Daily Alcohol Consumption May Affect Heart Health

15 Sep 2016 --- New research suggests that long-term alcohol consumption, even as little as one drink a day, could enlarge the heart’s left upper chamber (atrial) and increase the risk of developing atrial fibrillation. The study disputes the common perception that moderate alcohol intake is good for the heart.

The research was published in the Open Access Journal of the American Heart Association/American Stroke Association and the Journal of the American Heart Association.

“Our study provides the first human evidence of why daily, long-term alcohol consumption may lead to the development of this very common heart rhythm disturbance,” said Gregory Marcus, M.D., senior study author and associate professor of medicine specializing in cardiac electrophysiology at the University of California at San Francisco.

“We were somewhat surprised that a relatively small amount of alcohol was associated with a larger left atrium and subsequent atrial fibrillation.”

"The primary purpose of this study was to try and identify a mechanism that might explain the observed relationship between alcohol consumption and atrial fibrillation. We found evidence that a substantial proportion of this relationship appears to be explained by enlargement of the left atrium."

Atrial fibrillation is a common condition in which the heart beats irregularly and fails to properly pump blood, increasing the risk for stroke and blood clots. Previous research has shown associations between drinking alcohol and ventricular cardiomyopathy, a condition where the heart has trouble pumping and delivering blood to the rest of the body.

Researchers analyzed data on 5,220 participants, 54 percent of who were women of an average age 56. They each underwent electrocardiograms (EKG) to measure electrical activity of the heart.

The results showed that of 17,659 EKG scans taken over six years, 1,088 incidences of atrial fibrillation were detected. Chronic alcohol consumption was also associated with higher risk for incident atrial fibrillation.

One alcoholic drink a day, roughly 10 grams, was associated with a 5 percent higher risk of developing new-onset atrial fibrillation, while two drinks a day, 10 grams of alcohol, was linked to a 0.16 millimeter larger left atrium.

Approximately 24 percent, and up to 75 percent, of the relationship between regular alcohol consumption and atrial fibrillation risk could be traced back to enlargement of the left atria.

The relationship between atrial fibrillation and alcohol consumption remained even after considering other heart health risk factors, such as high blood pressure, diabetes, or smoking.

Researchers stated that the observational findings do not suggest that drinking alcohol directly causes heart problems. However, the results question the popular consumer belief that moderate alcohol intake benefits the heart.

Marcus explained, “"In our statistical analysis we found that, on average, about one drink a day was associated with a small but statistically significant increased left atrial size and increased risk of atrial fibrillation. However, it is very likely that the risk of atrial fibrillation in the setting of alcohol is quite variable across various individuals."

How regular alcohol consumption influences the size of the left atria or the heart’s electrical activity is unclear and warrants further investigation.

“Our hope,” Marcus said, “is that by understanding the mechanistic relationship between alcohol and atrial fibrillation we might learn something inherent to atrial fibrillation in general that could help identify new ways of understanding and treating the disease.”

The team will continue research into the area. Marcus added, "We have several ongoing studies examining the fundamental mechanisms involved, including animal studies to understanding the molecular underpinnings of these observations and a randomized trial in humans examining how the electrical properties of the heart change in the presence versus absence of alcohol."