Study Finds Drinking Alcohol Associated With Heart-Rhythm Disorder
Using long-term hospital-admissions data from Texas, researchers found a link between drinking alcohol and atrial fibrillation
By Ron Winslow
June 20, 2016
A study comparing hospital admissions in “wet” versus “dry” counties in Texas offers a surprising new perspective on how alcohol consumption may affect the health of your heart.
The analysis found that people living in dry counties, where sales of alcoholic beverages are prohibited, had a higher risk of being hospitalized for a heart attack or congestive heart failure than people living in wet counties, where such sales are allowed. But residents of wet counties were at elevated risk for a heart rhythm disorder called atrial fibrillation.
The report, published last week in the British Medical Journal, or BMJ, is the latest to address a long-running controversy in heart-disease prevention: Does alcohol contribute to, or protect against, heart disease?
Researchers took advantage of the legacy of Prohibition-era laws in Texas to compare heart-related illnesses where access to alcohol had been curbed for decades with illnesses where alcoholic beverages have been commonly available.
The upshot: “It’s not so simple that alcohol is good for you or alcohol is bad for you,” says Gregory Marcus, associate professor of medicine at University of California, San Francisco and senior author of the study. “Rather it depends on the individual.”
Chronic heaving drinking is strongly associated with a host of medical conditions, including alcoholic liver disease, cognitive decline and heart-related problems, such as high blood pressure and alcoholic cardiomyopathy, a precursor to heart failure.
Studies also link excessive drinking or occasional binge drinking to an increased risk of atrial fibrillation, a quivering of the heart that can cause blood to pool in its upper chambers, increasing risk of stroke.
“It’s very clear that dumping a whole lot of alcohol on the heart can lead to rhythm disturbances like afib,” says Kenneth Mukamal, associate professor of medicine at Harvard-affiliated Beth Israel Deaconess Medical Center, Boston.
But a significant body of research suggests that when it comes to heart attacks, people who drink moderately-generally, up to a drink a day for women and two drinks for men-are at lower risk than even people who refrain from drinking.
That’s a popular finding among people concerned with heart risk. “Patients will ask me, ‘Is it ok to drink alcohol?’ ” Dr. Marcus says. ” ‘Isn’t it a good idea to have a little red wine for your heart?’ “
Dr. Marcus, who treats patients with atrial fibrillation, adds, “It’s always hard for me to answer that question.” The effect of moderate drinking on afib isn’t clear.
In fact, most research on the risks and benefits of moderate drinking suffers from a lack of randomized trials. Studies are generally based on patients’ own reporting of how much alcohol they consume, which isn’t always reliable. And the studies have produced conflicting results. Observational studies can reveal an association, but they don’t prove a cause and effect.
The new study, funded by the National Institute on Alcohol Abuse and Alcoholism, is also observational and has other limitations. But among other things, it takes questionable patient reporting out of the picture. Jonathan Dukes, a cardiology fellow at UCSF, is lead author of the study.
“We saw this as an opportunity to approach the question in a completely different way,” Dr. Marcus says. It also was a chance to study the issue in a huge number of people.
For the study, Dr. Marcus and his colleagues analyzed records from a state database of all patients in Texas over 21 years old who were admitted to a hospital between Jan 1, 2005, and Dec. 31, 2009.
During that period, 47 of the state’s 254 counties were wet, 29 were dry, and seven switched from dry to wet. Alcohol sales in the remaining counties were only partially restricted, and researchers excluded those patients.
The analysis included just over 1 million people with at least one hospital admission from wet counties and about 60,000 from dry counties. In the counties that switched, the analysis covers about 43,000 hospitalized patients before the conversion and a similar number after.
The hospital records showed significantly higher misuse of alcohol and cases of alcoholic liver disease in the wet counties-a finding researchers said validated the premise that even though residents of dry counties could obtain alcohol elsewhere, consumption was much lower there.
Differences in heart-related effects between wet and dry counties were modest. Prevalence of atrial fibrillation was about 5% higher in wet counties, while prevalence of heart attacks was 17% lower. New hospitalizations for afib during the study were 7% higher in wet counties while those for heart attack were 9% lower.
In counties that switched from dry to wet during the study period, the risk of new cases of atrial fibrillation was also 7% higher, the researchers found, while heart-attack admissions were similar before and after the change. That a higher risk of afib was found in both the longtime and recently-converted wet counties “was the most consistent and we think most robust finding” in the study, Dr. Marcus says.
But the study didn’t connect individuals’ drinking amounts to risk of afib or other outcomes. So it doesn’t offer insight into what level of alcohol consumption may confer benefits and where harm might begin.
Beth Israel’s Dr. Mukamal, co-author of an editorial accompanying the study, said the findings generally make him “feel a little better” that research indicating moderate drinking reduces his risk of a heart attack is true. But the study “doesn’t get us all that much closer to the individual’s decision” in weighing whether moderate drinking is good or bad for the heart. Dr. Mukamal called for a randomized trial of alcohol consumption to address the question.
More broadly, the findings suggest that communities that ease restrictions on alcohol sales can expect more alcohol-related illness, more cases of atrial fibrillation and fewer heart attacks.
Dr. Marcus thinks it will require connecting a person’s genetic profile with patterns of behavior and exposure to alcohol “to understand what an individual person’s risk looks like.”
Meantime, he has several studies under way to better determine the relationship between alcohol and afib. In one randomized trial, he is using instruments threaded into the interior of the heart to monitor alcohol’s impact on the electrical functioning of the heart.
In another, patients known to have intermittent afib are fitted with an adhesive heart monitor on their chest, and wrist and ankle devices that objectively record alcohol consumption by measuring alcohol in perspiration. The hope is that learning more about the timing between a drink and an afib episode will shed light on mechanisms of afib that could lead to new treatments or ways to manage risk.