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Varying effects of fish consumption on atrial fibrillation

May 18, 2006

BOSTON-Eating fish rich in omega-3-fatty acids may have different effects on the heart's electrical function, according to a study presented today at HEART RHYTHM 2006, the Heart Rhythm Society's 27th Annual Scientific Sessions. Although previous studies have found that fish consumption may protect against the development of atrial fibrillation (AF), the most common type of heart rhythm abnormality, a new study found that eating fish more frequently was associated with a higher risk of developing atrial fibrillation among healthy male physicians. After adjustment for multiple risk factors for AF, lifestyle factors, and other dietary factors, men who ate fish more than five times a week were at a 61 percent increased risk of developing AF as compared to men who ate fish once a month.

The study, "Relationship Between Fish Consumption and the Development of Atrial Fibrillation in Men," analyzed data from almost 17,700 male physicians in the Physicians' Health Study. The men reported on their fish consumption in 1983; 15 years later they reported if they had been diagnosed with AF. Of these participants, 1253 (7.1 percent) developed AF at the 15-year follow up. The analysis was adjusted for multiple cardiovascular disease risk factors and lifestyle habits.

These findings are similar to those reported previously in a relatively young Danish population where the average age was 56, but stand in contrast to those from a U.S. study conducted among an older population of men and women over the age of 65. In this older population, fish consumption was associated with reduced risks of developing AF. In addition, omega-3 fatty acid supplementation reduced the risk of developing AF after cardiac surgery in a randomized clinical trial.

Dr. Aizer, attending electrophysiologist, New York University Medical Center and one of the study authors, commented, "It is important to recognize that within the same population as this current study, fish consumption was associated with lower risk of sudden cardiac death, which is the result of a much more life-threatening cardiac arrhythmia, ventricular fibrillation."

The study authors noted that previous studies suggest that omega-3 fatty acids may accentuate vagal tone. Enhanced vagal tone has been shown to protect against ventricular fibrillation and sudden cardiac death, but may promote atrial fibrillation in select individuals. Dr. Aizer said the current study's findings may be influenced by the relatively young, healthy population of physicians where vagal tone may have a more significant impact.

"The message of this study is not to stop eating fish. AF is a complex condition that requires the interaction of a number of risk factors to develop. Fish may have different effects on different people. Lifestyle and dietary habits need to be tailored on an individual basis to promote overall health. Clearly, more investigation is needed to reach a more definitive answer about the multiple effects of omega-3 fatty acid on the heart's electrical function," Dr. Aizer concluded.

GYMR