“Ours is the first study to point to a mechanism by which a lifestyle factor can sharply alter the electrical properties of the heart to increase the chance of an arrhythmia,” said study author, Dr. Gregory Marcus, associate chief from cardiology to research at the University of California, San Francisco.
The research on atrial fibrillation, published Wednesday in the Journal of the American College of Cardiology: Clinical Electrophysiology, was unique because it was a randomized, double-blind clinical study – considered the “gold standard” in research.
Marcus and his team put 100 cardiac patients diagnosed with AFib – the most common life-threatening heart rhythm disorder – under anesthesia and then injected enough drink to bring the blood alcohol level to 0.08% – one just above the legal limit in the United States.
The change they saw was surprising: alcohol seemed to immediately affect the heart’s natural recovery period in a way that could trigger an atrial fibrillation event.
“The electrical changes we observed in the pulmonary veins … would increase the chance that atrial fibrillation would occur immediately and be maintained,” said Marcus.
“It is the first human demonstration of the immediate effects of alcohol, directly on the heart,” said Dr. Marco Perez, director of the Inherited Cardiac Arrhythmia Clinic at Stanford University Medical Center, who was not involved in the research.
“This study, however, does not address the question of whether moderate alcohol consumption is ‘good or bad’ for the heart or not, particularly in the long run,” added Marcus. “It just helps us understand the possible mechanisms behind the observations that people who drink have higher rates of arrhythmias.”
A growing concern
AFib is an irregular heartbeat often described by many sufferers as a “tremor”, “vibration” or “flip-flop” of the heart in the chest.
It can cause blood clots, heart failure and other heart related complications.
“It can also increase the risk of heart attack, dementia, kidney disease. All of these things are probably long-term risks,” said Marcus.
“Age is one of the most important risk factors, so with the aging of the population, it is becoming more common,” said Marcus.
The obesity epidemic is also contributing to the growth in numbers, along with other risk factors, such as hypertension, diabetes, chronic kidney disease, smoking and, yes, alcohol consumption.
“There is a long history of evidence that alcohol can increase the risk of atrial fibrillation, unlike the findings about coronary artery disease or risk of heart attack,” said Marcus.
This, of course, goes against what we have always been told in the past – drinking in moderation can really help the heart.
“This is an extremely important distinction,” said Marcus. “Many in the lay public easily combine different forms of heart disease – assuming that when one refers to heart disease, they mean a heart attack or a blockage of the coronary arteries that supply blood to the heart.
“So it may well be the case that alcohol – at least in moderation – is healthy for some types of heart disease and harmful for other types of heart disease,” said Marcus.
- CNN Interactive: Do you drink too much?
Is alcohol really good for the heart?
Some studies, however, are beginning to question the benefits of any alcohol to the heart.
“There are studies that actually report a benefit for moderate alcohol consumption, but these are not ‘randomized and controlled’ studies and are probably confused by the fact that people who engage in moderate alcohol consumption can do other things (like exercise ) that are good for the heart, “Perez said via email.
“However, there are some genetic studies that suggest that even the modest use of alcohol has a detrimental effect on clinical outcomes,” added Perez.
According to Bell, the “take-home message” from his study is that “people should not drink under the belief that doing so will lower their risk of disease”.
“And those of us who choose to drink should minimize their intake if we are to prolong our lives and well-being,” said Bell.