Consuming high-doses of fish oil is an unsuccessful means of reducing atrial fibrillation (AFib) in patients with a history of AFib not receiving conventional antiarrhythmic therapy, according to results of the AFFORD trial published Sept. 29 in the Journal of the American College of Cardiology.

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The trial was a double-blind, randomized, placebo-controlled, parallel-arm study, led by principal investigator Anil Nigam, MD, Department of Medicine, Montreal Heart Institute, Université de Montréal, Montreal Heart Institute Research Center, Montreal, Quebec, Canada, who sought to evaluate the influence of high-dose fish oil on AFib recurrence, inflammation and oxidative stress parameters. Drawing from 337 patients with symptomatic paroxysmal or persistent AFib within six months of enrollment, Nigam et al. randomized their subjects to fish oil (4 g per day) or placebo and were then followed on average for 271 ± 129 days.

With a primary endpoint of the first symptomatic or asymptomatic AFib recurrence lasting ≥30 seconds, results showed the event occurred in 64.1 percent of patients in the fish oil arm and 63.2 percent of patients in the placebo arm (hazard ratio: 1.10; 95 percent confidence interval: 0.84 to 1.45; p=0.48). Further, high-sensitivity C-reactive protein and myeloperoxidase were within normal limits at baseline and decreased to a similar degree at six months.

The authors conclude that “the lack of a beneficial effect of fish oil on AFib recurrence in [this study] may be at least partially due to its lack of effect on these pathophysiological processes, which have been implicated in AFib development and progression.” They add that their results “provide conclusive evidence that fish oil has no role in the rhythm-control management of patients with paroxysmal or persistent AFib.”

“Clearly, [this] data, in combination with data from previous randomized trials, do not support the practice of using n-3 polyunsaturated fatty acids as a substitute for antiarrhythmic drugs to prevent recurrent AFib events,” writes Christine Albert, MD, MPH, Center for Arrhythmia Prevention, Brigham and Women’s Hospital. “However, given the potential pleiotropic actions of n-3 polyunsaturated fatty acids, it is quite plausible that these agents might be more effective at preventing, rather than reversing, the development of the atrial substrate associated with AFib and/or that longer term therapy may be required to have a significant impact on atrial remodeling in patients with established AFib.”

“Clearly, [this] data, in combination with data from previous randomized trials, do not support the practice of using n-3 polyunsaturated fatty acids as a substitute for antiarrhythmic drugs to prevent recurrent AFib events,” writes Christine Albert, MD, MPH, Center for Arrhythmia Prevention, Brigham and Women’s Hospital in an editorial comment.  “However, given the potential pleiotropic actions of n-3 polyunsaturated fatty acids, it is quite plausible that these agents might be more effective at preventing, rather than reversing, the development of the atrial substrate associated with AFib and/or that longer term therapy may be required to have a significant impact on atrial remodeling in patients with established AFib.”

Keywords: Inflammation, Anti-Arrhythmia Agents, C-Reactive Protein, Fish Oils, Fatty Acids, Omega-3, Peroxidase, Atrial Remodeling, Oxidative Stress, Atrial Fibrillation, Arrhythmias, Cardiac

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