MONDAY, Nov. 15, 2010 (HealthDay News) -- Omega-3 fatty acid supplements don't cut back on recurrences of atrial fibrillation, a type of irregular heartbeat that can cause stroke, new research suggests.
"We now have definitive data that they don't work for most patients with AF [atrial fibrillation]," said Dr. Peter R. Kowey, lead author of a study appearing in the Dec. 1 issue of the Journal of the American Medical Association that is also scheduled to be presented Monday at the American Heart Association's annual meeting in Chicago. "Although we can't exclude the possibility of efficacy in sicker AF patients, it would be hard to believe that it would work in that population and not in healthier patients. So for practical purposes, yes, [this is] the end of the line in AF."
This study, the largest of its kind, looked at patients with AF who were otherwise healthy.
"We cannot say there is any convincing evidence of a role for omega-3 in the prevention of atrial fibrillation," added Dr. Ranjit Suri, director of the Electrophysiology Service and Cardiac Arrhythmia Center at Lenox Hill Hospital in New York City, who was not involved with the trial.
The study was funded by GlaxoSmithKline.
Omega-3 fatty acids, which are found in fatty fish such as salmon and albacore tuna, had showed some promise in preventing heart disease in earlier trials.
Of the total 663 outpatient participants, 542 had paroxysmal atrial fibrillation, which appears suddenly and resolves on its own, and 121 had persistent atrial fibrillation, which needs treatment.
Participants were randomized to receive either a placebo or 8 grams of omega-3 supplements daily for the first week, followed by 4 grams a day for the remaining 23 weeks of the trial.
The doses used in the study are available only by prescription and are "higher than doses previously published in studies," said Dr. Robert Block, a cardiologist and assistant professor of community and preventive medicine at the University of Rochester Medical Center.
At the end of six months, 46 percent of those in the placebo group and 52 percent of those taking omega-3 supplements experienced recurrences.
The numbers of paroxysmal AF patients in the placebo and treatment groups who had AF recurrences were about equal (48 percent and 52 percent, respectively), the investigators found.
In patients with persistent AF, more patients in the omega-3 arm had recurrences than in the placebo group (50 percent and 33 percent, respectively).
But experts haven't ruled out a possible role for omega-3 in other types of patients, such as those with heart failure.
"Our data do not speak to other cardiac indications," said Kowey, who is president of the Main Line Health Heart Center and a professor of medicine and clinical pharmacology at Jefferson Medical College in Philadelphia. "There has been conflicting data there as well and a clear need for definitive studies like ours in those indications."
"Omega-3 may be helpful in patients with high triglycerides and bad overall cholesterol profiles or people prone to electric storms in the heart who are at risk of sudden death," said Suri.
Block recommends that patients with cardiovascular disease eat two servings of oily fish weekly, or three over-the-counter omega-3 capsules a day.
In those with no cardiovascular disease, "there is no practical definitive benefit," but they still might also want to eat fish regularly, he said.
The Heart Rhythm Society has more on atrial fibrillation.