TORONTO — Patients with cardiovascular disease on an oral regimen of omega-3 fatty acid had a 73% reduced risk for developing atrial fibrillation in a retrospective, observational study of more than 11,000 patients.
Although the study controlled for identified confounding factors, it cannot be considered definitive because it involved an uncontrolled, retrospective study, Brian J. Barnes, Pharm.D., and his associates reported in a poster at the 14th World Congress on Heart Disease.
In addition, the analysis did not include information on the dosages of omega-3 fatty acids taken or the duration of treatment. “The optimal dose of omega-3 fatty acid to prevent atrial fibrillation is unknown,” Dr. Barnes and his associates said in their poster. The new finding warrants a prospective study to better document the impact of omega-3 fatty acid on the incidence of new-onset atrial fibrillation, they said.
The study included 11,360 patients with cardiovascular disease who were seen in the cardiology service during 2005–2007 at the University of Kansas Medical Center, Kansas City. The review excluded patients who had atrial fibrillation before starting treatment with omega-3 fatty acid, as well as patients with incomplete echocardiography data.
The study group included 8,760 patients with no omega-3 fatty acid exposure (77%), and 2,600 with exposure (23%). The patients who received omega-3 fatty acid were older (average age 66 years) than those with no exposure (average age 63 years), and also sicker, with a higher prevalence of coronary disease (57%, compared with 29%), and diabetes (23%, compared with 19%), and higher rates of using other cardiovascular drugs such as statins, aspirin, and ACE inhibitors. But an enlarged left atrium (more than 4 cm) was more common among the patients not on omega-3 fatty acid (75%) than in the patients taking omega-3 fatty acid (61%).
During follow-up, the rate of new atrial fibrillation was 23% among patients not taking an omega-3 fatty acid, and 9% among those on an omega-3 fatty acid, said Dr. Barnes, a researcher in the department of pharmacy practice.
In a multivariate model that included all of the known differences between the two groups at baseline, omega-3 fatty acid use was linked with a statistically significant, 73% reduction in the rate of new atrial fibrillation, said the researchers at the congress, which was sponsored by the International Academy of Cardiology. Other variables linked with a reduced risk for atrial fibrillation were statin use (linked with a 24% risk reduction), and a history of diabetes (linked with a 15% risk reduction). Variables linked with an increased risk for atrial fibrillation included age of 60 years or older, which boosted the risk about 3.4-fold, compared with patients aged 30–45 years; valvular disease, which raised the risk by 75%; an enlarged left atrium, which raised the risk by 33%; and male gender, which raised the risk by 17%.
Possible mechanisms by which treatment with omega-3 fatty acid might cut the risk for atrial fibrillation include anti-inflammatory and anti-arrhythmic effects.