaped Curve and Beer versus Wine/Spirits
The first study looked at the association of total and beverage-specific alcohol consumption with the occurrence of atrial fibrillation in >400,000 participants in the UK Biobank database over an 11 year period.
A J-shaped association of AF and total alcohol consumption was observed, with the lowest risk of AF associated with consuming fewer than 7 drinks/week.
Beverage-specific analyses demonstrated harmful associations of beer/cider consumption with risk of atrial fibrillation at any level of drinks per week greater than zero
In contrast, consumption of red wine, white wine, and spirits at low levels (up to 10, 8, and 3 drinks/week, respectively) was not associated with increased risk.
The authors concluded that in a predominantly white population, “low levels of alcohol consumption (<7 U.K. standard drinks [56 g alcohol]/week) were associated with lowest AF risk. Low consumption of red and white wine and very low consumption of spirits may not be associated with increased AF risk, whereas any consumption of beer/cider may be associated with harm”
Although statistically well done, this study comes with all the known limitations of an observational study. Beer drinkers, in my experience, are a lot different from red wine drinkers in many ways, many of which are not measurable. These confounding variables associated with the choice of alcohol type may account for the different associations between certain beverages and AF risk.
How Much Alcohol Am I Drinking?
To make sense of these alcohol/AF studies and apply them to your patient or your own consumption you must be able to calculate the grams of alcohol consumed.
The above study used the UK definition of a standard drink, 8 grams, but in the US the standard drink is defined as 14 grams of alcohol. The risk of AF is lower until 7 UK drinks per week at which point it goes up and at around 14 UK drinks per week (which is 112 grams per week or 112/7 = 16grams per day).
To calculate your grams of alcohol consumption you must know the volume in ml. and the alcohol content. If you are drinking at home it is easy to get this data and plug it into a calculator to determine how many grams of alcohol have entered your body.
The NIAA simplifies things for you if you consume “standard” drinks:
In the United States, one “standard” drink (or one alcoholic drink equivalent) contains roughly 14 grams of pure alcohol, which is found in: 12 ounces of regular beer, which is usually about 5% alcohol. 5 ounces of wine, which is typically about 12% alcohol. 1.5 ounces of distilled spirits, which is about 40% alcohol.
Most Americans, however, are not consuming the “standard” drink and a substantial amount of their alcohol consumption (albeit less than pre-pandemic times) occurs in bars and restaurants rather than at home.
Whereas the volume of a wine pour and wine percent alcohol is more or less constant, the other two drink varieties can vary substantially due to the explosion of craft beer and craft cocktails.
For example, my brother-in-law gifted me a 4-pack of an excellent local craft beer (Tropical Lightning, Wilmington Brewing Company) which comes in 16 ounces cans and has an alcohol content of 7.4%.
When I plugged these numbers into Eric Roehm’s online calculator I better understood why I get such a great buzz while drinking it:
When I consume a can of Tropical Lightning, I am consuming 22.4 grams of alcohol, equivalent to almost 3 UK standard drinks and to 1.6 US standard drinks. This is not the beer my father drank or the Coors I drank in college.
Real Time Data Proves Acute Alcohol intake Triggers AF
The second important AF study of 2021 was published in November in the Annals of Internal Medicine and documented systematically something that many patients have reported to me: alcohol is an acute trigger of AF episodes.
Greg Marcus and colleagues designed a fascinating study that determined participants’ alcohol consumption in real-time by having them press a button on their ECG monitor every time they had a standard alcoholic drink, and by having them wear a transdermal alcohol sensor. r.
Participants were fitted with a continuous electrocardiogram (ECG) monitor and an ankle-worn transdermal ethanol sensor for 4 weeks. Real-time documentation of each alcoholic drink consumed was self-recorded using a button on the ECG recording device. Fingerstick blood tests for phosphatidylethanol (PEth) were used to corroborate ascertainments of drinking events.
Of 100 participants, 56 had at least 1 AF episode. An AF episode was twice as likely with 1 alcoholic drink in the preceding 4 hours and 3.5 times as likely with 2 drinks in the preceding 4 hours. The AF episodes were associated with higher peak alcohol levels in the preceding 12 hours.
Thus alcohol consumption and increasing alcohol concentration are indeed associated with a higher risk of a discrete AF event happening just a few hours later.
Marcus, also published earlier this year, a study showing that acute alcohol can change pulmonary vein refractory periods. Given that AF likely originates from the pulmonary veins this provides a mechanism for alcohol to trigger AF events.
Adding these observations to what I knew previously I think these suggestions for advice to patients from a recent editorial are reasonable:
For secondary AF prevention, the message should be alcohol abstinence, especially if alcohol is a personal trigger for acute AF episodes. For primary AF prevention, it is possible that continued consumption of some alcohol may be reasonable, but the exact threshold is unclear and is likely a very low amount
If you have AF and want to minimize your AF episodes don’t drink alcohol. If you don’t have AF try to stay in the “low-risk consumption” category as defined by the NIAAA: